Let's diagnose my Transmission/Clutch issue!

Illustration for article titled Lets diagnose my Transmission/Clutch issue!

Hey guys. I could use some help figuring out what’s going wrong with my hydraulic clutch/Manual Transmission.


The Problem

I cannot get my car to go into (any) gear while it is running. I depress the clutch, and I push the gear selector lever (“The Shifter”), and no dice.


What Happened?

Last Friday, I was driving. Everything worked as normal (no new noises/weird smells/vibrations). I pulled away from a light in first gear. When I depressed the clutch to shift into second, suddenly the clutch pedal felt funny (stiff, kind of...I dunno, bubbly?) and I couldn’t get the car into second. “That’s Odd” is (a paraphrase of) what I thought, so I released the clutch pedal, depressed it again, and successfully shifted into second. I didn’t wait long to try again, and since then, I’ve not been able to get the car to go into gear. I had the car towed home.


The Initial Theory

The Clutch Release Bearing (AKA Throwout bearing) has been making a whining noise for the last two years. Due to other clutch system failures, I have a new (as in new parts, within the last 100 miles)

  • Master Cylinder (Exedy)
  • Slave Cylinder (Exedy)
  • SS braided line that connects the Master to the Slave (Custom)
  • Clutch Pedal bracket Assy. and Spring (OEM-but-new)

Since all of that stuff has been recently improved, and my clutch release bearing was old, My initial theory was that the bearing seized up on the shaft, and the weirdness I felt in the pedal was pushback from the bearing.


Where things started to go wrong

Pulled the transmission and bought what I thought was the correct clutch release bearing. The old bearing was confirmed to be bad (had a wobble. Was uneven, etc). Put it (and the transmission) in, only to find that the throw out arm was totally bottomed out. The bearing was the wrong size, approximately half an inch too “tall”, and was presumably pressed all-the-way up against the pressure plate, probably at least partially disengaging the clutch. Transmission got pulled again, proper bearing was purchased (I measured this time), installed, Transmission is all-the-way back into the car now.


Current Status

  • The car still cannot go into gear while running.
  • The car can go into all of its gears while the engine is not running. Everything feels smooth
  • If I put the car in gear and try to start it, the car bumps.
  • The clutch is fully bled (very high confidence in this. I’ve become a clutch-bleeding god over the last couple months for presumably unrelated reasons)
  • If the clutch pedal is depressed, the slave actuates the clutch fork arm smoothly and what appears to be fully.
  • The clutch pedal no longer has that stiff (“bubbly”) feeling anymore; it feels totally normal

What that means to me is that my transmission is still fully functional (“Why is this even a question?” You might be wondering. My grandfather is pretty good at this car stuff, and his current theory is that something in my transmission broke/fell off/something. At this point, I disagree with him). What’s failing is in the clutch system, and, more specifically, I think I might have broken or damaged my pressure plate.

I did examine the pressure plate a bit the first time I had the tranny out, and it looked fine. After we put in the wrong bearing, I really didn’t inspect it much more, but I suspect I may have broken or otherwise damaged it pretty severely with the wrong bearing.


The Master Plan

First, I hope to get some sage advice from you guys. I’ll try whatever you’d like, I’ll take pictures, w/e. I just want my car to work.


Besides that, tonight I’m going to try to put the car into second gear and start it. I’m hoping I can get it moving without the clutch. I’ll then attempt to clutchless shift it into (at least) first, second, and third. I figure if I can accomplish that and nothing feels obscenely broken through the shifter, that the tranny is indeed fine.

Thanks for reading. Hopefully somebody can give me some advice

If you feel like it matters, My car is a 1990 USDM Nissan 240SX with an RB20DET swapped into it.



Thanks everybody for all the advice. We’ve all had good, constructive conversations. I was able to drive the car around the block last night by starting it in gear and shifting without the clutch, so, as many of you surmised, it’s not the transmission. Since this is ostensibly my daily driver, I am going to replace the clutch, pressure plate, throw out bearing (again) and flywheel from a kit. If that doesn’t work, I guess I’ll be back for round two.

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