Flywheel Bolts for the 60-degree V6

[The Dark Side of Will]

Shear on the flywheel bolt and play in the hole is not relevant.

The clamp load from the bolts and the friction between the flywheel and crank flange is what keeps the flywheel in place. The bolts are not side loaded.

[Series8217]

Shear on the flywheel bolt and play in the hole is not relevant.

More play in the hole = less surface area contact under the head. That's bad.

I still think my Fidanza flywheel might have kept some bolts tight if the holes were actually the right size.

[ericjon262]

thought I would add too, I saw somewhere someone saying that the 3500 flywheel bolts are a different pitch, I don't remember where I saw it, but they aren't.

[The Dark Side of Will]

When using an aluminum flywheel, the smaller surface area under clamp load leads to a greater surface pressure and greater tendency to creep.
That doesn't affect an iron or steel flywheel until the holes are close to the size of the bolt head.

My point was that the holes don't have to have a close fit because of shear on the bolts.

[ericjon262]

Fidanza 60V6 flywheel (P/N 198261) + Bully stage 4 (P/N 04-1594c) need a pressure plate bolt length approximately 18.5mm under the head. called ARP, they offer a bolt for Ford 302-351W V8, '86-'95,(P/N 150-2202) that is 20mm under head. included are .095" washers, which bring the under head length to 17.587mm, so about a millimeter short, but should be fine for just about any application.

http://arp-bolts.com/kits/ARPkit-detail ... cordID=475

[Series8217]

Fidanza 60V6 flywheel (P/N 198261)

Stay away unless you plan on modifying it to fix the creep problem.

Mine (came loose 3 times): http://realfierotech.com/phpBB/viewtopi ... =3&t=10853
sspeedstreet: http://www.fiero.com/forum/Forum2/HTML/129350.html

[ericjon262]

hmm. I want to run it because I spent money on it... but I don't want to be taking it apart to that degree on a yearly basis either... I wonder if the counterbores could be milled down and a spreader plate installed to prevent the problem.

[The Dark Side of Will]

There's a stock part that does that... it gets mentioned every time someone has this problem. Wish I had the part number...

From the thread Steven linked:
http://www.fiero.com/forum/Forum2/HTML/129350.html#p7

[ericjon262]

the trick will be to find it... might be better off getting an old flex plate and cutting it up.

[The Dark Side of Will]

It's a GM part... there was a similar one on my Northstar. Should be cake to get with the part number.

[Series8217]

There's a stock part that does that... it gets mentioned every time someone has this problem. Wish I had the part number...

From the thread Steven linked:
http://www.fiero.com/forum/Forum2/HTML/129350.html#p7

It's not that simple to implement. Fidanza had a problem with their first 60-degree V6 flywheels breaking off from the hub area. There are multiple failures documented on the J-body forums and elsewhere. They addressed the problem by making the center of the flywheel thicker. In order to do this and still have the OE flywheel bolt head to clutch plate clearances, they counterbored the bolt holes. If you mill the flywheel down to allow the plate to be used, you're back to the old flywheels that break off.

I suspect the flywheels were breaking due to fatigue from pressure plate engagement/disengagement loads. Even my second-gen Fidanza flywheel flexed a lot -- I could watch it move as the clutch pedal was depressed.

sspeedstreet identified some steel insert washers and had them installed in his 2nd-gen Fidanza flywheel after it came loose. It hasn't come loose again... yet... but I don't think he's been driving the car that much.



Also found this today: http://www.fiero.com/forum/Forum2/HTML/133235.html#p8

Another loose aluminum flywheel...

Anyway, this isn't really on topic since it's not related to the flywheel bolts but the flywheel material itself.