Topics

Flywheel bolts


Mick O'Connor
 

Need to buy new longer flywheel socket head screws as am installing plate and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black oxide finish ?


Mick


mikeGoog
 

FWIW, Mick,

Use your Engineering loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness) change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com


Marc Bourget
 

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com







jabcamit@...
 

 I don't think it matters (fully threaded versus plain shank, rolled versus cut thread). As long as the bolts are (and remain)  tight there is adequate  friction between  flywheel and other engine bits, so they don't move relative to each other and  so the load on the bolts is purely a constant tension. (1/4" bolts are better than than 5/16"  or 3/8th bolts (more stretch so tension better maintained as the joint settles).

 Shear forces only develop AFTER the joint has failed - then its just a matter of time until  the flywheel falls off. Joints without dowels are better because this gives more friction contact area and the load (from the joint tension) is spread across a wider area so less movement (= reduction in bolt tension) during settling. 

I think there is a belville version of the Nordlocs. Perfect (if there is room to fit them)  as  joint settling won't result in any loss of tension.

BobP


Mick O'Connor
 

FWIW Mike,
Your response was as useful as a chocolate teapot !
My question (which you failed to answer) was “is this the correct Unbrako part number for the flywheel bolts”.
Your comment on shanked or full thread bolts just agreed with my comment as to why Jab didn’t use shanked bolts in this application.
So, I used my engineering loaf and moved your reply to my ‘junk folder’

Mick


On 11 Feb 2021, at 14:05, Marc Bourget <marcbourget@...> wrote:

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com







mikeGoog
 

Oh Dear Mick,
 
Purely triggered by your very correct initial question I tried to add my tuppence worth agreement: no intention of querying your thought pattern.
As for the bolt shank: thread length needed calls for knowledge of the thickness to be clamped with necessary allowances as well as step size availability of suitable quality steel ‘Unbrako’ (?) socket headed bolts.
 
Regards,
 
mike.
 

From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 3:09 PM
To: main@jabcamit.groups.io
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW Mike,
Your response was as useful as a chocolate teapot !
My question (which you failed to answer) was “is this the correct Unbrako part number for the flywheel bolts”.
Your comment on shanked or full thread bolts just agreed with my comment as to why Jab didn’t use shanked bolts in this application.
So, I used my engineering loaf and moved your reply to my ‘junk folder’
 
Mick
 

On 11 Feb 2021, at 14:05, Marc Bourget <marcbourget@...> wrote:

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.
 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com







Virus-free. www.avg.com


Mick O'Connor
 

Bob,
Thanks for the info but I just want to know if the Unbrako socket screw’s part number Is correct ?
1/4 may be better but I have a 5/16 crank. Unbrako don’t offer a choice on thread type and only offer full thread screws in small sizes.
I’ve probably answered my own question !
Mick

On 11 Feb 2021, at 14:17, jabcamit@... wrote:

 I don't think it matters (fully threaded versus plain shank, rolled versus cut thread). As long as the bolts are (and remain)  tight there is adequate  friction between  flywheel and other engine bits, so they don't move relative to each other and  so the load on the bolts is purely a constant tension. (1/4" bolts are better than than 5/16"  or 3/8th bolts (more stretch so tension better maintained as the joint settles).

 Shear forces only develop AFTER the joint has failed - then its just a matter of time until  the flywheel falls off. Joints without dowels are better because this gives more friction contact area and the load (from the joint tension) is spread across a wider area so less movement (= reduction in bolt tension) during settling. 

I think there is a belville version of the Nordlocs. Perfect (if there is room to fit them)  as  joint settling won't result in any loss of tension.

BobP


Jay Scheevel
 

Just added a pdf file that will be useful to you Mick. Here is the link:

https://jabcamit.groups.io/g/main/files/Unbrako_engguide.pdf

 

Jay

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of mikeGoog via groups.io
Sent: Thursday, February 11, 2021 8:17 AM
To: main@JabCamit.groups.io
Subject: Re: [JabCamit] Flywheel bolts

 

Oh Dear Mick,

 

Purely triggered by your very correct initial question I tried to add my tuppence worth agreement: no intention of querying your thought pattern.

As for the bolt shank: thread length needed calls for knowledge of the thickness to be clamped with necessary allowances as well as step size availability of suitable quality steel ‘Unbrako’ (?) socket headed bolts.

 

Regards,

 

mike.

 

From: Mick O'Connor via groups.io

Sent: Thursday, February 11, 2021 3:09 PM

Subject: Re: [JabCamit] Flywheel bolts

 

FWIW Mike,

Your response was as useful as a chocolate teapot !

My question (which you failed to answer) was “is this the correct Unbrako part number for the flywheel bolts”.

Your comment on shanked or full thread bolts just agreed with my comment as to why Jab didn’t use shanked bolts in this application.

So, I used my engineering loaf and moved your reply to my ‘junk folder’

 

Mick

 


On 11 Feb 2021, at 14:05, Marc Bourget <marcbourget@...> wrote:

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.

 


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts

 

FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com





 

Virus-free. www.avg.com


Marc Bourget
 

Touchy, Touchy!   :^)

The neverending story of typewritten vs. spoken communications.   Senders lack tact and recipients often fail to consider that failing and respond to the "wrong inference".

Never seen either of you be snarky up to this point,  don't see the need to start!

Onward and upward


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of Mick O'Connor via groups.io <mickoconnor909@...>
Sent: Thursday, February 11, 2021 7:09 AM
To: main@jabcamit.groups.io <main@jabcamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW Mike,
Your response was as useful as a chocolate teapot !
My question (which you failed to answer) was “is this the correct Unbrako part number for the flywheel bolts”.
Your comment on shanked or full thread bolts just agreed with my comment as to why Jab didn’t use shanked bolts in this application.
So, I used my engineering loaf and moved your reply to my ‘junk folder’

Mick


On 11 Feb 2021, at 14:05, Marc Bourget <marcbourget@...> wrote:

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com







Ken MacLeod
 

I’m not answering the question either, just suggesting that many have used ARP bolts. They have a good head size and more completely apply pressure to the Nordlock washer.

On Thursday, February 11, 2021, 12:15 PM, Marc Bourget <marcbourget@...> wrote:

Touchy, Touchy!   :^)

The neverending story of typewritten vs. spoken communications.   Senders lack tact and recipients often fail to consider that failing and respond to the "wrong inference".

Never seen either of you be snarky up to this point,  don't see the need to start!

Onward and upward


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of Mick O'Connor via groups.io <mickoconnor909@...>
Sent: Thursday, February 11, 2021 7:09 AM
To: main@jabcamit.groups.io <main@jabcamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW Mike,
Your response was as useful as a chocolate teapot !
My question (which you failed to answer) was “is this the correct Unbrako part number for the flywheel bolts”.
Your comment on shanked or full thread bolts just agreed with my comment as to why Jab didn’t use shanked bolts in this application.
So, I used my engineering loaf and moved your reply to my ‘junk folder’

Mick


On 11 Feb 2021, at 14:05, Marc Bourget <marcbourget@...> wrote:

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com







jabcamit@...
 

Hi Mick, I understand that (what you wanted to know). I wasn't responding to you - I was responding to another contributor on this thread. Many people still fail to understand the first step in the  sequence of events that causes bolt failure. 

Have a look at this thread  (no-one shout at me if you are already using these and I'm telling you something everyone knows - or feel free to shout if it makes you feel better))

https://www.nord-lock.com/en-gb/nord-lock/products/x-series-washers/

BobP 


Mick O'Connor
 

Mike,
This isn’t a new design or idea,
Jabiru specify Unbrako socket head screws for the flywheel attachment. For a 5/16 crank, the screws are 5/16 x 1 1/4 UNF. If you update the fixing to steel plate and Nordlok washers, you need same screw but 1 1/2” length to account for added thickness  of the plate and washers (7mm in my case).
These Unbrako screws are available in 1932 or 1960 spec.

Mick

On 11 Feb 2021, at 17:15, Marc Bourget <marcbourget@...> wrote:

Touchy, Touchy!   :^)

The neverending story of typewritten vs. spoken communications.   Senders lack tact and recipients often fail to consider that failing and respond to the "wrong inference".

Never seen either of you be snarky up to this point,  don't see the need to start!

Onward and upward


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of Mick O'Connor via groups.io <mickoconnor909@...>
Sent: Thursday, February 11, 2021 7:09 AM
To: main@jabcamit.groups.io <main@jabcamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW Mike,
Your response was as useful as a chocolate teapot !
My question (which you failed to answer) was “is this the correct Unbrako part number for the flywheel bolts”.
Your comment on shanked or full thread bolts just agreed with my comment as to why Jab didn’t use shanked bolts in this application.
So, I used my engineering loaf and moved your reply to my ‘junk folder’

Mick


On 11 Feb 2021, at 14:05, Marc Bourget <marcbourget@...> wrote:

Parallel point - I remember a hint not to select a grip length equal to the thickness of the part you're attaching.


From: main@JabCamit.groups.io <main@JabCamit.groups.io> on behalf of mikeGoog via groups.io <mikephallam@...>
Sent: Thursday, February 11, 2021 5:54 AM
To: main@JabCamit.groups.io <main@JabCamit.groups.io>
Subject: Re: [JabCamit] Flywheel bolts
 
FWIW, Mick,

Use your Engineering  loaf !

E.G. Are they rolled threads as opposed to cut ?
And IMHO plain shank has a better chance of not cracking at the (stiffness)
change of section to parallel rather than close to the bolt head.

mike.

-----Original Message-----
From: Mick O'Connor via groups.io
Sent: Thursday, February 11, 2021 1:47 PM
To: JabCamit
Subject: [JabCamit] Flywheel bolts

Need to buy new longer flywheel socket head screws as am installing plate
and Nordlok washers.
I’m surprised Jab didn’t specify bolts with a suitable length plain shank
rather than dull thread items?
Can anyone confirm these are the correct Unbrako items :
5/16” x 1 1/2” UNF socket head cap screw (full thread) 1936 Unbrako black
oxide finish ?


Mick








--
This email has been checked for viruses by AVG.
https://www.avg.com