Weird tranny behaviour

[Reverend]

I have brand new exedy clutch and 77 5 speed. Here are symptoms:

-When cold and put to reverse, it makes loud whining sound for few seconds, then it stops. Happens sometimes when put to 1:st gear too.

-I have bleeded clutch twice and adjusted slave cylinder rod several times to find proper "release" for clutch, for some reason i have to pump twice when cold to be able to engage gears. After that i can drive with smooth shifting for at least 20 mins.

-After that shifting becomes gradually more harder, until i can barely shift gears. I got stuck in the middle of intersection (2 separate times) cause i could not switch to 1:st gear, i sweared and pumped clutch for like 10 times, after that it worked again. Clutch was feeling the same all the time, no sloppyness.

What can cause these symptoms? Even i have properly (or at least in my standards) bleeded the clutch, can it still have air somewhere or is there something wrong in the clutch itself? I really need to know this soon.

[beermanpete]

The whining noise could be a a bad pilot bearing. Did you replace the pilot bearing?

The soft pedal is most likely a bad master cylinder.

[Reverend]

Master cylinder is almost new (2 years old.) And its not soft at all! Thats whats bugging me.

[Zed Head]

Pop the rubber boot off of the slave cylinder and see if there's fluid inside that has leaked past the piston. The boot will hold quite a bit of fluid before it shows on the outside.

[ggunder]

I don't want to interrupt this thread, but the same thing happened to me yesterday. It seemed like the longer I drove and the hotter the day, the more difficult shifting became until the car was not drivable. My daughter had to help me push it into the garage!

Today I adjusted the clutch rod to the limit of it's length and the problem seemed to go away. I did not drive it around more than about 15 minutes, so maybe it was not a great test. My clutch is new, but the master and slave cylinders are old. I have the later (close ratio) 5-speed transmission instead of the original 4-speed. The Master has fluid in it and there are no signs of leaks. Could this be a problem with the linkage being incorrect for the 5-speed? It is worth noting that my slave cylinder did not even have a return spring until a few weeks ago and is the older style with an adjustable rod.

[Captain_Zeros]

Tip: just because your master cylinder has fluid in it doesn't mean it isn't leaking internally. Fluid can leak around the internal piston seals and cause the system to not work well. If you've got a helper, have them press the clutch while you lay eyeballs on the slave cylinder and clutch fork.

Also, mismatched pressure plates & throwout bearing collars can cause all kinds of weird clutch behavior, if the stack is too short then your clutch will never unlock fully, if the stack is too tall then the clutch will be partially unlocked all the time! Anybody who recently replaced their clutch should check out this bit of info: Nissan Throwout Bearing Collar Specs Comparison Measurements

Always keep throwout bearing carriers and pressure plates as a matched set, there are a ton of permutations from various years and models of Nissan.

[Wade Nelson]

I have to pump twice when cold to be able to engage gears. After that i can drive with smooth shifting for at least 20 mins.

.

Having to "pump up" a clutch indicates there's air in the lines / slave / master that you are compressing. Once the air *bubble* is sufficiently compressed, then the clutch operates normally.

You get air in the lines by having a leak, a loose fitting, and most often, a leaking seal in either the master or the slave.

A leaking seal may or MAY NOT cause fluid to be lost, what it IS doing is allowing air to be admitted - on the return stroke.

You can replace the slave, the master, get a "kit" and just replace the seals, or, lots of times, you can simply take them apart, clean them,

and re-assemble. But frequently you take one apart and see visible damage to the seal, a nick past which fluid/air will leak.

Start by re-tightening all you fittings and your bleeder valve. Sometimes that's all it takes.

I'm working on the ASSUMPTION you have matched clutch parts / sleeve, etc. and your problem is only with the hydraulics.

[mgood]

ggunder, I had the same problem, as me car got hotter the car was harder and harder to put into reverse. The master finally failed, did not leak but the O rings inside failed. The fluid was black in the master and would not pump the fluid. I replaced both the master and slave and all is fine.

[Reverend]

I dismantled the master and put it back together. It worked fine for 250 miles, then it started to act like that again. I also have NEW (5/8) spare master cylinder, with shorter pushrod (about 1 inch) so i replaced the pushrods and tried that. It did not even give pressure..(??!!). Master cylinder pushrod was at max so it should have been enough. Switched back to old one and it works, but as said above, is sloppy again. I wonder what i did wrong with that new master cyl. Only difference is that its not Nabco and it has bigger reservoir for brake fluid (and shorter pushrod). Its hard for me to believe that 2 year old rebuilt oem part fails but i guess weirder **** has happened in Z world.

[Reverend]

Swapped the old one back... worked for sometime, but i was too afraid to be left on road with broken cylinder so i put the new one back. No go. Why the heck the old one gives some pressure and new one aint giving nothing??? Its driving me crazy.

[Captain_Zeros]

Dumb question time.

You bled the new master cylinder, right?

What technique did you use?

[Reverend]

Pumped pedal a few times with bleed nipple closed to gather some pressure, then opened bleed (while clutch still pressed) I have special bleeder tool attached to slave cylinder, but i still have my wife helping me out so i can see does the slave move or not. Of course i bleed the system everytime i change something, im not that dork