I completed a T56 swap into my originally A4 car about oh idk 15k miles ago roughly, and it had been going really well until yesterday.

I'm pretty certain what I'm dealing with is an issue with the master/slave cylinder hydraulics, and I'm looking for confirmation or other theories before I order the parts.

Main symptom is that the clutch isn't fully engaging (I think I'm using that term right, it's always confusing talking about clutches engaging/disengaging and clutch pedal up/down) or to put it another way, the engine is not being fully disconnected from the trans. Also, the pedal feel has changed slightly (I think) and the catch point as you release the pedal has changed significantly, ie since the clutch is basically still caught a little bit when the pedal is against the floor, I only have to let it up a tiny amount for it to be fully caught. This is obviously making standing starts very tricky and shifting gears has also become quite difficult. I can access all the gears right now, but it basically takes double clutching and rev-matching, and even then there's some grinding on gear entry.

The fluid level in the master cylinder is ok, there are no obvious leaks, and I do still have resistance on the clutch pedal, and it does still rebound on it's own, but it's maybe 20% easier to depress than it was before this issue showed up. And it seems to me that when it is in gear and the clutch pedal is all the way out, that it has every bit as much gripping force as it ever did, and is not even hinting at any slippage.

stock or less HP level, stock flywheel, stock T56, SPEC Stage 3 clutch and pressure plate (overkill I know, but it's what came with the trans swap deal)

I have myself convinced that new hydraulics will solve this, as it just feels like I'm not getting enough stroke out of the slave cylinder/clutch fork travel as I should, and if I could just get the clutch fork to pull back a little more and release the friction disk a little more, everything would be fine.

But I'm obviously open to confirmation of my suspicions or alternate theories.

Thanks in advance!

 

Yes it's quite possible you have air in the lines somewhere. It's best to have one person watch the reservoir while the other pumps the **** out of the clutch to see if any bubbles rise to the top and to watch to ensure the reservoir does not run dry. Also, check for leaks.

 

In your opinion, would this be something that would get worse the more I use the clutch pedal? This started happening on my way home last night and got worse on my drive to work this morning, which is about 130 miles each way.

 

no the problem will not go away on its own and it will just get worse

sounds like your hydraulics are failing be it the MC or slave. The more common issue is failing MC

what you are describing is "disengagement" issue

You can buy either a MC or slave or buy both as a "sealed" system which won't require bleeding (difficult) assuming you don't break open the system to install it (should not have to)

 

Thanks for the advice everyone, I have gone ahead and ordered the AC delco sealed MC/SC sealed set since I had to order by noon today to get amazon's next-day prime shipping. Hopefully I can make it home tonight and install it tomorrow and get back up and running.

If new hydraulics don't happen to fix this issue, is there anything else I should look at?

 

I had a similar situation a few months back. When I depressed the clutch pedal, I could still hear what I would describe as something rotating and scraping in the clutch area. It sounded like the hydraulics weren't disengaging the clutch enough. It also wouldn't let me shift like it was stuck on the flywheel.

I took it to a local shop telling them I was certain it was the hydraulics. They called me back and told me that the hydraulics were fine but it needed a new clutch assembly. I was floored because there was absolutely no slippage. I told them to do the job but be sure to provide me with the old clutch assembly.

Sure enough, I got the car back and it was drivable again. Still the old master and slave on it. I took a look at the assembly that they removed and one of the springs had blown out completely.

That was, as far as I know, the stock clutch on my 94z with no modifications at all. About two months after I purchased it. I'm not saying that's what's going on here, but I would say your next step might be to check the assembly. Especially if you and the previous owner of the clutch have/had a penchant for hard launches.

 

While I really appreciate your advice, I hope to hell you're wrong, LOL.

I had actually read of similar accounts that did sound somewhat like what I'm experiencing due to broken/missing/FUBAR'ed springs from the friction disk. I really hope I can get out of this jam without dropping the trans though. just getting it in the one time by myself was almost more than I could handle.

 

Absolutely no offense taken! I hope that I'm wrong too! I would never be able to handle a clutch install myself, so my hat's off to you for even doing it once.

 

the symptoms point to a hydraulic issue....but it could be the clutch or bent lip on the TO bearing. The later generally results in some form of noise though.

The hydraulics, on LT1, or not hard to replace vs pulling the clutch out. Ideally the new hydraulics will resolve the issue but if not than the tranny will need to come out to look at the clutch

 

Thanks for the additional info. Since my car was an A4 previously, I have experience installing the hydraulics and do admit it's not bad, except for that doggone ubolt design on the MC, like, I get it, it's the perfect application for a ubolt, but man was I surprised to learn that the holes I drilled for it from inside the car were basically completely blocked by the brake booster.

Also since it was a swap with a t56 without a well documented history, I have no idea what noises are normal/abnormal. The puck style clutch and dynomax bullet muffler also don't help matters, but I don't think any new noises accompanied the newly semi-functioning clutch.

Also, if I'm not mistaken, it seems like if am stopped, with the car in gear, and clutch pedal depressed, if I leave my foot down, over time it seems like the clutch starts grabbing more and more, which in my mind further points to the hydraulic pressure bleeding down, due to leaks/air.

 

LOL, have fun with that "U-bolt". I did not put it back in, just some nuts and bolts with locks.

 

Yeah, I had the same idea but wanted to try it the factory way first, I fiddled with it for about 39 minutes before I got lucky. I had told myself that if it didn't work after 40 minutes that I would find some regular nuts/bolts for it, LOL

 

Yes R&R the trans is absolutely no fun, even with a few beers!, Pulling it was not as bad as trying to install it, If you have to pull the trans, I highly recommend you try and get the car as high as possible and a trans jack with all of the angle adjustments makes it a hell of a lot easier than trying to muscle it it back into place...

 

IDK if you installed new or used hydraulics when you did the A4/T56 swap but the new hydraulics will come with the slave "strapped" closed. Just install it that way. The 1st time you push the clutch pedal the plastic straps break leaving the plastic cup on the slave piston. you need that cup on the piston end.

Yeah pulling the MC from pedal assembly likely is not fun. I did my A4/T56 swap in a B-body and that pedal assembly is custom using the F-Body hydraulics so pulling my MC is also a PIA under dash-hard to feel bolts also.......but easier/faster than pulling the tranny :-)

 

It sounds like you've found your issue, most likely. But if it turns out to be something else, here's something else to consider. I've changed out my clutch more times than I can count but something I've noticed on quite a few of them is after they've been run hard for along time, there is a significant amount of forward and back play in the throw out bearing. This seems like it could cause your issue because you can't pull the pressure plate as far away anymore. Just another idea.

 

So it wasn't the hydraulics...Anybody want to buy a brand new ACDelco sealed MC/SC combo, seriously, I'll sell it cheap!

Leaning towards some kind of TOB/PP/Clutch plate failure at this point.

I decided to resurrect one of my other cars while I muster up the courage to pull that T56. The other car just needed a new front axle shaft, and at this point I was happy to swap that thing out versus dealing with the T56 again

 

I'm really sorry to hear that, what a gigantic pain in the ***. I know its sacrilegious around here to mention shops doing the work, but if you're having a tough time mustering up the will to get it done, my clutch job was right around $800 out the door with a stock replacement unit. It might be worth it to you to get everything back up and running!