hi, i have an 1275 which i have rebuild but i have just noticed that it has pot uni's. so i'm struugling to know what would the best and cheaps way to do a conversion on and engine or drive shafts.
am i able to change over the diff in the motor now and put i on the 1275 or change the drive shafts. if i have to change the drive shaft what is the best, quickest, easyest way to do it.

thanks
craig volk

We assume you wish to convert to hardy-spicer uni's. If so, this will involve changing the output shafts on the diff. If not, your only other option is the rubber universals and frankly, I think that would be a bad move With either option, you will also need to select the appropriate drive shafts and I think there's 3 different sizes. No doubt the good Doctor would know!

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

Drive shafts to my understanding are all the same.
You should be able to just find any old shaft with the ball end and put it into your CVs.
Are you running discs at the moment?
If not it's recommended to do so with the 1275.


BTW, I like your car, I see it on the way to work occasionly!

Don't know why you want to change from Pot Joints...Never had a problem with them

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Stop Licking the Dog...I Don't Care Who Started It

hi, i have rubber uni's in the car now and the 1275 which is in my shed has pot uni's. i'm swopping motors. if i have to change the drive shfts would i have to pull the wheel bearings, ect all out and re put it in the new shafts.

i have drums.

thanks

No real reason to change from pot joints, but if you do, you also need the diff output shafts, side covers (if going S), uni joints and drive shafts.
There are 3 sorts of driveshaft:
1.Pot joint ones
2. Rubber uni ones
3. Cooper S ones.
Pot joint ones are longer and different at the inner end.
2 and 3 are dimensionally the same, both splines and shaft length, but the S ones are stronger. So they say.

Pot joints ones last longer than either the rubber joints or the S Hardy Spicers..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

hi, thanks for your reply. but you didn't say if changing the drive shafts is a huge task. do i need to completely pull apart the front drive to fit the new drive shaft or can i just pull out the old ones and slot in the pot ones.

thanks

So what's so special about the rubber joints or spicers that make some people swear by them? Less friction for more power?

In the beginning, Issigonis and his mate Alex Moulton created the rubber U/J. And it was good. But if oilz got on it or people overtightened it, it carked it. But really it wasn't bad, the Morris 1100 used them too.
When the Cooper S started getting serious power for competition in the mid 60s the rubber joints were inadequate. BMC dug into the parts bin, voila! Hardy Spicer U'Js (actually, they are identical to a 1920s Austin 7 tailshaft one, even the spline is the same).

These were used on Cooper S, MiniMatic, Morris 1100S/1300, and Oz Clubman GT. Yes they are stronger. But they don't last forever, although pretty easy to change.

Pot joint is pretty much a CV, with parallel tracks so the shaft can plunge in and out. They last for ages, as long as the grease stays in.

As for power, a pot joint will have less losses.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.