4kq, slipping clutch :(

[Robert M]

  Thanks for the detailed reply, Roy.  Pretty obvious that I'll be doing a 
clutch job, so I have some part related questions as well.

My current parts list is as follows:
1.  Slave and master
2.  Connecting hose
3.  Clutch kit (disc, pp, TO bearing)
4.  Tranny mounts x2
5.  Pilot bearing
6.  Throwout bearing guide sleeve
7.  Rear main seal
8.  Driveshaft seals x2

Questions:

A)  Have I forgotten anything?! (either for the clutch job or because it's 
easier to do with the transmission out)

B1)  Do I really need to replace the throwout bearing guide sleeve?
B2)  There seems to be two different ones available, call them Cheap ($3) 
and NotSoCheap ($15).  What gives?

C) There seems to be two different pilot bearings available, again cheap and 
not so cheap.  Any help?  In this case they appear to be different...

D)  Is there a transmission input shaft seal I should swap?  Couldn't find 
one in the FA but the FA and I don't always get along...

E)  Any intel on the least painful place to get part #2?

F)  I assume the downpipe has to come off (sweet).  Is that gasket reusable?

TIA,
Robert
'87 4kq

>From: "E. Roy Wendell IV" <erwendell at mac.com>
>To: quattro at audifans.com
>Subject: Re: 4kq, slipping clutch :(
>Date: Tue, 6 Dec 2005 12:30:17 -0500
>
>snip
>>... that said, it does indeed seem odd that the clutch only slips in 4th
>>gear ...
>
>Not really, and I imagine that it slips even worse in 5th gear. The higher 
>the gear the less mechanical advantage in the provided by the transmission 
>and therefore a higher torque load on the clutch. Slipping clutches always 
>show up at full throttle in high gear first. Running in a lower gear and 
>higher rpm provides the same torque at the wheel but much less at the 
>flywheel which is how you can get a car with a worn clutch to limp along 
>for a while. Top speed of course is limited.
>
>>... the failure of the pedal to return to the full up position is not 
>>likely
>>to be related.  I'd imagine that you're getting a bit of leakage past the
>>internal seal in the master cylinder ... I've found that bleeding the 
>>clutch
>>can restore function, but it may require a clutch M/C swap.
>
>Yup, hydraulic problem it is. The "return" spring on the pedal assembly 
>isn't, actually it pushes the pedal down. The return force is provided by 
>the clutch pressure plate diaphragm spring via the throw out bearing, 
>clutch force, slave cylinder, fluid, and master cylinder. When the 
>hydraulic system no longer seals and keeps a direct relationship between 
>pedal position and throw out bearing position then the pedal starts getting 
>lower and lower and/or magically sinks down to the floor by itself. 
>Temporarily you can limp along by hooking the clutch pedal with your toe 
>and lifting it back up. Don't sit at a traffic light or anywhere else for 
>that matter with the car in gear and the clutch depressed. When the clutch 
>hydraulics get really bad the clutch can engage no matter what you are 
>doing with the pedal. The clutch itself is spring loaded to the engage 
>position. Once you loose the ability to transmit a force to it via the 
>pedal to counteract the pressure plate spring it will engage and your only 
>resource is quick action with the brake and key.
>
>>Since we're talking about a car that is approaching its 20th birthday, and
>>which very likely still sports the same clutch components it had when it
>>rolled off the production line ... if you do decide to do the clutch you 
>>may
>>want to consider replacing (or rebuilding) the master and slave cylinders
>>and replacing the flexible line in the clutch circuit ...
>
>Ditto. Good luck with rebuilding the clutch hydraulics. The kit is 
>difficult to find and both the master and slave cylinder bores are likely 
>rusted beyond the point where a hone will restore a smooth bore. No one 
>ever bleeds these systems and the fluid in the clutch slave has likely been 
>there since 87 and is about 50% water. Rust pitting of the cylinder bore is 
>the usual source of failure since the rough surface cuts and abrades the 
>chevron seal on the piston. Then the fluid bypasses the piston and 
>therefore develops no force.
>
>Roy Wendell
>Morgantown WV, USA
>turbo quattro type 44 times 3
>
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