1980 928 Clutch won't engage

[realestate00]

I just purchased a 1980 928, being told that the slave cylinder needed replaced. (fullish me to believe someone). Now that I can get underneath it, the slave cylinder was replaced and engaging/disengaging the clutch. You can go through all the gears but the car will not move, even when revving the motor some. Is this common to when the car needs a full clutch replacement or is there something else that I should check?

[kennner]

Sounds like a worn out clutch

[JK McDonald]

Hey Realestate, There are a couple of things that you might check before you start a major disassembly. The 80 model 928 actually has a stacked dual clutch assembly installed within the bell housing. Normally this setup will at least try to move the car to some extent unless your baby has both clutches completely burnt up or very badly glazed.

1st Have you verified that the transmission shift linkage is intact and you are actually engaging the gear sliders inside the transmission ? There is a two piece external shift rod that rides horizontally along the top of the bell housing/torque tube/transmission that can sometimes be a problem. The console gear shift lever sits approximately in the middle of these two rods. Check to see if the anchored ball socket on the top (front end) of the torque tube has not popped off and the universal joint at the transmission end is attached properly.

2nd Perhaps the splines on one of your rear drive axles is broken or one of the viscosity joints at each end of a drive axle has failed internally.

3rd There is a short stub shaft that connects the output of the clutch assembly to the primary drive shaft within the torque tube. Their coupling clamp within the bell housing (drop the lower inspection plate) or the splines on the stub shaft or the primary drive shaft may have failed.

What is the old saying about buying a used car - believe nothing they say and half what you see....

Good Luck, Michael

[aluminum]

Sound stupid But: just some tests
without starting the motor Place the car in gear like 1st gear > and by hand
( motor and brake off ) try to roll the car .
Now the car ( Level Ground ) should roll in Neutral but in Gear it should feel at least some resistance Evan if the Clutch is slipping badly .
Also the nose test : ha ha ( I know your not laughing just now sorry )
Point being > if the Clutch is slipping badly or just some with the motor running and trying it you should smell a brunt smell a STRONG Burnt SMELL >> do You ? if not > Then follow
JK McDonald excellent post

[realestate00]

Thanks for all the feedback. I have verified that the shift lever is working and actuating the transmission. I have not checked the rear drive axles. (that sounds like a dreaded problem to have), but will. I am hopeful that what lies behind door no. 3, the coupling clamp, sounds promising.

Weirdly, not smell...

I have a couple of questions that maybe someone could help with.

1. So, can the clutch, with all associated parts (including the pilot bearing) be replaced w/o removing the transmission tube and transmission? I found a pictorial (Rennlist Discussion Forums) that went through the clutch replacement which I would be fairly confident with.

2. But, the adjustment of the double disc clutch center ring as explained sounds complicated. I'm mechanically inclined (not a professional) but could not really understand what was being accomplished. Same website listed above.

If anyone could direct me to a comprehensive R&R reference, I would greatly appreciate it.

Oh, and I see where Pelican Parts no longer carries the clutch kit for my 1980 928, anyone suggest another source?

You guys rock...

[lfausty]

a wrong sl cyl part? you got right yr part replacement for 1980 78-82? 928 --- --- 18. 83-86? is different 928--- ---19 , so on ..... maybe clutch not extending too much or too little, throw out is 14? 17?

[realestate00]

I'll check this out...When I bought the car, the owner swore that he had it checked out by a technician (PeeWee, go figure..) who stated that the master cylinder slave cylinder ( I'm sure that you know what I'm referring to) is bad. Would that have anything todo with the clutch not engaging?

[neil30076]

Don't panic, If the master or slave was replaced there is a very good chance they did not bleed it properly.
Use search here and over on rennlist - you will find many posts.

[Pete R]

Usually a failed or poorly bled slave or master would make it hard to DISengage. But it may be possible that something else went wrong.. like the slave pin fell out and wedged the clutch open (unlikely but perhaps possible)

yes all you have to do is drop the housing under the clutch, torque tube and tranny stay put.

Intermediate plate adjust is easy. I'll look at one and refresh what I do so I don't explain it badly and confuse anyone.

[cal928]

Here is a quick check. I was lucky to find a mint early factory service information book (metalic copper color cover161 pages metric size sheets identification number 4582.21) On page 45 it shows a side cut away assembly of the clutch. on the bottom of the housing, in front of the slave cylinder is item #17 an inspection plug. The book says to remove it and look into the inspection hole with a flash light. If the clutch plates are good you should see the slave cylinder piston rod. If they are worn out you will see the clutch release lever.

[Landseer]

Yes.

The entire clutch assembly can be removed. Fairly easy compared to other cars. Both engine and TT stay in-place.

Hardest part for me is usually driving-out the alignment pins ( I think 80 has them ).

Be careful not to drop the assembly on your face as you work with it.

Do not fear the adjustment. I learned that all I needed to do was pry the three "T" s on the intermediate plate to the rear position with a screw driver. Worked fine on a brand new clutch / plate assembly. Worked fine also on a worn one.

The bleeding of the clutch hydraulics is almost impossible without a tricky technique. (Master is mounted on such a crazy angle that it can trap air --- I usually burp it into the cockpit) There are descriptions how to perform this.

I think you should have about 3/4 inch of slave rod travel. Pedal should be high and give resistance above the spring detent. Note that master replacements sometimes have pistons that require length reduction to allow full slave stroke. Another quirky nuance.

There isn't a great all-encompassing clutch thread. But plenty of pictures and posts here and rennlist to help.

I have posted good pictures of the system before.

Not engaging is a new one, unless front or rear couplers are loose / damaged / gone.
I've heard of rear couplers getting loose and being stripped, but leaving input shaft splines intact.
There is an inspection port in the rear to check coupler bolt torque.

Pull the bell housing as a first step.

[Mrmerlin]

and instead of trying to drive out the flywheel pins,
loosen the the 4 bolts on the bell housing so there are about 4 turns from coming out,\
then remove the 2 rear trans mount bolts,
then you can slide the TT/trans back enough to have the clutch assembly drop out without messing with the pins,.
Make sure to use the 3 U shaped spacers for the PP pins the wire should be about 3mm thick a coat hanger is too thin.
this lets you have extra clearance to remove the top of the clutch pivot arm.
You want to replace the pivot bushing if you take it apart unless it looks new the bushing presses onto the ball then the arm fits over the bush

[realestate00]

Thanks to all for such good information. I checked out all possibilities and end up removing the clutch. The hardest part was the bolts holding the Y-pipe to the exhaust manifords. (go figure) Once remved, I found that both discs were worn to the rivets. I'm not sure how much machining can be done to the intermediate plate. Does anyone know? In addition, does can anyone lead me to where I might find a used one? Thanks in advance for your help.

[ltbordo]

what are these shims I hear about to hold the clutch together during disassembly?