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‘78 Clutch and torque tube bearing replacement with hydraulics, Need some help/advice
Hey all,
I’m at the tail end of my clutch and TT bearing replacement and have run into some issues. I’ve tried to search as many previous threads as possible before starting a new one, but can’t find my exact issues, so here goes. I replaced the TT bearings with Black Sea bearings using Constantine’s and Dwayne’s procedures and the wsm, thanks Constantine, thanks Dwayne, it went great. The problems I’m having now are with the clutch.
Some brief history of the car before the TT/clutch replacement, up and down shifted into all gears without grinding 95% of time, with some grinding into 1st and 2nd 5% of the time. Clutch slipped pretty good under hard acceleration hence the replacement and throw out and pilot bearings made some noise. Clutch master had slight leak on front seal into cabin by pedal
For clutch parts I tried to source all the original parts I could, but ended up with some equivalents. Parts are:
Sach pressure and friction plates
throw out bearing from roger
FTE clutch master and slave
new blue, flex and hard lines
New ball cup bushing
new pilot bearing
shaft and splines were in good shape so I didn’t replace
Clutch went in pretty good, I followed the wsm. I decided to first try just replacing the guts of the master as mine were the same size as the originals, no mods needed. Bled the system, using vacuum bleeder and slow pumping the slave. Clutch pedal felt good so I fired it up and it grinds 1,2 and reverse, shifts the rest. Noticed clutch master still had same leak even with new internals, so I replaced everything on the hydraulics and bled the system using Stan’s procedure of removal and doing it on the bench, which is really slick, thanks Stan. With everything back in and new master, the master has the same leak on the front seal into the cabin and also has a little click at the end of its travel now. Clutch shifts the same, still grinds 1,2 and reverse. I checked my slave action and I’m getting good movement, but realize I have a leak and probably still some air. I’mthinking though I have a problem with both the clutch itself and the hydraulics, super fun
Is anybody using these FTE clutch master and slave parts with success or are they crap?
One of my friction plates has little extension on its hub the original did not have. In the wsm it talks about this part superseding the old part, but does anybody know if it is correct for my car? If not, do you think it could cause the clutch not to disengage? It looks like I could just cut it off with a grinder and it would be the same length as the original, is this a good idea or a poor decision? I’ve had the clutch apart twice and inspected all the usual stuff, ball cap, tried running that longer hubed disc in I and II position, although manual says it’s disc Ii, with same results.
Clutch parts I used
The new friction discs. The ones I pulled out were both short like the far one. Now I’ve got few more fractions of an inch in the II disc, which in this case I don’t think is a good thing
I did not replace the intermediate plate due to its cost, I simply blew the dust off with compressed air and put it back in the clutch pack. Am I at the point where I should just replace it?
Can it be adjusted and if so what do these adjustments do and would they help?
Any help or advice is appreciated, Josh
Last edited by Oldewoodupes; 05-18-2018 at 11:16 PM.
Did you adjust the intermediate plate as per WSM? I would also sort out the hydraulics. Even the slightest lack of travel can cause tough engagement. Reverse and 1st are the most sensitive to this issue.
Thanks Guy. I didn’t adjust the intermediate plate. I’ll look into tomorrow. As for the master, I guess I’ll try another brand, but these FTE’s are nice cuz they are the same size externally and internally to the originals. What did you use on your Ob? Did you have to adjust your intermediate plate?
Thanks granprix, I may take you up on that. I’ll try to adjust mine in the next couple of days and see how it goes. At this point I’d pretty much give my right eye to get this puppy working, so I might just spring for a new one. I’ve never driven 928 with fresh torque tube bearings and a proper working new clutch. I can’t wait, this is killing me.
There's so many tricks to these clutches, it's a wonder they ever release.
You must modify the piston in the master...the new masters do not have adequate travel.
There's multiple threads about doing this.
Is the clutch feed hose properly routed? There's multiple threads about this, also.
Without properly adjusting the "H" stops on the intermediate plate, it is almost hopeless for the clutch to release.
If the clutch shaft has wear on the splines, the new discs will hang up on this wear and not release. I make more economical replacement shafts from superior materials and better design, BTW.
Thanks Greg. I was fully expecting to have to modify the master, but my new replacement was the same externally and the piston and spring internally was also the same size, so I didn’t modify. The piston is a bit different design, but I don’t think that matters. Either way it’s a nice replacement size wise, but not a quality one as the front seal is already leaking.
Checked feed line, looks good.
i will try adjusting the intermediate as you describe and outlined in the wsm. I guess I just dismissed this as I thought because there is nothing to really tighten down just pry on the intermediate, everything would kind of just adjust itself where it wanted to be after a few engagements and releases. Can the adjustments to the intermediate be made with the clutch in just removing the bell housing or does it have to be pulled? The wsm looks like it can be done in place
My shaft splines looked good, but if it comes to it I’ll replace.
If you do need to replace the short clutch shaft, here is a picture of the Precision motorwerks (Greg Browns') new stub shaft on the left. It's a thing of beauty
Thanks Greg. I was fully expecting to have to modify the master, but my new replacement was the same externally and the piston and spring internally was also the same size, so I didn’t modify. The piston is a bit different design, but I don’t think that matters. Either way it’s a nice replacement size wise, but not a quality one as the front seal is already leaking.
Checked feed line, looks good.
i will try adjusting the intermediate as you describe and outlined in the wsm. I guess I just dismissed this as I thought because there is nothing to really tighten down just pry on the intermediate, everything would kind of just adjust itself where it wanted to be after a few engagements and releases. Can the adjustments to the intermediate be made with the clutch in just removing the bell housing or does it have to be pulled? The wsm looks like it can be done in place
My shaft splines looked good, but if it comes to it I’ll replace.
thanks again
If the new master was the same as the old one....it's been replaced before and didn't get modified. Modify.
I've been where you're at...a hundred times. At one point in time, I planned on taking these clutches in and out multiple times, in order to get them to release properly....lost my *** on almost every clutch job I did.
Today, I've finally figured them out....and it is rare to have issues....however there are a boatload of tricks.
Don't forget that if you push the clutch short shaft too far into the pilot bearing, it will fall into that "void" behind the end nub and will "flail" around in the pilot bearing. You must push in the shaft until it bottoms out in the pilot bearing and then pull it back out 3-4mm's for it to be proper. If you look at my shaft, I altered the design, so that this isn't an issue.
Another trick I use, which may help you. Don't hook up the torque tube shaft until you confirm the clutch releases. Use a prybar to pull back the T/O arm (you can put the end on the pressure plate and pull back.) Reach up and see if you can freely spin the short clutch shaft. If things are correct, you can sit there and "play" with the T/O arm and "feel" exactly where the short shaft starts spinning freely.
If the clutch releases at a "reasonable" position in the travel (not at the very farthest point of travel), hook up the true tube shaft....the clutch itself releases, mechanically.
From this point forward, if the clutch doesn't release, you've got a hydraulc issue.
If you are manually bleeding the clutch with the pedal, there is a step that really helps. Take a robust screw driver and put it up through the lower hole in the bell housing....sideways. Have someone operate the clutch pedal and have them slowly pump the pedal, while you attempt to keep the T/O arm levered to the rear (without prying out the slave pushrod.) After 3-4 pumps, the arm should be back as far as possible and you can release it. The pedal will then be firm and the clutch travel will be much farther than you can achieve, without this step!
The original clutch line that goes under the starter makes bleeding these things a tough job. Not to keep pushing on my stuff, but my one piece flexible line that routes around the front of the starter is literally light years easier to bleed.....and eliminates the need for the above step, if bled when the slave is out of the bell housing.
Mr. Merlin (genius 928 guy) has the best instructions for doing this...maybe he will post them, here, again.
Getting back to being able to post thanks IB...
Thanks Greg for making great products that work the first time .
The part he makes is easy to install and will be even easier to bleed.
What I do is put a piece of saran wrap over the MC opening then fit the cap,
this will reduce the amount of fluid that drains while you work.
Clamp the old flex line , so fluid wont drain.
remove the B nut fitting from the slave and connect the new banjo bolt and line, snug the loose parts.
Loosen the flex line at the sway bar mount,
remove line securing clip then remove the old line from the mounting area,
then quickly connect the new line and snug it up.
When the line looks like its fitted/ routed well tighten the lines .
Remove the saran wrap from the MC.
Verify you have a full clutch fluid indication,
I suggest to use ATE gold fluid for the hydraulic system.
open the bleeder on the slave till the air comes out .
do this a few times leaving the bleeder open only for a few seconds.
Remove the slave from the bell housing,
open the bleeder again,
hold the bleeder upwards and open it
let any remaining air come out ,
do this a few times to insure its free from air.
Then push the rod into the slave slowly while holding the line port uppermost.
hold the rod in the slave for about 30 seconds,
then let it go,
the spring will push itself to full extension.
Repeat this sequence a few times working slowly,
what your doing is forcing the fluid back up the lines to the MC tank and any air along with it.
Once this is done reinstall the slave to the bell ,
taking care to fit the greased pushrod to the release arm,
make sure the lines are all tight,
then go press the clutch. You should have a nice solid clutch with almost instant movement of the slave cylinder.
NOTE also make sure the MC pushrod is properly adjusted,
you want about 2MM of freeplay so the MC piston is fully returned.
NOTE make sure the release arm bushing is also in good condition to replace it can require different techniques.
I like to take a dremel with a sanding drum and open up the white bushing opening so its easier to fit over the ball,
put some DC111 on the inside of the bushing.
NOTE as previously suggested the new MC should be modded as they are not made the same as the original,
the New MC should have about 4.5mm removed from the tip of the piston,
then remove 1 winding of the spring, this so the spring doesnt go into coil bind and shatter,
if that happens spring shards will be sent to the slave and the seals will be damaged.
Fixed! Thanks Guy, Greg, Mark and Stan. I owe you all a beer.
My clutch release issue was 100% the intermediate plate. Thanks Guy and Greg for keeping me on target with this. The wsm says explicitly to adjust this also or clutch won’t release, but I ignored it because there wasn’t any bolts for precise adjustment or for lock down and my spaces on the H tabs were about the 1mm the wsm asks for. I won’t make this mistake again. Here’s how I got my clutch to work:
Get the clutch pack in the car. Don’t hook up the driveshaft clamp yet, I used Greg’s trick he describes above, very slick thanks Greg. Spin the pack and pry both sides of the 3 H tabs towards the rear of the car. It was tricky to get in both sides of the tabs on mine, but it’s essential. It didn’t seem like I moved them at all, I mean not even a .001, but it made all the difference. Like no release with hydraulics to full release with my hand difference. Once all tabs are pried back, Pry release arm back to release clutch pack. Check clutch release by spinning short shaft with hand. If nothing, keep prying H tabs until you get release. It doesn’t take much. Once it releases hook clamp and everything up and you’re done. My clutch shifts like butter now, every gear up and down, no grinding. I’m almost wondering if a manual car wouldn’t benefit from this adjustment yearly? It’s fairly simple once you do it.
I got my hydraulics sorted as well, after I got the clutch to release using Stan’s bench top procedure. Thanks Stan.
i mentioned earlier when I ordered my friction discs I made sure they were for a ‘78 but one came with a slightly longer hub, disc II. It doesn’t make a difference clutch works great.
I also didn’t modify my master as the new FTE was the same size externally and internally. Here are the pics:
Old cylinder and piston on inside. I assume it’s original as it had the factory paint still on the bolts.
Glad its working well,
now that you posted pictures of the pistons of both MCs its quite apparent that this unit cant be modified.
the one that gets modded is the one with the piston that has a rod coming from the innermost end,
and about 4.5 MM would get cut off the tip and also a coil of the spring so it wont go into coil bind,
This is done to increase the MC stroke
I have a 1980 928S Euro. This discussion is targeted to the 78-79 but doe sit also apply to the 1980's? If not, what were the changes. My clutch seemed to be intermittently dragging which caused it to be difficult to get into any gear. Replaced the clutch master and slave cylinders but still have the problem. I haven't tried all the bleeding items in these posts but I will. I also haven't compared the internals of he master from what I believe is the original (at least it hasn't been replaced since 1985 when I purchased the car) to the new one.
05-18-2018, 09:13 PM
‘78 Clutch and torque tube bearing replacement with hydraulics, Need some help/advice
