Flybry07

Hello everyone!

Long time reader but had yet to jump in!

I purchased an 84 928s last month with some clutch issues as it would not go into gear.

I replaced a cracked clutch pedal, replaced everything in the clutch hydraulics ( had a bad blue hose and air in system) bled it many times with the power bleeder and pushing the slave rod in method and still can't get this clutch release right! It drags!!

The clutch is I believe is bled properly the pedal is firm but it presses the master cylinder piston in slightly before full pressure is felt. It's not a dead spot as there is resistance there (and a faint fluid sound) but it feels soft for just a small amount of initial travel then very positive.

The car drives now but grinds into reverse and fights to go in and out of gears. It does not slip or chatter either.

The clutch grabs slightly when immediately lifted off the floor but does not fully engage until near the top of the pedal travel.

I tried the "pry the clutch release arm past where the slave pushes it and have an assistant pump the pedal to move the slave push rod out more" method and it does work! The shifter falls effortlessly into first and reverse. However as soon as the pedal is released and then re applied it looses that extra length.

I also took a look at the pivot ball at the top of the bell housing and the ball is there but the plastic cup is cracked and worn. ( is this it?)

I am becoming very frustrated and need some guidance!! Please help point me in the right direction!!

Thank You!!

Ben Allison

Have you done the intermediate plate adjustment? The three little 'T' tabs to move the intermediate plate. Sometimes the clutch is dragging because this is out of adjustment.

Also, have you replaced the release bearing or greased the clutch shaft (or replaced any other components on the clutch itself?). I cracked the clutch pedal on my '84 also (PET lists an updated part and the used one I picked up from Mark A was much beefier, but I'm sure you've figured this all out already . When I replaced the clutch, pressure plate, release bearing, pilot bearing and pivot arm bushing (cup), the clutch pedal effort went down significantly. You might have some binding that keeps the pivot arm from traveling fully.

GlenL

+1 on mis-adjusted intermediate plate.

The clutches don't seem to be all the same in how to best adjust them. Mine works with prying the Ts all the way open. Forget spacing the plates.

Your description sounds like there's still air in the line. Sounds like you may have done this but I get the best result doing a bleed with the slave rod shoved all the way in and the bleeder tipped up a bit. Takes two people.

Make sure there's a bit of play between the pedal and the master. That is, the pedal goes down like 1/4" before beginning to press on the master.

And, as Ben said, make sure the discs and moving well on the intermediate shaft. That shaft will wear and cause the discs to bind in place. Whatever the source of the problem, the clutch isn't opening fully so the tranny input never stops turning.

Lizard928

My bet is #1 on the clutch still having air.
To bleed pull the guts out of the master cylinder slowly until the primary (2 seals on shaft) can be seen and tilt the rear down allowing the air to escape.

If that isnt the case then yes the clutch is out of adjustment.

Flybry07

Thanks for the replies! I have not done anything physically with the clutch yet. Yes Ben that newer pedal is much better and not hollow like the old one!!

I'll do my last bleeding attempt tomorrow!

To bleed the master by removing the piston slightly do I need to pressurize the fluid reservoir first with the power bleeder?

mark kibort

intermediate plate for sure!!

Look for 1mm gap off the ears of the H adjusters. If it looks like a big gap, you are rubbing on the pressure plate, if there is no gap. Unlikely, its rubbing on the flywheel. If the clutch parts are in good shape that will be the situation. You cant push the H adjusters all the way open and not have it drag on the pressure plate. (unless the pressure plate has some wear along with the discs and maybe the int plate. If all 3 have just .25mm of wear, the adjusters can work all the way pushed back. if new, its unlikely. So, give it a look. Its pretty easy. the cover comes off with the 8 or so 13mm bolts, then just rotate the crank to see all 3 of them, and adjust by pushing them together with a long thin flat head screwdriver. If you go too far. (no gap), you can open them up with a big flat head on the the pressure plate itself forcing it against the spring pressure. (there is a rounded lip on the Int plate right next to the "H"'s that you can lever on to open them up) the gap should only be about a couple of business cards thick. (ie. 7 to 1mm or so)

Mrmerlin

I think you need to do some investigating, with your old master cylinder see how much travel the piston has.
Seems that the newer pistons dont go as far as the older units, this can fixed by removing the new master piston and grinding the tip down about 1/4 of an inch and then slotting it.
Next is to check the H tabs on the I plate these have to be adjusted or possibly one of the discs will drag

Sailmed

Only pressurize that cylinder if you are "The Flash"
Quite often when I rebuild the master and slave, which should be done as a pair IMHO, I bleed the slave first. After everything has been re-installed in the car, bleed that slave, and then put a small Tupperware container and a few paper towels under the master cylinder to catch fluid. Remove the pedal clip and master C clip. This allows you to pull the boot up, and draw the plunger out of the master cylinder slowly. As you are drawing it back, with a very slight downward angle of the inside rod end, you will see fluid start to come out. Push your plunger back in slow enough that the air travels out the top last, thus bleeding the cylinder. Had you pressurized the reservoir, you would have made one heck of a mess.
Now install your plunger shaft on the pedal, push down and install your C clip, and slide your boot back down. Don't forget to install the pedal clip.
As stated by the wizards above, if your clutch is out of adjustment, even this won't make it work... But it's still the cats meow for bleeding.

Always stretch before exercise. By following the above you agree to the possibility of severe injury during contortionist yoga yada yada yada....
What you do physically with your clutch is your own private business.
Not responsible for accidents, injuries, or misuse of the equipment.

Flybry07

Great! Thanks for the help guys! I'll try the bleeding first then move to the H adjusters. I read the 13 pages of Marks clutch adjustment but still am a bit unsure of which way they are to be pushed where the gap should be etc. Are there pictures of the procedure being done in the car?

Also I take it from your replies that the worn clutch arm ball cup is most likely not a culprit?




Thanks again!

928worldwide

Yeah Brian that's the ticket- pain to bleed that system

123quattro

I also think this sounds like the intermediate plate. I did not break any of the clutch hydraulics when I pulled the engine two weeks ago. It worked fine prior to taking the engine out. After reinstallation it drug badly. I started the car in gear and went for a drive. Being careful to match speeds when shifting I drove it for a few miles. It "re-adjusted" itself and is back to working as well as it ever did. I wouldn't normally recommend doing this, but with headers on my car you can't take the cover off and easily adjust the intermediate plate. Do what Mark says....

mark kibort

I have a picture on the thread that shows the H's. You will open your bell housing up and see the H's. just look at them. they will more than likely have wide gap. 2-3mm or so, you press on top of the H's with a flat screw driver and lever them down. they move pretty easily. the easier they move, the worse, but they all move. do it slowely and move them down unti there is just a faint gap. thats all you need. what that is doing is giving a little gap so that the intermediate can move backward when the clutch is engaged. ( the lever arm pulls the pressure plate to release pressure. the intermeadiate plate has little very weak springs that follow the pressure plate rear ward to allow the flywheel to spin freely and not drag on intermedate plate. that little gap, any gap at all will allow this to happen, unless your discs are shreaded .
too much gap and when the pressure plate pressure is removed, the intermediate plate is pressed on to the discs, which are pressed on the pressure plate and it keeps just enough friction to not release. this is why too much gap is bad and DOESNT work. (there was some talkabout moving them all the way back, but that can cause as much of a problem as no gap).

When scots clutch weak "H" adjusters were going, we would have to close that gap after ever race. street driving wouldnt effect them.

hope that helps.

mark kibort

They really cant adjust themselves as they are floating, but that friction, that is really faint, can be reduce with temp or the clutch master and slave will pull back the plates slightly more as that system changes with temp. When scots were bad, i couldnt even get it in gear, but if i pushed the pedal again, then it would barely get in gear. (like pumping the clutch pedal). anyway, the intermediate plate floats and never touches the forward tabs and only comes to rest on the rear ward "H" tabs via that slight spring pressure which cant do anything no matter how fast you release the clutch pedal. Those 3 flat springs dont have a lot of force to press on the "H" adjusters.

GlenL

Mark and all,

I've had total success just cranking them all the way to the rear. Other people have reported the same.

Obviously the simplest adjustment is "all the way" and I suggest trying it first. I spent a lot of time trying to do the FWSM and DEVEK approaches before getting frustrated and cranking them back. Too easy not to make the first try always time to fiddle with it which is inevitable with the other approaches.

123quattro

Well, I drove it for a few miles and it "fixed" itself. It was dragging heavily prior to the drive.