My friend has a BMW 318i E46. It has started crabbing under acceleration. I had a shot today and if you accelerate gently nothing happens but if you go for moderate acceleratation the rear crabs out to the right mainly.

It basically feels awful and dangerous and I have told her to not move it until her garage opens again on the 3rd as she has two small children.

I know nowt about suspension set ups on any cars, especially RWD. Could it be grabbing brakes? Could there be someything broken in the suspension?

Cheers

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What would Daddy Pig do?

Probly a knackered bush ( or 6 as theres lots back there ) or a torn floor around the rear subframe mounts.

If its the former they must be pretty dead to be shifting under the modest power of a 318. And, being a 318 makes it quite unlikely to be the latter.

I assume tyre tread and pressures have been checked?

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cheers,

Harry

Too many old sheds.

If it's under acceleration, it could be anything from worn trailing arm bushes, broken suspension or subframe mounts, broken/worn diff mounts etc.

Needs a man with a jack and a torch.

Updated December 21, 2012 at 4:42 PM

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Worn bushes or ball joint in the rear. I'm not that familiar with the modern rear sus geom to know which one, but whichever acts as the rear toe link.

Updated December 21, 2012 at 4:42 PM

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Cheers,
Mike

E46's are notorious for rear trailing arm bushes.

never heard of one crabbing before though

Cheers guys, fingers crossed for bushes of some kind, assuming they wont break the bank.

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What would Daddy Pig do?

Daddydadbo said...

Cheers guys, fingers crossed for bushes of some kind, assuming they wont break the bank.

Not unless you want them fitted

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Cheers,
Mike

Well, it depends which ones and how many. They're wry some to the e36 setup so a big bush at the front of each trailing arm two lateral links from subframe to back of the trailing arm on each side, all with a bush at each end plus 4 subframe to body bushes.

To do the whole lot is probably a couple of days work plus parts.

Hopefully it's just the trailing arm front bushes which can be done on the car and probably a couple of hours work plus a wheel alignment.

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cheers,

Harry

Too many old sheds.

Hopefully she can have it looked at and a quotation. " days labout aint going to be cheap, even at an indy!

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What would Daddy Pig do?

just another old bmw with knackered bushes

when i rebuilt my e36 there were 13 i changed at the rear alone

This is caused by the extreme torque of the engine twisting the chassis clockwise. That's why you only feel it under acceleration.

Try removing the ///M badges one by one until it's manageable on the street.

Nab it's just the torque steer affecting the front wheel drive. It's too powerful for it.

Isn't crabbing when the chassis of the vehicle is not aligned with the body?

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Formal education will make you a living; self-education will make you a fortune.

Peter could have a good point but i think he could be looking at it the wrong way

E46s as standard (all of them) have an M badge on the right hand side of the boot lid

Add another M badge, to the left hand side.

Im not going to go into how the badge adds more power, but it sounds like the power is uneven (could be a worn badge)

Add a second M badge to the left and see if that balances it out

If it over balances, add a Type R badge, different amount of torque innit

No because cars haven't had a separate body and chassis since the 50s

It's when the rear wheels aren't aligned with the centreline of the body.

Most noticable on 106s and saxos with a torsion beam rear end where they've banged a wheel on a curb and knocked the beam out of line.

You'll get a similar effect if the bushes which control where the rear wheels are pointing are knackered.

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cheers,

Harry

Too many old sheds.

I would also say bushes unless she's not telling you about hitting an object at some point over the past few weeks.

Orange Cola said...

I would also say bushes unless she's not telling you about hitting an object at some point over the past few weeks.

You're assuming she'd have noticed banging a kerb at speed, other than the fact that it put her off adjusting her mascara in the mirror.

*ducks knives from Evana and Caroline*

She has put it in a ditch before but it was fairly grassy and ages ago so if something had been broken I would hope she had notcied it before now.

Thinking back I drove it after she stuffed it as she was convonved there was something wrong. It felt fine at the time.

Hopefully it will be trailing arm bushes. Another suggestion someone gave was rear axles can "unweld" themselves. Not so sure about that one?

Thanks for your suggestions chaps.

re the mascara comment. She is a goth single Mum who listens to Florence and Nine Inch Nails, not really a mascara kind of girl.

No/probably before anyone asks.

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What would Daddy Pig do?

If the rear is pushing out the left, check the right rear wheel. And vice versa.

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The Clio 200 - has gone

If the welds have corroded or age hardened then its possible they have cracked.

I'd agree with (most of) the above. E36 & E46 are well known for getting through trailing arm bushes but I've not heard of one crabbing as a result. It usually just makes them feel as if they're skipping sideways over bumps.

Need to get it up in the air and take a look.

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I think my neighbour misunderstood when I said 'I can't wait for the next 911'