Clutch recommendation needed for L88/454 10.5"

[KAOS]

The clutch just started slipping so I need your help on a new clutch. I have Chris McSpeed's (aka Killer) 69 vette and it has an awesome 454 bored 60 over edelbrock fuel injected 540HP engine with the stock lightweight 14lbs L88 flywheel. He said he went through like 3 different clutches/brands until the last one being the centerforce dual friction CTF-DF161675 finally decided to hold and not burn up in 2,000 miles. This one has about 7,000 miles on it of which 4,000 miles were from me for which of course I was not the most kind/gentle with my new toy. I can go with another centerforce dual friction clutch but would like others opinions on what would be a good street/strip 10.5" clutch for a car that puts down over 400rwhp on a Mustang dyno and redlines at 6,500rpms.

btw...this sucker spins to 6,500rpms so quickly its insane and I have no problem driving around town in heavy stop & go traffic with the light weight flywheel

 

[Belgian1979vette]

Maybe a double clutch

 

[BBShark]

I have no personal expereince with this clutch setup but have heard that people like the Mcleod Street Twin.

 

[KAOS]

Just a quick update...I discovered the current clutch is only rated for 425ftlbs torque so that is the reason why it burned up so quickly since I am pushing 400rwhp which is 500+crank HP. I spoke with Centerforce and I am going with their new Light Metal clutch. Its not cheap but is rated for 600+HP and will not chatter like a drag strip clutch and also is 3lbs lighter than their normal clutch assembly. So I will have even less rotating mass pairing up with my already light 14.7lbs Quartmasters flywheel allowing me to put more HP to the rear wheels and spin the engine a tad faster to 6,500rpms. Should be a fun combo indeed. I am ordering the parts next week and then installing the following week.

Rob

 

[brngrhd]

Just a quick update...I discovered the current clutch is only rated for 425ftlbs torque so that is the reason why it burned up so quickly since I am pushing 400rwhp which is 500+crank HP. I spoke with Centerforce and I am going with their new Light Metal clutch. Its not cheap but is rated for 600+HP and will not chatter like a drag strip clutch and also is 3lbs lighter than their normal clutch assembly. So I will have even less rotating mass pairing up with my already light 14.7lbs Quartmasters flywheel allowing me to put more HP to the rear wheels and spin the engine a tad faster to 6,500rpms. Should be a fun combo indeed. I am ordering the parts next week and then installing the following week.

Rob

or ask dv8 about how he like his spec 3+ that will hold what you got for sure...

 

[pcf_mark]

I have a Spec III behind an LS6/L88 clone that runs mid 11's on street tires. I incinterated a stock clutch, ate up an larger diameter GM clutch then went with a Spec. It has never given me any issues but a larger left leg. The pedal effort is definitely higher than stock. You can call their tech line and get a smart, motivated car person on the phone. They will steer you to the right parts.

 

[KAOS]

I had a new light metal centerforce clutch (3lbs lighter than stock clutches) installed about 1,500 miles ago. All has been good relatively until this morning when all of a sudden I could no longer push the clutch pedal more than 0.5" before it felt like I was pushing on a brickwall. When I started the car I could hear like a funny whirling noise that sounded like the air intake was "off center" so I popped the hood but all was good so I thought I must be hearing things and this was not a "new noise" but sure enough it must be related tot he clutch problem. I talked to the guys at Centerforce and they said it can be 1 of 2 things. Either the angle the clutch fork hitting the throw-out bearing is off at an angle such that it split the throw-out bearing or the retaining ring that holds the weights snapped and now the weights are stuck out there on the outer edges of the pressure plate. Its getting taken apart tonight or tomorrow.

Any thoughts if it is the TO bearing on how to prevent this from happening again?????

 

[KAOS]

We got the clutch/tranny out to see what happened. Looks as if the stock L88 flywheel was re-surfaced in-correctly on a slant/angle??? It has severe burn/scorth marks on one side with several stress cracks running right through the steel. I don't have the monies to burn up another fancy LM Series Centerforce clutch so I am going with a Spec Stage 3 assembly. I hope to have the car back on the road by Wednesday next week.

btw...the rest of the clutch/pressure plate looked to be toast as well

 

[Twin_Turbo]

Let me do a quick highjacking here...anyone have experience with the Centerforce DFX???

 

[redvetracr]

Quartermaster triple disc...but you have to drive it like you stole it...

 

[MYBAD79]

Looks as if the stock L88 flywheel was re-surfaced in-correctly on a slant/angle??? It has severe burn/scorth marks on one side with several stress cracks running right through the steel.

I would think that if the flywheel surface is not perpendicular to the crank centerline that will kill any clutch.... wouldn't this put tremendous stress on the flywheel bolts ?
It seems you're lucky it didn't let go at 5000+ rpm

 

[big2bird]

I talked to the guys at Centerforce and they said it can be 1 of 2 things. Either the angle the clutch fork hitting the throw-out bearing is off at an angle such that it split the throw-out bearing or the retaining ring that holds the weights snapped and now the weights are stuck out there on the outer edges of the pressure plate. Its getting taken apart tonight or tomorrow.

Those CF clutches with the weights are CRAP

 

[big2bird]

We got the clutch/tranny out to see what happened. Looks as if the stock L88 flywheel was re-surfaced in-correctly on a slant/angle??? It has severe burn/scorth marks on one side with several stress cracks running right through the steel. I don't have the monies to burn up another fancy LM Series Centerforce clutch so I am going with a Spec Stage 3 assembly. I hope to have the car back on the road by Wednesday next week.

btw...the rest of the clutch/pressure plate looked to be toast as well

Install a SFI billet flywheel. That flywheel might grenade with stress carcks and other issues.

 

[KAOS]

I got a new GM OEM stock L88 steel flywheel along with a complete Spec Stage 3 cltuch setup on the way. It has a Lakewood SFI bellhousing on it so all is good there incase I ever do grenade the flywheel/clutch.

Thanks for the tips & suggestions....

 

[KAOS]

What happened to my clutch? I recently had a new Centerforce LM series clutch installed. I have about 1,500 miles on it. When I first picked up the car from the mechanics it seemed as if all was good as it was super smooth and easy to press in. Well...sure enough a few hundred miles later it stiffened up a bit but was "tollerable" for me. Then all of a sudden one day I could hear this strange noise and then about 15 miles later I could no longer push in the clutch. The pedal would not move more than 0.5" towards the floor. I replaced the clutch with a Spec Stage 3 thinking that maybe it was something with Centerforce as when I ordered the new clutch I had not yet taken apart the old clutch.

These are pics of the old clutch & stock L88 flywheel. There are heavy burn marks about 3/4ths of the flywheel. What would cause this?
1. Flywheel resurfaced on an angle?
2. throwout bearing mis-aligned?
3. wrong sized TO bearing?
4. vertical alignment of the bellhousing is incorrect?
5. ????

Now my concern is that the new clutch does not feel right either. At times it feels like it won't fully disengage since I now grind going into reverse and then now it also slips under full WOT power shifting. I just can't win with clutches and manual transmissions. I am thinking I have got the exact same problem again that both mechanics have missed (2 separate mechanics as the car broke down when I was out of town). You can see where about 2/3rds of the flywheel & pressure plate are scrotched really bad leading me to believe that the vertical alignment of the bellhousing is not correct or the flywheel was resurfaced incorrectly.

 

[KAOS]

would having a too short of TO bearing cause this problem?

I ordered a 1.125 TO bearing as per Centerforce but now I see that some other companies say it should be a 1.375 TO bearing such as Hayes?

My concern is that the new clutch seems to be both not wanting to fully disengage (grinds going into reverse) and also is only partly engage (slips under WOT 6,000rpms shifts for about a full 1 sec). Would having a too short of TO bearing cause this problem? Any harm in trying to go with a 1.375 TO bearing? Would this give the clutch more travel to fully engage & disengage?

 

[big_G]

If the clutch is slipping and there is sufficient pedal "free-play' your clutch is toast. I've always had good luck with Centerforce clutches...my money is on incorrect install/set-up.

 

[KAOS]

Thanks guys for the great help and details on how to identify the parts and do some simple checks/measurements.

I can confirm that I have a short TO bearing.

I spoke with the 2nd mechanic that did the 2nd clutch install and he confirmed the adjustable clutch pivot ball was already set to exactly a "long" stock GM size pivot ball and that in order for him to get proper clutch fork movement that leaving it at this position was best also.

I have been in touch with Centerforce tech department and shared the links with them from the forum with the pics asking for their opinion since I am still under the 90 day warranty. The tech person was very helpful and they asked that I send in the entire clutch assebly/flywheel/etc. and they can put it into some kind of machine they got and re-create what was going on. They suggested that "maybe" the clutch fork was pressing on the TO bearing at an odd angle which I guess would put more pressure on one side of the pressure plate vs. more evenly distributed. Something about being able to use a dial indicator to examine the wear marks on the TO from the clutch fork to determine this. He was not sure on why all of a sudden I could not depress the clutch pedal except maybe the TO bearing got off angle/center? I know that when the car arrived to the mechanics via tow truck they tried re-hooking back up the clutch linkage after they ran the engine to help it steer better and were able to press in the clutch to put the car back in gear to move it but said it was very still but at least moveable. I could not move it more than 1/4" without feeling like I was going to seriously break/bend something.

I need to show the local mechanic here that did the CF first install the parts so they have the opportunity to comment as its only fair. If they did setup the install incorrectly then I will be certain to request for my labor monies refunded at the very least. I have done plenty of business with them over the years so hopefully we can resolve this peacefully.

I will keep you all posted on what both the mechanic and CF says went wrong.

 

[big2bird]

I just don't get it. What I remeber about these cars as a kid was that a stock 10.5" clutch lasted 30,000-50,000 miles with no problem, and ran fine. Did they get hot sometimes? Hell ya. But you can't pop any clutch all the time. WTF is with all this "performance clutch" crap?:********:

 

[1Michel]

I just don't get it. What I remeber about these cars as a kid was that a stock 10.5" clutch lasted 30,000-50,000 miles with no problem, and ran fine. Did they get hot sometimes? Hell ya. But you can't pop any clutch all the time. WTF is with all this "performance clutch" crap?:********:

Well.... all painted or powder coated, they look good.

Good marketing will sell anything I guess.
Nice packages catchy words like performance, speed, high output in in big colourfull adds in magazines pages.

 

[pcf_mark]

Before you get too crazy put the car in the air and take off the drive shaft. With it in gear have someone press the pedal. If you can turn the output shatf with the yoke you are home. If not you are stuck and need to get the bigger throw out bearing. When I converted to hydraulic I went through partial release hell. This was the only way to be sure. Do not leave everything connected and try to spin the tires. You have so much leverage that it can overcome a partial release. Easy check.

 

[KAOS]

quick mini-update....

I took the clutch assembly to Horse Power Sales of Pompano (forum sponsor of the Corvette Drag Racing Challenge Series and widely known for producing many amazingly fast C4~C6 vettes). I wanted a totally independent opinion on what was going on since my knowledge of clutches is non-existent. The mechanic there explained to me some of the basics about how it works and then showed me the wear patterns on the pressure plate side of the disk vs. the fly wheel side. The clutch disk is almost totally worn down on the pressure plate side so he believe the clutch was always dragging on the pressure plate side and not the other side eliminating any problems with the flywheel. He thinks that either the pressure plate is defective not allowing for enough clearance or the pressure plate was not installed correctly but found it hard to believe due to the severe wear on the disk & uneven burn marks that it would be from an incorrect install like torquing down the pressure plate bolts wrong. He did not believe it was from an incorrectly installed TO bearing.

I am fast becoming a clutch expert. The mechanic that originally did the install will see it tomorrow morning and then I will be sending off the clutch assembly tomorrow afternoon to CF to get their final opinion.

Lastly...they told me of a brand new Z06 they had installed a Spec Stage 3 in and when the guy did a high rpm shift the clutch disk blew off and literally went right through the dash. They have had 3 newly installed Spec Stage 3 clutches fail this year and now will no longer install them. They said the guys insurance company (StateFarm) hired an indpendent expert to observe the damages as they were going after them since they installed it and also GM and Spec. When the expert guy saw that the clutch disk had literally spun off and ripped right through the dash there was no more question that it was a defective part. This all came about as I now have a Spec Stage 3 installed that I am now having different problems that I never had before I was explaining to them. I can't believe my luck...looks like I got two bad clutches back-to-back.

 

[big2bird]

Another arguement for a scatter shield type bellhousing. Ask Big Daddy Don.

 

[KAOS]

I got some great news from the guys at Centerforce today!!! I am getting a complete new clutch assembly from them. I sent them off all my parts, etc. for evaluation and possible warranty claim if it was due to defective parts.

They discovered some of the fingers on the pressure plate varied in height which could have resulted in the uneven wear. Also, the wear marks of the TO bearing are close to center, however, the geometery may be slightly off not allow full clutch release whcih could also have contributed to the problem.

I am a very happy person getting a new clutch assembly since the Spec stage 3 clutch that I replaced this with is slipping and giving me vibration problems. While it does suck to have this happen in the first place going through 2 different clutches and paying twice for a clutch install it is great to have a company that still stands behind the products they sell. They could have easily said it was some sort of installation problem and then I would have been screwed as there is not much I could do once it got to a finger pointing blame game between the mechanic and the parts especially since I supplied the parts.

 

[SmokinBBC]

At least they are supplying a new clutch. Unfortunately, you have to pay again to have it installed:bomb: Or is the shop going to cut you some kind of deal?

 

[KAOS]

The mechanic that did the first install did say if it was not his fault he would cut me a deal on the labor. Hell...I have spent probably close to $8K with them over the past 4 years and always paid bill on time so hopefully they will cut me some slack.

 

[KAOS]

I finally have Kaoss (Killer) back in my hands again. I picked it up this morning...ran 3 miles down the road to get tires balanced and alignment for good measures and then vroom vroom for about 40 mins down I-95 from Pompano to Miami this morning listening to the sweet sound of sidepipes and I almost forgot how much fun the car is to drive and fast too.

"Crossing fingers" and "knocking on wood" thus far all good. I can't hammer the throttle yet for another 450 miles to let the clutch break-in properly so that sucks but I did manage to stretch her legs up to 120mph running in 5th gear at about 80% throttle. There were no more weird driveline vibration issues like before with the Spec Stage 3 clutch as the stick shift was steady & smooth. It cost a pretty penny to have these guys do the install, Horse Power Sales, but in speaking with the mechanic he did blueprint the entire install with runout of the flywheel after it was bolted up, bellhousing, air-gap, etc. and had all solid "no BS" answers. He found a few interesting things not correctly installed like the new needle pilot bearing was installed backwards, the bellhousing apparently needed different dowel pins to better center it on the block, and he had to resend the flywheel back because after the first re-surfacing job it was something like 0.002" out of spec in one area from the machine shop. The clutch pedal now is a lot stiffer than the 3 clutches that I had in there before and also stiffer than my centerforce clutch that was in my previous red 69 vette. It also has a more consistent stiff feel all the way through depressing the clutch as before you would kind of feel an initial stiffness and then it would ease up as you pushed further but this one seems to be stiff throughout the operation. Ugghhh!!! I just hope it all holds together for at least the next 20K miles. If not then I am going with a 200R4 and be done with this clutch maddness. I must say that Centerforce was very professional and customer friendly testing out the clutch to see what/if anything was a manufacturer defect and then they sent me a complete new setup but before doing so they said they spec'd out the assembly to make sure all was perfect so I would not have any problems.

Also I had a drag racing modification done to the trans since we were at the "while I am at it" junction. I sent the trans to a guy named Bob @ Performance Transmission 217-935-5352 in Clinton, IL. The main reason I sent it to him was to make sure the trans was all healthy since I was having clutch problems I wanted to eliminate any other issues and inaddition to him finding a 5th gear spacer had broken free and started chewing up 4th gear where it got wedged in the casing he "lightened/drilled out" 2nd & 3rd gear taking out almost 2lbs of material between the two gears. The idea is that the gears have two much rotating mass for the synchro's to stop them and allow smooth high rpm shifts from 6,000+rpms. The trans feels a bith notchy due to the new parts installed and setup but Bob said it should break-in nicely resulting in very smooth operation and quicker high rpm shifts after several hundred miles. Thus far it feels great...but as with the clutch time will tell after everything is broken in properly, etc. He races what he builds and is passionate about his work and the cost and turnaround time was very reasonable. Taking out almost 2lbs is some serious weight reduction but he assured me that the gears would still hold the about 550 crank HP I am putting out.

I have a few misc items to address like installing a new tach (already got it) and a full detailing and then check everything over now that the car is in my hands to make sure every last nut & bolt are secured correctly, etc. But by this Sunday I think I will finally be able to say everything is working 100% correctly and be able to just drive and enjoy cruising around town and to dinner putting on another 450 miles as quickly as possible so I can get Kaoss to the drag strip for some 1/4 mile fun and also report back in about a month how everything is doing after the 500 mile break-in period.

btw...the mechanic could not find anything wrong with the spec clutch that was in there and why it would not hold the power even at only 80% throttle (it was slipping). It looks brand new (has about 700 miles on it) and he said there were not any unusual wear marks on the flywheel wheel. I am not sure what I am going to do with a $700 spec stage 3 clutch and the lightweight pressure plate. Maybe I will eBay it and if it sells for maybe $50 vs. $700 for a new setup somebody will have better luck with it than I did.