Morning all,

Has anyone fitted the very pre formed dished spring diaphragm?




Best shot I have atm. I have fitted this along with a new ring and friction plate as I was doing a spline lube and taking off the sidecar subframe is such a chore I wanted to do as much PM as possible. Also replaced rear main seal and gearbox input seal.

Long story short. Did it, put it back together, watched it not work.

1. The clutch is permanently disengaged (can hold and stop the output shaft turning in at least 4th and 5th gear - effectively: slipping).
2. The pressure piston is recessed about 5.5mm from the face of the gearbox.
3. Everything about the release arm, pivot and rod is as expected, but the adjusting bolt has to be almost fully wound in before it makes contact with the piston (but once it does, clutch lever action feels normal but makes no material difference to power transfer or the ability to move thru the gears).
4. No apparent return action on the release rod.

Last night I concluded that I had put the spring plate in backwards i.e. convex side facing engine - thereby putting the spring plate out of reach.

Just taken tranny back out and:




Bugger! it’s ok. 

I can’t get beyond any diagnosis other than the release rod is needing to go too far in before the spring is actioned and, as the plate is concave forward, leaves only the idea that the centre portion of the new spring plate is further away from the friction plate than the old style.  i.e. a bit recessed.

Obviously, got to strip the pack now and do some measuring of the old and new spring plates (nb. the new friction plate is the generic one from motobins), may just refit with the old spring and test again. 

But if someone wants to tell me that I’m an idiot and should have done an easier this or that, I’ll take it.

Off with the family now to see Jumanji, please let me know when I can leave the game and get back on the outfit.

Update. 
The release rod or diaphragm don't stack up as cause as clutch is perpetually close to disengaged. 

With gearbox off the pack is tight and will turn engine by hand.
If it's only a problem with gearbox on, could gearbox be bearing on the clutch Spline, seperating the plates?

This would also explain the release rod issue.

Describe your method of aligning the clutch hub before tightening the clutch pack to its housing.

Were the original piston assembly and clutch rod used, or were replacements installed?

Did the transmission easily slide into contact with the intermediate housing or did it need to be pulled into position by bolting it up?

I used the pukka tool to centre the pack during build and for mounting to the housing.

The piston assembly and rod are what I took out. Rod tested for true, lightly cleaned with wire wool and tipped with castrol moly paste.

I made a couple of studs to help sliding the gearbox into position, it all went pretty easy, with some fiddling of the output shaft until the trans input shaft meshed with the friction plate splines.

It was pretty much an easy push fit until the last - the LH side closed in on the intermediate a mm or so before the RH side, I tapped this easily into place with a soft mallet.

Just to add, the release rod slides through the tunnels without binding beyond the slightest catch at the very end where I assume its engaging with the spring plate hole.

I have measured the new friction plate splines and they are the same length as the oem I took off.

I assume I have put the pack together incorrectly, and in the a.m. plan to measure new to old pack thickness, distance from friction plate spline vs the available distance from the front of the gearbox case to test the gearbox compressing the pack plates theory, and anything else I can get a vernier on.

TIA for the help Laitch

I cant make your picture big enough to see if the clutch splines are facing out or not? The spline boss needs to be facing out is it??

Sure is K. 

I also noted on a Chris Harris vid this am that the release rod pressure piston also sits high in its housing (flush with the gearbox casing?). That was on a 75 so not sure if it applies to the 100, but mine is sitting around 5mm recessed and is certainly the reason I have to screw the adjustor so far before engagement.
Dismantling the pack today, so will post any interesting pics.

I’ve marked as solved - but only inasmuch as it’s now working. Obviously assembly error but I can only guess at what.

Gearbox out
Clutch pack out (inspection with clutch in situ showed nothing remarkable)
Clutch dismantled - all plates in correct order and orientation.
Put it back together.
Put it back in.
Reinstalled the gear box. It was obvious straightaway that the push rod pressure piston was going to sit higher in the input shaft tunnel than my previous effort.
Clutch arm adjustment bolt made contact with the piston with over a cm unused (last time I had a mm or so to spare after touch down).

Clutch now operating as expected. I can’t stop the output shaft by hand in any gear until the clutch is pulled in.

I did nothing different this time than previously, beyond: paying extra special attention to the way the three housing cover pins engaged with the locating holes in both the pressure plate and housing.

My best guess is that either the pressure plate wasn’t seated fully/evenly (pins fouling) or likewise the locating pins weren’t sat correctly in the clutch housing.

If you had to lever the clutch apart in the first place, my very large bet is on the locating pins not being straight. They bend really easily.

No Dai, they took a bit of wriggling but no more. They certainly need the pressure plate ring dropped straight on or the last pin will bind.
That said, I can only assume it was connected to bedding those pins correctly either through the plate - or more likely into the housing - that made it ok, although I am really surprised that I could torque down the housing and then the gearbox without apparent difficulty.

Not to mention the mystery of how any of that would cause the pushrod to seat so deep that the adjuster could barely reach it.

Good News TSP any solve is a good solve even if a little perplexing.

Thanks Keith,
I smile to think that my first technical question a year ago was about tyre sizes, and now I’m rebuilding clutches (badly).
Talk about ‘know your bike’ - all down to the patience and generosity of the team on this forum.  

Merry  Everybody, Stu