Clutch recommendation needed for L88/454 10.5"

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

Maybe a double clutch

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

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

KAOS said:

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

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

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.

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?????

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

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

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

KAOS said:

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.

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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

KAOS said:

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.

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Those CF clutches with the weights are CRAP

KAOS said:

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

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

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....

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.

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?

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.

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.

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?:bullshit:

big2bird said:

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?:bullshit:

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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.