Looking for some conformation before I start to pull the gearbox.
I started the engine for the first time last weekend and it is running beautifully so have been pretty pleased with myself. However, I have problem with the clutch/gearbox…it won’t go into gear with the engine running. If I kill the engine, engage any gear and restart, it is fine and I can move the car by releasing the clutch. However, the car creeps quite a bit when I go to start. This tells me that the clutch is not fully disengaging. I have adjusted the clutch mech so that it is way over-adjusted (with the release bearing pushing heavily on the pressure plate) and I still get the same results.
I have a standard JH Moss gearbox but have fitted a 9 1/2” clutch disk and pressure plate but retained the standard release bearing. My current thinking is that I should have fitted a matching release bearing as fitted with the 9 1/2” clutch which would allow a deeper throw.
I have just been looking at the amount of movement I have with my current setup at the release arm, and there really isn’t much - about maybe 1/2” or so. Does the later release bearing really make that much difference?
Would really appreciate someone to confirm that either my release bearing definitely won’t work with a 9 1/2” clutch or have another issue I haven’t considered.
Sounds like a gearbox out job I’m afraid.
The 9.5 diaphragm clutch won’t work with the 10 inch spring clutch release bearing, and visa versa.
This is one of the most discussed subjects on this forum. There’s loads of pictures and info.
Also comments on the quality of the release bearings themselves, as there’s some rubbish around.
South to have to bring you the bad news.
Just to consider: I had this problem when trying to get me TC Special in gear after the restoration. Engine off everything worked fine. Engine running, the gearbox was spinning.
Pulled the engine/box and found that the 2 alignment pins holding the flywheel to the crankshaft were a hair too long and were dragging on the clutch plate springs. They were a taper fit but were made just a hair too heavy.
It never occurred to me to check for clearance before tightening the pressure plate.
Appreciate your replies, it has confirmed my suspicions. I have also spent some time reviewing a lot of previous threads on the subject.
Getting the gearbox out shouldn’t be a big issue - I’ve already got the floors and tranny covers off. Just need to remove the clutch shaft and support the rear of the engine. Looks like there should be just enough room to lift and pull back the transmission to remove.
I had two reasons. Firstly, I did this conversion on my Etype and it’s definitely much lighter to operate and is a relatively simple job to convert.
Secondly, I had one on the shelf!
Anyway, I think that I’ve solved the problem so don’t need to pull the gearbox. Will report back once I’ve taken it for a drive.
So I now have everything working great - and I didn’t need to pull the gearbox or remove anything! Thought I’d report my findings and the actual outcome of fitting a 9.5” clutch to a 120.
Firstly, I can testify that you CAN use the standard 10.5” release bearing with a 9.5” clutch pack. I’d actually go so far in saying that there is no difference in operation whether you use the release bearing from a 9.5 kit or 10.5 kit with the 9.5” clutch.
I would also like to state, that if you have a standard power engine, there is no advantage in using a 9.5” clutch pack over the factory 10.5” pack. I state ‘standard power’ as one advantage of the 9.5” clutch is that it has a higher clamping force than the 10.5” unit so with a high output (race) engine, there would be significant benefit.
So back to my original problem of not being able to disengage my 9.5” clutch using the 10.5” release bearing.
I did a lot of forum reading and all the articles I found stating that the 10.5” bearing would NOT work with the 9.5” clutch, none of them gave any technical reasons. I then came across an article written by Francis_Thibaud who stated that the travel to release a9.5” clutch is much less than a 10.5” clutch. Eureka! I jumped back into the car and now with the gearbox cover removed, I slowly depressed the clutch pedal. Sure enough, after getting only half way through the travel ,the clutch disengaged!
To cut a long story short, i have adjusted the pedal stops and now have perfect clutch operation. The only slight issue is the fact that the pedal travel is now halved (great for legroom!) and negates the ease of depression. I imagine that the operation now the takes the same pedal pressure as the 10.5” clutch - hence my statement that there is no benefit.
Anyway, I’m sure this will raise other questions, but just thought I’d report my findings for anyone else thinking of doing this.
The MGTC and earlier MG cars had this problem, and they solved it with a clutch limiting bolt in the case. You allow the TOB to move about 1/16" and set it so that’s as far as it will go.
