Real Fiero Tech

I just installed a Fidanza aluminum flywheel on my 3.4 DOHC. The flywheel bolt holes are larger than the ones in the stock iron flywheel. Where the stock iron flywheel was stopped from rotating against the crankshaft by the bolts, the Fidanza flywheel can rotate at least 5 degrees before the bolts hit the sides of the holes. The stock setup didn't use a crank dowel but there IS a dowel hole. Should I find a dowel that fits and install it? I don't like the fact that there's just a small part of each bolt touching the flywheel.
Also the flywheel holes are recessed; if there were some washers that fit these recessed holes that would center on the bolt that would work too... but Fidanza just says to use the stock fasteners and torque specs.
I have the motor and transmission mated already and sitting on the cradle but this is bugging me. Anyone have some ideas or experience with this setup?

Pics?

Are the bolts self centering, or can you install it so that the flywheel holes touch all the bolts? I don't think it could move, but I would just cock it in the direction of travel anyways. Using washers might cause problems.

Get on the phone with A Fidanza Engineer, and if you dont like what he has to say, ask for someone else. The fastening of the flywheel to the crank is a simple matter, that should have been engineered well, there should be no slop. Worst case, have a machine shop turn some custom washers for you that center the thing.



Flywheel tech hotline 1-800-891-3608

yea I don't think its supposed to be that way.

I was thinking of installing one of these on my car too but the clutch used from WCF woudlnt' work with the fidanza flywheel.

If its tight, I don't think its going to rotate at all. Then again I have no idea what sort of forces are on that flywheel when the clutch is engaging at wot shifts.

I used this piece on my 3.4 DOHC as well, and have the same complaints, then some. The problem I encountered was that the bolt heads were so big, and the bores so small, that I could not get a socket cleanly onto the bolt head once it was snug. It took very careful torquing to ensure it didn't slip right off, and it still slipped on a few occasions. I probably could have, and should have, used washers to space the bolts out, but the factory did not have washers. I was able to get the bolts up to torque though, so I don't foresee any problems. A pic:

The primary force holding the flywheel in place is friction. Aluminum has a very high coefficient of friction.

The contact force is provided by the tension on the bolts.

I'd say try it. Bolts make poor shear pins, so they should get shear loading.

Fidanza called me back earlier today and their tech said that it shouldn't be an issue; just tighten them to factory specs. Guess we'll see how it goes. The centerbore on the flywheel does center it on the crank so its not like it will be non-concentric..

The Dark Side of Will wrote:The primary force holding the flywheel in place is friction. Aluminum has a very high coefficient of friction.

The contact force is provided by the tension on the bolts.

I'd say try it. Bolts make poor shear pins, so they should get shear loading.

I put 600 miles on my old flywheel bolts with all 6 of them loose doing 5k RPM clutch drops on new 255 width tires without breaking them. That's zero friction between the crank and the flywheel. Only the bolts were keeping it from spinning. These bolts make beautiful shear pins apparently. Also why does GM put a shoulder on them that is perfectly fit to the flywheel bore? Seems like they figure they'll be doing something besides clamping, but maybe that's just for safety in situations like I had where I didn't tighten or I overtightened and yielded them..


Aaron, my socket didn't fit in the holes either, but I was still able to tighten them because my socket was cut straight; it didn't have little fillets at the corners. In this case, cheap socket FTW!

Series8217 wrote: Aaron, my socket didn't fit in the holes either, but I was still able to tighten them because my socket was cut straight; it didn't have little fillets at the corners. In this case, cheap socket FTW!

That honestly pisses me off. I tried like 6 different Craftsmen sockets, and finally resorted to my Craftsmen impact sockets, which I don't think a person can break. Although they didn't go into the bore, their cut is very accurate and I was able to get the bolts to torque with them.

Yeah, I didn't bug the tech about that since I had already torqued mine properly, but someone ought to bring it up to them..

Ya, those FW bolts have a freaking thin head on them. I use a set of midgrade sockets, such as Craftsman / Mastercraft etc. and take them to the bench grinder and grind the opening face down so that I'm, left with a sharp opening when I need it.
Those precious extra fractions on an inch grip on the FW bolts can make a world of difference.

Series8217 wrote:Fidanza called me back earlier today and their tech said that it shouldn't be an issue; just tighten them to factory specs. Guess we'll see how it goes. The centerbore on the flywheel does center it on the crank so its not like it will be non-concentric..

Call them back, and ask for them to fax you a letter to that effect and see how they react then. Get it in writing somehow. Just in case.

It's printed in the instructions included with the flywheel.

I Don't recall anything that caught my eye, but I'm using a very non-recommended method to bolt the flywheel down:




The Pinto bolts vs factory



Fidanza flywheel in place. There are 2 hardened washers on each bolt, since I didn't find a thick enough one to keep the longer ARP bolts from bottoming out. It misses the clutch disc by 1/8"... So far, so good. Torqued to 85 ft/lb IIRC, ARP spec with 30W oil, using red loctite on the threads.

Blue Shift wrote:Torqued to 85 ft/lb IIRC, ARP spec with 30W oil, using red loctite on the threads.

Is the oil only on the flange/head of the bolts then?

cactus bastard wrote:

Blue Shift wrote:Torqued to 85 ft/lb IIRC, ARP spec with 30W oil, using red loctite on the threads.

Is the oil only on the flange/head of the bolts then?

Threads and the underside of the bolt head. I lubed the underside of the head and applied locktite red to the threads. It's really not hard to remove it with LTR in there. I read somewhere that loctite was formulated to approximate the lubricity of 30W oil for torquing shit down. We shall see, I guess.

Well, I ran the car and it hasnt fallen apart yet. I only drove it for a few minutes.. had to go back down to LA soon after, and I took the Volvo.

There was still a rattling sound coming from the transmission area. After I found that my flywheel was loose before, I didn't really check the clutch plate for loose springs. Maybe this rattling is from loose/defective clutch springs.. or its the Getrag rattle that a lot of people have talked about.

I rebuilt my transmission since the loose flywheel incident.. It has new input shaft and output shaft bearings... all new blocker rings.. etc.. I didnt replace the rear case bearings, but thats because they felt fine. They're different from the ones I had before though. I'm using a different gearbox side of the case. I do have replacement case bearings I can install if they are possibly the problem.
The noise goes away when I disengage the clutch, just as before. It sounds like marbles in a tin can. I had this noise last time I put the car together (when the flywheel bolts werent torqued right) so I assumed it was from the loose flywheel. Now that that's no longer the case.. maybe I do have loose clutch springs or something? I used this same transmission (well, parts of it) with a different clutch before and it wasn't rattling. It rattled with the loose flywheel and the Spec 3. Now it rattles rebuilt but with the Spec 3. Others with stock clutches on the other forum have reported the rattle too. Blue Shift says his car does it as well and he has a Stage 2, which is what I used to have when it was all silent.
These noises are driving me nuts!

FWIW, brand new Spec 3 and Fidanza flywheel with stock bolts here, and it's silent and functions perfectly. So I'm not sure what isn't right with yours, but I remember for a while they were sending out bad clutches, maybe you got one?

Mine was drop shipped from Spec in July; I'm pretty sure its even newer than yours..

Then it's absolutely newer than mine, as mine also sat on a guy's shelf for a few months before he gave up on the project.

Maybe they messed up a new one?

Yeah, or it's something else, like whatever the Getrag rattle is that other people have experienced and thought was a bad input shaft bearing..