Towing a car with LSD

[jac-in-a-box]

I need a little advice guys please...

Can a car fitted with a LSD be towed on it's rear wheels? - E36 M3 Bog standard LSD. Handbook makes no warning about this.

Towman who's just arrived says yes. Recieving garage, BM specialist, says no and wants it on a flat bed recovery truck.
It's about to be towed 40 odd miles.

Thanks

[v8 jago]

I dont think you can. I might get told diffrent shortly, But i wouldnt. Better safe than sorry, As they say.

[JakeR]

I would have to say, if it was my car, I would go with the BM specialist, not the towman...

just my 2p...

[junder]

Mercs tend to have a button on the dash with a picture of a car being towed on it.. Have the BMW's got anything similar ?

[jac-in-a-box]

Thanks guys...no, no button as in Merc.

Trying to work out myself what the consequences might be. I can understand, I think, the pitfalls in a 4WD/AWD car with an uneven split of drive front and rear.

If anyone has got the definitive answer it would be appreciated

[rev-erend]

I would have though it would have a warning in the owners manual if it was a problem.

Cars fitted with the RV8 LT77 gearbox could not be towed for long as the pump in the gearbox did not run unless it was in gear.. or so I believe.

[stevieturbo]

Scary thought that a car might have its only driven wheels on the ground, rotating in the exact same was as if it was driving......

Why exactly would this pose a problem ??


4wd is a different story for obvious reasons. Its either all 4 on the ground, or none.

[SprintV8]

junder said:

Mercs tend to have a button on the dash with a picture of a car being towed on it.. Have the BMW's got anything similar ?

That's to turn off the movement sensor for the alarm nothing to do with the diff etc.

[toohuge]

Forgive me if this sounds stupid, but couldn't you just tow the car with the front wheels on the ground?

[GreenV8S]

If it's rwd then you will very probably find that it mustn't be towed with the driven wheels on the road. That's regardless of whether it has an LSD. I don't see why the LSD would care one way or the other, but usually the gearbox is lubricated by a pump on the input shaft and unless the gearbox can tolerate being run 'dry' you can damage it by towing long distance or at high speed. At the end of the day I'd trust the BMW specialist to know more about it that the recovery truck driver.

[GavinPearson]

The issue is whether the car being towed sees any conditions different from normal.

The LSD alone would see nothing different to normal, so it's not a problem.

If the gearbox contains an oil pump then that might be a problem.

On AWD 4x4's being towed would send the centre diff into a frenzy - that is why you tow on all 4 wheels or put the car on a flatbed.

[wildoliver]

As above LSD should be fine, and the abuse doled out being towed is nothing compared to full throttle round a corner.

The gearbox may not be fine.

[jac-in-a-box]

Thanks for replies guys

Absolutely nothing about taking precautions in the handbook even though it mentions towing.

Fingers crossed all will be well!

[Pumaracing]

This really is only a matter of incredibly basic common sense. An LSD does absolutely nothing unless both wheels are rotating at significantly different speeds when one has started to spin because the power applied has exceeded the available grip. A car being towed can't conceivably spin one of its wheels. They just trundle along at the same speed. The LSD can't possibly be operating. Even if it was it would only be doing what it does in normal use which it is designed to last a lifetime of.

Any BMW "specialist" who doesn't understand the basics of how an LSD works might perhaps need to be treated with a degree of caution.

Dave Baker
Puma Race Engines

[hoach]

Auto box dont do it

Manual box no problems.

The last post is right, think about it. LSDs apply friction through clutches from one side if the other wheel spins so all traction is not lost.

get on with it!

[BB-Q]

RAC states that a RWD must be towed with the rear wheels lifted to prevent damage to the 'box, or flat towed or completely lifted (I'm a patrol). I don't 100% agree with that but it's not worth the risk.
If you can front lift it then you can rear lift it- don't be lazy, just turn it round!

[liner33]

You need to remove the prop shaft to tow a auto any distance , a few miles is normally fine