Date   

Re: Flywheel cap screws

Mick O'Connor
 

Ken,
Looks like ARP do not offer socket head screws, only 6 or 12 pt bolts.
I know someone who used ARP 12pt bolts for the flywheel, they onlybfitted because he had a belt driven alternator, so plenty of room for the bigger head compared to a socket head screw.
Mick 

On 20 Feb 2021, at 14:13, Ken MacLeod <kmacleod777@...> wrote:

ARP manufacture high quality bolts. They are available from several reliable sources: Jegs or Summit racing.

Ken


Sent from Rogers Yahoo Mail for iPad

On Saturday, February 20, 2021, 8:32 AM, Pete Twissell <petetwizz@...> wrote:

Indeed so Ron.
Buyer beware!

On Sat, 20 Feb 2021, 12:17 Ron Milan via groups.io, <ronmilan=verizon.net@groups.io> wrote:
Pete:  My understanding of the rational of purchasing AN fasteners in addition to an almost infinite incremental selection of grip lengths, is that the credibility of the fastener can be traced.  Quality assured ???  Although one would want to believe that branded fasteners Unbrako, rather  "uMbrako" as you refer to---, SHOULD be a consistent high quality fastener.  After all, many folks rely on said fasteners to protect their life and limb.

Integrity cannot be substituted and is not always universal in our word today!.

Ron M

-----Original Message-----
From: Pete Twissell <petetwizz@...>
To: main@jabcamit.groups.io
Sent: Sat, Feb 20, 2021 6:52 am
Subject: Re: [JabCamit] Flywheel cap screws

It is worth noting that the strengths indicated by bolt grades are minimums, and that there are a lot of very dodgy manufacturers who will mark bolts as whatever they want to sell, regardless of properties.
At work, we once bought a batch of "Unbrako" bolts. After some failures and an investigation, it turned out they were marked "uMbrako" (my capitalisation) and they were fakes.


On Sat, 20 Feb 2021, 11:46 Mark Dunstone, <mark.dunstone@...> wrote:
Yes, to all that.  My experience with propellor bolt breakage:   I had 8.8 MPa ‘high tensile bolts’, and perhaps they were, but they were also very brittle.  After around 150 hours 4 broke in flight, necessitating an out landing in a rape seed paddock. With a wood prop these bolts are not torqued much at all.   Changed to 3,2Mpa bolts which easily handle the minimal torque, but are malleable rather than brittle, and the problem was solved..at least for the next 600  hours when the VW conversion was replaced with a Jabiru.  When investigating this (after the out landing) I noticed I could have purchased 8.8MPa bolts that could be bent and which weren’t brittle.


Re: Flywheel cap screws

Ken MacLeod
 

ARP manufacture high quality bolts. They are available from several reliable sources: Jegs or Summit racing.

On Saturday, February 20, 2021, 8:32 AM, Pete Twissell <petetwizz@...> wrote:

Indeed so Ron.
Buyer beware!

On Sat, 20 Feb 2021, 12:17 Ron Milan via groups.io, <ronmilan=verizon.net@groups.io> wrote:
Pete:  My understanding of the rational of purchasing AN fasteners in addition to an almost infinite incremental selection of grip lengths, is that the credibility of the fastener can be traced.  Quality assured ???  Although one would want to believe that branded fasteners Unbrako, rather  "uMbrako" as you refer to---, SHOULD be a consistent high quality fastener.  After all, many folks rely on said fasteners to protect their life and limb.

Integrity cannot be substituted and is not always universal in our word today!.

Ron M

-----Original Message-----
From: Pete Twissell <petetwizz@...>
To: main@jabcamit.groups.io
Sent: Sat, Feb 20, 2021 6:52 am
Subject: Re: [JabCamit] Flywheel cap screws

It is worth noting that the strengths indicated by bolt grades are minimums, and that there are a lot of very dodgy manufacturers who will mark bolts as whatever they want to sell, regardless of properties.
At work, we once bought a batch of "Unbrako" bolts. After some failures and an investigation, it turned out they were marked "uMbrako" (my capitalisation) and they were fakes.


On Sat, 20 Feb 2021, 11:46 Mark Dunstone, <mark.dunstone@...> wrote:
Yes, to all that.  My experience with propellor bolt breakage:   I had 8.8 MPa ‘high tensile bolts’, and perhaps they were, but they were also very brittle.  After around 150 hours 4 broke in flight, necessitating an out landing in a rape seed paddock. With a wood prop these bolts are not torqued much at all.   Changed to 3,2Mpa bolts which easily handle the minimal torque, but are malleable rather than brittle, and the problem was solved..at least for the next 600  hours when the VW conversion was replaced with a Jabiru.  When investigating this (after the out landing) I noticed I could have purchased 8.8MPa bolts that could be bent and which weren’t brittle.


Re: Valve springs

Laurie Armstrong
 

I doubt it will have a detrimental effect.

, Laurie

On 20 Feb 2021, at 7:00 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
Laurie,
I guess it will take a longer than 30 hrs to have detrimental effect ?
Got to assume that lots of solid lifter Jabs have had double springs installed.
Still strange that my tests showed strengths to be same

Mick

On 19 Feb 2021, at 18:47, Laurie Armstrong via groups.io <laurie.armstrong88=yahoo.com.au@groups.io> wrote:

I fitted the double valve springs about 30 hours ago to my solid lifter Jabiru and had heard the same ‘advice’ which caused some worries. It has been running beautifully though.

Thanks, Laurie

On 20 Feb 2021, at 4:50 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.
Consider that !
Mick



Re: Flywheel cap screws

Pete Twissell
 

Indeed so Ron.
Buyer beware!

On Sat, 20 Feb 2021, 12:17 Ron Milan via groups.io, <ronmilan=verizon.net@groups.io> wrote:
Pete:  My understanding of the rational of purchasing AN fasteners in addition to an almost infinite incremental selection of grip lengths, is that the credibility of the fastener can be traced.  Quality assured ???  Although one would want to believe that branded fasteners Unbrako, rather  "uMbrako" as you refer to---, SHOULD be a consistent high quality fastener.  After all, many folks rely on said fasteners to protect their life and limb.

Integrity cannot be substituted and is not always universal in our word today!.

Ron M

-----Original Message-----
From: Pete Twissell <petetwizz@...>
To: main@jabcamit.groups.io
Sent: Sat, Feb 20, 2021 6:52 am
Subject: Re: [JabCamit] Flywheel cap screws

It is worth noting that the strengths indicated by bolt grades are minimums, and that there are a lot of very dodgy manufacturers who will mark bolts as whatever they want to sell, regardless of properties.
At work, we once bought a batch of "Unbrako" bolts. After some failures and an investigation, it turned out they were marked "uMbrako" (my capitalisation) and they were fakes.


On Sat, 20 Feb 2021, 11:46 Mark Dunstone, <mark.dunstone@...> wrote:
Yes, to all that.  My experience with propellor bolt breakage:   I had 8.8 MPa ‘high tensile bolts’, and perhaps they were, but they were also very brittle.  After around 150 hours 4 broke in flight, necessitating an out landing in a rape seed paddock. With a wood prop these bolts are not torqued much at all.   Changed to 3,2Mpa bolts which easily handle the minimal torque, but are malleable rather than brittle, and the problem was solved..at least for the next 600  hours when the VW conversion was replaced with a Jabiru.  When investigating this (after the out landing) I noticed I could have purchased 8.8MPa bolts that could be bent and which weren’t brittle.


Re: Flywheel cap screws

jabcamit@...
 




This is how I see it.

If the bolt  (assuming from any reputable maker) torques up to the specified tension without failing (irrespective of  manufacturer/grade), then it won't fail if the joint stays tight. The maximum forces the bolt sees are during the torquing process (90% of that force spent overcoming under head and  screw-thread friction, only 10% in tensioning the screw.  After tightening that 90% force no longer exists. 

The fly wheel joint fails if joint compression is lost (then allowing cyclic shear forces on the bolt). The less stretched the bolts are during assembly  the more likely this is to happen. Jabiru fitting bigger and bigger bolts reduced rather than increased flywheel attachment reliability because they were less stretchy. 

Locite is bad because the joint tightness cannot be subsequently tested by torquing. The bolt might be providing zero tension but the loctite prevents it from turning when torque tested. Nordloc washers overcome this (screws wont unwind due to vibration etc  but tightness torque can be checked.

Nordloc X series (effectively a Nordloc washer with additional Belleville characteristics) is perfect as  the Belleville spring effect will maintain bolt tension if/when the joint settles. 

BobP


Re: Flywheel cap screws

Ron Milan
 

Pete:  My understanding of the rational of purchasing AN fasteners in addition to an almost infinite incremental selection of grip lengths, is that the credibility of the fastener can be traced.  Quality assured ???  Although one would want to believe that branded fasteners Unbrako, rather  "uMbrako" as you refer to---, SHOULD be a consistent high quality fastener.  After all, many folks rely on said fasteners to protect their life and limb.

Integrity cannot be substituted and is not always universal in our word today!.

Ron M

-----Original Message-----
From: Pete Twissell <petetwizz@...>
To: main@jabcamit.groups.io
Sent: Sat, Feb 20, 2021 6:52 am
Subject: Re: [JabCamit] Flywheel cap screws

It is worth noting that the strengths indicated by bolt grades are minimums, and that there are a lot of very dodgy manufacturers who will mark bolts as whatever they want to sell, regardless of properties.
At work, we once bought a batch of "Unbrako" bolts. After some failures and an investigation, it turned out they were marked "uMbrako" (my capitalisation) and they were fakes.


On Sat, 20 Feb 2021, 11:46 Mark Dunstone, <mark.dunstone@...> wrote:
Yes, to all that.  My experience with propellor bolt breakage:   I had 8.8 MPa ‘high tensile bolts’, and perhaps they were, but they were also very brittle.  After around 150 hours 4 broke in flight, necessitating an out landing in a rape seed paddock. With a wood prop these bolts are not torqued much at all.   Changed to 3,2Mpa bolts which easily handle the minimal torque, but are malleable rather than brittle, and the problem was solved..at least for the next 600  hours when the VW conversion was replaced with a Jabiru.  When investigating this (after the out landing) I noticed I could have purchased 8.8MPa bolts that could be bent and which weren’t brittle.


Re: Flywheel cap screws

Pete Twissell
 

It is worth noting that the strengths indicated by bolt grades are minimums, and that there are a lot of very dodgy manufacturers who will mark bolts as whatever they want to sell, regardless of properties.
At work, we once bought a batch of "Unbrako" bolts. After some failures and an investigation, it turned out they were marked "uMbrako" (my capitalisation) and they were fakes.


On Sat, 20 Feb 2021, 11:46 Mark Dunstone, <mark.dunstone@...> wrote:
Yes, to all that.  My experience with propellor bolt breakage:   I had 8.8 MPa ‘high tensile bolts’, and perhaps they were, but they were also very brittle.  After around 150 hours 4 broke in flight, necessitating an out landing in a rape seed paddock. With a wood prop these bolts are not torqued much at all.   Changed to 3,2Mpa bolts which easily handle the minimal torque, but are malleable rather than brittle, and the problem was solved..at least for the next 600  hours when the VW conversion was replaced with a Jabiru.  When investigating this (after the out landing) I noticed I could have purchased 8.8MPa bolts that could be bent and which weren’t brittle.


Re: Flywheel cap screws

Mark Dunstone
 

Yes, to all that.  My experience with propellor bolt breakage:   I had 8.8 MPa ‘high tensile bolts’, and perhaps they were, but they were also very brittle.  After around 150 hours 4 broke in flight, necessitating an out landing in a rape seed paddock. With a wood prop these bolts are not torqued much at all.   Changed to 3,2Mpa bolts which easily handle the minimal torque, but are malleable rather than brittle, and the problem was solved..at least for the next 600  hours when the VW conversion was replaced with a Jabiru.  When investigating this (after the out landing) I noticed I could have purchased 8.8MPa bolts that could be bent and which weren’t brittle.


Re: Flywheel cap screws

Pete Twissell
 

The 'grades' referred to are the ultimate strengths and yield percentage for the fastener, whether it be metric or Imperial.
A 12.9 grade bolt had an ultimate strength of 1200 MPa and will yield at 90% of that.
A bolt marked simply as 8 is likely to be 8.8, UTS 800 MPa, yield at 80% of that.


On Sat, 20 Feb 2021, 11:03 Ron Milan via groups.io, <ronmilan=verizon.net@groups.io> wrote:
Mick/All:  Someone with more familiarity than me can chime in; but, grade "8" is an SAE fastener grade rating and 12.9 is a metric fastener grade rating. Since JABIRU manufactured the engine using SAE fasteners, all engine fasteners are SAE (fraction of an inch sized with threads per inch). Grade 8 would be what one would most likely be able to locate and purchase for the 5/15" fasteners that were being discussed.  The "12.9" would be a metric bolt grade rating soft to hard (5.8, 8.8, 10.9, 12.9).  I do believe that a metric grade 12.9 is actually harder than a grade "8" SAE fastener.  I must admit that harder is NOT always better because there is a point where the elastic modulus is so compromised that the bolt just snaps rather then bends. What you are crushing, bolt/fastener in tension, is also relevant in the engineering criteria of what "grade"  fastener should be used.  One is attempting to stretch the fastener to facilitate holding it in a torqued "specific clock" position. If the substrate crushes or collapses the stretch is no longer valid-the "torque"  stretch is lost.  Of course the Nordic lock washers and "loctite" are assisting holding the "clock" position in this specific scenario. 

As always, my two cents worth, your mileage and results may vary!

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io>
To: main@jabcamit.groups.io
Sent: Sat, Feb 20, 2021 5:24 am
Subject: Re: [JabCamit] Flywheel cap screws

Ron,
More the reason to get 12.9 rated screws

Mick

On 20 Feb 2021, at 02:35, Ron Milan via groups.io <ronmilan@...> wrote:

Most socket head cap screws are rated at grade 8 for what that is worth.

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: main@jabcamit.groups.io
Sent: Fri, Feb 19, 2021 12:51 pm
Subject: Re: [JabCamit] Flywheel cap screws

George, 
That is stupidly cheap, what is the spec of these bolts (cap screws) ?
Mick

On 19 Feb 2021, at 17:48, George Andre <glandre@...> wrote:

Found what I need at Fastenet, ordering by mail and all of 51 cents each. 
Now to remove the old ones that are glued in without breaking one off in the crankshaft. 
George

On Friday, February 19, 2021, 09:49:44 AM CST, Jay Scheevel <jay@...> wrote:


Have a look at these and see if you can find what you need.
 
 
Jay
 
From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of George Andre
Sent: Friday, February 19, 2021 6:49 AM
To: main@jabcamit.groups.io; main@JabCamit.groups.io
Subject: Re: [JabCamit] Flywheel cap screws
 
Jay, I have a couple of Fastenet dealers nearby so will try that, BUT, what exactly is the description? (size, head style, etc.) In my experience, one does not want to tell them it is for an airplane as they think this brings on some unwanted liability. In the past I have had to say it is for an experimental tractor I am building. thanks
George
 
On Friday, February 19, 2021, 02:43:12 AM CST, Mick O'Connor via groups.io <mickoconnor909@...> wrote:
 
 
George,
You are correct about  1 1/4” cap screws do not give enough grip with the  extra thickness of the plate and Nordlok (4.5mm).
1 1/2” length will compensate for the extra 4.5mm.
I’ve sourced correct specification 12.9 high tensile cap screws in 1 3/4” length with a 14mm plain shank.
1 3/4” gives about 5mm clearance at the bottom of the thread.

Mick


> On 19 Feb 2021, at 00:02, George Andre <glandre@...> wrote:
>
> I bought the kit last year and from this discussion the bolts supplied (1.25”) will not be long enough to engage sufficient threads. So I need 6 replacements of the 1.75” length. So whoever is finding a source please let me know or put me down for a set. Thx. George André. 3300 s/n 987
> Glandre@... , St Louis MO
>> On Feb 17, 2021, at 13:31, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
>>
>> Jay,
>> Wasn’t thinking anything, just that in my search for suitable flywheel bolts, I happened across some other options that may be an improvement or detriment or neutral, namely longer grip length and a shank .
>>
>>
>>> On 17 Feb 2021, at 19:06, Jay Scheevel <jay@...> wrote:
>>>
>>> Hi Mick,
>>>
>>> The shank is irrelevant since the critical stress point is a thread that is not engaged, and that will be present whether shank or no shank. If you are thinking the shank will provide shear resistance, then if the bolt is in shear, the joint has already failed and it will fall off shortly anyway. The resistance to shear is in the clamping of the flywheel to the crank and that is a frictional force which is maintained by the preload of the bolts. 18mm sounds like that is enough engaged thread.
>>>
>>> Jay
>>>
>>> -----Original Message-----
>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>> Sent: Wednesday, February 17, 2021 9:27 AM
>>> To: main@jabcamit.groups.io
>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>
>>> Jay,
>>> Forget about suppliers, I’ve found a supplier. The plain shank is only 8mm, so not an issue.
>>> If I go 1 3/4” length,  it will engage with 18mm of the 23mm depth of thread.
>>> So back to my questions :
>>> is a plain shank beneficial ?
>>> Is using 18mm of a 23mm thread OK ?
>>> I’m thinking both are OK
>>>
>>>>> On 17 Feb 2021, at 16:14, Jay Scheevel <jay@...> wrote:
>>>>
>>>> Maybe you can buy the box of 200, then bag them up in 20's and sell them on ebay for a profit.
>>>>
>>>> As far as the joint goes, that's a critical area, Mick. You need at least 4 full threads engaged and the first thread inside the crank is usually chamfered, so doesn't count. The unthreaded bolt shank can be a minefield, if it travels into the threaded area, it will mess up your torque and other nastiness. The holes in the crank are not fully threaded to bottom, so there is that same issue there. I prefer the non-belleville version of the nordlock because they do not change the stiffness of the joint as they compress. Best to measure very carefully.
>>>>
>>>> Jay
>>>>
>>>> -----Original Message-----
>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>> Sent: Wednesday, February 17, 2021 8:57 AM
>>>> To: main@jabcamit.groups.io
>>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>>
>>>> Surrey in England. The local ones don’t hold the stock and the bigger suppliers will only supply in boxes of 200.
>>>> I have found a supplier but only with an 8mm shank.
>>>> Is a shank OK in our application and is it OK to go deep in the threads ?
>>>> Standard 1 1/4” bolts only go 11mm into the thread. If I add the spreader washer and Nord-Lock (5mm), standard won’t enough ‘grip’.
>>>> The thread depth is 23mm, lots of room
>>>>
>>>>
>>>>> On 17 Feb 2021, at 15:39, Jay Scheevel <jay@...> wrote:
>>>>>
>>>>> Where are you located, Mick?  If you have a Fastenal dealer near you, they will supply in small quantities for walk-in customers.
>>>>>
>>>>> Jay
>>>>>
>>>>> -----Original Message-----
>>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>>> Sent: Wednesday, February 17, 2021 8:05 AM
>>>>> To: JabCamit <main@jabcamit.groups.io>
>>>>> Subject: [JabCamit] Flywheel cap screws
>>>>>
>>>>> Replacing my cap screws as im fitting a steel spreader washer and Nordloks.
>>>>> Struggling to find a fastened co. who will supply small quantities. Is there any reason not to fit longer screws that go further into the crankshaft ?
>>>>> The depth of the thread in the crank is about 22mm and a 1 3/4” cap screw will go 14mm into the crank thread. Also this cap screw has 8mm of plain shank .
>>>>> Mick
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>






Re: Flywheel cap screws

Ron Milan
 

Mick/All:  Someone with more familiarity than me can chime in; but, grade "8" is an SAE fastener grade rating and 12.9 is a metric fastener grade rating. Since JABIRU manufactured the engine using SAE fasteners, all engine fasteners are SAE (fraction of an inch sized with threads per inch). Grade 8 would be what one would most likely be able to locate and purchase for the 5/15" fasteners that were being discussed.  The "12.9" would be a metric bolt grade rating soft to hard (5.8, 8.8, 10.9, 12.9).  I do believe that a metric grade 12.9 is actually harder than a grade "8" SAE fastener.  I must admit that harder is NOT always better because there is a point where the elastic modulus is so compromised that the bolt just snaps rather then bends. What you are crushing, bolt/fastener in tension, is also relevant in the engineering criteria of what "grade"  fastener should be used.  One is attempting to stretch the fastener to facilitate holding it in a torqued "specific clock" position. If the substrate crushes or collapses the stretch is no longer valid-the "torque"  stretch is lost.  Of course the Nordic lock washers and "loctite" are assisting holding the "clock" position in this specific scenario. 

As always, my two cents worth, your mileage and results may vary!

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: main@jabcamit.groups.io
Sent: Sat, Feb 20, 2021 5:24 am
Subject: Re: [JabCamit] Flywheel cap screws

Ron,
More the reason to get 12.9 rated screws

Mick

On 20 Feb 2021, at 02:35, Ron Milan via groups.io <ronmilan@...> wrote:

Most socket head cap screws are rated at grade 8 for what that is worth.

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: main@jabcamit.groups.io
Sent: Fri, Feb 19, 2021 12:51 pm
Subject: Re: [JabCamit] Flywheel cap screws

George, 
That is stupidly cheap, what is the spec of these bolts (cap screws) ?
Mick

On 19 Feb 2021, at 17:48, George Andre <glandre@...> wrote:

Found what I need at Fastenet, ordering by mail and all of 51 cents each. 
Now to remove the old ones that are glued in without breaking one off in the crankshaft. 
George

On Friday, February 19, 2021, 09:49:44 AM CST, Jay Scheevel <jay@...> wrote:


Have a look at these and see if you can find what you need.
 
 
Jay
 
From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of George Andre
Sent: Friday, February 19, 2021 6:49 AM
To: main@jabcamit.groups.io; main@JabCamit.groups.io
Subject: Re: [JabCamit] Flywheel cap screws
 
Jay, I have a couple of Fastenet dealers nearby so will try that, BUT, what exactly is the description? (size, head style, etc.) In my experience, one does not want to tell them it is for an airplane as they think this brings on some unwanted liability. In the past I have had to say it is for an experimental tractor I am building. thanks
George
 
On Friday, February 19, 2021, 02:43:12 AM CST, Mick O'Connor via groups.io <mickoconnor909@...> wrote:
 
 
George,
You are correct about  1 1/4” cap screws do not give enough grip with the  extra thickness of the plate and Nordlok (4.5mm).
1 1/2” length will compensate for the extra 4.5mm.
I’ve sourced correct specification 12.9 high tensile cap screws in 1 3/4” length with a 14mm plain shank.
1 3/4” gives about 5mm clearance at the bottom of the thread.

Mick


> On 19 Feb 2021, at 00:02, George Andre <glandre@...> wrote:
>
> I bought the kit last year and from this discussion the bolts supplied (1.25”) will not be long enough to engage sufficient threads. So I need 6 replacements of the 1.75” length. So whoever is finding a source please let me know or put me down for a set. Thx. George André. 3300 s/n 987
> Glandre@... , St Louis MO
>> On Feb 17, 2021, at 13:31, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
>>
>> Jay,
>> Wasn’t thinking anything, just that in my search for suitable flywheel bolts, I happened across some other options that may be an improvement or detriment or neutral, namely longer grip length and a shank .
>>
>>
>>> On 17 Feb 2021, at 19:06, Jay Scheevel <jay@...> wrote:
>>>
>>> Hi Mick,
>>>
>>> The shank is irrelevant since the critical stress point is a thread that is not engaged, and that will be present whether shank or no shank. If you are thinking the shank will provide shear resistance, then if the bolt is in shear, the joint has already failed and it will fall off shortly anyway. The resistance to shear is in the clamping of the flywheel to the crank and that is a frictional force which is maintained by the preload of the bolts. 18mm sounds like that is enough engaged thread.
>>>
>>> Jay
>>>
>>> -----Original Message-----
>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>> Sent: Wednesday, February 17, 2021 9:27 AM
>>> To: main@jabcamit.groups.io
>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>
>>> Jay,
>>> Forget about suppliers, I’ve found a supplier. The plain shank is only 8mm, so not an issue.
>>> If I go 1 3/4” length,  it will engage with 18mm of the 23mm depth of thread.
>>> So back to my questions :
>>> is a plain shank beneficial ?
>>> Is using 18mm of a 23mm thread OK ?
>>> I’m thinking both are OK
>>>
>>>>> On 17 Feb 2021, at 16:14, Jay Scheevel <jay@...> wrote:
>>>>
>>>> Maybe you can buy the box of 200, then bag them up in 20's and sell them on ebay for a profit.
>>>>
>>>> As far as the joint goes, that's a critical area, Mick. You need at least 4 full threads engaged and the first thread inside the crank is usually chamfered, so doesn't count. The unthreaded bolt shank can be a minefield, if it travels into the threaded area, it will mess up your torque and other nastiness. The holes in the crank are not fully threaded to bottom, so there is that same issue there. I prefer the non-belleville version of the nordlock because they do not change the stiffness of the joint as they compress. Best to measure very carefully.
>>>>
>>>> Jay
>>>>
>>>> -----Original Message-----
>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>> Sent: Wednesday, February 17, 2021 8:57 AM
>>>> To: main@jabcamit.groups.io
>>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>>
>>>> Surrey in England. The local ones don’t hold the stock and the bigger suppliers will only supply in boxes of 200.
>>>> I have found a supplier but only with an 8mm shank.
>>>> Is a shank OK in our application and is it OK to go deep in the threads ?
>>>> Standard 1 1/4” bolts only go 11mm into the thread. If I add the spreader washer and Nord-Lock (5mm), standard won’t enough ‘grip’.
>>>> The thread depth is 23mm, lots of room
>>>>
>>>>
>>>>> On 17 Feb 2021, at 15:39, Jay Scheevel <jay@...> wrote:
>>>>>
>>>>> Where are you located, Mick?  If you have a Fastenal dealer near you, they will supply in small quantities for walk-in customers.
>>>>>
>>>>> Jay
>>>>>
>>>>> -----Original Message-----
>>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>>> Sent: Wednesday, February 17, 2021 8:05 AM
>>>>> To: JabCamit <main@jabcamit.groups.io>
>>>>> Subject: [JabCamit] Flywheel cap screws
>>>>>
>>>>> Replacing my cap screws as im fitting a steel spreader washer and Nordloks.
>>>>> Struggling to find a fastened co. who will supply small quantities. Is there any reason not to fit longer screws that go further into the crankshaft ?
>>>>> The depth of the thread in the crank is about 22mm and a 1 3/4” cap screw will go 14mm into the crank thread. Also this cap screw has 8mm of plain shank .
>>>>> Mick
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>






Re: Flywheel cap screws

Mick O'Connor
 

Ron,
More the reason to get 12.9 rated screws

Mick

On 20 Feb 2021, at 02:35, Ron Milan via groups.io <ronmilan@...> wrote:

Most socket head cap screws are rated at grade 8 for what that is worth.

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: main@jabcamit.groups.io
Sent: Fri, Feb 19, 2021 12:51 pm
Subject: Re: [JabCamit] Flywheel cap screws

George, 
That is stupidly cheap, what is the spec of these bolts (cap screws) ?
Mick

On 19 Feb 2021, at 17:48, George Andre <glandre@...> wrote:

Found what I need at Fastenet, ordering by mail and all of 51 cents each. 
Now to remove the old ones that are glued in without breaking one off in the crankshaft. 
George

On Friday, February 19, 2021, 09:49:44 AM CST, Jay Scheevel <jay@...> wrote:


Have a look at these and see if you can find what you need.
 
 
Jay
 
From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of George Andre
Sent: Friday, February 19, 2021 6:49 AM
To: main@jabcamit.groups.io; main@JabCamit.groups.io
Subject: Re: [JabCamit] Flywheel cap screws
 
Jay, I have a couple of Fastenet dealers nearby so will try that, BUT, what exactly is the description? (size, head style, etc.) In my experience, one does not want to tell them it is for an airplane as they think this brings on some unwanted liability. In the past I have had to say it is for an experimental tractor I am building. thanks
George
 
On Friday, February 19, 2021, 02:43:12 AM CST, Mick O'Connor via groups.io <mickoconnor909@...> wrote:
 
 
George,
You are correct about  1 1/4” cap screws do not give enough grip with the  extra thickness of the plate and Nordlok (4.5mm).
1 1/2” length will compensate for the extra 4.5mm.
I’ve sourced correct specification 12.9 high tensile cap screws in 1 3/4” length with a 14mm plain shank.
1 3/4” gives about 5mm clearance at the bottom of the thread.

Mick


> On 19 Feb 2021, at 00:02, George Andre <glandre@...> wrote:
>
> I bought the kit last year and from this discussion the bolts supplied (1.25”) will not be long enough to engage sufficient threads. So I need 6 replacements of the 1.75” length. So whoever is finding a source please let me know or put me down for a set. Thx. George André. 3300 s/n 987
> Glandre@... , St Louis MO
>> On Feb 17, 2021, at 13:31, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
>>
>> Jay,
>> Wasn’t thinking anything, just that in my search for suitable flywheel bolts, I happened across some other options that may be an improvement or detriment or neutral, namely longer grip length and a shank .
>>
>>
>>> On 17 Feb 2021, at 19:06, Jay Scheevel <jay@...> wrote:
>>>
>>> Hi Mick,
>>>
>>> The shank is irrelevant since the critical stress point is a thread that is not engaged, and that will be present whether shank or no shank. If you are thinking the shank will provide shear resistance, then if the bolt is in shear, the joint has already failed and it will fall off shortly anyway. The resistance to shear is in the clamping of the flywheel to the crank and that is a frictional force which is maintained by the preload of the bolts. 18mm sounds like that is enough engaged thread.
>>>
>>> Jay
>>>
>>> -----Original Message-----
>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>> Sent: Wednesday, February 17, 2021 9:27 AM
>>> To: main@jabcamit.groups.io
>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>
>>> Jay,
>>> Forget about suppliers, I’ve found a supplier. The plain shank is only 8mm, so not an issue.
>>> If I go 1 3/4” length,  it will engage with 18mm of the 23mm depth of thread.
>>> So back to my questions :
>>> is a plain shank beneficial ?
>>> Is using 18mm of a 23mm thread OK ?
>>> I’m thinking both are OK
>>>
>>>>> On 17 Feb 2021, at 16:14, Jay Scheevel <jay@...> wrote:
>>>>
>>>> Maybe you can buy the box of 200, then bag them up in 20's and sell them on ebay for a profit.
>>>>
>>>> As far as the joint goes, that's a critical area, Mick. You need at least 4 full threads engaged and the first thread inside the crank is usually chamfered, so doesn't count. The unthreaded bolt shank can be a minefield, if it travels into the threaded area, it will mess up your torque and other nastiness. The holes in the crank are not fully threaded to bottom, so there is that same issue there. I prefer the non-belleville version of the nordlock because they do not change the stiffness of the joint as they compress. Best to measure very carefully.
>>>>
>>>> Jay
>>>>
>>>> -----Original Message-----
>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>> Sent: Wednesday, February 17, 2021 8:57 AM
>>>> To: main@jabcamit.groups.io
>>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>>
>>>> Surrey in England. The local ones don’t hold the stock and the bigger suppliers will only supply in boxes of 200.
>>>> I have found a supplier but only with an 8mm shank.
>>>> Is a shank OK in our application and is it OK to go deep in the threads ?
>>>> Standard 1 1/4” bolts only go 11mm into the thread. If I add the spreader washer and Nord-Lock (5mm), standard won’t enough ‘grip’.
>>>> The thread depth is 23mm, lots of room
>>>>
>>>>
>>>>> On 17 Feb 2021, at 15:39, Jay Scheevel <jay@...> wrote:
>>>>>
>>>>> Where are you located, Mick?  If you have a Fastenal dealer near you, they will supply in small quantities for walk-in customers.
>>>>>
>>>>> Jay
>>>>>
>>>>> -----Original Message-----
>>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>>> Sent: Wednesday, February 17, 2021 8:05 AM
>>>>> To: JabCamit <main@jabcamit.groups.io>
>>>>> Subject: [JabCamit] Flywheel cap screws
>>>>>
>>>>> Replacing my cap screws as im fitting a steel spreader washer and Nordloks.
>>>>> Struggling to find a fastened co. who will supply small quantities. Is there any reason not to fit longer screws that go further into the crankshaft ?
>>>>> The depth of the thread in the crank is about 22mm and a 1 3/4” cap screw will go 14mm into the crank thread. Also this cap screw has 8mm of plain shank .
>>>>> Mick
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>






Re: Valve springs

Mick O'Connor
 

Disadvantage of looking at old items is that that they can be out of date and you lose the advantage of new comments/information.
I made a lever mechanism that compressed each spring from free length to coil bound. I used a spring balance to apply the compression.
Tried different methods but all showed double spring same as my old single spring. My old spring was well within length spec in manual 

Mick

On 20 Feb 2021, at 02:33, Ron Milan via groups.io <ronmilan@...> wrote:

Mick:  If you search the archives, you will discover that I mentioned sometime ago that the double spring is/was not necessarily equated to more spring pressure.  I feel that double springs have several potential advantages, if one brakes there is still some spring pressure to hold up the valve and double springs should have a greater dampening effect.  

What height did you measure this 6kg pressure, installed height, full lift height or other dimension?

I certainly would use the double springs as long as there is no coil bind during the compression of full valve open height.

Again my two cents worth your mileage and results may vary!

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: JabCamit <main@jabcamit.groups.io>
Sent: Fri, Feb 19, 2021 12:50 pm
Subject: [JabCamit] Valve springs

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick






Re: Prop, flywheel bolts

Mick O'Connor
 

Jay,
Your link leads to #10-32 screws ?
They are very small and not flywheel type

On 19 Feb 2021, at 23:19, Jay Scheevel <jay@...> wrote:

Went back and checked a past order that I made. I had to buy a box of 100 (genuine Unbrako), but the price was not bad from this outfit.

 

https://www.mscdirect.com/product/details/67802488

 

Jay

 

 

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Steve Rance via groups.io
Sent: Friday, February 19, 2021 2:13 PM
To: main@jabcamit.groups.io
Subject: [JabCamit] Prop, flywheel bolts

 

Several years ago I was asked to remove the broken studs in the 2200 crankshaft, the prop departed on climb out. Aircraft fortunatly was high enough to turn round and land back on runway. What happened was the owner had put longer bolts in after fitting a supplied spacer behind the prop hub, the bolts bottomed out at the same time as lightly gripping the prop. Always check thread depth by inserting all bolts and measuring there is sufficient grip of at least 2 -3 full turns before bottoming out.

I have done several flywheels and prop hubs in the meantime and also found it impossible to find Unbrako UNF cap screws. All the big suppliers want to sell you a large expensive box which has to be specially ordered. That aside having done several flywheels and prop hubs in only one case found bolts marked UNB, presumably for Unbrako and that was an early engine. All of the subsequent 3/8” Bolts were marked YFS or TMS of origin unknown, so I assume the manufacturers by buying elsewhere are saving money or Unbrako supplies unavailable, another problem is stocks of Unified screws are drying up and only metric fasteners are readily available in UK.

 I have had an old box for years of Unbrako screws (wrong size) marked with the usual approvals and made in Brazil so they can be made anywhere to keep costs down.

Reminds me years ago we had a new Mill delivered at our works, we were having a quiet break when there was a loud crack like a gunshot, it took a while but it came from a M16 capscrew that let go off the milling machine bearing flange, snapped right under the head, it was unplated but clearly flawed.

 

Steve

 

Sent from Mail for Windows 10

 


gudgeon pin contact surfaces question

glen english LIST
 

(question)
Hi. All (6) my pistons show, pretty much identically :

wear in the gudgeon pin mating surfaces on the piston.
On two sides opposite each other per end. perfect symmetry everywhere.

It tells me where the thrust has is taken up. . Not much, but you can feel it with your finger. 400 hours.

The pins fit nice and snug , no play in any direction with oil in there.
Have kept pins matc hed to pistons (like everything else)

Normal ?
Had film of carbonized something on the sides in there which I got off, nice and shiny now- where the thrust hadnt been (sides) .

finally now have the ring grooves clean. top ring groove had carbon hardened like diamond....


Re: Flywheel cap screws

Ron Milan
 

Most socket head cap screws are rated at grade 8 for what that is worth.

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: main@jabcamit.groups.io
Sent: Fri, Feb 19, 2021 12:51 pm
Subject: Re: [JabCamit] Flywheel cap screws

George, 
That is stupidly cheap, what is the spec of these bolts (cap screws) ?
Mick

On 19 Feb 2021, at 17:48, George Andre <glandre@...> wrote:

Found what I need at Fastenet, ordering by mail and all of 51 cents each. 
Now to remove the old ones that are glued in without breaking one off in the crankshaft. 
George

On Friday, February 19, 2021, 09:49:44 AM CST, Jay Scheevel <jay@...> wrote:


Have a look at these and see if you can find what you need.
 
 
Jay
 
From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of George Andre
Sent: Friday, February 19, 2021 6:49 AM
To: main@jabcamit.groups.io; main@JabCamit.groups.io
Subject: Re: [JabCamit] Flywheel cap screws
 
Jay, I have a couple of Fastenet dealers nearby so will try that, BUT, what exactly is the description? (size, head style, etc.) In my experience, one does not want to tell them it is for an airplane as they think this brings on some unwanted liability. In the past I have had to say it is for an experimental tractor I am building. thanks
George
 
On Friday, February 19, 2021, 02:43:12 AM CST, Mick O'Connor via groups.io <mickoconnor909@...> wrote:
 
 
George,
You are correct about  1 1/4” cap screws do not give enough grip with the  extra thickness of the plate and Nordlok (4.5mm).
1 1/2” length will compensate for the extra 4.5mm.
I’ve sourced correct specification 12.9 high tensile cap screws in 1 3/4” length with a 14mm plain shank.
1 3/4” gives about 5mm clearance at the bottom of the thread.

Mick


> On 19 Feb 2021, at 00:02, George Andre <glandre@...> wrote:
>
> I bought the kit last year and from this discussion the bolts supplied (1.25”) will not be long enough to engage sufficient threads. So I need 6 replacements of the 1.75” length. So whoever is finding a source please let me know or put me down for a set. Thx. George André. 3300 s/n 987
> Glandre@... , St Louis MO
>> On Feb 17, 2021, at 13:31, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:
>>
>> Jay,
>> Wasn’t thinking anything, just that in my search for suitable flywheel bolts, I happened across some other options that may be an improvement or detriment or neutral, namely longer grip length and a shank .
>>
>>
>>> On 17 Feb 2021, at 19:06, Jay Scheevel <jay@...> wrote:
>>>
>>> Hi Mick,
>>>
>>> The shank is irrelevant since the critical stress point is a thread that is not engaged, and that will be present whether shank or no shank. If you are thinking the shank will provide shear resistance, then if the bolt is in shear, the joint has already failed and it will fall off shortly anyway. The resistance to shear is in the clamping of the flywheel to the crank and that is a frictional force which is maintained by the preload of the bolts. 18mm sounds like that is enough engaged thread.
>>>
>>> Jay
>>>
>>> -----Original Message-----
>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>> Sent: Wednesday, February 17, 2021 9:27 AM
>>> To: main@jabcamit.groups.io
>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>
>>> Jay,
>>> Forget about suppliers, I’ve found a supplier. The plain shank is only 8mm, so not an issue.
>>> If I go 1 3/4” length,  it will engage with 18mm of the 23mm depth of thread.
>>> So back to my questions :
>>> is a plain shank beneficial ?
>>> Is using 18mm of a 23mm thread OK ?
>>> I’m thinking both are OK
>>>
>>>>> On 17 Feb 2021, at 16:14, Jay Scheevel <jay@...> wrote:
>>>>
>>>> Maybe you can buy the box of 200, then bag them up in 20's and sell them on ebay for a profit.
>>>>
>>>> As far as the joint goes, that's a critical area, Mick. You need at least 4 full threads engaged and the first thread inside the crank is usually chamfered, so doesn't count. The unthreaded bolt shank can be a minefield, if it travels into the threaded area, it will mess up your torque and other nastiness. The holes in the crank are not fully threaded to bottom, so there is that same issue there. I prefer the non-belleville version of the nordlock because they do not change the stiffness of the joint as they compress. Best to measure very carefully.
>>>>
>>>> Jay
>>>>
>>>> -----Original Message-----
>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>> Sent: Wednesday, February 17, 2021 8:57 AM
>>>> To: main@jabcamit.groups.io
>>>> Subject: Re: [JabCamit] Flywheel cap screws
>>>>
>>>> Surrey in England. The local ones don’t hold the stock and the bigger suppliers will only supply in boxes of 200.
>>>> I have found a supplier but only with an 8mm shank.
>>>> Is a shank OK in our application and is it OK to go deep in the threads ?
>>>> Standard 1 1/4” bolts only go 11mm into the thread. If I add the spreader washer and Nord-Lock (5mm), standard won’t enough ‘grip’.
>>>> The thread depth is 23mm, lots of room
>>>>
>>>>
>>>>> On 17 Feb 2021, at 15:39, Jay Scheevel <jay@...> wrote:
>>>>>
>>>>> Where are you located, Mick?  If you have a Fastenal dealer near you, they will supply in small quantities for walk-in customers.
>>>>>
>>>>> Jay
>>>>>
>>>>> -----Original Message-----
>>>>> From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
>>>>> Sent: Wednesday, February 17, 2021 8:05 AM
>>>>> To: JabCamit <main@jabcamit.groups.io>
>>>>> Subject: [JabCamit] Flywheel cap screws
>>>>>
>>>>> Replacing my cap screws as im fitting a steel spreader washer and Nordloks.
>>>>> Struggling to find a fastened co. who will supply small quantities. Is there any reason not to fit longer screws that go further into the crankshaft ?
>>>>> The depth of the thread in the crank is about 22mm and a 1 3/4” cap screw will go 14mm into the crank thread. Also this cap screw has 8mm of plain shank .
>>>>> Mick
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>






Re: Valve springs

Ron Milan
 

Mick:  If you search the archives, you will discover that I mentioned sometime ago that the double spring is/was not necessarily equated to more spring pressure.  I feel that double springs have several potential advantages, if one brakes there is still some spring pressure to hold up the valve and double springs should have a greater dampening effect.  

What height did you measure this 6kg pressure, installed height, full lift height or other dimension?

I certainly would use the double springs as long as there is no coil bind during the compression of full valve open height.

Again my two cents worth your mileage and results may vary!

Ron M


-----Original Message-----
From: Mick O'Connor via groups.io <mickoconnor909@...>
To: JabCamit <main@jabcamit.groups.io>
Sent: Fri, Feb 19, 2021 12:50 pm
Subject: [JabCamit] Valve springs

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick






Re: Prop, flywheel bolts

Jay Scheevel
 

Went back and checked a past order that I made. I had to buy a box of 100 (genuine Unbrako), but the price was not bad from this outfit.

 

https://www.mscdirect.com/product/details/67802488

 

Jay

 

 

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Steve Rance via groups.io
Sent: Friday, February 19, 2021 2:13 PM
To: main@jabcamit.groups.io
Subject: [JabCamit] Prop, flywheel bolts

 

Several years ago I was asked to remove the broken studs in the 2200 crankshaft, the prop departed on climb out. Aircraft fortunatly was high enough to turn round and land back on runway. What happened was the owner had put longer bolts in after fitting a supplied spacer behind the prop hub, the bolts bottomed out at the same time as lightly gripping the prop. Always check thread depth by inserting all bolts and measuring there is sufficient grip of at least 2 -3 full turns before bottoming out.

I have done several flywheels and prop hubs in the meantime and also found it impossible to find Unbrako UNF cap screws. All the big suppliers want to sell you a large expensive box which has to be specially ordered. That aside having done several flywheels and prop hubs in only one case found bolts marked UNB, presumably for Unbrako and that was an early engine. All of the subsequent 3/8” Bolts were marked YFS or TMS of origin unknown, so I assume the manufacturers by buying elsewhere are saving money or Unbrako supplies unavailable, another problem is stocks of Unified screws are drying up and only metric fasteners are readily available in UK.

 I have had an old box for years of Unbrako screws (wrong size) marked with the usual approvals and made in Brazil so they can be made anywhere to keep costs down.

Reminds me years ago we had a new Mill delivered at our works, we were having a quiet break when there was a loud crack like a gunshot, it took a while but it came from a M16 capscrew that let go off the milling machine bearing flange, snapped right under the head, it was unplated but clearly flawed.

 

Steve

 

Sent from Mail for Windows 10

 


Re: Inlet valve

Pete Twissell
 

Re. Being pulled off the forum:
I run a couple of groups on groups.io.
Every now and then, I get a notification that a member has been 'evicted' because they have marked a message from the forum as spam.
Invariably, this is because the members email application has automatically marked a message as spam.
If I'm quick, I can send the member an email to let them know what's happened, but often as not, they've just logged in again and sorted the issue themselves.

On Fri, 19 Feb 2021, 16:17 John Miller via groups.io, <skypics234=aol.com@groups.io> wrote:
I really like how easy it was to pull the heads o the earlier models. The Gen 4 requires the entire jug just like "real aircraft engines" to come off.

I have a valve compressor that I built for my Gen 3 and it looks like I won't be needing it anymore so it will go into my junl drawer.

By the way. I was pulled off this forum earlier. The forum manager said I had the forum listed as SPAM so he/she cut me off.

I checked my SPAM folder and see that this isn't true. Don't know what made him/her think that.

John M


Prop, flywheel bolts

Steve Rance
 

Several years ago I was asked to remove the broken studs in the 2200 crankshaft, the prop departed on climb out. Aircraft fortunatly was high enough to turn round and land back on runway. What happened was the owner had put longer bolts in after fitting a supplied spacer behind the prop hub, the bolts bottomed out at the same time as lightly gripping the prop. Always check thread depth by inserting all bolts and measuring there is sufficient grip of at least 2 -3 full turns before bottoming out.

I have done several flywheels and prop hubs in the meantime and also found it impossible to find Unbrako UNF cap screws. All the big suppliers want to sell you a large expensive box which has to be specially ordered. That aside having done several flywheels and prop hubs in only one case found bolts marked UNB, presumably for Unbrako and that was an early engine. All of the subsequent 3/8” Bolts were marked YFS or TMS of origin unknown, so I assume the manufacturers by buying elsewhere are saving money or Unbrako supplies unavailable, another problem is stocks of Unified screws are drying up and only metric fasteners are readily available in UK.

 I have had an old box for years of Unbrako screws (wrong size) marked with the usual approvals and made in Brazil so they can be made anywhere to keep costs down.

Reminds me years ago we had a new Mill delivered at our works, we were having a quiet break when there was a loud crack like a gunshot, it took a while but it came from a M16 capscrew that let go off the milling machine bearing flange, snapped right under the head, it was unplated but clearly flawed.

 

Steve

 

Sent from Mail for Windows 10

 


Re: Valve springs

Mick O'Connor
 

Laurie,
I guess it will take a longer than 30 hrs to have detrimental effect ?
Got to assume that lots of solid lifter Jabs have had double springs installed.
Still strange that my tests showed strengths to be same

Mick

On 19 Feb 2021, at 18:47, Laurie Armstrong via groups.io <laurie.armstrong88=yahoo.com.au@groups.io> wrote:

I fitted the double valve springs about 30 hours ago to my solid lifter Jabiru and had heard the same ‘advice’ which caused some worries. It has been running beautifully though.

Thanks, Laurie

On 20 Feb 2021, at 4:50 am, Mick O'Connor via groups.io <mickoconnor909=btinternet.com@groups.io> wrote:

I got new ‘double’ valve springs from Jab with my head overhaul kits.
I’ve been advised not to use them on a solid lifter as they may accelerate can love wear. Manual says ‘you must’ renew valve springs at top end o/h. Out of curiosity I made up a jig to measure the spring strength.
Double springs measured 6kg, old single spring same at 6kg, big spring from double set on its own 5kg and the small inner spring 1kg.

Consider that !

Mick








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