MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - 1275 Gearbox Leak

OK, I am finally at he two months of the year I get to work on my project(s).

SO, I decided to pull the drive line (again) after a noisy first motion shaft bearing and a significant oil leak. Looks like I am leaking around the first motion shaft.

I assume this is a common issue as Moss sells a front cover plate (The one inside the bell housing that the clutch fork mounts to) with a seal. Any other solutions? Is there a "Speedy Sleeve" available for the first motion shaft?

At least the rest of the Transmission looks very good, despite being apart and all over my bench!

I am planning on a built kit with bearings, synchros, gaskets..... anything else I should do while I am in there? The shift forks look great!

-Steve
Steven Conant

Check the layshaft for wear - it typically wears where the needle rollers contact it. Probably change the needle roller bearings too. Change needle roller bearing between first and third motion shafts. Hopefully the end spigot of the 3rd motion shaft is in good condition. The straight cut first and reverse gears tend to wear but you'll know how quiet/ noisy it was. But there's an argument that if you change these gears you may need to change the laygear too (to minimise noise). It then gets expensive so leave alone if they're ok. Check laygear end float (on re-assembly) and change its rear thrust washer if excessive. Also, change rear output shaft seal (should come with kit).
Bill Bretherton

I got my cover plate and seal from Heathrow Transmissions (great guys, would thoroughly recommend them) and it was a fit and forget part. Not a drop from the giggle pin since I fitted it.
R Cohen

I've thought about the modified front cover but they're quite pricey. Since the engines tend to leak, a bit more oil from the g/box might not matter - personal choice I guess.
Bill Bretherton

I "think" I have the engine sealed up pretty well. The gearbox was bad! Mostly a really wet inner bell housing.....engine backplate is bone dry!

I agreee, on the $$$ on the modified front cover.....just curious if anyone else had a solution.
Steven Conant

So, I decided to avoid the drip pan under the car and I purchased the Moss front cover. Assembled the tail shaft and everything and realized the whole trans locked up.

Diagnosis: I am getting interference on the new cover (yes, I reinstalled the old cover, no binding!) I did some measuring and I found a few things.

1. The seal looks GREAT!
2. The inside of the cover is much more shallow than the original....
3. The inner diameter seems to be the same size as the flat of the nut on the first motion shaft.

Grrrr!

I called Moss, and I am waiting to hear back from Tech Support....but looks like I need to do some significant grinding make this work.

The only possible thing I can think of is that I crossed the bearings on the first motion and 3rd motion shaft on the rebuild. However, the old front cover has no binding.

So much for getting this engine and trans back in the midget today.....

Steve


Steven Conant

Update....

Spoke with Moss technical late Friday afternoon. IT was suggested I check the shim pack. That didn't do it so out came the mini-grinder. Problem solved!
Steven Conant

Steve, have you rebuilt the g/box?
Bill Bretherton

Bill yes I did, I am hoping everything is correct as I am now at the awkward stage of reinstalling the motor and trans into the car.
Steven Conant

It might sound like a silly question, but have you checked that you can select all of the gears?

It is possible to assemble the first gear assembly incorrectly and then you can’t engage second gear. Don’t ask how I know!

Best to find out before installation.
Dave O'Neill 2

Yes, good suggestion Dave. I incorrectly assembled 1st gear but realised before installing it in the box. Had to re-do those 3 springs and plungers.....
Bill Bretherton

Dave and Bill, thanks for your responses.....yes, all gears selectable before it went back into the car. This was my second trans rebuild, however it was at least 13 years ago??? (The first one though very abused was so much easier....)

Drive line is installed, I did the motor trans and driveshaft as one unit approach after struggling with my giant hands in the shifter opening.....my assistant was losing patience with me.

The car is completely apart for a respray so she won't be roady worthy for a bit but I have some local dirt roads so after I bleed the clutch, there may be a "ride" (That is if I can find the seat bolts.......)

thanks again!
Steven Conant

This thread was discussed between 08/07/2019 and 07/08/2019

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.