Input shaft bearing advice please

Post by **lokistail** » Wed Oct 14, 2009 11:10 pm

Hi, have got an early (non-rib) box behind an 850 motor. Everything's fine apart from a bearing noise in neutral, but only when the clutch is out. There's enough free play to keep the thrust bearing clear (and anyway I think it would be a carbon one?), so I'm suspecting it's the input shaft bearing (as soon as you depress the clutch it goes away). Can anyone confirm this diagnosis please? And also, does replacement mean a full box stripdown, or can it be replaced from inside the bellhousing? Cheers

Post by **bmcecosse** » Wed Oct 14, 2009 11:14 pm

Welcome to the Forum! First check - is there sufficient oil in the gearbox ? It could be any part of the box that's rattling - not just the input bearing - most likely the laygear shaft and/or bearings. Yes - it's pretty much a strip down - may as well sort out any other parts while in there! Hardly worth rebuilding a smooth case box - just search out a replacement - ribbed case is much better/stronger. Well done on the 850 engine - very rare! Been looking for one for a while now.

Post by **PSL184** » Wed Oct 14, 2009 11:15 pm

A common failing but I've never changed one as they are just noisy and don't seem to have any other effect on the operation of the box.

Post by **bmcecosse** » Wed Oct 14, 2009 11:18 pm

The shaft should be supported by the oilite bush in the cranktail - if that's worn or missing - the input shaft can rattle about.

Post by **rayofleamington** » Thu Oct 15, 2009 10:03 pm

The shaft should be supported by the oilite bush in the cranktail - if that's worn or missing - the input shaft can rattle about.

if it's worn or missing, the gearbox input bearing will wear 10 times faster... so even if it was ok, it'll soon be rattling.

Post by **Mick_Anik** » Fri Oct 16, 2009 6:45 pm

Welcome!

In answer to the question about whether you can replace the input shaft bearing without stripping the gearbox....

I have done this.....jiggling about with various made-up tools to pull out the bearing - but I can't for the life of me remember which car I did it on. I have the feeling that it wasn't a Moggie, but perhaps someone else can confirm whether or not this is possible. Otherwise, I'd have to go down to a cold workshop and work it out for myself, or check through the manual. Unfortunately, I'm rather burnt out due to my having spent two days on the roof unblocking the chimney, and my eyes are shot from copious amount of soot.

On the 'plus' side, after fifteen years in Poland, I was finally able to buy an exceedingly good version of a Cornish pastie today, at a restaurant in our local market town. Bigger than my hand, it was, and despite its containing sweetcorn kernels, it was quite like the real deal!

See? Life's not so bad, in the end, if you just plod on regardless, with hope in your heart and a pocketful of cash.

Post by **lokistail** » Fri Oct 16, 2009 8:04 pm

Hi Everyone, thanks for the info. Slightly embrassing, after having a better look it is a ribbed case box... I drained the cream fudge out of it, flushed it a kazillion times, and stuck some proper oil in. Not entirely quiet, but a whole heap better. Running it without the prop on, you can hear a slight noise in all gears, but bearing in mind there's no trans cover on at moment, I reckon I can live with it. So plan is to leave well alone for the time being - it's either going to be fine or get noisier, time will tell.

BMC - I assume it's an 850 - 8AG engine prefix?

Mick - Happy Pastie-ing...!

Cheers all

PS: I'd better own up, the engine and box is in a 1935 Austin Lichfield... But our lass does run a '58 850 Moggie with Minilites as her daily driver...

Post by **LouiseM** » Fri Oct 16, 2009 8:15 pm

I assume it's an 850 - 8AG engine prefix?

8AG signifies a 948cc Morris 1000 GPO Van engine. See here:

http://www.mgcars.org.uk/news/news498.html

Post by **bmcecosse** » Fri Oct 16, 2009 10:01 pm

The '8' will indicate an 848 engine - it does in every other circumstance. I think the ref here says 948 then 8AG after 1962. In no other reference (through all the Minis etc) does an engine beginning with '8' not have capacity of 848cc. So - yes - it appears you have 2 of the rare 848cc in-line engines !
After two good 'high speed' blasts in my warmed up 1098 today - I'm not so sure I want an 848 now anyway!!

Post by **lokistail** » Tue Oct 20, 2009 9:49 am

I'd better check her engine numbers as well then, I'm sure it was sold to us as an 850 (other than replacing the gearbox and dumping the Weber in favour of a sensible SU, I've never worked on it at all). I'd no idea they were rare at all - are they desirable? The Austin would be just as happy with a bigger lump in I suspect.....

Post by **Mick_Anik** » Tue Oct 20, 2009 10:00 am

Re the input shaft bush in the back of the crank....

It's handy to have a first motion shaft in the workshop - this can be used to check loose play in the bush (I'm assuming the bush wears rather than the shaft), and comes in useful when you want to centralise the clutch plate.

Not the easiest thing to acquire, though.

Post by **mike.perry** » Tue Oct 20, 2009 10:09 am

8AG signifies a 948cc Morris 1000 GPO Van engine

Sorry to have to correct you but GPO never used the 948 engine, they went from 803 to 1098 in in the Minor van in 63/64. They used the 848 engine in the Minivan
I think that the 8 prefix was also used on Gold Seal exchange engines. Could be wrong on that though.

Post by **bmcecosse** » Tue Oct 20, 2009 2:24 pm

Unless they used '8AG' for their 803 engines - - but i'm inclined to doubt that and confirm it really IS an 848 engine ! I know the 'story' above is the standard version - but is it borne out with any hard evidence ? Does anyone have a GPO van with an 803 engine in it - from say 1961/62 ?