I had a couple of posts about noise in the clutch on my 3.4DOHC 5-speed with a Fidanza aluminum flywheel here: https://www.fiero.nl/forum/Forum2/HTML/129134.html and here: https://www.fiero.nl/forum/Forum2/HTML/129179.html. Once I got everything apart I found the six flywheel bolts backed out. It was suggested a new thread be started so the actual problem would be the topic.

This was not my first aluminum flywheel on a car. I had a custom Tilton Engineering aluminum flywheel on a turbocharged Olds 215 V8 and never had a problem with it. I had heard stories about problems with Fidanza (and others), but I discounted them because of my previous experience.

I'm sure this is solvable, but I'm going to go back to a steel flywheel because I don't want to deal with this again.

Neil

Did you "Locktight" the bolts ? use "star" washers ?

I think the "solution" is use the red or green loctite, and ARP bolts.

The clutch is going out on my del Sol, so I just bought a whole kit that includes clutch and a Fidanza Al flywheel. Also grabbed the ARP bolts for both the flywheel, and the pressure plate. Haven't pulled the plastic off the flywheel to look at its instructions yet, but I'm pretty sure Fidanza recommends using red or green loctite.

Found this thread when looking up issues related to the flywheel, as I know a lot of Hondas are running the Fidanza flywheel: http://www.preludeonline.co...-247309/#post3031549

I think what really happens is not the bolts turning and getting loose, it is the aluminum cold flowing out from under the bolt heads. After the aluminum has flowed out, the bolts are not tight any more, but not because they have backed out. The locktight will keep the bolts from backing out, but won't do anything about the cold flow problem. Increasing the area that the bolt heads contact would be a help, I would consider uning one of the steel plates that are used under the bolts when a flexplate is installed, that should spread the load better than just the bolt heads contacting the aluminum flywheel. Larry

When you say "Cold Flowing" do you mean the aluminum actually is soft enough to deform from the pressure of the bolts? Or is it a product of the thermal cycling and the bolt pressure?

I don't have an aluminum flywheel, but am just curious..

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Build thread for my 88 + 3800NA swap

The aluminum is slowly squeezed out from under the bolt heads so they loose their tension. same type of thing as extruding aluminum. Aluminum is very soft compared to steel so takes a different type of fastner to get the same performance out of it. As soon as the tension is reduced enough the flywheel starts moving under the bolt heads which makes things much worse. Having an aluminum flywheel come loose is far more common than having a steel one come loose. Larry

quote Originally posted by trotterlg: Increasing the area that the bolt heads contact would be a help, I would consider using one of the steel plates that are used under the bolts when a flexplate is installed, that should spread the load better than just the bolt heads contacting the aluminum flywheel.

If anyone has a picture of one of those steel plates, maybe they could post it. Thanks.

This from a 3.1 but you will get the idea, they are used on flex plates because they are thin and also need to spread the load over a larger area so they don't crack around the bolts. It is easy to see how small an area really is in contact with the bolt head. Larry

[This message has been edited by trotterlg (edited 07-17-2013).]

quote Originally posted by trotterlg: This from a 3.1 but you will get the idea, they are used on flex plates because they are thin and also need to spread the load over a larger area so they don't crack around the bolts. It is easy to see how small an area really is in contact with the bolt head. Larry

I considered reinstalling mine with the steel plate (in fact, one place referenced tack welding the heads of the bolts to the plate!), but the seats for the bolt heads are recessed below the rest of the surface face. Unless you turned the whole face down to the same level the plate would be over dead air space.

[This message has been edited by sspeedstreet (edited 07-17-2013).]

quote Originally posted by trotterlg: This from a 3.1 but you will get the idea...

Thanks for the picture!

quote Originally posted by sspeedstreet: ... the seats for the bolt heads are recessed below the rest of the surface face. Unless you turned the whole face down to the same level the plate would be over dead air space.

This was what I was wondering about (after reading those excellent links in the other thread). I suppose another option would be to machine little spacers/washers that would precisely fit in each recess under the steel plate.

Assuming that using a steel plate was a possiblility, since the flywheel bolts would now be sticking out further, would there be any danger of the bolt heads then interfering with anything to do with the clutch?

[This message has been edited by Patrick (edited 07-17-2013).]

quote Originally posted by trotterlg: The aluminum is slowly squeezed out from under the bolt heads so they loose their tension. same type of thing as extruding aluminum. Aluminum is very soft compared to steel so takes a different type of fastner to get the same performance out of it. As soon as the tension is reduced enough the flywheel starts moving under the bolt heads which makes things much worse. Having an aluminum flywheel come loose is far more common than having a steel one come loose. Larry

Even if that is happening, I wouldn't expect it to happen within the span of only 100 or 5 miles of usage. The keyword in your description is "slowly." It'd take quite a lot of torque, or heat, or both, to do that within 105 miles, I would think.

quote Originally posted by trotterlg: I think what really happens is not the bolts turning and getting loose, it is the aluminum cold flowing out from under the bolt heads. After the aluminum has flowed out, the bolts are not tight any more, but not because they have backed out. The locktight will keep the bolts from backing out, but won't do anything about the cold flow problem. Increasing the area that the bolt heads contact would be a help, I would consider uning one of the steel plates that are used under the bolts when a flexplate is installed, that should spread the load better than just the bolt heads contacting the aluminum flywheel. Larry

Bingo.
The materials science term is "creep".
The somewhat elevated temperature of engine operation speeds the creep.
However, if you go drag racing or similar and dump a lot of frictional heat from the clutch into the flywheel, you'll speed it up that much more.
I hear that Ford had problems with aluminum flywheels in supercharged Mustang Cobras and has since gone back to iron/steel.

Also, aluminum is no longer used for wiring in buildings for that reason... the electrical connections loosen up and can start fires.

I had this problem with the Fidanza aluminum flywheel I had modified to install on my Indy's SD4 engine when i switched it from automatic to a Getrag 5-speed transmission. It came loose not long after, started rattling and basically ruined it.

I used ARP bolts cut to correct length and used Locktite (see below) but I still thought I had F-'d something up. I thought maybe I had cut the bolts too long and they were bottoming in the crank holes instead of clamping the flywheel properly. I replaced it with a stock Duke flywheel - no problems since.



Oddly enough, I have NEVER had a problem with the aluminum flywheel on my GT. It's been on there since 2001. I'm not sure what "brand" it is, but I know it is NOT a Fidanza flywheel.


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3.4L Supercharged 87 GT and Super Duty 4 Indy #163

[This message has been edited by fierosound (edited 07-18-2013).]

Geez, the more I read about this, the more reluctant I now am to buy a Fidanza aluminum flywheel for an '88 Formula I'm about to acquire (which needs a clutch). I'll be autocrossing the car, and I don't wish to be dropping the cradle every few months dealing with a loose flywheel.

Interesting. Luckily for me, I've never had this problem with the Fidanza flywheel on my 3.4 V6.

quote Originally posted by fierosound: Oddly enough, I have NEVER had a problem with the aluminum flywheel on my GT. It's been on there since 2001. I'm not sure what "brand" it is, but I know it is NOT a Fidanza flywheel.

Must be a critical difference in how they're made and/or how they attach to the crank.

quote Originally posted by Blacktree: Interesting. Luckily for me, I've never had this problem with the Fidanza flywheel on my 3.4 V6.

Seeing as how this is apparently quite a common problem with these Fidenza flywheels (and not just with Fiero applications), what is it that you've done that might've improved its longevity?

How long has it been installed?

Is this a car you drive much?

Do you ever "push" it at the track/autocross?

[This message has been edited by Patrick (edited 07-18-2013).]

quote Originally posted by trotterlg: Increasing the area that the bolt heads contact would be a help, I would consider uning one of the steel plates that are used under the bolts when a flexplate is installed, that should spread the load better than just the bolt heads contacting the aluminum flywheel. Larry

Unfortunately the Fidanza flywheel has counterbores around the bolt holes, so the spreader plate isn't going to work.

The reason the Fidanza has counterbored holes is because they used to make the flywheel centers the same thickness as the iron/steel flywheel but the centers would break off (http://www.j-body.org/forum...php?f=41&t=34558&a=1) so they increased the thickness.

West Coast Fiero sells some really nice looking aluminum flywheels that have a large fillet going from the hub to the friction area. They are also a bit thicker than the steel flywheels (which is convenient if you intend to use the longer ARP flywheel bolts). I suspect that the large fillet makes them significantly stronger in that area. Since they drill the bolt holes for your application you can have them sized correctly for the shoulder on the bolts you're using, and get optimum under-head contact.

I ended up just replacing my Fidanza with a stock iron flywheel when it came loose the second time though.

[This message has been edited by Steven Snyder (edited 07-19-2013).]

Man, after reading all this, I am so glad that an offer I made to a member here on his Fidanza aluminum flywheel wasn't accepted.

quote Originally posted by Patrick: How long has it been installed? Is this a car you drive much? Do you ever "push" it at the track/autocross?

I installed the flywheel in 2006. Since then, I've driven the car about 15k miles. I've been to the drag strip several times, and have autocrossed the car a couple times as well.

I'm really not sure why my experience has been so different from everyone else. When I installed the flywheel, I just torqued the bolts (new bolts) to factory spec, in 10 ft-lb increments, and that was it. No loctite, no special washers, none of that. When I removed the flywheel a couple years ago to replace the friction surface, the bolts were still tight.

Blacktree, you could have the early production one if it's that old. Some of the early Fidanza flywheels had centers pop out (see the link in my previous post) and then Fidanza changed the design. The early ones could have been a different alloy, and also maybe have better fitting bolt holes. That could explain the difference.

My flywheel has the counterbores for the bolt heads.