Remeber, it could be anything from the wheel bearings to the 3rd motion shaft in the gearbox if it's related to car speed and not engine speed. That means it could be:

- 3rd motion shaft bearings
- Diff gears or bearings
- Inner or Outer CVs
- Wheel bearings.

If you've done the wheel bearings and the CVs feel fine (if there's no movement the CVs should be fine in a straight line, provided your suspension isn't lowered or sagging), you're right that it may be the diff. But it may also be the gearbox. My 3rd motion shaft bearing disintegrated and was making a lot of noise - it's pretty much the hardest thing to get to in a mini.

Years ago I had a Mini with a funny noise in the left front that I could never find, it turned out to be a dry inner pot joint.

Worn side cover bushes won't cause rumbling (they just help the seals to leak), but worn diff bearings will.

The whole lot has to come out, then the diff housing removed to get the diff & its ball bearings out.
You will then find more problems- a worn diff pin and spider gears for a start.
New bearings have to have preload set with shims on assembly. Get someone to help that has done it before. Or, read up on the manual...

re the side cover bushes, if worn they need replacing; then, being supplied undersize bore, they need machining out to fit the pot joints.

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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.

G'day Fellas,
thanks for you replies.
I have a side cover bush coming, Ausmini 2a3538 about $19 so when it gets here I will whack it in with shims if they are on that side, Passenger, and run it without shafts .

I will give it the screwdriver to ear test, but if it's really crook inside it will be pretty apparent from 10 feet away, I'll report back then,
see you later Joe.

G'day,
opps, read Minisport for bits, I also ordered two tear drop front sub frame to body mounts, 21a 2624, about $22ea.

I ran my callipers over each pot, both 1.248", the drivers side is firm in it's bush while the pass. is sloppy.

I had to make a two arm wedge to dislodge the drivers side pot, no amount of levering with large screwdrivers would move it but a wallop
with a hide hammer on my two arm wedge and she popped out,
see you after I get the bits and run it, Joe.

With the side cover off you can see the ball bearing, check if the plastic cage has busted (all the balls then sitting in the bottom).
If so it's engine out time.

re fitting the shims- the new black gaskets are much thicker than the old brown paper ones. So they need extra shims.

_________________
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 drmini,
thanks for that, I replaced the wheel bearings and hubs too (they had deep groves where the bearing ran) because the plastic cages had disintegrated and thought she'd be sweet but it made no difference to the racket.

One day the whole shebang will have to come out anyway as the diff ratio is so low,
Joe.

Most likely your 3rd motion bearing then. Time for a gearbox rebuild.

I can't wait!

G'day,
if you remember I was mighty perplexed by the load crash bang rattle coming from the front while driving, I replaced all the bits I thought could cause it but it was still there,
one suggestion made was to check the front sub chassis to body mounts, mine are tear drop type mounts, both sides were stuffed due to the gap between the body and the sub chassis being 25mm and the mount width being more like 15-16mm so when the mount to tear drop mount were tightened the mounts tore apart, what that all means is that the sub chassis was really only being supported by the back mounts alone, I packed them out with 5/16" insertion rubber, no wonder it was flapping around.
After all the front end work, drum brake reline, brake booster fitted it drives pretty good, a lot of gear noise and a loudish clicking coming from the drivers side in top gear (the previous owner reckoned it was the clutch) don't know about that but time will tell.
I notice the vertically mounted brake master cyl is wet around the mount gasket, after removing the nuts and brake lines can I lift it off the firewall, the push rod looks difficult to work on inside the car,
thanks again for suggestions, Joe.