Inner pot joints.

[36inter]

Not being too up to date with drive shaft pot joints I found out yesterday whilst helping a mate out that there are two different internal dimensions to the inside of the socket part (the bit that goes into the diff) and they do not appear to be interchangable, the bearing cage of the larger type will not go in the smaller pot, is this common knowledge and am I miles behind everyone else (the wife always said I was on my own!!!). It would appear that the earlier ones are smaller than the later ones, was there a switch when Metros came in or perhaps A+ engines.

Anyone

Pete

[Dean]

we found this out a year ago, best to find another engine with pot joints with the larger socket and pop them off the diff, lever bar between the out put case and the pot joint, they just pop off with a bit of force, care full not to damage the output casing tho, caution oil may come out as well so be quick
the end of the drive shaft with the bearing cant be removed,
we found they were about 3-4 mm internal different

i think you may be right to about being A+ and metros

[36inter]

Thanks Dean, we had no problem swapping bits over, it was just an unexpected problem, we thought, 'now thats odd'.....

Pete

[GraemeC]

If you are doing the job properly it shouldn't matter as the joint should be treated as a whole item - they're notreally servicable other than the gaiter and you really shouldn't mix and match parts of joints as they will wear to each other.

the end of the drive shaft with the bearing cant be removed
Sorry - please explain. The whole joint (ie cup, bearings, cage and 'inner race' is one part and should be removed from the drive shaft to leave a normal splined shaft.

[36inter]

Hold on there GraemeC, if I was a touchy sort of bloke that gets upset easy I could take oFFence aT the INSINUation that I HAD NoT DONE MY JOB PROPERLY, as it is I am not that sort of bloke and I think I might not have explained myself fully.

A friend who is a little mechanically challenged had another friend helping him replace an engine, they had mixed and matched parts, even thrown away parts and generally got in a mix and came to me with a cup and a shaft with a bearing on it that would not go together, now, like I said a am not too familiar with pot joints and had assumed they were all the same, apparently not.

We had a rummage through my spares and discovered two different sizes, how odd we thought, anyway I picked a 'SET', smacked the odd one off his drive shaft and put the matching set on, sound good to you?

The post was not intended to be a 'how to' or 'this is the proper way to do it' more a "I did'nt know there were two different sizes and when or why might they have been changed"

I'm still cool, no worries

Pete

[Dean]

well you learn something every day,

i have taken the bearings and the cage part, but always found the inner race not to budge and looks like its bonded in some way to the drive shaft, but it sounds like it could be removed with a hell of a lot of force

when we did the same on my mates car we spent a bit of time trying to get ot to go in till we go the calipers out and measured p and found it was too small, and thought the same as you.." how strange"

[GraemeC]

No offence was meant just poor wording on my part. Apologies. As you have fitted a set then the comments were a little unfounded.

But to take this into discussion - my concern is that there are (at least) two obvios different sizes, but who is to say that there isn't a lot of different sizes and some which look/feel to match might not and then fail? For anything other than a temporary fix I wouldn't want to mix and match parts of pot joints, especially not worn ones.
Unfortunately mixing and matching is too common (especailly as it is the easiest way to remove driveshafts from the car) and I didn't want to leave misleading info to anyone else looking in for help/advice later.

[36inter]

Dean, I gripped the shaft in a vice, with jaw protectors on I might add and with a brass drift it is quite easy to knock the inner bearing off the shaft. That has been my experience anyway.

[36inter]

No offence taken GraemeC, just pulling your leg.

I am sure in an ideal world keeping sets together would be good but to me it is a fairly simple yet clever and robust design which takes a lot of abuse (comments on that statement welcome). I have in the past mixed parts, after inspection I might add and had no problems. Has anyone else had porblems with pot joints?

The joint is technology stolen from submarines as I believe it was a drive joint associated with the periscope?

[guru_1071]

there are two sizes (no idea why) and yes, ive been caught out with it before.....

it is good practive not to mix parts up as they all wear together, but lets face it, in the old days every one did, when odd vibrations, rattles, knocks, massive oil leaks, miss matched scrapyard tyres etc where all considered part of owning minis (or was that just me?)

[Mini4Ever]

i think you may be right to about being A+ and metros

This is also my experience. The A+ ones (but not only on Metro's: also on Mini's) have a larger cage than the earlier ones. It's not a good idea to put earlier shafts/joint internals into A+ pots.

[36inter]

Guru, that just summed up my entire early Mini ownership, except for scrapyard tyres, G800's were my favourite then.

[JC T ONE]

in the old days every one did, when odd vibrations, rattles, knocks, massive oil leaks, miss matched scrapyard tyres etc where all considered part of owning minis (or was that just me?)

Nope