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Discussion Starter #1
What is the ususal break-in period for new clutch? Anyone have specific procedures they normally follow?

I'm asking because I usually put about 250-500 miles of easy driving with a few power runs on mine before I really drive it hard or go to the track.

I put 250 on this one and tonight at the track it started slipping on me, I was just running on nittos launching fairly easy and did start to smell.

Cluch is a D&D SHD dual friction disk with the Motorsport style pressure plate.

Did I just totally hose the new disk, should I continue breakin and hope it comes around?
 

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I'd say continue breaking it in and hope it comes around... Thats your only option unless you want to pull the clutch and inspect... I put a SPEC stage 2 in my Cobra last monday and have currently about 300 easy around town miles on it... I have taken it to 5 grand a couple times, but shifted slowly and cautiously...no hard shifts or launching on mine yet, and its going to stay that way until 500... The clutch does seem to be pretty good now (basically no chatter on take off, shifts are smooth), but I'm still going to wait 500 until I really get on it... I still have slight chatter in reverse and if I don't really feather the clutch while slowly blipping the throttle, I will get some chatter when parking the car in the garage... I was told this is normal and usually will be completely gone after about 1000 miles... SPEC told me 300 break-in miles, but for me, its better to be safe than sorry especially when I would hate to pull the clutch again...:mad:

Good Luck...
 

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Clutch has a break in period.................doohhh!!!

I just had mine changed about three weeks ago with 5 races
under my belt so far......my guess is it to late to break it in.

No side effects yet.....................now I'll worry. I never heard
of breaking a clutch in.....say it isn't so?

If so who long and how easy is easy?
 

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Oh yea mine come from D&D to 169.00 10.5" I wish I had gotten
the 11" bad boy. Pedal pressure is nothing I like to feel
something there anyway my .02.
 

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98COBRA#770 said:
...I never heard
of breaking a clutch in.....say it isn't so?

If so who long and how easy is easy?

Yeah, the "going-rate" is something like ~500 miles of street driving, give or take.
 

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Well, I don't know if anybody read my other threads on my problem with the 11" pressure plate and Spec Stage 1 clutch, but here is the short.

Bought new 11" pressure plate from D&D and a Spec Stage 1. Put them in, and it chattered beyond belief, almost undrivable. Pulled them out, turned flywheel, put them back, still chattered.

I said (*&&(* it and took the car to the track and beat the ((^%*& out of it with slicks and 6000 RPM dumps.

No smell, no slip, but still chatters like a mother*&)_)_((**&^*(&!

I guess that I will just pull it out again, but I am damn tired of doing that. :mad: :mad:

I would like to be able to drive my car around town again.
 

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So can you guys tell me what those guys that mainly race their cars, with much less street time, do? Many of these guys install a new clutch and head strait to the track and beat the sh*t out of them, or dont care to drive it around for 300-500 street miles.I drive my Vobra on the street, but when the new trans/ clutch goes in this winter, I may not even drive it on the street before going racing.

Whats a guy to do? PRAY!?!?!?!?!?!?
 

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There must be something in the install, flywheel surface, or some variable we're not thinking about to cause all these different reports on clutch problems and frustrations. I'm guessing a mismatch in the surfaces on these severe complaints like Doc Dave's.

Last summer I installed a SPEC 3 Al FW combination in my 98. It was what everyone said to use at my HP level, even though I'm not much of a drag racer. I just could never get to liking that combination. I don't even think it was the fault of SPEC, I was told it was like this, I just didn't listen. The clutch was very stiff, chattered when cold ( no chattering if releasing at a little higher RPM than normal) even after long careful breakin, and I never could get used to the way it released (quick...would be difficult to work with DR's MHO) , and I have been driving manual cars for 45 years. However, it may be the hot ticket for launching on slicks. A lot of folks on here report loving that clutch. So...I made the mistake, not SPEC. I blame myself for lack of knowledge and purchased the wrong clutch for my use and personal liking. It was taken out a few days ago, and is in perfect condition, and has no flaws at all, and no sign of any problem with install.

Lamotta ordered a SPEC 2 clutch, and refinished the stock FW, and now I can't believe how nice it drives. No chattering driving out from the shop. Almost stock pedal effort. The FW weight matches the tune in the computer RE how fast RPM drops when coming off throttle, making it a lot easier to drive smoothly. Cruise control works better. I can't believe the difference. I am happy with my car again.

Notice how this report differs from so many others. There is something subjective about our views about clutches. MHO
 

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I followed the instructions that came with my Spec Stage II and broke it in for about 500 miles before I raced it...works great and it's smooth as butter on hot glass...
 

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I've had a Spec 2, 3, and 4 in my car over the last year. The diaphragm type clutch is very touchy because of the very small amount of travel it makes from full pressure to (hopefully) full release. The very high mechanical advantage is the only way to keep the pedal pressure low and the clamping force high.

The problem is that everything has to be perfect to avoid any chattering. The plate has to be perfectly flat, the flywheel has to be perfectly flat, and the disk better not have any very small high spots. If there is any variation in the disk thickness, it will chatter at best, and cause a hot spot at the worst.

All the "break in" is for is to wear down the high spots on the disk before you get it too hot. But only very small imperfections can be "worn down" during the break in period.

My stage 2 disk was perfect when it went in but started slipping mid year after 40+ runs. I put in a stage 4 (paddles with a hub) and it was off enough that it wouldn't disengage. I couldn't visually see anything wrong, but one paddle was slightly out of line with the other three. Could have happened in shipping or after I got it. Sent it back. Replaced with a Stage 3, which chattered very slightly for a few days, but has been perfect ever since. I have a spare plate and disk ready to go in when needed.

I just think the tolerances on the disks have to be a little tighter to reduce the number of not quite right installations. The costs would have to go up.

The alternative is to use a pressure plate with much less mechanical advantage, resulting in much higher pedal pressure and less sensitivity to the variations in the disk.

I'll take my chances.

Joe Lynch
 

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Discussion Starter #11
Joe that is good info, thanks. When we replaced this clutch I didnt bother having the flywheel turned.
There was some bluing, and some obvious hot spots but I took some sand paper discs scuffed the surface and knocked out a few, then went back over the disk with a Scotch brite/3m pad.

The surface looked and felt pretty good after that. we installed the MotorSport 11" Clutch pressure plate and the D&D SHD Disk(dual friction).

Clutch felt very good no chattering at all, extremly smooth and seems to grip well. I put about 250 miles on it and went to the drag strip.

I made a soft pass and I smoked the clutch on the first pass, I cant say that it was slipping down the track but I definatly slipped it WAY too much off the line and it was smelling
And I think the clutch was slipping and spinning instead of the tires.

I let it cool and made another pass that seemed to go better but the clutch was still smelling.

Questions would be:

1. once the clutch starts slipping like that or the driver smokes it, does it recover before it gets outright cold?

2. will not turning the flywheel affect the gripping surface and not let the clutch grap as much as necessary?

3. Will the cluch material start bedding itself into the flywheel and start preforming as necessary.

Joe, any opininions you have would be greatly appreciated.
 

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I've had a clutch (in our 427 Vette) get too hot and smell yet work fine again after it cooled down. But the source of the heat was me manually slipping the clutch to control spin. The disk was fine.

If you did the same to your disk--intentionally slipping it, but a little too much, then it will probably be fine. If it was slipping because it had a high spot on it and wasn't clamping down on the full surface area of the disk, then it will slip again until either the high spots wear down, or the localized heat becomes too much and the friction material fails and comes loose from the disk.

I know the clutch people always require that the flywheel be resurfaced or the warranty is void. But the last one I did didn't take 0.003" cut to smooth it out. It probably would have been fine.

About the only way to tell if a flywheel is flat is to cut it. I've changed disks that were worn but not slipping yet without cutting the flywheel. But I assumed the surface was good because there was no damage and the disk had not yet failed.

My opinion is that yours will be OK after a few more street miles. The Vette clutch above is still working perfectly, even after getting it hot once.

I have found that my car is really pretty easy on clutches. This is because the gear ratio is outrageously low with the 4.56 gear and 26" tires. The clutch doesn't have to slip much on launch. It doesn't really have to slip at all. I would expect to have much more trouble with a 3.73 gear, say.
 
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