Showing the clutch to a friend today, I noticed something which is illustrated by the series of pics below.

The first one has the pressure plate resting on the clutch plate to hold the clutch surface level. Check out the angle of the thrust bearing surface which has the straight edge on it.



Measuring the difference from side to side shows a serious slope on that surface.





This issue explains why the graphite was so worn down on the thrust race and also explains the shudder.
The big question is why did it occur? I'm sure the clutch worked ok initially.

As I have to wait for the new clutch kit I've resurrected a plan that was rattling around in my mind for a while.
The OD box I acquired a few years ago now is identical to the box I just took out except for the OD. The date stamps are about 8 months apart in '67 so I'm going to assume the 'gearbox' innards are the same.
A cursory look inside each indicate to me that the worn 1st/reverse gears in the OD box are ok? in the other box and some - one in particular of the other gears in the non od box appear to have lost some of the case hardening appear to be ok in the OD box.
So I'm going to strip them both and mix and match the 'good' stuff into the OD box and stuff that back into the car.

I've already taken off the OD assembly and am reluctant to dismantle that. It turned about strangely, having a hard spot in it. I took it to the Auto transmission guy who has had my Patrol and fixing it, (another expensive story for another forum Here! ) anyway he's already expressed no interest in doing the project so he's sort of impartial and his opinion after checking it out was that it's not worth risking a dismantle - just put it in.
So that's what I'm going to do after establishing that the solenoid works.
Any bearings that are easy to get and replace in the gearbox, I'll do that too.

So that's the plan!

I'll take some pics of the OD and link to them from here later today.



From what I can see here, there seems to be a significant thickness of clutch material here. Presumably the inside clutch would be the same.





I really don't want to pull this down!

10.20am next morning. Had a bad night last night woke up at 5.00am in a cold sweat hypo. Happens very seldom and pisses me off when it does. The change in routine yesterday I attempted to mitigate with my insulin dosage, unsuccessfully.
Anyway that's the reason for the late start. Getting old with Diabetes sucks big time.

These comments relate to questions posed by others and the photos which are here.
http://s114.photobucket.com/albums/n255/sweep_2006/Clutch%20revisit/
Motor and gearbox mounts were new at the same time and I'd looked at those and there seem solid and fine. This was something I had thought of as a definite possibility as well. The gearbox stay rubber bush is a bit 'gooey' but it cops a bit of oil so it's to be expected and I'll replace it. It was new also.

Flywheel was machined at the time also. You can still see the machining marks on it. Maybe the surface was a bit coarse but that doesn't show more wear on the clutch disk on that side.

Clutch fork doesn't show any play at the pivot but the pivots on the actual thrust bearing seem a bit dry and gritty. I suspect the bearing material is a bit soft. I will replace it.

I don't believe that I'm a 'clutch rider' and always shift to neutral at lights and release the clutch pedal. Did have the clutch pedal return spring break a few months ago and haven't got around to replacing it yet but the clutch shudder pre dates that.

First motion shaft has a little play but not that much to my untrained eye.

The six springs on the clutch plate cannot be moved with my hands. The clutch plate sits flat on the flywheel and on the pressure plate.

Now, one thing I have discovered. There is a ring of excessive wear on the pressure plate and some signs of shudder where the line of rivets are. And the clutch disc is worn more on the pressure plate side than the flywheel side. I'll try to get a photo of the wear pattern on the pressure plate. It has certainly not worn evenly and seems to have 'hard' spots in it. There is a definite 'ridge' at the edge of wear on the pressure plate.

The wear pattern on the pressure plate is not even around the surface. Below is one side that I described above:



Below that is a pic on the opposite side which shows a smoother more even wear pattern.



Some more closeup pics are here:

http://s114.photobucket.com/albums/n255/sweep_2006/Clutch%20revisit/Pressure%20plate%20closeups/

Maybe this is the 'smoking gun'. Anyway I'm going to replace the whole lot.

There's a post on the forum dealing with this and much of what is written here comes from that post.

2.30pm here, started about 1pm, just came in to have a cup of tea while I wait for the gearbox to drain.
Following the library checklist and trying to do a minimalist stuff removal. I'm only doing the clutch - no 'while I'm at its'.

5.15pm and I'm struggling with that seasickness thing. I've thrown up once and felt better straight away after that. I've only got one side of the g/box cross member to take off, hook up the chain block, remove front engine mounts and I think that's it.

But I feel real bad and I'm sorry I started. I need a bit of recovery time.

Well it's out and apart. 9.15pm here and I'm having some dinner.

Got it out about 7.30pm and on the stand. Split the gearbox off and nothing seems to be out of place or loose or anything.




Apart from what appears to me to be excessive wear for 10k mls it all seems ok.




I'll inspect the thrust bearing and lever tomorrow more closely but DAMN I wanted to find a smoking gun.

Just occurred to me that I haven't said why all this, especially because the prospect of a Nissan box conversion was where I was at, last time we were here. I pretty much gave up on the Nissan because of the damage to the reverse gear and the prospect of throwing good money after bad. The deteriorating clutch meant I had to do 'something'!

Some history, if you've come in late.

Rebuild few years ago. New clutch plate, pressure plate, thrust bearing and rebuilt MC and slave. New hose and flywheel machined.
After a while it developed a bad shudder on takeup in 1st and 2nd but only sometimes. Couldn't find anything external so I figured had to be something internal.

Got to the stage that when it played up it became almost impossible to take off in 1st and change to second without the car jumping about something fierce.

I suppose I'll just put a new clutch kit in and see what happens. While it's out I'll have a bit of a look in the gearbox to see how it compares with the crappy OD that I've got. Maybe some swap and change may be in order.

I bought these about 12 months ago, they turned up with the new fuel tank sender just before I had my heart op. Truth is I mainly got them because they had the grease nipples and I couldn't see how I could lube the ones I had and even though they seemed ok when I put them back in I only filled the boot with oil. So for the cost and the fact that I didn't pay for postage I got them thinking that one day...

Well after a discussion on the forum about toe-in http://www.mgexperience.net/phorum/read.php?1,2001545 I decided to change these yesterday.
Annoyed now that I didn't take any photos but.
Did think that I would centre up everything and remove the parts and replace while it was on the ground - stupid thinking!
So I jacked it up as far as I could get it and put jack stands under the chassis rail just as it straightens out under the floor.
Took the two wheels off and laid into the ball joints to break the taper. Figuring that they'd only been there for a few years they should come off easily. Well they didn't and I was at the point were I thought 'I'm going to do serious damage here' when they popped off.
Did one at a time and put new ones on close to where the old ones were.
Thinking about the alignment I decided to try to get them as close to parallel to the back wheels as possible first then drop it and adjust the toe-in using the long straight edge method Pooch and I talked about in the forum post.
While the car was still in the air, hanging I put the straight edges on each wheel and sighted to the back tyre with the steering held in the centre spot with a bungee cord. It was pretty easy to sight this and make the adjustment to get it in line.
What I was really after was some baseline that would make both wheels the same and then adjust equally each side when it was back on the ground.
Did all this, torqued the nut, 35lbs, tightened the lock nut and took it for a quick spin.
Steering felt different but ok.
Came back, set the front wheels up on some steel plates with formica on top with oil between them, tied off the steering and proceeded to adjust the toe-in.
Well it was spot on! Didn't need to adjust. So at the point when you hang the wheels loose they must be parallel and the geometry of the suspension when it's loaded give you the correct toe-in. Or, which is more likely, I fluked it.
Took it for another run and it felt good, steering nice and straight and felt good in the corners.
So there you go!

Took the tail section off again yesterday and took a few pictures.

Below is what the magnetic drain plug looked like.


And here are a few pics of the reverse idler gear. You can clearly see massive damage to a series of teeth with one having been broken off.
If you look closely it appears to have been run with the gear not fully engaged.
The large straight cut gear that the idler engages with shows some wear on the lower edge of the teeth but I think it's serviceable - given that it is only reverse and won't get a huge amount of use with me.



I also priced one of the bearings at about $9.50 so to replace the main bearings is not a big cost - even though they seem ok.

My plan is to take it apart enough to get the bearings off and the reverse idler. Then give it a good clean to remove any 'shrapnel' and then reassemble with the new gear and bearing.