On my way home wed night, something went in the tranni on a hard downshift. I pulled the tranni to take a look, and a spring has come out of the clutch disc. This is the SLP LT4 pressure plate kit, and I've had it in for 30k or so miles. I've never had a problem with it until now.

In looking for a replacement flywheel, I found Autozone & Advance carry a flywheel called "Standard Flywheels". Is this a flywheel rebuilt from an LT1 core? If so, it should be counterbalanced for an LT1, right? Anyone ever use this before? (It's only ~$55 from Advance)

Was this failure due to a defect, too much power (Last week, I only dynoed 285 rwhp 310 ft/lbs), or was it just driver error? What would you guys recommend replacing it with? I definitely need something for a daily driver, but strong enough to hold a few more bolt ons (headers, tune, etc ...).

Thanks for any input,
Thomas.

 

I've looked at those before and done some reading on them, basically it's just a reman unit as you said. As far as reman I would assume just a basic inspection for cracks & min. thickness and a resurface. It's probably your best option if you don't want to pay lots of $ for a new/aftermarket one or don't want to deal with a machine shop in getting the original resurfaced. I'm not sure on balancing though. You'd either have to contact them or wait until it arrives and look at the flywheel yourself.

It could be due to a defect, although I'm sure hard downshifting wasn't helping any. I've done a couple nasty downshifts before (enough to squeal the rear tires) on my stock clutch and never had any problems.

What kind of new clutch are you looking for?

 

If the "Standard Flywheels" flywheel is a reman stocker for ~$55, that's great. I am looking for an inexpensive flywheel to replace this one with. I would have my original turned, but I already did that when I put the SLP clutch kit in, and thought it would be best to replace it this time instead of having it turned down again.

For a replacement clutch, I'm looking for something smooth to engage and still able to hold a little over 300hp with no issues. I read good things about the McLeod Performance Clutch Disc (7500 rpm shifts) and am considering going with this disc.

Does anyone know if I can just have my LT4 PP resurfaced, or do I need to replace it? I've never had a pressure plate turned before, and don't even know if machine shops can do it.

Thanks for the input,
Thomas.

 

I've never heard of a pressure plate being resurfaced. Don't know if it can be done or not. If it was me I'd take a piece of sandpaper and a block and make it even again so the new disc would break in properly, or else get a new one.

 

Do you have pictures of the disc/spring? I can help diagnose it if I can see it.

 

No problem. Here are pics of the disc, the pressure plate, and the flywheel.

What do you think?

Thomas.

 

Looks like the spring wore away at the window (opening where spring is) and caused a stress riser. This is very common in disc failure. When you downshift hard or when you take off from a start and dont slip the clutch enough, the spring compresses to its solid length (can't compress any more) so all the rotation energy gets put into the cover plate and flange (cover plate is the piece that broke). Repetition of that causes failure.

Main possibilities for failure, the radius on on the window corner (where it broke) wasn't shaped comepletely/good finish during stamping and the spring was not transmitting loading in a completely rotational direction (out of plane loading, like trying to split the assembly apart).

Kind of hard to explain in words without showing someone. I think I have a simliar feeling in my clutch now. Hope this helps. If not I'll try to get some pictures and labels for anyone who wants more.

 

Thanks for the explination. So basically, it wasn't a good enough disc to hold up to the abuse I gave it?

What do you think about the pressure plate ..... Should I reuse it as is, get it resurfaced, or just replace it?

Thanks again,
Thomas.