Diffs and halfshafts

Hello all,

About 2000 miles after refitting original diffs to my S3 it has sheared a half shaft at the back. I don't want to go through that experience again - stuck in the middle of a 7 lane junction in huddersfield with no handbrake...had to run it into the curb, jump out to put the free-wheelers on before I could go...or stay stopped...

I've refitted a new shaft (10 minute job) but it is still making an odd grinding noise. I checked the bearing by jacking up and putting a breaker bar under the wheel with the shaft off. That seemed ok and everything looks straight dead straight.

It makes a dullish griding noise when under load at low speed but seems quiet at higher speed or on the overrun...any ideas where to look next? I didn't do anything to align the diffs other than do the nuts up gradually is there a knack to it?

Cheers

Dom

Did you clean out all the broken bits of shaft? - I assume it was the drive member end that snapped so any bits might have found their way into the wheel bearings. Or possibly the drive member splines are worn and allowing the shaft to move?

Or theres a bit in the diff end clonking about

Thanks lads,

Tha halfshaft had twisted off at the end but hadn't lost any bits, I had a good look. It had sheared at the end just inside the flange plate.

It sounds as if it is rubbing on the inside of the stub axle but I couldn't see any obvious marking....

Something is definitely not lined up right. It's a standard 2.25 petrol and not been doing any hard work so shouldn't be breaking shafts surely or do they just do that?

D

My brothers 2a used to break em all the time don't know why though

What might cause alignment problems? Diff not seated in axle properly, drive member badly distorted, wheel bearings worn/badly adjusted, axle casing bent.
What might snap driveshafts? old or poor quality shafts, excessive backlash in driveshaft, vehicle left in 4wd. tyres too big for vehicle.
Even if the shaft breaks cleanly there will be bits generated - check the bearings.

alignment can be bent stubs, badly loose bearings or even a bent axle (the last one happens even more rarely than the first two)

driveshafts snap, it's just an accepted thing, so far i've seen two snap both on 2.25 petrol engined 88s with 4.7 diffs and 7.50 tyres both happened on tarmac, first just as the owner pulled away from the kerb the second as a mate put the power on going around an island, they slowly twist until they can't take it anymore, of course the harder you accellerate the more likely you are to twist them

big tyres can aggravate the frequency in which you snap shafts due to the leverage they pass back, wheelspinning and suddenly gaining traction shockloads doesn't do them any good either

i run a 200tdi engined bitsa as a daily and all around hooligan tool, it's on 7.50 tyres and has 3.54 diffs, has towed up to 2.5 tons up Hatton Hill (that's a big hill) along with plenty of other towing, it's also been heavily used offroad in the pay and play stuff, so far (touch wood) i haven't broke a diff or halfshaft

I've just had the other halfshaft out for a check and it looks ok to me.

Looking at the one that snapped it had twisted off as described I've triple checked for any bits floating around and can't see anything and the bearing is dead smooth and steady. All I can think of is the stub isn't on right, the spacing collar is wrong or the axle is bent as you say. Any of which would tend to try and bend the shaft all the time as the wheel spins....

I'm just working on the street in the freezing cold so not got the kit to take off the stubs this week but will try and dismantle the stub and triple check everything...

I don't want it happening too often, its not that it is expensive or difficult but you don't half look like a tit when you can't take your foot off the brake to get out and put the FWHs on!

Dom