Clutch / Clutch Hydraulics Issue

[datsun65]

Background: Roadster with 5sp transmission. Transmission shifts nicely into all gears. When driving in gear, there is no clutch slipping. You can rev up & down the gear selected, without issues. Half the time, it shifts like silk from one gear to the next.

Problem: Occasionally, when shifting between gears (any gear or to neutral), the shifter moves out of gear, but it seems the clutch is not releasing. For example, if I shift from 2nd to Neutral, the shifter will be in neutral (I can wiggle it around), but the clutch plate still seems to be engaged (but not in gear). The result is when I next try to put into ANY next gear, there will be grinding.

I've tried swapping out clutch hydraulics, but still haven't been able to remediate the issue.

The car had sat for nearly 35 years. I think it is the clutch not consistently releasing. Outside of replacing the clutch, are their other suggestions to help loosening things up? Can this still just be clutch hydraulics?

Thanks.

[C.Costine]

The first question would be, when you are experiencing the problem, depressing the clutch pedal as normally, do you feel the normal resistance from the pedal? Since it works properly half the time and you have replaced the save cylinder and I assume you got it properly bled, I wouldn't tend to suspect the clutch operation unless it didn't feel right. I have never experienced this myself, but on a forum that I frequent there was a post about a clutch that sometimes would not release. It turned out to be that the clutch disc was disintegrating and pieces of the material were slipping in between the clutch and the pressure plate or flywheel and the remaining good parts of the disc causing a no release condition. Another possibility, though remote is that rust from the clutch has gotten onto the splines causing a temporary hang up there. It is not unusual to get rust on the splines, but it is usually powdery and causes no problems. Scaly rust however could cause a problem, but it should get turned to powder fairly quickly. So there is something that you could hope is your problem because it would soon go away by itself. There is a remote possibility of a problem with the fork or the fingers, but it is unlikely for those parts to be intermittent.

Colin

[datsun65]

Thank you for the feedback, Colin.

I drove the car for about an hour today around the neighborhood. The issue occurred a half-dozen times over the hour period. Most commonly noticed when I bring the car to a stop and try to shift from 2nd or neutral into first. Thinking the timing of my shifting when driving (from 1st to 2nd or 2nd to 3rd) is also helping to avoid the issue.

Going to keep putting some miles on the car over the next week to see if things improve. On a positive note, the engine (sitting for 35 years) is running better and better with some fresh miles. Originally had a can or two of seafoam mixed with older gas. But, now the seafoam and older gas has burned off and the engine is starting to really starting to come back to life.

[jrusso07]

Three guesses/questions

1) hydraulics are soft - what happens when you pump te clutch 3 or 4 times before shifting?

2) transmission input shaft is somehow coupling to gear train... sludge, rust, tolerances?

3) clutch disc is contaminated with something... I would guess it .doesnt do it under load (driving), but more often when stopped?

[datsun65]

Thanks, Joe.

1) No Difference when Pumping. I have changed out hydraulics with new units and still have the same issue.

2) Not sure.

3) Yes. Seems to be more frequent when stopped. Thinking the clutch disc is compromised.

Will keep putting on some miles, and hope it may burn off , but may need to install a new clutch kit.

Thanks for the input, Joe.

[Gregs672000]

Ya, if it's sat for 35 years with an unknown clutch, you know exactly that; nothing about it or its condition! Or that of the trans either... did you inspect the gear oil?

[datsun65]

Thanks, Greg.

Yes, previously inspected gear oil. Changed it twice during the past couple of years. Nothing alarming.

Will give the car a few more hours of seat time, before deciding to pull.

Thank you.

[jrusso07]

Another thought is that the clutch release bearing sleeve gets caught up on the input shaft. Crude or somthing holding it there. How is the cutch return spring - strong enough to pull it back consistently?

You might be abe to lnspect sleeve and shaft through the clutch fork boot port.(remove the slave cylinder from transmission and the boot and look at shaft - still a long shot with the fork in the way...you cant pull the fork through the bell housing and it could be a real bitch to get back in if it comes loose.)

[theunz]

You could also spray some WD40 on the shaft while the boot is out. Be careful not to spray much and get it on the clutch. Maybe a little spray and then operate the clutch, then repeat a few times.

[datsun65]

Joe, Mike.

Great idea. I plan on putting the car up on jackstands all the way around, and will see if I can carefully clean the shaft once the boot is removed.

Thank you.

Dan

[pebbles]

Dan have you intentionally tried to slip the clutch? Like rolling along at 50 mph in 4th, and slowly push in on the pedal till it slips? Just to measure where in the pedal throw, it disengages.
.
For years I have had a terrible habit (Bum knee) of not pushing the pedal completely to the floor. In many cases that last 2" is needed to fully disengage a hydraulically operated clutch, IME.

Also Could be collapsed fingers or broken arm on the pressure plate.

[spyder]

I changed my clutch rubber line to the Goodrich stainless line and it surprised me how different (stiffer) the pedal feels.

[jrusso07]

I changed my clutch rubber line to the Goodrich stainless line and it surprised me how different (stiffer) the pedal feels.

Agree hose can be a weak link, I had one that would blow up like a balloon when using the clutch.