Let's diagnose my Transmission/Clutch issue!

"TwoFortified" (twofortified)
08/25/2016 at 14:22 • Filed to: None

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.

Results

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.

DISCUSSION (20)

SidewaysOnDirt still misses Bowie > TwoFortified
08/25/2016 at 14:29

It’s fucked so you may as well just give it to me. More seriously, it’s probably your throwout bearing, but make sure your clutch pedal assembly is set up correctly. It’s possible that you aren’t depressing the clutch fully. When I lowered the pedal on my BRZ too far, it behaved like this.

crowmolly > TwoFortified
08/25/2016 at 14:32

Please confirm:

If you put the shifter in N and try to start the car with the clutch pedal pressed, it starts.

If you put the shifter in 1 and try to start the car with the clutch pedal pressed, it bumps.

Wrong Wheel Drive (41%) > TwoFortified
08/25/2016 at 14:33

If you hadn’t said you already replaced the master, slave, and line then I would have immediately suggested the slave cylinder was at fault. Even given that information, I would still suggest that something went wrong there and is still your issue. Definitely try starting the car with it in gear, if it works fine then yeah it is going to be somewhere clutch related. If you already took the transmission off the car, why didn’t you do a full clutch job? That is usually included when you do a throwout bearing anyways. Either way, you probably should provide more info on the car and what other mods you might have.

TTercel > TwoFortified
08/25/2016 at 14:34

Try adjusting the clutch pedal pushrod, it may have been tampered with before.

TTercel > TTercel
08/25/2016 at 14:36

Also why didn’t you replace the whole clutch while you were in there? When my throwout bearing went on my Subaru it took the pressure plate with it. Also also was the shaft the throwout bearing rides on smooth or damaged?

FTTOHG Has Moved to https://opposite-lock.com > TwoFortified
08/25/2016 at 15:02

Since it seems like you have the most likely culprits covered - did you look at the flywheel? It’s unlikely, but possible that the clutch disk is sticking to the flywheel. It would have to be either pretty damn rusted or warped for that to happen, though. In any case, the next time you pull it apart, I would replace the flywheel, clutch, and pressure plate all in one go.

TwoFortified > crowmolly
08/25/2016 at 15:28

Confirmed

TwoFortified > FTTOHG Has Moved to https://opposite-lock.com
08/25/2016 at 15:29

Noted. Since the clutch and Pressure plate are already going to have to come off, I’ll look at it. At the very least, I’ll get it resurfaced if it looks bad (though it’s been resurfaced within the last couple years)

TwoFortified > SidewaysOnDirt still misses Bowie
08/25/2016 at 15:29

Assy is good. Everything was shifting fine for weeks, then suddenly nothing. I think the adjustment is ok (though I had considered it as a culprit). I’ve seen that Slave actuate enough to know about how far it has to travel to make the magic happen, and it’s travelling far enough now.

TwoFortified > Wrong Wheel Drive (41%)
08/25/2016 at 15:31

I didn’t do a full clutch job because I don’t have ready access to a clutch and pressure plate. I have to order them. It was a time/money efficiency thing...which backfired on me horribly.

What more do you want to know about the car? It’s an S13. It has an RB20DET in. I’ve got a LSD...Some lowering springs...I don’t know what info you’d like, but I’ll give it to you.

crowmolly > TwoFortified
08/25/2016 at 15:31

You have a problem with your TO bearing/hydraulics.

Just guessing, but it sounds like the flywheel/disc/PP is fine. Your clutch is not de-coupling so your crank is staying engaged with the input shaft.

Can you get a visual on the TO bearing during its operation? Have somebody push the pedal while you watch to see the clutch actuate?

TwoFortified > TTercel
08/25/2016 at 15:32

I believe the Slave is throwing all the way. I’ll double check

TwoFortified > TTercel
08/25/2016 at 15:33

Because I don’t have ready access to a clutch/pressure plate/flywheel. All of it has to be ordered. Since this is a daily, I was trying to fix it quick, and it backfired on me.

The input shaft looked fine to me and a buddy of mine. No noticeable damage.

TwoFortified > crowmolly
08/25/2016 at 15:37

I’d need X-ray vision, as the bellhousing is in the way...unless there’s a trick I’ve never heard of before. I _have_ seen the Slave actuate (as it’s positioned on the outside of the tranny) and that looks fine to me.

Your second and third sentence seem...like opposites to me. If you think the clutch isn’t de-coupling (as I do), why would you think the PP is fine? Its entire purpose is to do the de-coupling, right?

In my mind, either the TOB isn’t pushing on the PP hard enough/throwing far enough, or the PP is so fucked it isn’t decoupling the clutch (or, as mentioned by somebody else, it’s possible-if-unlikely that the Flywheel is so badly warped that the PP is doing its job, but the clutch is still touching the Flywheel anyway. I feel like that would lead to chatter more than anything though)

Wrong Wheel Drive (41%) > TwoFortified
08/25/2016 at 16:05

Well that info doesn’t really help me, but someone that is knowledgeable in S13s specifically might care. I just know my clutch slave cylinder gave me hell in my Miata and I had to replace it twice. Once was some shitty autozone replacement and then two weeks later was an OEM replacement which worked out just fine. And bleeding it took over an hour to get it right. But now everything is just peachy!

crowmolly > TwoFortified
08/25/2016 at 16:06

It could be the PP but you said nothing really jumped out at you as messed up and they are pretty simple. Diaphragm clutch, right? A flywheel or clutch assy failure that’s this bad would probably have SOMETHING visible. But again, I am doing this sight unseen. I am thinking that the TO might still be too tall, or there’s not enough force behind it to do its job.

http://forums.nicoclub.com/clutch-release…

Is this your type of setup? Are you SUUUURE that it’s the right TO bearing? Same height compared to the old one? Is the sleeve it moves on free of burrs/deformity? Is the TO bearing seated in the fork properly?

Edit:
Wait, did you actually pull the PP and check the friction surface or did you just pull the trans?

TwoFortified > crowmolly
08/25/2016 at 16:15

First I bought the whole throwout bearing assembly, so I wouldn’t have to use a pneumatic press. That bearing/assembly was wrong. The second one I bought was just the bearing. Its diameter wasn’t 100% perfect, but it was within 1/10th of an inch, and now that I’m using the old assembly (by swapping the old bearing for the new in a press), I’m pretty sure the height is correct.

The sleeve looked fine, and the bearing is affixed to the fork correctly.

The interesting thing about that nicoclub posting...somebody recommended popping the dust cover off the throw out arm. I had never considered that. It’s pretty easy to get that dust cover out of the way...And maaaaaybe I’d be able to see in there while the magic is happening. Totally worth a shot.

crowmolly > TwoFortified
08/25/2016 at 16:16

Yeah man, do that. Maybe you can look inside and see if the fingers of the PP are moving or not.

TTercel > TwoFortified
08/26/2016 at 09:25

Last thing I can think of is a bent clutch fork.

TwoFortified > TTercel
08/26/2016 at 12:26

I had considered that as well. Examined the fork as thoroughly as one might examine it (without actually taking it out of the transmission). Looks good.