Sam Ruger

I bought my '96 LT4 off an Oklahoma car collector. In turn, he had found it on an Atanta, Georgia car lot. He said they had put in a new clutch.

About a thousand miles after I bought it, I noticed clutch chatter in reverse. I E mailed the seller about the work order for the clutch. No reply. This went on for months. I contacted the Chevy dealership that did the work. Since I didn't buy the car from them, they refused me their work order. They did not deny they sold the car or replaced the clutch.

Of course, one can only drive so far before things get worse. They did.

I consulted with a well known on line DMF specialist and my local trani shop. They were not in agreement. The trani shop wanted my car in and out in 24 hours. They did not want it sitting around while parts arrived as per the DMF specialist who requested photos of the trani inspection to decide what was wrong.

So I had to buy everything, in advance, that could possibly be wrong or the shop would do so, with overnight shipping, and probably include a worthless POS Chinese throw out bearing and put it in.

So I bought the very LAST OEM throwout bearing left in Germany, then ordered SPEC's Stage 2 clutch and their extra mass flywheel. I take it all to the shop and authorize them to replace the slave and clutch forks as they saw fit.

And I asked for all the used parts back in return as I handed them a blue painted SPEC pressure plate, flywheel, pilot bushing, and US made throwout bearing.

And, today, they handed me back a blue painted SPEC pressure plate, flywheel, pilot bushing, and US made throwout bearing.

WTF?

The shop had taken out the exact same stuff (installed by a Chevy dealership in 2011) I had given them to put in!

This shop had 25 years experience and analyzed what went wrong. It was not SPEC. The error occured when some dumass Chevy shop mechanic ("Mr. Good Wrench") applied way too much lube to the throwout bearing. Centrifugal force spun it out on the clutch and resulted in a hot spot on the flywheel. Everything ruined.

The slave and clutch forks were all brand new, exactly as the seller claimed.

And now, because of "Mr. Good Wrench" I'm out nearly $ 2,000 for a job that should never have been needed to be done at all except for this dumass and his love for lube.

But I will say the following:

SPEC's US made throw out bearing is nylon lined. There is no possible way for SPEC's products to damage an input spline on a trani. The trani shop was stunned when I asked.

"You couldn't damage that for anything," they replied.

But it was on my workorder that it be inspected.

The reason it was on my work order was because of Internet claims trying to link SPEC with spline damage. Those claims are pure crappola. Between the spline and the throwout bearing it woud be SPEC's throwout bearing that was damaged. Anything else is impossible.

And I have a SPEC made heavy duty throw out bearing they claim to be superior to LUK's (and obviously China's) with less than 5,000 miles on it that I will sell for $ 100 to prove it.

Or you can buy the Chinese one for $ 44 and discover the difference.

But all is not well in "Sam Ruger land". As long as the trani was out, I had them replace the seals and trani fliud. I chose Amsoil as I use it in my motorcycles.

I drove home listening to that trani howl.

If the people who buy the lightweight SMF flywheels are happy, they must be frigging deaf. It's louder than the engine and there's nothing LOUDER than a corvette engine.

So my "clutch story" is not only to share my tale of woe for one mechanic's over exubberance with lube but also to ask about trani weight oil. I'm aware that the trani wasn't actually designed for GM's recommended oil weight. That weight exists only for one European car. However, it's much heavier.

Having shared my tale of woe I'm hoping someone will share theirs on using the heavier European oil. What effect does this have on gear howl? I would think it would lessen it.

But what else does it do?

I have messaged SPEC to make sure I did not accidentally get a "lightweight" flywheel. If I got the right one then I will say this:

I don't like Amsoil.

Seals

I too have a 96 CE lt4 with 30k on it that had a new clutch put in right before my purchase. It chatters in 1st and reverse. I had it checked out by the corvette paramedics in NJ and they told me I still have the duel mass pp in it. Was told that I can replace it or live with it. I am living with it. After I milk it out of first a little, it fine.

mtwoolford

Sam, I've taken the liberty of editing your distressing, but I'm sure, too often true story

I have a 96 with a SPEC stage 3 plus clutch and lightweight billet steel flywheel.

First, I went with a Stage 3 metallic lined clutch disc rather than a Stage 2, because, in my experience, not only do they last longer than organic or ceramic faced disc, but more to the point, as your situation illustrates, it is possible to contaminate a clutch with lube or oil, and a metallic disc is much more tolerant of this type of abuse.

Second, While I am somewhat deaf, I am not "frigging deaf" . Initially, my clutch was somewhat noisy, but as I drove it, (I theorize) the springs in the sprung hub of the clutch disc softened up somewhat and the noise decreased significantly (or with a extra mass flywheel, will go away completely ?);

Lastly, I change my transmission oil on a regular basis, and I always use whatever the Chevy dealer recommends and sells, always with good results; and no, I have no experience with Amsol or BMW oils.

Sorry that you went through so much misery, but it appears you tackled this job head on and have done everything right. good luck

Klondike

For your trans oil, AmsOil makes what I think is the very best thing you can put into a ZF6. It's their synthetic "Manual Synchromesh Transmission Fluid". It's SAE 5W-30
I've run it in mine for about 4 years now and it beats everything else by a long way. The trans is quiet and shifts like butter. When I used the Castrol recommended oil it shifted like a Peterbuilt! Oil technology has come a long way since the ZF was made and they have a lot better stuff out there now and the AmsOil is the best of the bunch.

lt4obsesses

I recently put in the Spec 22lb FW with the Carolina Cutch stage 2 on my hotcammed LT4. Also, run the Amsoil fluid. while I experience the chatter, although not in reverse, but in nuetral and at low rpm acceleration, I don't get alot of "howling".

Sam Ruger

I'll run it with the Amsoil for awhile in it and see if the howl goes away. It shifts great with Amsoil.

Sam Ruger

OK. It sounds like the neighbor's cat is caught in the gear box. I can't imagine this much gear whine will disappear on it's own. I have confirmed I was shipped the "extra mass" flywheel. So I'm thinking of changing to Castrol TWS 10W60 or drop Amsoil for GM's "special additive". Opinions?

856SPEED

I can tell you that even the heavier steel aftermarket flywheels will not completely dampen the gear noise of a ZF6 tranny. The black tags are even a little worse...the later model blue tags had gears cut a little different but have a lower torque rating (not much). Both blue and black tag transmissions are built very well and can take a lot of punishment; that said it comes with the cost of gear noise; like the rock crusher M22's of yesteryear. Unless you have the extremely heavy OEM dual mass FW that GM utilized to dampen the transmission noise from the ZF, you will have some gear noise at neutral, some in the higher gears at lower RPM put to a load, like going up hills. The heavier after market steel FW's out there will help, but will not completely mask it like the extremely heavy OEM unit. The transmission is probably fine (as long as you are running synchromesh fluid at the proper level). Also you might notice when pushing in the clutch at idle, it goes away or if you raise the idle speed with the accelerator somewhat it goes away; this is normal ZF noise with a aftermarket FW.

Now clutch chatter is usually a different story. I have clutch chatter in reverse and a little in 1st gear. That is because I run an aluminum, lightweight FW with a Stage 2 SPEC pressure plate/disc that has a pretty good clamping force and good friction material. This happens when you let the clutch out at lower RPM's. That can also be caused from contamination from oil or other fluid on the FW as well. It is interesting to me about your results with AMSOIL in it; others seem to like it quite a bit; but I guess that is hard to determine right now in your situation what is actually going on.

Now there is the ZF DOC out there who others on the forum have had great luck with I believe add a shim or something to the transmission to eliminate the noise all together regardless of the FW/clutch set up; others who know more about that can chime in or do a search on ZFdoc; lots of stuff on Bill at ZFdoc that I have read here all with good results.

I would assume based on the story here you have "normal" clutch operation if you are running "aftermarket" clutch parts; other than your GM mechanic and his love affair with over lubricating parts!; Just guessing based on personal experience

lt4obsesses

My next thought is this, what throw out bearing did this latest installer use? You said the Spec was nylon lined, but was that the one that was put in this time? If they put a throw out from the black tag, it won't have this lining and will cause all kinds of noise on your blue tag.

Also, just to be clear, the only thing that gets lubed on the throw out bearing is where the fork attaches to it, that's it, nothing else.

I, nor anybody else, can really to a noise diagnosis from a description. What you call a loud howling may be the normal gear whine of the ZF to someone else. However, I would take it back to this latest installer and have them drive test it. If the sound is pronounced, and it has the correct amount of fluid in it, then there is probably something else at play here. When I did my conversion, one of the important things I kept coming across in my research and conversation with Jim Jandik at Power Torque, was the importance of making sure the transmission was fully seated before torqing down the bolts. It can be a very teadeous process, and some may be tempted to tighten the bolts before everything is aligned. The transmission should be within a 1/4 inch of the bellhousing before tightening the bolts. So, perhaps, your selected shop, in the 24 hr in/out requirement, tried to cheat on the alignment?

Proper TO bearing?
Proper TO bearing installation?
Proper alignment?
Proper installation of driveshaft? (indexed and reinstalled as such)

Point is, I really don't think trans fluid is your issue here. I personally would not take my car to shop that insisted it be in and out in 24 hours for this kind of proceedure. I'll bet money this is where things went south. JMHO

bob guzzy

I doubt the same guy, that put your clutch in, that put my clutch in my 90, but I found the same thing, grease all over the place.

I took apart what was suppose to be a clutch that was in the car for 10K miles, they didn't even bother to clean up inside.

When I put a clutch in I like to have as close to operating room like conditions as I can get, some of these guys treat a clutch like crap they never bother to wash and degrease anything, some don't bother to wash there hands before touching the clutch plate.

It's bad enough this 90 has the clutch beater axle,333(great for an automatic) but a greasy install topped it off

Z51JEFF

I switched to Amsoil in my 91 ZR-1 thinking this might quite down some of the trans howl,it didnt so next time around Ill run the Castrol.I didnt read your entire post but is this the only transmission shop in your area,if so business must be hoppin over there.

Klondike

The dual mass flywheel acts just like the front harmonic damper. It keeps the crankshaft pulse vibrations from rattling those big gears in the ZF when it is in neutral. With a solid single piece flywheel, all those pulses get right to the transmission. In neutral there is nothing loading the other end of the gears, so they clank back and forth like a coffee can full of marbles. I've heard the black tag ZF is worse because the gears are straight cut and a little heavier than the blue tag that has beveled gears. It doesn't hurt anything, but is annoying as hell with the clutch released idling in neutral. Some people say it rattles a bit under light load at highway speed. No oil is going to silence this unless it was so thick you couldn't shift it either.

Sam Ruger

I contacted "Doc" who asked for me to record the noise and send it to him. Impressive reply for someone not getting paid to reply.

There's no gear noise with the trani in neutral and clutch out.

I considered the possibility that the trani is misaligned but figured if I took it back to the shop they'd just deny it. Any suggestions?

The howl seems to have actually decreased. Why I don't know. Perhaps I've gotten used to the noise. I have certainly learned to turn the stereo up.