Gearbox/Clutch Issues - HELP!

[nejpearson]

I have just had a reconditioned gearbox fitted to my 1963 Minor. (You may remember I posted on the forum a month or so ago for advice as to whether or not I should upgrade my gearbox/brakes)

I decided to purchase a recon 1098 gearbox and was also advised by a number of people to install a new clutch plate and clutch bearing while the gearbox was out.

Yesterday evening, I left my mechanic with a shiny new 1098 gearbox and also a 1098 clutch plate and a clutch release bearing.

This evening, I popped in at the garage to see how he was getting along, only for him to inform me things were not looking good:

Firstly, He had installed the new gearbox but not the new clutch plate; as the clutch plate I had supplied him was not the correct diameter... Apparently my old clutch plate was approx. 160mm, while the new one is too big at 180mm.

Secondly, and much more upsetting was the fact that even with new gearbox installed with the old clutch plate, it won't engage gear...It would seem that the splines on the new gearbox that connect with the clutch plate are not quite long enough... It will engage if you start the engine in gear (clutch depressed) but it is not possible to change gear!!!

So, does anybody know what I should do?!

In the first instance, it seems odd that I have a smaller clutch as all my paperwork indicates I have a 1098cc engine, something I have gone along with happily since I got the car back in May last year. Tommorrow I'll be double checking the plate on the engine to see if my paperwork is correct, and that I actually do have a 1098cc engine!

However, my moggy was built in 1963, when they had only just introduced the bigger engine... Did Cowley ever produce cars fitted with a 948 clutch alongside a 1098 engine and gearbox? Is this even possible?

The mechanic suggests a whole new 160mm clutch/clutch cover, although I wonder if it would be better, more efficient, and even possible to install a 180mm clutch from the later 1098cc minors. They must have had a larger clutch plate for a reason?!

Finally, does anyone know plausible reasons why the gears aren't engaging properly, Is it likely to be the splines in gearbox or could it be solved with a new clutch? The mechanic said that something is not stopping spinning when the cluch is depressed and thus the gears don't engage. As you can tell, my lack of mechanical knowledge lets me down at this point!!

Thank you for reading, and for the good advice you always give!!

Edward Pearson. (Penniless, frustrated and upset because I miss driving my car!!!!!!!)

[bmcecosse]

The 948 engine did indeed have a smaller clutch - so your first move is to check if you DO have a 1098 engine. As far as I know, the gearboxes all have the same input shaft -splines/length etc - so that can't explain the non-releasing clutch. Is it possible the 'mechanic' has taken the clutch plate out - found the new one didn't fit - and then replaced the old plate the wrong way round ? Another possibilty is that I think the 948 box had a different clutch fork - this may have been fitted to your old box to work with the 948 type clutch, and so that fork would need to be transferred to the new box to get the same working relationship. I suspect this is what has happened. Obviously the later/larger clutch was fitted to handle the higher power output of the 1098 engine - to fit that to your engine you need a complete flywheel and clutch assembly from a 1098 engine - and that would then match up with the release fork in the 1098 gearbox.

[IslipMinor]

Edward,

Starting at the beginning - do you know for certain which size engine is fitted? They have a disc on the LH side of the engine towards the front, under the tappet covers, which should say either 948 or 1098. The changeover date was around Setember 1962, but earlier cars could have been registered for a while after the changeover date.

Next the original gearbox - do you still have it or photos of it? Is/was it a 'smoothcase' or 'ribcase' box?

Once we know both these we can look at the possible solution. As Roy says there are a number of differences between the engines and gearboxes.

If a 1098 box is fitted to a 948 engine there will be a problem disengaging the clutch, because the gearbox input shaft cover is different, and positions the clutch fork further away from the flywheel to accomodate the bigger, 7 1/4" diameter, 1098 clutch. The clutch fork is common, it is the front cover that is different, but not interchangeable, as the fixing bolt pattern is different too!

There is a possible way around this, but let's be sure what was fitted originally first?

[bmcecosse]

Ahh yes - it's the cover that differs - not the fork. Well spotted Richard. I hadn't thought of the possibilty that the original box was a 948 and not a 1098 either!!

[mike.perry]

Scroll down and have a look at the topic on 'throw out and clutch release bearing'. That will show the differences. Have a look at your gearbox. If it has a smooth casing then it is a 948 box. If it has a ribbed casing then it is a1098 box.
The clutch pressure plate is much larger in the 1098 box than in the 948 box. The clutch drive plate is 6 1/4" in the 948 box and 7 1/4" in the 1098 box.
I don't do metric measurements on a Morris Minor.
I think that you have to change the engine back plate to fit a 948 box to a 1098 engine and vise versa.
I must speed up my typing. You sneaked those last two entries in whilst I was composing my reply.

[bmcecosse]

Certainly the 1098 engine has a thicker/stronger backplate - but I don't think it is essential to change it when changing gearbox. There will be enough adjustment to take up the slight difference.

[mike.perry]

I had a feeling that the bolt holes were in different positions

[PSL184]

Sounds to me like its a 948 car and you're trying to fit a 1098 gearbox. If you look at the right side of the engine (from the front) you should see "950" cast into the block. If its a 1098 engine you should see an alluminium tag bolted to the front right side of the timing cover by the breather pipe. If you still have an engine number on the top of the block it starts with a "9" for a 948 or "10" for a 1098. If you want to fit the 1098 box you will need the 1098 flywheel and clutch. I fitted a 948 engine into a 1098 car (opposite way round to your problem) and I don't remember changing anything else....?

[bmcecosse]

All A series engines have same 'bolt hole' pattern for fitting gearbox or transfer case in Mini application!

[mike.perry]

Rusty Memory again!!
It was about 1970 that I last had a 948 engine

[Kevin]

Well at the least it must have a 948 flywheel as the clutch plate bolts are in a different position.
To help your mechanic in case he is not familiar with the differences the first one is a 948 smooth case and the second is a 1098 rib case.

<br><br>
<br><br>

[bmcecosse]

So - any feedback on what happened ?????

[mike.perry]

I agree. It's nice to know if your advice worked. It makes it worthwhile. Courtesy too.

[nejpearson]

Hi there, thank you all very much for the advice; I have been busy with work, so I appologise about the late feedback.

So to update you on the progress so far:

I checked the engine and there is a tag on the right hand side of the engine as you stand looking into the engine bay. It is painted green like the engine, and clearly says 1100!!! Also, there is a number on the top right that starts with: 10...

So I'm 99% sure the engine is 1098.

As for the gearbox, both old and new are the ribbed 1098 type.

So, It appears that for whatever reason, I have matching 1098 gearbox and engine, but a clutch from a 948 engine.

The mechanic belives the problem is the old clutch; something about the clutch plate sticking...??? But also, the length of the splines/shaft are slightly different on the new gearbox, which he says he could easily modify in tow with a new 948 clutch plate and cover.

I asked if he could upgrade to a 1098 clutch, but he said this would not be compatible with my current flywheel.

Should I go for a 948 clutch? Does anybody know why my car is like this? And would it be difficult/expensive to upgrade to a 1098 clutch (what would be involved in changing the flywheel to match)?

Once again, thanks for the advice. You're a smashing group of people!!!

Ed (feeling a lot happier - still penniless!!!)

[PSL184]

Just get a 1098 flywheel which will then mate up with the clutch and gearbox you have just bought - Why you have a 948 clutch in is anyones guess !!!!

[bmcecosse]

Seems odd the splines etc should be different - they should be the SAME. Can you take the box back ?? I doubt the plate is stuck - that only happens after months/years of standing he's making it up now !!! Check again he hasn't put the plate back in wrong way round ! You would need to swap the complete flywheel and clutch for a 1098 one - only 4 bolts - just need to find one. Otherwise - i can only suggest the old gearbox has been modified to allow it to work with the 948 clutch - so either apply these mods to the 'new' box - or swop the flywheel.

[mike.perry]

Definately fit a 1098 flywheel and make sure that you have the correct gearbox end plate to take the correct clutch forks and a 1098 thrust bearing. Anyone on this forum got a spare flywheel?

[PSL184]

I'm sure I have one somewhere

[bmcecosse]

Definitely will be the best long term solution.

[Kevin]

I also would have thought that the larger 1098 clutch would last longer then the smaller 948 one.