240SX clutch

D

DavidM

New member
Hasn't been a new thread in forever so thought I'd start one. What makes the clutch fork return after it's pressed upon by the slave cylinder? Is it the fingers on the pressure plate or is there some sort of spring inside the transmission housing that pushes the fork back out? I've had a recurring problem where the clutch sticks down. Whatever is supposed to make the fork push back doesn't work. I'm going to pull the transmission, but want to know what I should be looking for. And if the suspected culprit is the pressure plate then I want to go ahead and order a new one.

Thanks.

David
 
PP usually pushes the clutch fork back...replace the slave cylinder and possibly the master before you pull the trans. Chuck
 
Already replaced the master and slave cylinders, removed the clutch dampener, and replaced the stock rubber line with a braided one. When it sticks down it actually sticks disengaged. It doesn't happen all the time, but it was happening more frequently the last time I drove the car.

David
 
David - it's just the PP that pushes the T/O bearing & fork back; if you've already replaced the master & slave cylinders, and the clutch line, then you probably need to look inside the bell housing. One other possibility, did you check the hard line that runs from the master to the flex line? It that got dinged at some point it may be causing the problem. Otherwise I would guess PP. What clutch do you have in there now?
 
If the front cover of the trans that supports/slides the TO bearing is worn, it's possible that the TO bearing can get 'hung' on it and not release the clutch.

another issue- VERY unlikely on a stock-style setup- is that you're over-extending the clutch and actually turning the fingers on the pressure plate inside out. I doubt that's the case here though.
The fix for that is to add an adjustable pedal stop on the firewall. when I went to a Wilwood pedal assembly, I added one and just welded a small bracket with a nut to the floor, then use a bolt and locknut for the pedal stop.



Can you make this happen in the garage with the car up on jack stands? If so, then you can diagnose a bit further..

.... another brainstorm is the hydraulic fluid is dirty and chunks of crap are clogging at some restriction in the line. considering everything you've replaced, I bet that's not an issue.
 
It's a stock PP and disc as far as I know. Bob said he just used stock and that's probably what I'll use as well. Only a couple hundred bucks from Courtesy. I'll get a new TO bearing as well. I can't recreate the issue in the garage so it's been a guessing game. If the spindle that the TO bearing slides on is damaged is that something that can be replaced? I have a spare transmission I could scavenge parts off of if necessary. I don't know the condition of the internals on the spare so I'm not sure I'd want to use the whole thing, but that would be an option.

Thanks.

Edit: Is this the part that would need to be replaced if the TO bearing spindle is worn?
http://www.courtesyparts.com/32110-cover-assy-front-240sx-s13-1989-1994-p-69353.html
Looks like there's a sleeve that fits into the TO bearing that slides on the spindle from the front cover.
http://www.courtesyparts.com/240sx-...se-clutch-release/-c-1418_1419_1487_1501.html

Double edit: I'm just going to order everything from the PP/disc down through the front cover. If I'm going to replace one thing I might as well go ahead and replace it all.

David
 
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As I recall, didn't you tell me that this has only happened on track, at speed? The more I think about that, the more I think it's probably a PP issue. Is this the same one that was in there when you bought the car from Bob?

FWIW, my car had a stock type clutch when I started racing it, and it wasn't long before I started getting slippage about 15-20 mins into a race. While I know our cars don't make much more power than stock, we are still abusing them well beyond what the stock components were designed to handle. When I built the engine I replaced the clutch with an ACT heavy duty plate & 4-puck disc, and I've never had a bit of trouble since then - 5+ years and maybe 15-20 events later. YMMV
 
DavidM said:
It's a stock PP and disc as far as I know. Bob said he just used stock and that's probably what I'll use as well. Only a couple hundred bucks from Courtesy. I'll get a new TO bearing as well. I can't recreate the issue in the garage so it's been a guessing game. If the spindle that the TO bearing slides on is damaged is that something that can be replaced? I have a spare transmission I could scavenge parts off of if necessary. I don't know the condition of the internals on the spare so I'm not sure I'd want to use the whole thing, but that would be an option.

Thanks.

Edit: Is this the part that would need to be replaced if the TO bearing spindle is worn?
http://www.courtesyparts.com/32110-cover-assy-front-240sx-s13-1989-1994-p-69353.html
Looks like there's a sleeve that fits into the TO bearing that slides on the spindle from the front cover.
http://www.courtesyparts.com/240sx-...se-clutch-release/-c-1418_1419_1487_1501.html

Double edit: I'm just going to order everything from the PP/disc down through the front cover. If I'm going to replace one thing I might as well go ahead and replace it all.

David
Click to expand...

Yup, if you're going to replace the front cover, purchase 32110, 32113, and 32112. one each.
you'll know what kind of shape it's in as soon as you pull the tranny out of the car. They're not that expensive and they don't wear out often, but you never know. I've seen one or two wear out in probably 30 clutch jobs on various cars. both failures were on nissans with >150k miles.


I would not recommend an OEM pressure plate (or clutch disc) for a race car. they just don't hold up well enough in the long run. I've used ACT products for years and have been happy with them- pick any brand you choose, but do your tranny a favor and keep a sprung hub configuration. the solid hubs are lighter and rev a tiny bit quicker, but transfer much more shock load to the crank and to the tranny. this beats up on the baulk rings, which are a known weak link in the KA tranny.

(FYI, I've been through 2 trannies in the last 3 dbl nat'l weekends. eek!) one was just plain worn out, the other I missed 4th and tried to find 6th at 85mph. there went reverse! :eclipsee_steering:
eekfacepalm.gif
 
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Haven't done anything yet. Got all the parts coming to replace things this weekend. I ordered everything from the front cover through to the clutch disc. I'm going to stick with the stock disc and PP for now. At the rate I'm going with racing they'll last me a long time. I haven't raced since last year's ARRC. I'm going to do the ProIT to try and shake the cobwebs off before the ARRC race, but I'm still going to be slow.

David
 
Alrighty. I've got the transmission out. I see nothing that's immediately evident as the cause of my problem. The release bearing sleeve was fine and the pressure plate looks ok to me as well. The front cover appeared to be leaking so hopefully replacing it will stop the leak anyways. I've also put in a new release bearing/sleeve, clutch fork, and the little springs that hold it all together.

Now for the really fun news. The disc and PP are not even remotely stock. The disc is a 6-puck and unsprung. The PP is similar to stock, but the springs look a little beefier. There are no markings on either so I have no idea what's the manufacturer. I've attached a couple pictures. The first is comparing the stock parts to what I pulled off the car. The second is a closeup of the disc. I went back and checked my notes from when I bought the car from Bob and sure enough he said stock disc and PP. He even said stay away from Centerforce. So now I'm not sure what to do. I sure don't want to put the stock parts on and then have to pull everything apart again because it doesn't hold up. I've always heard good things about ACT and that seems to be what you guys are using. What came off the car was a 6-puck so I'd lean that way vs a 4-puck. The disc that came off was unsprung, but maybe that's not the way to go.

Any thoughts?

David

Edit: ACT has the heavy duty PP and a sprung and unspring 6-puck disc. I see how using the sprung would reduce vibrations, but the springs seem like they could be a failure point. I've had the unsprung in the car and the tranny doesn't seem any worse for wear, but maybe symptoms just haven't shown up yet. Earl, is your disc sprung or unsprung?
 

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Sprung hubs will make the tranny last longer as it reduces drivetrain shock during shifts and on/off throttle transitions. they add a tiny amount of rotating mass, but help to save your synchros and baulk rings.
 
The six puck is gross overkill. A three puck will work fine and be much lighter. You might see about having the original pp rebuilt and return the stock parts. I would do that before installing stock parts. (BTW, I run a 4 puck solid ceramic on a 250k plus transmission) If you have the original pp rebuilt, it can be checked for problems that may have been causing the clutch problem. Chuck
 
DavidM said:
Edit: ACT has the heavy duty PP and a sprung and unspring 6-puck disc. I see how using the sprung would reduce vibrations, but the springs seem like they could be a failure point. I've had the unsprung in the car and the tranny doesn't seem any worse for wear, but maybe symptoms just haven't shown up yet. Earl, is your disc sprung or unsprung?
Click to expand...

Mine is the solid 4-puck disc. It's a little rough to drive around the paddock, but once on track you can't tell the difference between it and a stock clutch - except for the no slipping part. The trans is a 100k+ mile one I replaced in '06 (before the new clutch), and it's still working fine. I wouldn't hesitate to put the same clutch back in next time.
 
A stock clutch set up is going to be fine. You probably wont notice any difference. For what it is worth, I used a "Zoom" clutch and PP in my 240 with great success. Thing looked brand new after three years of racing with it, when I dismantled the car.

Not sure if they still sell them or not.
 
I've got an ACT heavy duty PP and 6-puck solid disc on the way. I considered going with the 4-puck like Earl used, but I still drive the car on the trailer and thought the 4-puck might make that more of a PITA. Plus what I pulled off was a 6-puck and I figured I'd just stick with status quo for now. I may switch to a 4-puck disc at some point.

It occurred to me that my problem could be the clutch pedal isn't adjusted right and is pushing the release bearing too far. Matt mentioned this earlier. I replaced the clutch pedal assembly when I rebuilt the car as the old one was worn out. I don't recall adjusting the new one. I'll adjust things this time around to make sure that isn't a problem. It was about time for a new disc and I've replaced all the pieces parts so hopefully I won't have to touch the clutch again for a long time.

David
 
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