[Fot] TR4 ARP Flywheel Bolts Question

[Christian Marx]

My thought is that a dowel pin has no other function than matching the parts together. The pin is not a press fit in most cases.
This means, if the dowel pin get rotational forces, then all is too late and the car has to be parked.

The rotational force get transferred by the clamping force and the resulting friction between fly wheel an crank only.

Cheers
Chris 

Gesendet von meinem Windows 10 Phone

Von: Steve Yott via Fot
Gesendet: Donnerstag, 22. Juni 2017 12:55
An: 'Scott Janzen'; 'Barr, Scott'
Cc: 'FOT'
Betreff: Re: [Fot] TR4 ARP Flywheel Bolts Question

Properly made and installed that would be an good solution.  Issue is that if they are not sized properly and they should have a t-shape and be counter sunk they can cause even worse failure.

The right bolt used with the proper washer has a very large surface area and the bolt itself is shouldered resulting in a pretty strong install.

The next best thing to do IMHO is to install a second dowel pin.  The real purpose of the bolt is to hold the flywheel onto the crank but the main strength is the counter sunk flywheel over the face of the crankshaft and the dowels holding the rotation forces.  This way if the bolts should break you have two dowels which will prevent the flywheel from flying in an egg shape and destroying everything in its path.

Now the absolute best thing is to not use an aluminum flywheel!  There is a reason they are not allowed in Europe…..  Buy a steel flywheel and  use 6 to 8 bolts then most of the issues are gone.  

IMHO

Steve Yott

From: Scott Janzen [mailto:sjanzen at me.com] 
Sent: Monday, June 05, 2017 3:28 PM
To: Barr, Scott <sbarr at McCarty-Law.com>
Cc: timmmurphh at gmail.com; Steve Yott <tr4 at wi.rr.com>; STEPHEN BOROWSKI <biznzman at pacbell.net>; FOT <fot at autox.team.net>
Subject: Re: [Fot] TR4 ARP Flywheel Bolts Question

Don't you guys use steel inserts in those flywheel holes?

Sent from my iPhone

On Jun 5, 2017, at 7:55 AM, Barr, Scott via Fot <fot at autox.team.net> wrote:
This is what it looks like if you forget to chamfer the flywheel holes to clear the radius under the head. 
 
<image001.jpg>
 
From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of timmmurphh--- via Fot
Sent: Sunday, June 04, 2017 5:53 PM
To: 'Steve Yott' <tr4 at wi.rr.com>; 'STEPHEN BOROWSKI' <biznzman at pacbell.net>; fot at autox.team.net
Subject: Re: [Fot] TR4 ARP Flywheel Bolts Question
 
Thanks for the clarification Steve, that makes sense.
 
Tim
 
 
From: Steve Yott [mailto:tr4 at wi.rr.com] 
Sent: Sunday, June 4, 2017 4:56 PM
To: timmmurphh at gmail.com; 'STEPHEN BOROWSKI' <biznzman at pacbell.net>
Subject: RE: [Fot] TR4 ARP Flywheel Bolts Question
 
The reason they state to not use washers is they are afraid that the washers used will (1) not be hard enough and will compress under the bolt head and (2) all ARP bolts have very liberal radii between the head and shank.  If there is a tight fitting washer this would be strain on this radius and could break the head.
 
The 7/16” ARP bolts used on Chevy flywheels is what I fit to TR’6, late Spitfires and modified TR4 cranks.  These bolts come with the special washers to use with them.  I have used a proper washer under the 3/8” ARP bolts many times with no problems using a correct washer.  You can also use an ARP crown wheel bolt for the same purpose and these come with proper washers.
 
Steve Yott  
 
From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of timmmurphh--- via Fot
Sent: Sunday, June 04, 2017 1:59 PM
To: 'STEPHEN BOROWSKI' <biznzman at pacbell.net>; fot at autox.team.net
Subject: Re: [Fot] TR4 ARP Flywheel Bolts Question
 
FWIW
 
I just got a set of ARP 206-2802 flywheel bolts from Pegasus for the TR4.  They are for “BMC A series”.  The instruction specifically says, “DO NOT USE ANY WAHERS”, yes, all in caps for emphasis!  They further state that ARP will not be responsible for failures is washers are used.  The instructions also say, “Make sure there is an adequate chamfer under the bolt holes on the flywheel to clear the radius under the head of the bolt.”  Torque is 55 Ft-Lb with specified lubricants on the threads.
 
I’ve never had that much good luck grinding the ends of bolts and still having it square so as not to start it cocked and runing the female threads.  Maybe it’s just me😊
 
Tim
 
 
From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of STEPHEN BOROWSKI via Fot
Sent: Friday, June 2, 2017 3:28 PM
To: FOT List <fot at autox.team.net>
Subject: [Fot] TR4 ARP Flywheel Bolts Question
 
Does anyone have experience using the ARP flywheel bolts sold by Moss and others?
I understand that you may have to shorten the bolt or it breaks the rear seal???
Are they supposed to have a washer or not?
 
Thxs. Steve
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