Clutch adjustment

MidOHasp · #1 (**permalink**) 06-28-2004, 12:53 PM

For those of you who happened to watch any of my burnouts on Saturday, this problem is (relatively) unrelated:

2 WEEKS AGO (ahem...) I noitced that my clutch was slipping in higher gears (3,4, and 5). Heavy throttle applications, revs would just climb. I also noticed that the clutch takeup seemed to happen at the top of the pedal travel.

At the fling, I felt the same thing. I could easily white the tires in 2nd, but if I was cruising in 3rd or higher gear, and I got on the gas, the revs would climb (with no resulting increase in speed).

I haven't been able to diagnose if the clutch fork is coming back all the way (hydraulic clutch). Is there a chance that if I adjust the pushrod from the slave cylinder to the fork to be shorter, that this would alleviate the problem? Only 1800 miles on the clutch and not much of it has been like my weekend in London.

It feels like something in the adjustment. It used to take up about 1/2 to 2/3 of the way on the pedal travel, now it's in the last 1/2 inch.

Thanks...
JP

Mike Simard · #2 (**permalink**) 06-28-2004, 03:32 PM

You should settle in for some clutch adjusting. Do you have a threaded rod from the slave to the fork?
Theoretically, you should adjust it so that at rest the throwout bearing has no pressure and can spin freely. You may do that and then possibly not have enough travel to disengage the clutch. If that's the case, keep lengthening the pushrod until the car goes into gear without grinding. Hopefully you'll have enough total travel so that the throwout bearing doesn't have pressure on it when the clutch is out.
Good luck!

ENTDOC · #3 (**permalink**) 06-28-2004, 05:43 PM

JP,my car does exactly the same thing and it has from the beginning.I have a slave system and plan to adjust this week.I will keep you posted.It does seem odd though that there seems to be no slippage in first or much in second. chuck

Great Asp · #4 (**permalink**) 06-28-2004, 06:24 PM

Mid,

I have replaced (2) clutches in SPFs.

Your description, along with the age of your car (1670), sounds more like you pushed metal on the flywheel surface. I have 6,000 miles, and I have never adjusted the clutch.

Normally, an aluminum flywheel is installed on SPFs. Not ALL of the flywheel is aluminum, but the surface for the clutch is.

Adjusting does not seem to be the answer to me, but I hope I am wrong.

CenterForce makes a nice unit if you have to replace yours.

Eric

mylesdw · #5 (**permalink**) 06-28-2004, 06:39 PM

I had the same symptom and it was just a matter of adjusting the push-rod as already described. It does not need much adjustment to 'unload' the pressure on the clutch and all is well again.

Slippage will always be worse in the higher gears because the gearing causes the car to appear heavier as far as the engine is concerned. The engine applies the same torque to the flywheel but the resistance from the drive train is much greater in the higher gears.

sllib · #6 (**permalink**) 06-29-2004, 06:21 PM

For what it's worth, there was an article in one of the Ford magazines last month about break-ins. They claim that clutches have to be broken in just like brake pads, especially in hypo applications, or slippage results. If I were home I'd look it up for you.
Bill Stradtner

Excaliber · #7 (**permalink**) 06-29-2004, 10:37 PM

McLeod recommends 400 miles of STOP and GO driving, not freeway driving mind you!

I'm sure my setup will be VERY hard on the clutch. High first gear with sticky tires and well over 600 horse. I all ready burned the 11.5" unit and am installing the 12" McLeod.

,,,no matter what clutch I use, the high gearing and sticky tires WILL 'cause trouble if not used carefully. That is: DON'T drop the hammer on the clutch in ANY gear.

Just ran 11.904 at 121.27 with the "bad" clutch I got now. Nice gentle start with SOME clutch slippage which MAY have actually helped lower the ET. 60ft time was 2.0 seconds.

MidOHasp · #8 (**permalink**) 06-30-2004, 04:53 AM

Oinie,

Read all about your 1/4 mile at gasholes.com

I'll try the adjustment first and if that doesn't work, I'll replace it.

BTW, it was the Ford Racing "king cobra" clutch setup and I always wondered if it would hold up. If it was just adjustment, maybe it will hold up a few thousand more miles. If not, I guess I answered that question!!! McLeod or Centerforce, here I come!

Lowell W · #9 (**permalink**) 06-30-2004, 06:03 AM

Well, I'll be dipped in sh!t and rolled in the hay... Dammit, JP, it's too bad you didn't come by and notice my note for you on the seat of my car!

I had the IDENTICAL problem at the fling on Saturday. After a hot day of Columbus city driving and a couple of hard 2nd gear launches Friday night, I noticed, on the way to the Speedway station, that I could induce clutch slippage in 3rd or 4th gears and that I had no clutch free play. It was as if something had become bigger rather than worn smaller. My first thought was that I must've boiled the clutch fluid and a bubble was preventing the clutch from engaging fully, so I bled the clutch at the Speedway. No change. In London, I loosened the bracket which holds the slave cylinder to the block, allowing the cylinder to cock forward a bit and getting me enough free play to limp back to the hotel. On the way back to the hotel from London, I stopped and bought a hacksaw and a piece of 1x2, then, back at the Fairfield, Tom Walega (Thanks again, Tom!) and I blocked the clutch in the disengaged position, dropped out the operating rod and cut it about 3/8" shorter. Not having any other way to round the end, we decided to practice third-world auto mechanics and took turns rubbing the rod on the concrete. We had it about half done when a fellow Cobra owner (big thanks to the guy in the red FFR also!) brought us a file on his way back from getting dinner. We replaced the operating rod, adjusted the clutch and everything worked fine for the approximately 500 miles home.

So... we cured the symptoms but what the heck is the disease??? I've never experienced a clutch which gets tighter rather than looser. I suppose something might be wrong inside the bellhousing, but, aside from the above, the clutch behaved no differently from before, and now it's the same as when it was new. No chattering, no clunking; nothing. Is it possible that the slave piston or master piston suddenly stopped retracting fully into the cylinder bore? I don't think break-in has anything to do with this problem. This is a Centerforce clutch. My clutch (and motor) was broken in like a baby and, while I've drag raced it on several occasions, this clutch in a car this light is probably loafing 99% of the time. I agee that slippage would not be as noticeable in first or second gear because, with the lower overall gear ratio, the clutch doesn't have to work as hard. Also, since revs build faster in the lower gears, you don't have as much time to notice the slippage.

Eric: I haven't replaced any rear tires, either.

So... what the heck here? Why would a heavy duty clutch, properly broken in suddenly need to be adjusted for MORE free play, with NO other detectable changes?

And, for any of you undecided guys reading this thread, had this been a big block motor, accessing the the clutch slave cylinder from the top would have been impossible, even for a guy with my long skinny arms.

Lowell

MidOHasp · #10 (**permalink**) 06-30-2004, 06:46 AM

Lowell,

Sorry I never met up w/ you at the Fling... i was looking forward to it!

Sounds like your problem WAS identical to mine. So the adjustment theory is hopefully correct. I wish I knew what could have possibly caused this. I know I have a leaky clutch line that I'm going to replace, but I'd assumed that would cause the opposite problem. I wouldn't be able to disengage the damned thing. In any event, glad you got yours fixed up. The pushrod I have between the slave cylinder and the fork is threaded, so I will adjust it back a wee-bit.

Thanks all...

JP

392cobra · #11 (**permalink**) 06-30-2004, 06:56 AM

Less free play as the clutch wears is the norm.

As the disc wears and gets thinner,the fingers/diaphram moves out towards the release bearing.

JP,
Good to see you have a threaded adjustment rod.Makes life a lot easier.

Excaliber · #12 (**permalink**) 06-30-2004, 09:53 AM

Fred has it right, as the clutch wears down you have to "back off" the linkage to get the free play back.

My threaded adjustment rod was not "locked" in position and backed itself off giving me so MUCH freeplay it was hard to shift when I first got the car.

Lowell W · #13 (**permalink**) 06-30-2004, 02:12 PM

Weeelllll... I didn't believe you guys, but now I guess I do. I looked in a manual for another vehicle and it mentioned leaving space in the clutch master cylinder for the extra fluid as the clutch wears.

I should have mentioned in my previous post that the adjusting nut on the operating rod was at the beginning of the threads so there was no way to "shorten" the rod besides cutting some off and then adjusting the nut back out to give the correct free play.

So... I guess we know what caused it now, don't we?

Lowell

MidOHasp · #14 (**permalink**) 06-30-2004, 02:17 PM

Lowell, what you're saying is there's not enough adjustment in your nut to take care of the length of the rod?

I'm pretty sure I understand now. Thanks for clearing that up.

Lowell W · #15 (**permalink**) 07-01-2004, 11:07 AM

JP,

Well...sorta... I guess another way to put it is that my rod is so long that my nut is 'waaaay down there... Or...uh...I know, I know: When my rod's all the way in, my nut...uh... No, I mean, when I pump this thing up, the rod... Well, let's just say it's no longer a problem: I have the solution in hand!

Lowell

G.R. · #16 (**permalink**) 07-01-2004, 09:49 PM

now that was an answer

GeorgiaSnake · #17 (**permalink**) 07-02-2004, 03:01 AM

I've had the same problem with my setup. I have shortened the rod twice (cut nearly an inch off). First and second no problem. Slippage when I apply full throttle while running 60, 70, 80 in third or fourth gear. I can move the clutch arm when the clutch is disengaged so it must be loose enough

Is it time for a better clutch and pressure plate assembly to mate up with my aluminium flywheel? Could I have glazed the clutch disc when this first happened?

Randy

MidOHasp · #18 (**permalink**) 07-02-2004, 04:36 AM

Quote:

Originally posted by GeorgiaSnake

Could I have glazed the clutch disc when this first happened?

Randy

New question, thanks for bringing up that possibility...

If that's the case, can you score the clutch disc surface with some sand paper to remove the glaze? Had that happen to some brake discs once after a day at the track. Though I toasted the brakes, but I just bled the fluid and hit the pads with 100 grit for a few seconds. Like new...

Clutch seems like a different animal. Maybe not?