lilspit1

I have a 1994 LT1 with a 6 speed standard transmission.

My clutch has started to slip and I am getting ready to put in a new clutch assembly.

I have been told that I will have to replace my flywheel because dual mass flywheels cannot be turned or resurfaced.

Is this accurate?

If so does anyone have a recommendation for what make and type of flywheel to install?

Should I install a single mass aluminum?

StealthLT4

I'm far from an expert on the subject, but are you sure you have to replace the flywheel? Can't you just do the clutch?

In case you do need to, I'd go with a lightweight steel flywheel. Much more durable than Al, and the not-so-extreme lightness will greatly help drivability as well.

Strick

If you don't have any upgrades in horsepower, don't bother going to a single mass wheel. You can find new dual mass wheels on flea bay at fair prices. Make sure you need a new dual mass. Check it out using the FSM.

dchildress

I also have a 94 with about 94K on it. I had my clutch replaced about 8K ago and the idiot that did it convinced me that I did not have to replace the DM and he could simply turn it. WRONG ANSWER!!! It chattered and was hard to engage. I had less than a couple inches of take up making it rough to engage smoothly. Worse yet, it started a terrible vibration at 3000 to 3200 rpm then again at 4000 to 5500 rpm. This vibration would actually hurt your head if you had the top on it shook the car so bad. I finally gave up and bought a new DM off Ebay from a guy that bought a crate LT4 and hooked it up to an automatic. A second clutch kit and flywheel later (and a ton of bleeding of the cylinders) and it is back to smooth again. Best thing, the vibration is gone.

Short answer, yes you should replace it.

Do a search on the subject.....this comes up all the time.

1stvette94

This is probably going to cause some debate, but I just replaced the clutch on my 94 with a zoom stock replacement clutch from jegs for 300. Comes with the clutch, pressure plate, throwout bearing, roller pilot bearing and alignment tool. All I did was scuff up my flywheel with heavy grit sand paper. I only have 67k on my car and the flywheel appeared to be in very good condition. No stress cracks and pretty smooth. I drag race the car and have about 30-40 runs on the new clutch. I had over 150 on the old clutch. It is working great! I could not be happier with the results. It grabs great, far better then the old one witch was slipping. It engages smoother now when I take off. The old one would make the car buck a little. I think it depends on the condition of your flywheel if you can do this. I did it because I race with someone who is a gm mechanic and does a lot of performance work on vettes. He told me I should be fine using the old flywheel if it looks good and your not making a ton of power, which I'm not. I have about 330-340 chp right now. If you are going to do this, there should be a paint mark on the old pressure plate. Make sure you mark the flywheel where this paint mark is. The new pressure plate will have a paint mark as well that you need to match up to the old one.

GREGGPENN

When I asked the ZFDoc (ZFDOC.com), Bill, who's the "expert" on ZFs, said to do as described above. However he said to use maroon scrubbies vs heavy grit sand paper. The point is to clean vs resurface before reusing. He also said a couple of bluish spots are normal. OTOH, bad wear would require replacement.

He said you can take a pic of the DMF after disassemby and email it to him. Assuming it's a clear enough pic, he would be able to advise on your need to replace or not.

gp

lilspit1

Thanks.

lilspit1

Any suggestions on what type of flywheel to install?

lilspit1

move up

RandyJ75

Do a search on DM flywheels. Since you have not told us how many miles your car has, it is hard to say. Common thought is that they should be replaced at about 120K. As for what to replace it with, remember that if you do not use a DM, you will hear some noise from your ZF transmission. Go to the site Greg mentioned and do some reading.

Randy

lilspit1

I have 50,000 miles on the car.

The clutch has just started to slip and only does it when it is put under a lot of stress. There does not appear to be much slippage at normal driving and shifting.

The car is not raced and is street driven only. No clutch popping or dragging.

Cyclonite

FSM = Factory Service Manual...not the 1" thick Haynes book you buy at autozone that covers 10 years worth of cars, but the 3" thick book that covers your one year of car. Check on fleabay for them, or in the back of your owners manual there may be an address to send off for one. Don't bother going to a dealer to ask for it...they'll just tell you to order it from your owners manual.

90steelblue

.. i went with a carolina clutch kit (stage II), and single mass Steel flywheel. feels very close to stock and was not too expensive.

Do some searching.. and you'll know more than most shops. When i brought up the subject of match balancing the fly wheels.. several shops here in NJ (including a chevy dealership) had no idea what i was talking about and never perform that service.

larryfs

96LT4GS

I put a centerforce dual friction clutch and a fidanza aluminum flywheel. It grips like you will not believe and I spent a total of about 400 bucks, but the downside is that it rattles like hell.

lt4obsesses

The FSM will say that ckutch replacement requires replacement of the dual mass flywheel. Is this absolutely neccessary? Depends on the condition of the flywheel. When I replaced my clutch, we just sanded it down a little, but it was in pretty good shape. You cannot turn a dual mass due to the rubber vibration dampening material in the center. Ala the previous post, it will ruin it.

If I had it to do all over again, I would have put in a single mass, perhaps aluminum, with a performance clutch. While you're in there be sure to check your clutch fork assembly. That we didn't do, and we had to go back in because for some reason the pivot ball had developed grooves that caused the clutch fork to rub against the pressure plate.

96lt4c4

The DM can be resurfaced if its not in to bad a shape. I did mine on a lathe. Removed about .005 of material. I installed a custom dual friction clutch with a new factory style PP. I had no problems at all, even launching the car at the drag strip.



If you put the flywheel in a lathe you can run Allen set-screws threw the front half of the flywheel into the back half to make the the 2 half's perfectly aligned. It takes a little setup to do it this way, maybe thats why everyone says it cant be done.

Crusin

I just had my clutch changed at a garage and they stated I should have the D/M/F machined. They did this and then installed the clutch. It shifted fine at low speeds but when I shifted into first gear and gave it some gas the engine just reved up. I tried this more than once with the same results. Happened in 1st and 2nd when given gas. Could the clutch be installed incorrectly or is it because the D/M/F was machined causing it to go out of balance? The machinest said that maching the flywheel wouldn't hurt anything. I am not to sure about that assessment. Any logical advice would be appreciated. Thank you

GREGGPENN

That's not a balance issue. It SOUNDS like the pressure plate isn't working correctly. That's assuming they didn't remove 1/4" of DMF material! LOL

What brand clutch set did you buy? Or was it provided by the garage?

I think it's on the garage to diagnose/fix -- if so.

cv67

As said clutch phasing and the balance is real important.

Wonder if that trans shop forgot that part.
No way would removing a few thou metal removal do that

Grease on the PP disc also will make it chatter.