car_ramrod

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!

bw_hunter

You might have air in the line. To bleed the lines:
1) jack the car up to hive you access to the slave cylinder on the bell housing.
2) remove the cap on the master cylinder.
3) remove the slave cylinder from the bell housing.
4) with the line fitting held highest, pump the cylinder, slowly, until a much harder resistance is felt. It takes a lot of pumps sometimes. When the harder resistance is felt keep inward pressure on the rod and install back into the bell housing.
5) top up the master cylnder...the fluid level should have dropped a little...
6) lower the car and give it a try!

Good luck!

car_ramrod

Thank you for the advice!

Chimera96

if the disengagement issues is not resolved by the bleeding method described, or returns shortly after, than the hydraulics are bad/failing. MC or slave but more commonly the MC

you can buy either separate or buy a MC/Slave/resovoir sealed system that requires no bleeding

car_ramrod

Thanks everyone for the advice, I cross posted this on another forum and everybody is pretty much in agreement. I went ahead and ordered the AC Delco sealed MC/SC unit since I had to make the 12noon cutoff time to get next day shipping on amazon. I'll update everybody with the outcome once I get it installed.

bw_hunter

Why would you buy a new one without trying to bleed the old one first?

JakeRobb

The new sealed system will almost certainly fix the problem, although you will have spent a lot more time and money with determining whether it just needed to be bled first. Too late now, though, I suppose.

When you press the pedal in, you are disengaging the clutch, which is the same as disconnecting the engine from the rest of the driveline. The easiest way to remember this is that the "dis" prefix for disengage and disconnect applies to the same event; those terms are equivalent here.

car_ramrod

So....it wasn't the hydraulics. The new MC/SC set provided the same results. Thinking it's a TOB/PP/friction disk failure at this point.

I'm selling the hydraulics cheap, if anybody wants an essentially new AC Delco sealed system

I'll eventually update this thread when I find the real culprit, but thankfully I've got one of my other cars back on the road while I muster up the courage to pull the T56 again...