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View Full Version : did my clutch blow out?



rsx858
06-16-2005, 01:48 AM
first of all my clutch was already very worn when i got the car (its a centerforce)

so heres what happened: all was working well until im waiting in the grid for my next session at lime rock (track day). as i let out the clutch to get moving, the car lurched forward as if i had dropped the clutch however i hadent. This was odd to me but everything seemed ok. the following 20 or so minute session went smoothly and i brought the car into the paddock and shut it off.
about an hour later i started it back up, (it was in neutral), i pushed the clutch in, and had trouble shifting into reverse like i always do. as soon as the stick went into reverse, the car stalled. I then put the car in first gear, pushed in the clutch, and again started the car, it lurched forward and stalled again (with the cluth still pushed in). by this point the clutch pedal felt light and awkward. I bled the clutch hydrolics which appeared fine and the clutch pedal remained light.

It seems to me that either my clutch pedal no longer disengages the clutch, or the clutch is broke all together.
It just seems odd to me that i didnt notice the problem when i was out on the track but rather when i was starting the car afterwards.

what do you guys think? what should i check before i can assume the clutch has bit the dust.
thanks

(89 rx7 gtu)

[This message has been edited by rsx858 (edited June 16, 2005).]

seckerich
06-16-2005, 07:29 AM
Either your clutch disk came apart or the fingers on the pressure plate are bad. Hate to give the bad news.You could look through the inspection cover while you have someone push the clutch and check the throwout is moving properly, but it will have to come out.

rsx858
06-16-2005, 04:26 PM
i have a new pressure plate and disc, but what other new parts will i need? will i need to replace the throwout bearing? also are there any special alignment tools needed? thanks

Daryl DeArman
06-16-2005, 06:13 PM
Don't bother replacing the pp and disc without replacing the release bearing.

You will need a clutch alignment pilot tool to make certain that the disc is centered in the pp.

While it is apart look at the pilot bearing in the end of the eccentric shaft and inspect the end of the trans input shaft for galling or abnormal wear. IF you have to replace the pilot bearing, now is the time. BUT I would NOT recommend replacing it if it is in good shape...they can be real difficult to remove.

lateapex911
06-16-2005, 07:17 PM
Originally posted by Daryl DeArman:
BUT I would NOT recommend replacing it if it is in good shape...they can be real difficult to remove.


Don't I know it..........

All good advice so far. The first rule in racing..if you think it might be a problem......it WILL be a problem...right when they say "1 minute".

Sounds like a pretty standard clutch job. PP, disc, and TO bearing. I use the 4 puck unit Mazdaspeed sells. Seemed just a tad grabby but it has broken in nicely.



------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

Eagle7
06-16-2005, 07:54 PM
<font face=\"Verdana, Arial\" size=\"2\">...IF you have to replace the pilot bearing, now is the time. BUT I would NOT recommend replacing it if it is in good shape...they can be real difficult to remove.</font>
MazdaTrix sells an expensive pilot bearing removal tool that's worth its weight in gold.

------------------
Marty Doane
ITS RX-7 #13
CenDiv WMR

[This message has been edited by Eagle7 (edited June 16, 2005).]

John Herman
06-17-2005, 07:04 AM
An be sure to resurface the flywheel.

Tak
06-17-2005, 08:01 PM
No disengagement and a funny pedal sounds like a broken pressure plate spring.

In the world of wacky, I've also had the pilot bearing disintigrate and wedge against the tranny input shaft. Same symptom (clutch wont disengage), but pedal feel is normal.

Tak
#29 ITA SFR SCCA

rsx858
06-20-2005, 04:39 PM
ok i just ordered the throwout, do you guys know where i can get the alignment tool?, mazdamotorsports said they didnt have it
thanks

dickita15
06-20-2005, 07:07 PM
you can buy a generic alignment tool at any napa. it is basicly a platic dowel with the end the diameter of the pilot bearing and then a larger section the size of the hole in the clutch disc. however the best tool is a spare input shaft from a junk tranny.
dick patullo

Mike Guenther
06-21-2005, 06:21 PM
This could also be just your slave cylinder leaking past the piston. Happens often and is a lot less expensive to replace.

tdw6974
06-21-2005, 09:13 PM
[/QUOTE]
MazdaTrix sells an expensive pilot bearing removal tool that's worth its weight in gold.

[/B][/QUOTE]
I can not sign on to Mazda comp catalog from this computer. Try This part Number and check mazda comp price 0000-09-0105


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Tom Weaver: Logistics & Technical Support Manager IE truck driver for 1980 RX-7 ITA #63
"Hemi Haulin' Rotary" Bill Weaver Driver- 2004 NYSRRC John Chave Award

tdw6974
06-21-2005, 09:16 PM
Originally posted by Mike Guenther:
This could also be just your slave cylinder leaking past the piston. Happens often and is a lot less expensive to replace. If the slave clyinder was leaking would it show up with fluid leaking? T W

Ron Earp
06-22-2005, 06:46 AM
You can also make your own alignment tool easily that will work well.

Get a long socket from your set that goes in the pilot bearing just perfectly. Then, find a second long socket that goes inside the clutch plate perfectly.

Wrap tape around 30% of the first socket until you increase its' diameter until it fits snugly into the second socket.

Whammo - instant custom clutch alignment tool that will work and fit well. I've done this more times than I can remember because everytime I get a "Universal" tool it fits no clutch/pilot in my immediate universe. Maybe there are good universal tools out there but the two I have bought in my life didn't do the job.

My method will require you to have long sockets and lots of different ones if you are to get the perfect diameter socket, but I imagine for most people that will be no problem.


------------------
Ron Earp
NC Region
Ford Lightning
RF GT40 Replica
White Jensen-Healey ITS
Silver "Skull" 260Z ITS
Email: "rlearp at gt40s.com"

Mike Guenther
06-22-2005, 11:33 AM
The slave cylinder doesn't have to leak externally to fail. If the leak is past the cylinder cup inside, the piston will not be able to oppose the force required to depress the clutch pressure plate. Hense it will feel like there is no clutch when you press on the pedal. You can get it into gear by force and will have plenty of clutch grip. If you're already in motion it is easy to change gears without the clutch, but it is much harder to engage a gear while the car is not moving. Get the car moving with a good push from another vehicle and try pulling the shifter down into 2nd gear (its easier than first). If you press on the gas pedal and the clutch feels good, like it isn't slipping, then it might be the slave cylinder. The piston cups get pretty hot on top of the tranny and they can loose their seal with the inside chlinder wall causing leak by internally.

Slave cylinder repair kits are very inexpensive. Replacement slave cylinders are cheap too.

bill f
06-22-2005, 04:12 PM
If the slave cylinder leaks, the fluid has to go somewhere, no? It has to show up inside the dust boot, and/or leak on top of the bellhousing.

No fluid...no leak.

No leak from either the clutch master cylinder or slave...

Remove transmission and fix clutch.

Good racing.

Bill

Mike Guenther
06-23-2005, 08:50 AM
Bill, the leak is from one side of the piston to the other side of the piston. When that happens no fluid leaks out of the cylinder and the piston force is reduced. The leak you are describing would be from the seal around the piston shaft and that would be external. The leak I am describing is internal. Like a master brake cylinder leak which may leak out the shaft seal and be evident externally but the piston still forces the brakes to work as long as you keep the fluid level up, but the brakes stop working when the fluid leaks past the piston O-rings, which is not visible from the outside. Internal leaks of a master cylinder are much more common than external leaks.

Check it by pushing on the clutch pedal and observing if the slave cylinder can push the throw out bearing lever and hold it in the extended position. If the piston doesn't extend or if it retracts while still holding down the pedal, the cylinder is not holding the fluid on the ram side of the piston - internal leak.

ddewhurst
06-23-2005, 01:08 PM
Mike, IIRC the slave cylinder has a rod/attached piston with an cup or o-ring & fluid on the non rod side. When the fluid leaks past the cup/o-ring there WILL BE FLUID at the dust cover & leaking out of the dust cover.

I would beleive that when you are talking about a master cylinder what you are really trying to say is that fluid can leak past one pistion o-ring (example front brake porotion of the master cylinder) into the other portion of the master cylinder (example rear brake porition of the master cylinder) without fluid leaking outside the master cylinder. When the fluid leaks past the piston/o-ring closest to the dust cover the fluid WILL LEAK into & past the dust cover.

I'll through another fish in the sea without being near the car. Disc splines tore out..

Have Fun http://ITForum.ImprovedTouring.com/wink.gif
David

Mike Guenther
06-23-2005, 03:35 PM
Thanks David, I do believe you are correct on the construction of the slave cylinder. It has a cup inside, but forgot that it only pushes one way. The springs on the throw out lever push it back in.

I have had one or two fail on my RX-7 and one on my BMW. The BMW one did show leakage, a lot of leakage. I don't remember ever seeing any leakage from the RX-7 slaves. They just wouldn't stroke the throw out lever.

its66
06-23-2005, 04:17 PM
That is what mine did. The slave wouldn't push the clutch fork, and the pedal had almost no resistance. No fluid leak. I got fluid out when I bled it, but it never got better. New slave cylinder, no problems. http://ITForum.ImprovedTouring.com/smile.gif

Jim

rsx858
07-06-2005, 03:07 PM
well the new clutch is in and the flywheel resurfaced, the old disc and throwout were blown to pieces. also is appears that the pilot bearing was loose in the shaft, and that the shaft itself not the bearing was the reason. it was obvious that someone had been in there before (im not the first owner) and that the pilot bearing is no longer properly secure. we secured the bearing as best as possible knocking it in and using loctite. So although my clutch is all set, i might be looking at more problems in the fututre.
thanks for all the help

Matt Rooke
89 RX7

ddewhurst
07-07-2005, 06:45 AM
Matt, thanks for forwarding the end results of your clutch issue. We all leanr form it.

Have Fun http://ITForum.ImprovedTouring.com/wink.gif
David