tansmission slipping issues

[speedstar01]

i recently purchased a second 240sx
i was so happy, has a clean body, one owner, 65k, nice grippy clutch when i test drove it. after about 30 mins(on the way home) the clutch started to slip bad.....the rpms would rev way up and i the car would barely move. slightly pissed i decided to put a clutch in it. i purchased a new OEM stlye clutch kit and put it in this week. while iwas under there i replaced the leaky old slave cylinder and bypassed that nasty clutch dampaner (the same procedure i did with my daily drive S13) i bled the system by myself with a bottle of brake fluid and a piece of rubber line and then again with my father (because i thought the pedal still felt way too soft) . i decide to take it out today and after about 15-20 mins of cruising around the clutch starts slipping again!!! it seems to do it only after it is warm!!! ive only put about 10 miles on this clutch...is the clutch breaking in?? is my clutch master cylinder bad? will it need replacing too? my clutch pedal is also way too soft but i thought it was due to the new clutch....the car shifts perfect without grinding and i cant figure out how to fix this!! please somebody help solve my problem!! thanks guys!!


Matt

[vvtisupra]

try adjusting the pedal rod. Under the dash behind the clutch pedal you can change the rod length. It might be too long so its engaging the clutch even when its not depressed. Since the threaded rod is aiming towards you you'll actually have to go left to shorten the rod. Make sure you undo the lock nuts on the rod. don't set the lock nuts just yet test drive it to where you have it where you want it then set the lock nuts. There is a second bolt (larger bolt) that compresses the spring load and the travel, you can play with that too. That is on the top left of the pedal. you'll have to move the seat back and really get in there, it will make it easier. Try that. Also you probably have glazed your clutch by now so give it some time hopefully it will burn off.

[aznpoopy]

might have an oil leak from the rear main seal on the engine, or the front gasket on the transmission.

[speedstar01]

to vvtisupra: it is dark out now but i will try playing with the pedal adjustment but that doesnt really explain why it slips only when it is cold...

and to aznpoopy: why would a leak cause tranny slippage?? i have yet to notice any leaks on this low mielage beast (it was quite dry under there) plus when i pulled the tranny off to replace the clutch it was dry in there so i dont think thats it thankfully!!

please keep the ideas coming guys!

[C. Senor]

i dont know if this is a possiblity since you say it grips for a little while, but i had the problem you are explaining, i had a bad clutch fork you might want to check that out...its like 5 bucks from the dealer, and it saved me some money when i bought my car.lol

[speedstar01]

a bad clutch fork? how can that go bad? lol and replacing that means taking the tranny off again!!! *sigh is there any way to tell the clutch fork is bad without removing the transmission?? also who diagnosed the fact that ur clutch fork was bad? could you be a little more specific about your clutch fork?? im baffled!!!!

[aznpoopy]

a leak would cause clutch slippage because grippy clutch surface doesnt like hot and slick oil.

if the clutch fork is bent or cracked you might encounter problems with engagement as well.

is the master cylinder original?

[TURBI]

I'm having the same problem with the clutch slipping after 15-20 mins of driving. I was told it was a bad pressure plate but now I'm not so sure. I replaced the clutch slave and master cylinders with non factory units and had problems adjusting the pedal too. I did not change the fork but I'm getting a new ACT kit and if it happens after the install, I don't know what the crap I'll do next... buy sr20... mechanics, help?

[johngriff]

only these issues will cause this problem.

Over engaged pedal: Make sure there is 1/4in play at least at the top of the pedal.

Bad clutch (likely)
Bad Pressure Plate (less likely)
Bad Flywheel (least likely)

All other issues with the clutch system will cause it to stick, not slip.

[speedstar01]

woot! i installed a new clutch master cylinder today and now there is no slippage. i took the car out for about an hour and it feels great. it was prolly an original master cylinder. so my car didnt need a new clutch after all....it was all in the master!!!!!

[johngriff]

lol.

You didnt need to. Your pedal was mis-adjusted. If the m/c goes bad, the clutch wont dissengage.

[speedstar01]

wait so does this mean that my pedal still might be mis aligned?? the car runs great now with no slipping after putting inthat new master cylinder. how do i properly adjust my pedal if it is still off??? TEACH ME!!!

[johngriff]

Because you were kind enough to ask, i took some pictures for you.

Here is the Pedal and Master cylinder out of the Car and apart.



When you slide the master cylinder through the firewall onto the pedal it looks somthing like this.



Now, when people say "to adjust the pedal/clutch" they are talking about this fork and threaded stud. Here it is all the way extended.



And all the way threaded in.



After everything is setup, you should have a "dead zone" at the top of the pedal about a 1/4". If it is tight all the way up, it may be too far extended, and halfway engaging the clutch.



So, it may have been too far engaged, and when replacing the mastercylinder, you readjusted the play during the install.... Hence no need to replace in the first place, just an adjustment. When the master cylinder goes bad, the clutch does not slip, it fails to disengage.



JohnGriff
Http://www.rpsport.net
Drifting Clutch

[Vatche]

mad props.... ^^^^^^^^^^^^^^^^^^^^

i know im gonna go check this out on my car tomorrow

[aznpoopy]

thanks for taking the time to put those pics together. very helpful.

[zugoi]

Nice post john griff. Thanks. My clutch pedal has been really soft and i was thinking it was the slave cylinder. I bought one and ive been to lazy to change it. If my problems dont get fixed then i will check out what you talked about john. Thanks

[koukidough]

wow you are the man

[speedstar01]

oh my lanta!! john griff IS indeed the man! thanks for taking the time to gather the informative pics.

[arminder_d]

It seems really wierd that the master cylinder fixed the problem lol. Doesnt seem logical at all. Did it use to just slip when you laid onto the throttle? thats what i take because you said it would over rev. It would point towards a bad clutch but then you replaced yours. When you did the job did you machine the flywheel and replace the pressure plate?

[g6civcx]

That's some crazy stuff. Thanks for the pix.

If you notice, the clutch pedal bracket is really thin. It's easy to break it after a while. Check to make sure that the pedal is indeed going in and out, and not side to side.

[speedstar01]

Originally Posted by arminder_d

It seems really wierd that the master cylinder fixed the problem lol. Doesnt seem logical at all. Did it use to just slip when you laid onto the throttle? thats what i take because you said it would over rev. It would point towards a bad clutch but then you replaced yours. When you did the job did you machine the flywheel and replace the pressure plate?

exactly, EXACTLEY!! thats why im baffled....actually when we took the old clutch out it had lots of life left on it LIKE it had been replaced at one point already (keep in mind this car is a one owner with 65k miles) but we replaced all the components,that came with the clutch kit, anyway. so it did get a new pressure plate and as for the flywheel.... it did not need resurfacing.

i think that replaceing the master cylinder helped to fix my problem because i moved slighty adjusted the clutch pedal without knowing it....

as for the pedal still being a little too soft....im not as concerned about that now because the car is running flawlessly without slipping so WOOT!!!

[speedstar01]

so has anyone else shared the same slipping issues as me?

[TURBI]

I have the same problem, but I just put in new slave and master cylinders. My clutch used to engage when released only an inch but it keeps getting higher so it must be the pedal adjustment. Also why does my car shake when accelerating from a complete stop after driving around for 20-30 minutes. I was told this is from the 15 year old pressure plate I didn't replace when the new clutch went in.

[arminder_d]

Originally Posted by TURBI

I have the same problem, but I just put in new slave and master cylinders. My clutch used to engage when released only an inch but it keeps getting higher so it must be the pedal adjustment. Also why does my car shake when accelerating from a complete stop after driving around for 20-30 minutes. I was told this is from the 15 year old pressure plate I didn't replace when the new clutch went in.

That is called clutch chatter. And yes you should have replaced that pressure plate and machined your flywheel when the new clutch went in. Depenting on what shape your pressure plate is in you may have even damaged your new clutch.

[trsilvias13]

john post alone should go under FAQ

[nisans13turbo]

Sorry to bring this old thread back but im curious on one question. So its better to have your clutch to grab sooner then later meaning when you press down onto the clutch and release bout 1" or 2 and it catches compare to if the clutches catches high?
Right now my clutch is catching high, and it'll slip if I drive on city road for more then 30mins but if im cruising on highway and stay on one gear my clutch doesnt slip.

Also, when im shifting slowly and constantly stepping on my clutch, I can feel some kind of winding - grinding - smooth vibrates on my clutch peda l, what does this mean?

Redtop
S13

Thanks

[Ninjabread]

After everything is setup, you should have a "dead zone" at the top of the pedal about a 1/4".

Is this play including the button/switch that the pedal hits when it is released or is that before?

[Dirty Habit]

Sorry to bump this. But I had a question and didnt want to start a new thread. Plus it has some helpful info in it.

For some reason after pulling my 240 out of winter storage, I only have first and second gear. It wont go into any other gear but those two and you dont have to push down on the clutch for it to engage. Would this be a problem a new master cylinder could solve or does it sound like something worse? Thanks.

[posdrift240]

Sounds like your Forks in the transmission have gotten bent or something. Are you able to go into any other gear with the engine not running?

[Dirty Habit]

I haven't started it up from the winter yet. Could this hinder it also? I need to flush some fluids etc on friday and Ill see what happens.

But it only goes into one and two when the engine is off. Again, without the clutch engaged.

When I rolled it out of the garage I realized what was going on.