[V8] clutch

Thu Nov 24 08:13:28 PST 2011

Hi Scott,

here is what I have done so far:

I have the original slave from the first clutch job - I just replaced it because I was in there. It is aluminum, the "new" one is iron. Both do the same thing, neither shows any sign of seal leakage, both look physically the same (aside from iron v aluminum)

The "best" bleed procedure seems to be:
	-> remove the slave (still attached to hose) from tranny
	-> hold vertical (bleeder nipple up) and do all the usual bleed steps.  I have a pressure bleeder, and do it manually as well.
	-> test (1) by compressing the slave piston against the frame rail (just hold it down with my palm), then having my trusty assistant (12 year old daughter) press the clutch pedal to the floor.  The piston extends about 1.25 inches, which is not the full travel of the slave, but does look to be about the full travel of the master.  The bores look to be about the same diameter so I would expect the distance traveled to be the same.
	-> test (2) let the slave spring fully extend the piston and bleeder valve closed. Everything should be full of fluid and the piston is bottomed out so if I (carefully) press the clutch I should immediately feel solid resistance with no springiness - and that is the case.

I am not sure what you mean with your test and the "burp".  If there is no air in the system, and I did that procedure, at the end, the clutch pedal should be up, the slave cylinder should be fully returned and expel any oil back into the master/reservoir so what would burp?  Is there any sort of check valve in there?

Another observation - when I install the slave, it looks like the piston rod hits the throwout arm such that I have to compress the piston about 1 inch - maybe even a little less.  That says I am not getting the full 1.25 inch throw.  Do you know if that sounds normal? or know what the typical throw of the throwout arm should be?  Is there something that could silently and quickly fail to cause this?

Again, if I start the car in gear, it is as if I am at the point where the clutch is just starting to release.  I can sit there and idle but cannot shift in or out of gear.  It makes no unusual noises and is smooth.

And on Rule #1 - are you thinking the new master could be bad? is there a difference in the V8 vs say a 200 in this part?  The new one behaves the same as the old one, and for that matter, I feel the same flexing of the new hose as I did on the old one.  That surprised me a little.

thanks
Dave

On Nov 24, 2011, at 8:19 AM, Scott Justusson wrote:

> Rule #1:  New does not mean known-good
> Rule #2:  Known-good is better than new.  See Rule 1
> Rule #3:  If a symptom points to a new part - see Rule 2
> 
> Dave:
> Without any other reading than the pedal, this says slave cylinder or air in the lines.  For slave, I bench bleed all slave cylinders prior to install. I also use a Snap-on pressure bleeder to bleed.
> 
> Test:  Take your hand and manually pump the clutch pedal 50 times, to the floor and bring it back up manually.  Crack the bleeder screw at the slave.  Does it burp with the release of the built up line pressure?  If not, likely bad slave.  OR, you haven't gotten all the air out, or there is a leak.
> 
> It's possible you have bent/faulty tines in the clutch PP.  Can you get the clutch to actually release?  Normally, I see Clutch to the floor with nothing as Master, clutch almost to the floor with something as slave, and no clutch release at all as faulty tines.  The only other thing I've seen only once, was a similar problem on a  'miss' of the TOB fork detent installing the slave.  
> 
> HTH
> 
> Scott J
> 92 v8 ABT Chipped
> 
> 
> -----Original Message-----
> From: Dave Saad <dsaad at icehouse.net>
> To: audi fan <v8 at audifans.com>
> Sent: Wed, Nov 23, 2011 9:58 pm
> Subject: [V8] clutch
> 
> well - this sucks.
> My clutch stopped releasing fully just a few days after I got the new rack 
> installed.  I hoped it was some sort of hydraulic problem - and it looked good 
> for a while that it was.  The master had a broken internal spring, and the hose 
> was looking like it might be stretching a little so I replaced both.  The slave 
> is good.  Still no go.  I can't imagine what might have gone wrong with the 
> clutch to cause this.  It made no sound.  It just won't release all the way.  It 
> was replaced about 70K miles ago.  The symptom is the pedal feels a little soft, 
> and is most of the way down before it starts to really feel like it is doing any 
> work.
> 
> I have tried bleeding the system every way I can think of and am (99.46%) 
> certain it is not that.  This is a real PITA to do by the way.  I think the 
> easiest way to bleed the clutch is to hang the car by the back bumper with a 
> crane so the air bubbles go to the top of the slave.  What I really ended up 
> doing was bleeding the system with the slave off the transmission and turned 
> vertical.  This of course made installing the slave lots of fun since you have 
> to compress it with your pinky while installing the bolt with your tongue - all 
> while blindfolded.  I hope DOT4 is not poisonous.
> 
> So - it looks like I will be pulling a motor real soon.  In the meantime of 
> course I am driving my beat up old '83 ranger with who knows how many hundreds 
> of thousands of miles on it.  It still has all original hydraulic parts for both 
> clutch and brakes.  It would still have the original clutch too except I changed 
> it a few years ago because I was towing my trailer and just could not believe it 
> was still good.  It was.
> 
> Grrrr
> 
> Dave
> 
> 
> 
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