LannyL81

Car is a 95 LT1, 137K miles on it. I have had it only since 110k.

Could this be the original clutch? It is the Valeo.

Disc thickness is right at 0.25"

As shown the pressure plate and DMF are discolored...but no leaking fluid and the inside plate moves freely.
Checked DMF for flatness.....had an area where I could get a 0.004" gauge between flat edge and flywheel surface. Most of the surface was a 0.002" gap.

So with this many miles on the clock...
1) just put everything back on?
2) replace the clutch and attempt to clean-up the DMF...$350?
3) replace clutch and flywheel (SMF)...$850?










All I wanted to do was to replace the leaking rear main seal....

blue94

Check the amount of movement in the DMF, if total is less than 1.5 inches scotch brite the flywheel and use it. If you get a stock type pressue plate and kit and do have to go with a SMF later then you should only have to change the disk to a sprung hub type.

The main question for you is how did the car/clutch drive before? If no issues maybe get a clutch disk and go (not sure if 25 is good or not)

LannyL81

Car drove fine...no issues whatsoever. This is a stock engine and I drive pretty easy.

PLRX

from the FSM

GREGGPENN

IMO, you don't even had to measure/conform to the 1.5" slop rule. Why? When the DMF springs are shot, you can hear significant rattling at idle. And, even then, it won't cause damage to the car/motor. It's an annoyance.

Since you weren't complaining about bang, bang, bang at idle, I have to think you've got more life in the DMF. I'd probably do a new clutch disc (and maybe PP while you're in there...depending on how many more years you plan to keep it.)

Reason I say not to worry about the DMF is fluid is the main reason one has to go. If you can keep the original clutch running, that might be better -- if the DMF seal craps out in the near future. It means you don't have to clean-up/save a new clutch (in the event of failure).

Also, Bill @ ZFDoc says clunking DMFs don't cause any harm. As long as the seal is still in tact, you can keep running it.

So, the main considerations [for replacement] are the seal and ability to hold when pulling hard.

LannyL81

The movement is no more than 1.5 inches....all smooth, no noise. I called Bill (ZF Doc) and talked with him....his recommendation is to scrotch brite the surface and put a new clutch in it.

I could just put a new disc in, but think it would be better to go with a new clutch kitl....due to questionable remaining life in springs and release bearing.

I have read where othes have gone to a lighter SMF steel flywheel from an F body, but never came across the details of what to use or what else had to be changed-out.

Expect that I will just order a stock clutch kit from Carolina Clutch and wait. Still need to R&R the rear main seal and CLEAN all the parts I took off.

Speaking of which....what is this putty-like stuff on the C-beam bolts? What is the purpose of this stuff?

GREGGPENN

If you haven't been keeping up with this subject over the last couple of years...and it kinda sounds like you haven't, there are issues with throw-out bearing replacements. As Bill probably told you, seals in the later years are pretty reliable too.

Since your clutch isn't slipping, no reason to assume the PP is bad either. IMO, invest as little as possible and reuse what you can. In this case, just get the disc and call it good.

If/when the thing shoots craps, then deal with the issue of learning about the SMF options. (There are a couple of threads on the subject.) Of course, when you convert, you'll need to replace ALL the parts. So, don't buy anything you don't have to (for a DMF) now.

What you do buy should be compared against eBay pricings. Afterall, DMFs, and DMF-related parts, should be considered firesale items.

It would be nice to say I'm wrong and someone is going to make a run of DMF FW's, but no one has reliably reported that yet. On top of that, the OEM FW's (from Valeo) are also discontinued -- which is why we've seen issues with Chinese t/o bearings.

93Rubie

http://powertorquesystems.com/

From what I read and hear, this gentleman knows his stuff, you might want to give him a call regarding good throwout bearings, etc...

blue94

use Jim as a source for parts and questions, may be a little more but US made and very good to deal with.

LannyL81

Yep...Bill recommended parts from Power Torque Systems.

I do remember reading a few threads about problems with T/O bearings...just did not pay much attention to them.

Although no slipping was noticed, I am still concerned about re-using the pressure plate. Coming up on 17 years and with almost 138k miles on it....there has been alot of shifting going on.

But the previous owner(s) must have treated the car good to have the orignal clutch last this long. And to think my 16 yr old daughter learned to drive a manual transmission with this car as well.....and it still looks good.

Power Torque Systems does not offer a clutch kit, only individual parts are listed on the website. Disc is $200, PP $300, T/O bearing $100, Fluted pilot bearing $14, and retaining clip $6...add shipping to all that and OUCH....all of this for a '95 that is worth about $6k. Yeah...I know, if money is the major factor...then do not own an older Corvette.

I will give Power Torque Systems a call.

LannyL81

Talked to Jim at Power Torque Systems.....

Have decided to re-use everything: scotch brite the flywheel and pressure plate, clean the inside of the bell housing, wire wheel all the bolts....put all back together.

Why? Because the clutch may last as long as the DMF does or as long as I retain this car. Should I still have this car when the clutch/DMF goes out...then I can either sell it or convert to a SMF/spring hub at that time.....but not now.

Thanks to everyone for all the information.

GREGGPENN

Just curious why you opted out of the disc too.

I think you're making the right choice (even if you do end up taking it apart again in the next year/two).

LannyL81

I did not replace the disc after talking with Jim at Power Torque Systems.
I told him about how I how measured the disc thickness of about 0.25" and he said a new one was about the same as the measurement depends upon hom much the disc is compressed. Also as long as all the disc pads looked the same, and how I drive....it was optional to replace. He said he just got a new supply of disc for Valeo and would send me one for $150....my choice.

I opt'ed not to...

LT4Racer

I would like to respectfully disagree with Gregg on a few items.

Concerning clutch components, I don't think it is a good idea to invest as little as possible. This is especially true if you are paying someone else, such as a transmission shop, a R&R fee for the transmission. Also, high mileage cars need attention. The car in this thread certainly meets my criteria for high mileage. What is not known or shared in the thread is if the previous owner provided some type of maintenance records along with the car. That's very important; otherwise we don't know if this is the cars original clutch or if it has been replaced.

If this is the original clutch and has seen an unknown amount of shifts during its 137,000 miles of use, the clutch components are probably on borrowed time. I would definitely replace the throw out bearing and pilot bushing/bearing. For the pressure plate, Valeo expected the diaphragm fingers on these Corvette plates to go 1 million cycles. Since the fingers are a piece of metal that flex everytime you press in and release the clutch pedal, they can and will metal fatigue. First, hairline cracks will develop. Eventually, fingers can crack all the way through and simply break off. The fingers exert what is know as clamp load in your clutch assembly; due to fatigue, over time the pressure plate may not be able to deliver its original clamp load rating. That means less holding power in your clutch assembly. I would have replaced the pressure plate in this situation as well.

It is incorrect to state that you need to replace all of the clutch components when converting your C4 from a DMF to a SMF. There are only three items that need to be replaced: the flywheel, the flywheel (crankshaft) bolts, and the friction disc. The bolts have to be replaced with shorter ones as the original GM bolts that secure the DMF are too long and will bottom out when used with a SMF. And yes, you need to use a sprung friction disc to replace the orginal solid friction disc.

Valeo is not the OEM for Dual Mass Flywheels. LuK is. Luk is the only manufacturer that made the 1989 - 1996 Corvette flywheels. Valeo manufuactured the pressure plate and solid friction disc. That was their contribution.

The fact that dual mass flywheels are discontinued has absolutely nothing to do with Chinese throw out bearings. INA is the German company that produced the original throw out bearings. Today, INA and Luk are sister companies, but INA certainly could produce the bearing assemblies for our C4's if they elected to do so. They have chosen not to.

I guess my point is that you have the transmission removed and the clutch is disassembled all the way to the crankshaft. You are completely torn down. Replace the clutch components because A, you can still get the OEM good (great) stuff parts and that is not going to last much longer, B, these parts could be original and future longevity/durability is very questionable, and C, if you paid someone else to tear this thing apart, why would you want to drop another $400 to $500 again just to replace a throw out bearing, etc?

This is my professional opinion, based in large part on the 10 months plus of research I did concerning OEM components design and current components availability for 1989 - 1996 ZF 6-speed transmission Corvettes.

LT4Racer

Correction.....I do offer clutch kits at Power Torque Systems. I assemble kits at the customer's request for which parts they would like included in their kit.

I don't show the kits on our website. The individual components are set up al a carte. I get a lot of requests for just one or two parts; for example, maybe someone would like to order a throw out bearing or friction disc only. I've even had customers order just a pilot bushing. I decided not to put kits on the website, and then have someone want to substitute a different component from what is shown in the kit. This way I can custom build each clutch kit. If you want an INA throw out bearing in the kit, I can do that. If you want to spend less money and go with a Valeo t.o. bearing, no problem. At one point this year, I had LT1 pressure plates, LT4's, LT4 Race, & LT5 pressure plates. Add to that both Valeo original friction discs, RAM Clutches custom solid discs, and multiple sprung friction discs, and that is a large number of combinations! I would rather build the kit for you and quote you for that particular kit.

Generally, clutch kits go out of here for $475 to $530. That's $100 to $200 off the individual components added together. To me, that's only marginally more expensive that what you would pay any other manufacturer/distributor/Corvette mailorder catalog for their Chinese component clutch kit. As far as I know, Power Torque Systems is the only business where you can order original real deal Valeo pressure plates, Valeo solid friction discs, & INA bearings at the same time and in one kit. The same also applies for OEM clutch forks, pivot studs, clutch master cylinders and clutch slave cylinders.

LT4Racer

For the record, this is not exactly what I told Lanny.

New Valeo friction discs measure .325" to .335". This measurement is taken about an 1/8" in from the outside edge and is an uncompressed value. You have to be careful with the calipers, as it is easy to compress the disc at this point. The discs are not perfect, so there is a small dimensional difference in a disc if you measure different spots on its perimeter. There is also a slight variance disc to disc.

The RAM Clutches custom solid friction discs I have here at the shop measure .295" to .300". These work well also and are a very high quality alternative to the Valeo disc.

I was able to persuade Valeo into making at least one more run of the solid friction discs......I bought the last inventory from them in February of 2011 and until just recently they had not manufactured another solid disc for our C4 cars. I would be very surprised if Valeo continues to manufacture this disc, as their intentions were to supply the F-Body sprung discs in any future kits. Valeo is aware that the dual mass flywheels are no longer being manufactured or even available through any means of distribution. As I'm (correctly) resurfacing used and sound DMF's, I would like to see these discs continued. What I would like and what will probably happen are often two different things!

In Lanny's case, a .250" Valeo friction disc should have been replaced without question. He gave me this value, but did say he might have compressed the disc when it was taken. He did not follow up with me on his uncompressed (free) value. If the .250" is a free measurement, sometime in the not so distance future this disc will have burnt the friction material down to the rivets. That would be a bad thing. And expensive, as it could have been easily replaced when the clutch was apart. Time will tell, or it will probably become the next owner's expensive problem.

LannyL81

When I measured the disc thickness I had the disc compressed. I agree that this disc is worn....but not worn-out...at least not yet. I decided to put everything back in as-is and continue driving it. This clutch may last another two years the way I drive or the car could be in an accident next week and totaled....no way of knowing....I just decided not to put the money into a new clutch at this time.

I did all the work myself, so there was no shop labor charges....only my time and I did get to learn "how to." Had I paid a shop...then yes the clutch would have been replaced. If I still have this car when either the spring fingers fail or the disc slips, then I will most likely replace the DMF and go to a SMF and of course a new clutch assembly. If I sell it...then the price I would get would reflect that a new clutch is needed...either now or near future. I would not sell to someone without telling this information....just not able to do this.

I have zero information from pervious owner(s) of this car. I expect this is the original clutch and since it is still going it appears that the car was taken care of and easily driven....as I do.

Again thank you for your time and information you provided. If I do replace the clutch in the future I will contact Power Torque Systems for everything.