Thread: OUCH I broke something

Perhaps the broken drive shaft was the result of the transmission jumping out of gear and back in so that underlying problem might need fixing as well, once the drive shaft is replaced.


Bob

That had crossed my mind Bob.

Lots of questions to ask when I pick it up.... and i'll be watching it very closely afterwards.

Originally Posted by rufusking

Interesting, I would have thought the centre diff would have locked to some extent and provided some drive to the front wheels.

Only in rock crawl and with the front wheels straight ahead.

Our Magna Steyr transfer cases are basically an open diff with an electronically operated clutch pack to offer various levels of diff locking. I wonder if, when your car's system worked out something had gone quite wrong, it disengaged the transfer case control unit so that it didn't attempt to lock the diff and inevitably cause more damage?

I read somewhere that earlier RR's (early L322 with NV box perhaps??) had a torsen centre diff - these work on a multiplicative principal where (at fully locked) depending on the setup, up to 8 times the torque driven to a slipping wheel (or axle) can be diverted to the other wheel or axle. Usually that's good, but if the slipping axle happens to have no resistance at all (one wheel in the air, for example) the effective torque applied is almost zero. Anything times zero is always zero, so the torque applied to the opposite axle is zero, and you get no drive! I've had three Audi quattro vehicles that all exhibited this phenomenon where you would get zero drive if you managed to get one wheel in the air, ie entering a particularly acutely angled driveway (my driveway!). Audi mitigated the problem to an extent by using the traction control to brake the offending wheel and restore the torque applied to it, but you'd still get this odd situation where you'd have no drive until the systems worked out what was going on, almost like waiting for an auto trans to kick down a gear.

Wonder how similar your scenario is to this?

What I don't quite have my head around is that you mentioned your trans was 'slipping in and out of gear' for a bit? That doesn't seem consistent with breaking an axle unless for some reason the flange had pulled out of the diff (broken snap ring?) and was just sitting there waiting for the right opportunity to be pulled all the way out... Looking forward to final diagnosis.

Hi Mark, when you say drive shaft, you mean the shaft from the gearbox to the rear diff??

AND for future reference Mark, select rock crawl and you'll have drive.

Did you have any times where you heard a noise on a tricky bit when out with the group at Lithgow, you may of landed on it or maybe had wheels spinning and then got grip suddenly, do you remember anything like that.

Good to see it's all fixed, must have been a bit of a worry, had you finished your trip??

Baz.

Sounds very odd Mark, I'd speculate as Bob has. Keep us in the loop !

Holden Astra. Awesome ! Haha better than a bike I suppose.

So how is the centre diff locked in these things?

Elf magik ! The computer decides when and if it is to be locked (in response to slip or in rock crawl mode). It's an electronic variable clutch style jobbie.