Won't go into gear

[Ptero]

s30 with a 5spd.  Not sure exactly which transmission it is, but it only has one exhaust hanger.

Parked the car a couple of years ago and due to having some issues with shifting.  My memory is bad on the best of days, but from what I remember it seemed as though the clutch would only engage part way when stepping on it.  (Engage?  Disengage?  Not sure if I'm using the correct wording)

Fast forward to today.

-Checked the master cylinder and it was full /w no leaks.

-Checked the slave cylinder and it's moving the clutch fork roughly 1" when pressed all the way in

-Bled the slave cylinder which gave lots of nasty colored fluid that had been sitting in there.  Kept topping it up with new fluid and now it's nice and clear when bleeding.

-Still the same issue.  To add to that, it really doesn't want to go into gear when the car is off.  Never mind on.  I can sometimes get it into a few of the gears while it's off, but some I have to push to get in gear while others are smooth and others are simply a no go.

 

I've seen lots of posts on here where it'll go in gear with the car turned off, but not on, which tends to be something with the master/slave/clutch pedal assembly.  But it doesn't appear to be any of those from what I've seen.  I'm trying to narrow things down before I pull the tranny to inspect for damage with the clutch/fork/etc.

 

Any help or suggestions would be appreciated.

[EuroDat]

If your slave cylinder is travelling 25mm then your problem is not in the master/slave cylinder.

It could be one or more issues:

1. A cracked clutch fork. The fork flexes and doesn't transfer all the movement to the pressure plate.

2. Dryed out input shaft slines or the splined section of the input shaft wasn't lubricated when installed and now dry. This can happen if it has been sitting for a long time. The clutch disc can not move freely away from the flywheel and remains semi-engaged.

3. Seized spigot bearing. That is the bearing in the flywheel that supports the front of the input shaft. It is actually fitted in the crankshaft. If it seizes then the input shaft keeps rotating with the input shaft.

All three means you unfortunately will need to drop the transmission to identify and solve the problem.

Edited April 14, 2020 by EuroDat

[Zed Head]

28 minutes ago, Ptero said:

I've seen lots of posts on here where it'll go in gear with the car turned off, but not on, which tends to be something with the master/slave/clutch pedal assembly.  But it doesn't appear to be any of those from what I've seen.  I'm trying to narrow things down before I pull the tranny to inspect for damage with the clutch/fork/etc.

Have you drained and checked the fluid?  Might just be that things are a little rusty.  You'll want to drain the fluid anyway if you have to pull it.  You might find metal parts that tell a story.

Check your shifter bushings also.  They can fall apart and not move the shift rod.

[EuroDat]

39 minutes ago, Ptero said:

-Still the same issue.  To add to that, it really doesn't want to go into gear when the car is off.  Never mind on.  I can sometimes get it into a few of the gears while it's off, but some I have to push to get in gear while others are smooth and others are simply a no go.

•  

This is normal if the clutch doesn't disengage. If you try and change gear without using the clutch you will find it difficult until the engine is running.

When you try to engage with yhe engine running? What happens with reverse? Does it grind or it just won't engage?

[Zed Head]

I have had several transmissions that would go through the gears without the clutch disengaged (clutch pedal down).  Maybe due to the sharpness of the synchro teeth and the fluid used.  Not arguing, just saying it's not a definitive clue about what the problem might be.

One thing that is close to having the clutch disengaged is to remove the propeller shaft.  That will let the output shaft rotate more easily.  Just friction and the weight of the gear train stopping it.

Either way, make a check list and check things.  Fluid, the drain plug magnet, the bushings, proper clutch operation, etc.  If the clutch disc is stuck you can try rolling the car while it's in gear and the clutch pedal is down.  That might break it free.  No need for an engine to try that.

[Ptero]

Excellent suggestions.  Thanks!  I'll be back with updates and a second round of questions I'm sure.

 

[siteunseen]

Did it used to go through the gears without problems? I know you said you parked it for that reason but was it ever right since you've had it?

[Ptero]

4 minutes ago, siteunseen said:

Did it used to go through the gears without problems? I know you said you parked it for that reason but was it ever right since you've had it?

Ehhhhhhh it's never been GREAT, but it was definitely driveable.  I've replaced the master & slave in the past as well as adjusted the clutch pedal assembly which had some good results;  however this time is different.

[siteunseen]

You've got the two transmission guys that'll help get it figured out. I'll just read along from here on out.

I asked because I had an issue with my shifter when I first put a 5 speed in mine. It wouldn't stay in 3rd or reverse.

[Ptero]

2 hours ago, EuroDat said:

This is normal if the clutch doesn't disengage. If you try and change gear without using the clutch you will find it difficult until the engine is running.

When you try to engage with yhe engine running? What happens with reverse? Does it grind or it just won't engage?

Shifter bushings are good.  I changed them to brass a few years back.  It had some gunk in there so I cleaned it all out, greased it and am able to change into all gears with the car off.  There must be some sort of reverse lock out from 5th into reverse though.  Can't go from 5th to reverse, but can do any other gear into reverse.

I can't put the car into gear with the engine running.  I haven't pushed crazy hard, but I also shouldn't have to.  When trying to go into reverse with the car on, it grinds unlike the other gears where it just won't go.

[Zed Head]

Try rolling it in gear with the engine off and clutch pedal down.  Measure slave cylinder travel when you press the pedal.  Sounds like you made some progress though.

[pogden]

I am by no means an expert, but here is my recent experience that sounds similar to yours. I am 5 years into the restoration of a 76 280Z that did not run when I bought it. I was told, by the PO, that it had been driven a couple of months before I bought it, but I don't know that to be true. I swapped the 4-speed for a rebuilt close-ratio 5-speed , but (like an idiot) I did not replace the clutch. The clutch disc was supposedly new, and to my untrained eye the pressure plate looked ok.

Fast forward to a month ago when I got the car running for the first time. It was still on jackstands, so I decided to run it through the gears - no dice. It shifted fine with the engine off, but with it running it just wouldn't go into gear, and like you I didn't want to force it. I had recently replaced the master and slave cylinders, blown out the lines, added fluid, and bled the system. I checked the travel on the slave cylinder while a friend (and Z expert) pushed the clutch - it smoothly moved the clutch fork about an inch, maybe a bit more. My friend suggested double-clutching (clutch to the floor, back up, then back to the floor), and it actually worked. By double-clutching, I was able to shift through gears 1-5, though it wasn't exactly smooth. Reverse was still a no-go. 

The local consensus was a clutch problem, so I dropped the transmission and removed the clutch. I bought a new M-pact kit from ZCarSource (just down the street from me here in north Phoenix), installed it, and it shifts beautifully now. Having said that and just read EuorDat's and Zed's suggestions, it's possible my clutch disc was seized (i.e., not sliding along the splines of the input shaft) - I never thought of that. When I installed the new clutch, I followed the directions in the FSM - I carefully lubed the splines (with the little tube of purple lube supplied with the clutch kit), mated the disc to the splines and ensured it slid back and forth nicely, and wiped off the extra before bolting the clutch assembly to the flywheel. It's possible I either omitted this step or used the wrong lube when I first installed the 5-speed several years ago.