violacleff Posted July 10, 2005 Share Posted July 10, 2005 After installing my new/used 280zx tranny, for some reason the slave keeps breaking, and leaking all the fluid out from behind the rod. I have tried 3 different slaves now and the same thing happens on each one. The first one it happened to was working just fine before I swapped the tranny. It will work fine for a few blocks/miles and then take an instant crap. I cant figure out what i'm doing wrong. One guy on zcar.com suggested that the rod was being overextended, but the first one broke (which previously worked great) without me ever adjusting anything. I did however adjust the clutch pedal afterwards because It wouldn't fully disengage. But lets say this guy is right. What if I were to give the clutch more play and weld an inch more of metal to the slave so that it pushes the fork sooner and doesn't "overextend" (if there be such a thing). Is there any other reason such a thing could keep happening other than my car being cursed? Quote Link to comment Share on other sites More sharing options...
datsunlover Posted July 11, 2005 Share Posted July 11, 2005 I'd say this guy culd be right, sort of.. The only way I can see the slave rod becoming 'overextended' is because the fork it's pushing on may be bent/worn. IE it has to travell further to disengage the clutch. IS your car a zx, or a Z? I'm not sure, but would guess the older 4 gears have a diffrent throwout fork.. just a thought. Quote Link to comment Share on other sites More sharing options...
Here comes trouble Posted July 11, 2005 Share Posted July 11, 2005 In addition to DL's post: Did you use the throw out bearing that came with the zx 5 speed.. There is considerabe difference in throw out bearing size over the Datsun production years and this will cause problem. You can also make an adjustable slave cylinder shaft out of a long grade 8 bolt's unthreaded shoulders to go in the slave cylinder and use the threaded part for the adjustment with nut and lock nut for the clutch fork side. Cut the unthredaed part for a slack fit with plenty thread on the back side for adjustment. Older Datsun's had an adjustable rod with a required hole in the clutch fork to take up the adjustment slack. Do not try to drill this hole when the clutch fork is installed...no go...requires drill press for hardended clutch fork. Quote Link to comment Share on other sites More sharing options...
violacleff Posted July 11, 2005 Author Share Posted July 11, 2005 So are you suggesting I change the fork? Quote Link to comment Share on other sites More sharing options...
datsunlover Posted July 11, 2005 Share Posted July 11, 2005 Thats what I'd look at first.. and maybe the bearing too. Quote Link to comment Share on other sites More sharing options...
violacleff Posted July 11, 2005 Author Share Posted July 11, 2005 Yeah I changed the T/O bearing when I swapped trannies. Quote Link to comment Share on other sites More sharing options...
PeterZ Posted July 11, 2005 Share Posted July 11, 2005 There are at least two different depths (or lengths) of release bearing collars. You might have the shorter collar installed. This could cause the release arm and bearing to move closer to the pressure plate drastically effecting the working angles of the release arm. The arm needs to be working through an angle 90 degrees to the input shaft. If the arm is already past the 90 degree angle there isn't enough movement to propely actuate the pressure plate. You might notice you need the full travel of the pedal to get the clutch to fully engage/disengage. Lengthening the pushrod will help by moving the slave cyl piston away from the end of the bore. If the angles are correct you may need to verify proper diameter master and slave cylinder bore sizes. Most often I've found customer cars to have the short release bearing collar when they would come in with trans swap clutch problems. PS you can usually see if the angle of the arm is already past midpoint of 90 degrees by sighting the line through the slave pivot, arm pivot and the release bearing contact. Quote Link to comment Share on other sites More sharing options...
Here comes trouble Posted July 11, 2005 Share Posted July 11, 2005 T/O bearing comparisons from Eric Nyerlin http://www.zparts.com/zptech/articles/trans_swap%20parts/4tobear_specs1.html Quote Link to comment Share on other sites More sharing options...
violacleff Posted July 12, 2005 Author Share Posted July 12, 2005 Ok now wer'e getting somewhere. PeterZ, you were correct, I did have to fully adjust my clutch pedal out. It seems that my problem is probably wrong T/O bearing collar. So you are saying that lengthening the rod will/might fix this problem without having to drop the tranny? Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted July 12, 2005 Share Posted July 12, 2005 I had this same problem with mine a few years back. Since I lacked the motivation at the time to properly troubleshoot and fix the problem, I went with the extreme solution: Installation of SBC with T-56 tranny. Started on that about 4 years ago and the car hasn't moved under it's own power since... Wish I would have known about this site back then. Good luck with the slave cylinder, it sounds like you're headed in the right direction. Mike Quote Link to comment Share on other sites More sharing options...
violacleff Posted July 12, 2005 Author Share Posted July 12, 2005 I'm ready to go the extreme solution and sell my car. Unfortunately I've F****d it up so bad its not worth a dime anymore. Anyways I'm trying to figure out exactly what motion is breaking the slave? The slave I have already has an adjustable rod, although I have the pedal adjusted all the way out because the clutch wouldn't fully engage. I don't understand how I could use a grade 8 bolt to lenthen it. If I were to weld a half in or so to the rod and then give my clutch pedal more free play would this solve my problem without having to change the t/o bearing? Or is my understanding of the problem way off? Quote Link to comment Share on other sites More sharing options...
PeterZ Posted July 12, 2005 Share Posted July 12, 2005 I don't think a longer rod will fix the problem correctly. With the release arm not working through the 90 angle the lever ratio is not correct; it will take much more travel to get the pressure plate to release and engage. You probably don't have enough throw with the slave cylinder to cover the misalignment of the release arm. When you say breaking the slave I'm assuming the piston is popping out of the end, correct. If so that is probably because the slave needs to travel more to make up for the ratio change of the misaligned arm. Quote Link to comment Share on other sites More sharing options...
fl327 Posted July 12, 2005 Share Posted July 12, 2005 you could try using a smaller slave cylinder, had the same issue of blowing up slave cylinders and going smaller on the slave solved it. Quote Link to comment Share on other sites More sharing options...
violacleff Posted July 12, 2005 Author Share Posted July 12, 2005 what year carries smaller slaves? I just talked to mike's z shop and he said that the collar in the 280z and zx were the same. I'm currently using a zx slave. Is the 200sx slave the one you are referring to? Quote Link to comment Share on other sites More sharing options...
fl327 Posted July 12, 2005 Share Posted July 12, 2005 I got mad and went to the junkyard and just started pulling slaves off nissan cars from 80s. There was a z in the yard so I kept bolting them up the z trans and made sure it worked. Check the bore size it should be stamped on the side of the slave, go to the yard and find one size smaller or even more smaller. Grab a few of them, and try them on your car, write down the name and year of the car, when one of them works, you can either go to the parts store and buy a new one of that size, or get your roll on. I chose the later and the slave hasnt broken yet, its been about a year and a half now. I use a 200sx, 83 or 85 im not sure, but the smaller size of it wiill be stamped on the case. Quote Link to comment Share on other sites More sharing options...
violacleff Posted July 20, 2005 Author Share Posted July 20, 2005 Ok, so I stuck an '85 200sx slave on and as I was bleeding it from underneath(my friend was pushing the clutch) I noticed that it broke on the extend. Now I have my clutch pedal adjusted all the way and I'm trying to figure out if "that" is whats actually causing it to overextend and break, if so would simply fabricating a longer rod and giving the pedal more play fix the problem? It seems it would. Quote Link to comment Share on other sites More sharing options...
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