My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Clutch decision
After a month and a half of deliberations, I finally pulled the trigger and ordered my new clutch today. I never really had issues with mine in 45,000 miles of driving, but I didn't beat on it much. It would shift clean @ 6600 rpm and at least go through the gears one time. I never pressed it more than that. Others, I know, have had several installed. Some have problems with the pedal sticking to the floor and some have slipping issues. The stock unit is made by Luk and is attached to a dual mass flywheel that is shock absorbing. The disc itself has an unsprung hub and is organic faced. The same setup is used in the Caddy CTS-V and their owners, for the most part, seem unhappy with their clutch performance, also. My first concern was some groaning, on take-off, from I'm guessing the flywheel. Also the thought of spinning a 2 piece cast flywheel up close to 7k rpm makes me nervous. My first car, a 65 Mustang, had a stock flywheel come apart and it almost sawed the car in half. I won't take the chance of that happening to the R!
The first option I considered was the LS7 clutch, but for my application it wasn't the right choice. It is also made by LUK, and in looking around the Vette forums they have some of the same issues that we do. At high rpm they will stick to the floor. In spirited driving they slip and boil the fluid and won't release clean. They have real nice street manners, as they attach to a lighter single mass flywheel and have a sprung hub disc with an organic lining. For a street driven, unmodified R it's probably a reasonable choice. Also, the setup is not real expensive.
My next look was at all the aftermarket clutches, and they all have mixed reviews behind LS engines in Vettes, GTOs, and CTSs. The entry level units tend to chatter and be harsh with slightly heavier pedal pressures. Monster Clutch possibly has the best following along with Spec clutch. It seems they are both reliable for racing, but are not really that street friendly. Prices are around the same as the LS7 package. They also have available twin disc units that are expensive and tend to be noisy.
A friend of mine works out at the GM Proving Grounds, close by, in Milford MI. He talks frequently with Mark Stielow, one of the test drivers there. Mark is well known in performance circles, and his latest 69 Camaro is currently making the rounds of all the car magazines. He runs a lot of the top end challenges and road and track events, for street cars. Anyway his latest ride has most of the current ZR1 Vette drivetrain in it, including the dual disc clutch. It seems GM realized the problems of the LUK clutches and went in an entirely different direction with the ZR1. They went to a German company named ZF Sachs, that does a lot of Formula 1 development on clutches, shocks, and harmonic balancers. They asked for and received a dual disc clutch with tremendous holding power, yet light pedal pressure and consistent feel. After nosing around a bit, I discovered a couple of the premier high performance shops in the country are endorsing and selling this clutch. Katech Inc and Lingenfelter Performance have both recently developed retrofit flywheels for mounting this clutch in just about any Gen 3 or 4 powered vehicle. The stock ZR1 flywheel WILL NOT work in anything but an LS9. The LS9 crank has a 9 bolt flywheel flange, where as all other LS cranks use a 6 bolt flange. I ordered the LS9 slave cyl., but it's just possible our stock slave may work - I'll measure both once I receive the new one. I wanted the LS9 anyway because of the mileage on mine and the desire to run an remote bleeder. The cost of this package is significant because of the custom flywheel, but either the billet steel Lingenfelter unit or the billet aluminum Kateck piece gives me piece of mind when I hit the strip! You can expect to pay $1300. - $1500. for one of these setups. I should have it in hand by the weekend and I'll post a few pictures then.
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Funny you should be doing that. I've got the LS7 setup to go into mine soon even though I'm at 55 k miles and still working. Guess we'll be able to compare notes soon.
The LS7 clutch is an improvement over stock (esp. a worn stock) but isn't designed for the track. Didn't think there were any for our trucks made to beat on that wouldn't also be a pain on the street. Your alternative sounds promising Topspin, bet there are others looking for the same compromise.
The cost of this package is significant because of the custom flywheel, but either the billet steel Lingenfelter unit or the billet aluminum Kateck piece gives me piece of mind when I hit the strip! You can expect to pay $1300. - $1500. for one of these setups.
Running the motor you've built, (don't know if you've got scatter shield), that's peanuts for the increased safety.
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Thanks for doing the leg work, looking forward to the pics and your opinion of performance. While you have all of this out, I wonder if Quick Time makes one of thier bellhousings for the SSR?
Wow Topspin...remember the good old days when you could just drive down to the local speed shop (on every corner) and pick up a ZOOM Power brute clutch and disc. Sure do miss those days!
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
I'll try to clear a few things up, if possible. The clutch I ordered is used in the ZR1 Corvette and is manufactured by Sachs. Sachs is a Germany based company that has plants around the world. I believe they have operations here in the States, but I don't know if they produce that assembly here. The engine in the ZR1 is the LS9, which shares some components with the LS3 and LS7, along with some dedicated parts one of which is the crankshaft. The crank has a 9 bolt rear flange that has a dedicated 9 bolt flywheel, so that flywheel will not bolt on any other Gen 3 or 4 engine. The dual disc clutch demands a somewhat unique flywheel. Both Lingenfelter and Katech have addressed this problem with custom flywheels that have the standard 6 bolt Gen 3/4 rear flange and the bolt pattern and offset needed to mount the LS9 clutch. These custom flywheels are what really drive the cost up, as they're around $800 per copy. The one thing you get is either a billet steel (Lingenfelter) or a billet aluminum (Katech) that will offer you explosion protection over the cast flywheels used in the factory applications. There's one other company in the market place with what they claim is a billet steel conversion wheel made by "the original flywheel manufacturer". It's a place called Zip Corvette and I know nothing about them or the product. Katech has great credentials in the Nascar and Trans Am circles and I have had dealings with them in the past and never been disappointed. I went with their aluminum wheel as it is rebuildable and is 7# lighter than the other.
Concerning the LS7 clutch, I just don't know what to think. It's built by LUK, just as our stock units are and is of very similar design with the self adjusting pressure plate. Some have problems with them exactly the same as some SSR owners have. The more I'm finding out the more I believe that the self adjusting feature contributes to the problem clutches. The pressure plate is designed to slowly ratchet, to maintain pressure, as the disc wears. Once the clutch slips excessively and generates enough heat to boil the fluid in the slave cylinder, the travel of the throw out bearing is compromised and the clutch adjusts when it shouldn't. This is a non reversible feature without removing the clutch. Then when the fluid cools and full travel is restored over flexing of the release fingers can occur and weaken the clutch. That could be why some work and some don't. Or possibly quality control is just poor in the manufacturing at LUK. Anyway I'm rolling the dice with the ZR1 setup, as I plan to build a larger displacement motor, with an 4" stroke, that will have more torque than the LS2.
Unfortunately, I won't have any road testing for a while here in balmy Michigan. I usually open the door for the first time around April 1st - a fitting day for me and my projects!
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Thanks for doing the leg work, looking forward to the pics and your opinion of performance. While you have all of this out, I wonder if Quick Time makes one of thier bellhousings for the SSR?
Quick Time currently doesn't make a bell housing for the SSR as it is unique. I had one ordered. When I went to install it the clutch wouldn't fit. There's an offset issue internally. Ross at quick time is willing to make them but needs an assembly with the housing to do so. Since I had an engine fire I haven't gotten to the point of pulling out the assembly and sending it to him. But I think this will happen in the near future. I think the price is somewhere between 400 and 500 dollars, if I remember correctly
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Greg, I probably won't go to a replacement housing with the billet wheel going in. I don't intend to drag race it much, but I wanted one or the other for piece of mind. It's possible that the one Wilddesert tried would work with the shorter single-mass clutch/flywheel setup.
Anne, it's good to see you enthused - if you were a little closer you could come and row the gears on it for yourself.
I hear ya Bruce, it is money well spent!
Hey Spook, how you been? I sure remember the old Borg & Beck and Long Style days! It's funny, back then you wouldn't be caught dead with a diaphragm style clutch in your street machine. Of course the drawback to the popular B & B was the severe pedal pressure. I remember remaking and beefing up clutch counter shafts and pivots all the time. Now, I believe every factory clutch out there is of the diaphragm design, because of the soft pedal feel.
I was very surprised at the line from the Clutch master cly. to the reservoir. On my R it's not clamped on either end and quite loose, with evidence of leakage, at both ends. If you have fluid loss, you might want to check there and clamp those areas.
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Last edited by Topspin; 02-17-2011 at 07:37 AM.
Reason: sp.
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Mr Sin, I certainly agree with you! By the way, I'm curious as to the condition of Dave's flywheel when you removed it? How "used up" was it compared to the first one you removed and what was the comparative mileage? Mine at 45k miles is getting noisy and has a weird shudder when starting out. I'll be real glad to scrap that thing!!
My project for tonight was mounting the new reservoir and remote bleeder. Got the bracket done, painted, and bolted in place. Now the fun stuff begins, trans. and clutch coming out.
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My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
After tearing the old junk out, I thought I'd do surgery on the old flywheel to see what makes it tick - oops I mean clunk!
Photo 1 is the 2 piece flywheel separated - not an easy task at all. This piece is not intended to be serviced, just replaced @ about $800!
Photo 2 is the guts of the wheel. It has 3 coil springs controlling 3 fingers for torsional load relief. I could see where the springs originally were in contact with the fingers, but now have a lot of clearance in each direction. I'd guess the heat and constant loading have relaxed the tension and compressed the springs. The two faces had all kinds of slop, both rotationally and in the forward/back direction too. I could measure .080" of separation between the two faces. It was probably getting to the dangerous point with 45k miles on the clock.
Photo 3 is the pressure plate, which was still in serviceable condition. It's interesting as it has different finger sizes and installed heights. They work in an progressive fashion to give a steadily increasing pedal resistance. The 3 lower fingers are what trigger the self adjusting feature. The disc showed only minimal wear.
Photo 4 shows the rear engine cover containing the rear main seal. It's a very good time, with the clutch out, to inspect and most likely replace the rear main seal. Mine is showing some sign of weeping, and oil contamination is certain death to a new clutch.
I'm learning about the hydraulic release system as I go. It's certainly counter to all I've ever learned about throw-out bearings. The slave has the t.o. bearing actually preloaded against the fingers, and is limited to .950" of travel. Wear will certainly be an issue with this setup and I'd replace the bearing any time I was in the bellhousing. I also plan to replace the pilot bushing while I'm staring at it. It MUST be removed with a puller. The old trick of packing grease in it and forcing it out with pressure is wrong on these engines. The cranks are core drilled and there is actually a welch plug, behind the bearing, that seals the oil passages. If that plug is disturbed, oil pressure, to the bearings, could be lost!
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Topspin, you say your flywheel is (was) pretty much junk at 45k. As we know you are, um... performance oriented , you probably used it pretty hard. How long do you think it would be safe for a driver that just cruises? Not babying it, but normal driving, just jumping on it occasionally.
From what you described, it would probably give some feed back before failing.
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Topspin, you say your flywheel is (was) pretty much junk at 45k. As we know you are, um... performance oriented , you probably used it pretty hard. How long do you think it would be safe for a driver that just cruises? Not babying it, but normal driving, just jumping on it occasionally.
From what you described, it would probably give some feed back before failing.
Find out soon, mine's coming out very soon. Approx 55k and never hard on the clutch.
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Actually Bruce, I'm not real hard on my stuff. I've probably run it hard, through all 4 gears, less than a dozen times in the past 6 summers. My wife loves going cruisin in it so much, I'm afraid to break it and get the verbal abuse. I really look at it as a cruiser, but I like knowing it will perform if needed. Also, I've had 4.56 gears in it for 5 yrs. so that helped considerably in terms of drivetrain wear and tear. I would consider my flywheel wear to be average at the worst. The clutch and flywheel surface actually looked great and would have many more miles left in them. It's the danger of the flywheel coming apart that was the real concern. I'm hoping to finally have the new setup in hand Friday and check the slave fit then. I'm anticipating having to make a spacer for the ZR1 slave.
Hdfl, I'm interested in how yours will compare at 55k miles.
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Find out soon, mine's coming out very soon. Approx 55k and never hard on the clutch.
That'll be interesting, to see if you have the same condition.
Quote:
Originally Posted by Topspin
Actually Bruce, I'm not real hard on my stuff.
I stand corrected.
Quote:
Also, I've had 4.56 gears in it for 5 yrs. so that helped considerably in terms of drivetrain wear and tear.
That should make life easier for the clutch.
Quote:
I would consider my flywheel wear to be average at the worst. The clutch and flywheel surface actually looked great and would have many more miles left in them. It's the danger of the flywheel coming apart that was the real concern.
Hmmm... that makes me wonder if they're all that way? I mean is it a design that is inherently self destructive, or a quality of assembly problem? If I remember correctly, the first one Lonnie took apart was pretty loose, but I don't remember the mileage.
Anybody with high mileage but operating smoothly, out there? If so, how many miles, and how do you drive?
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We routinely replace clutches on trucks with dual mass flywheels that have in excess of 100,000 miles. Though these flywheels often have a lot of slop, I have never seen one come apart other than loosing or breaking a damper spring. These trucks are diesels and are thus low rpm applications, but the trucks are usually worked hard every day. I don't think the average SSR driver has anything to fear about one of these flywheels letting loose in normal operation, but I do think the conversion to a single mass flywheel is a good upgrade and a fix for a lot of the complaints the stick SSR's seem to generate.
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Greg, I think you hit the nail on the head. this dual mass technology was really initiated with the heavy equipment industry in mind and migrated over to trucks, then cars. Using it in 3000 rpm applications is considerably safer than in 6500 rpm LS2s. Knowing that loading goes up at the square of the rpm increase, you're looking at more than 4 times the loading in our applications. Also, looking at all the moving parts involved, I'm not at all convinced any kind of dynamic balance is maintained, which also becomes more critical as the rpm increases. What really was eye opening was the lateral slop the flywheel had developed. It pulls the clutch/ disc out of perpendicular to the input shaft and would cause binding and excessive wear over the long haul. In fact, in writing that, possibly that is part of the sticking clutch issue? I've been snooping around several forums and the CTS-V crowd calls the noise from their dual mass the "Parade Clunk". I get it too, having experienced the rough ride in stop and go traffic. On one of the pickup truck forums, there were several complaints of broken dual mass units, with actual flywheel separation! Personally, I would never reinstall a dual mass unit. To me the theory is sound, but the mechanics of the unit I'm looking at are poor. A coil spring, seeing that kind of loading, and subjected to that amount of heat over a long period of time is marginal at best! In a racing engine, to this day, the valve springs continue to be the least reliable part of the entire engine.
As a side note, the stock SSR slave cylinder is on national back order. We all know how well GM looks after us SSR owners, so that's just another reason to look toward an Vette type assembly.
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Last edited by Topspin; 03-03-2011 at 08:26 AM.
Reason: sp.
My SSR: 05 6 sp. with 4.56 gears, ZR1 clutch, Edelbrock intake, Lunati cam, Crane rockers, C6 modified pan
Finally received my new clutch/flywheel, and my initial feeling is very positive. The total weight for the new pkg. is 48.5#, compared to 74# for the stock SSR pkg., and about 57# ( I haven't actually weighed one myself ) for the LS7 combo. The #s Katech and Lingenfelter are throwing around are 700 hp at the wheels and 800 lb. ft. of torque. Lingenfelter says " tested to over 700 hp " and Katech says " proven to 700 rwhp " - good enough for me, I trust both places!
Photo 1 is the Katech aluminum flywheel that has a replaceable steel friction surface.
Photo 2 is the slave side of the Sachs dual disc pressure plate. It has consistent finger shape, size, and height, unlike the LUK plates.
Photo 3 is the flywheel side of the clutch with one disc removed. I like the totally captured floater plate, that leads me to believe the claims of no noise from this dual setup. Both discs have sprung hubs along with Marcel mounted faces. They even have 2 piece springs, which I've never seen on a disc before, that should give a nice progressive cushioning.
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, you probably used it pretty hard. How long do you think it would be safe for a driver that just cruises? Not babying it, but normal driving, just jumping on it occasionally. 
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