I have a 91 Z28 that I am going to do a minor buildup on. I am planning on eventually getting a ZZ4 385 Fastburn. I would like to do a lightweight Flywheel but am not sure what works the best. Now to complicated things I"m not sure what trany I will have. As it looks now I may have a WC T5 at first and then eventually get a TKO 600. I also have a T56 in my other car but at this time I do not plan to remove it. Any Suggestions would be greatly appreciated. THANKS!!!

 

It kind of depends on what torque and rearend gearing you have. I have a 19lb on my 400 and with the 4.10 gear and 3.27 first gear of the tremec, its no problem.

 

The same flywheel will work for the T-5 or the TKO. You'd only need a different one if you went with a T-56 instead. Fidanza makes a really nice lightweight flywheel, but they're quite spendy (about $300). You can get GM lightweight one for about half that cost or less.

 

I currently have plans to run a 3.42 rear with about 425HP. I'm not even sure what the stock flywheel weight is, but I do think I want a single piece flywheel. I'll look around for the Fidanza and see what I can find. Thanks!

 

The factory GM lightweight flywheel is approximately 16 lbs. IIRC. The standard one is about double that. The lightweight one should work fine with 3.42 gears since that's what the 305, 5 speed Z/28 cars had for rear gears with the light flywheel.

 

I'm curious, why are you all asking what gears he has or plans to use? I didn't know it mattered, but what happens if he has the wrong gears?

Also, is this a significant mod (measurable freed up hp, increased traps), or is this one of those Airfoil-type, "scraping the bottom of the mod barrel for that extra .10" mods? No sarcasm intended, I genuinely want to know.

 

The advantage of the lightweight flywheel falls under the same theory as the advantage of an aluminum driveshaft. Less rotational weight means the motor spools up quicker. But you do need to have steep enough rearend gears and a light enough car to take advantage of this. If you have a really heavy car and not enough rearend gearing, a heavier flywheel helps you get all that weight moving easier when you drop the hammer. I'm running a 30 lb. Hays billet steel flywheel in my 69 Camaro, but I don't have to worry about it hurting the drivetrain too much from shock loading since I'm running a beefy Muncie 4 speed and a stout 12 bolt rear in that car. With a factory T-5 trans and the puny 7.5" ten bolt rear, a lot of shock loading on the drivetrain can be pretty destructive to the trans and rearend.

 

I'm running a GM light-weight flywheel with a 1LE alum drive shaft and 3.23's. No problems, though you have to learn to drive a bit differently, or at least I did (the lighter weight flywheel slows more quickly which is noticeable between shifts).

JamesC

 

I installed a Fidanza flywheel with a Sachs clutch over the summer. I've run 4 autocross events and an open track day since installing it. I'm very happy with it.