Would an LSD help in the snow

[urmm]

Maybe a silly question. Both brother in law and i have fairly nippy RWD german cars without LSD which are both a bit useless in the snow - When they get stuck they both spin one wheel. Would an LSD help as I would assume they would prevent this and give more traction?

[AJI]

You'd get much more grip from dedicated winter tyre rather than an LSD.
An LSD would help as it would allow power to go to the other wheel but if that wheel also doesn't have much traction then you'd still get spin.

[sherman]

The LSD didnt help on my Rx8 last sunday it slipped all over the place. If I changed gear(any gear) the back end kicked out a couple of feet. The car hasnt been out of the drive since sunday since it took 5 attempts to get it in to the drive.

[fastcarl]

it would depend what kind of LSD it was too, some need a minimum level of grip from the loose wheel to work, but on ice you may not generate the minimum needed to wind them up.


carl

[anonymous-user]

LSD will make you trip out big time! not what you want in the snow really!

[snotrag]

urmm said:

- When they get stuck they both spin one wheel. Would an LSD help as I would assume they would prevent this and give more traction?

a clutch type LSD will help but a torsen will only help if there is some grip on both wheels.

But there's an obvious trick which I thought all phers would know - in a rwd car with one wildly spinning wheel, you use the handbrake. One hand on the wheel, one on the handbrake. As you pull away and feel one wheel light up and spin the power away, you feather the handbrake to work as a diff lock, which speads the torque more evenly between the wheels and often is enough to drive you forward. You can do it in a fwd car too if your good enough and quick enough to do some very gentle left foot braking.

[DickyC]

The most impotant thing governing a two wheel drive car's ability in the snow, before any form of traction control, to my mind, is having the weight of the engine over the driving wheels.

Front engined, front wheel drive is best. Rear engined, rear wheel drive is a poor second. Front engined, rear wheel drive is bad. My step daughter's MGF is poor in the snow but so much better than my wife's SLK. The SLK has traction control and gizmos aplenty but I'd go so far as to say it's the worst car I have ever experienced in slippery conditions.

[urmm]

Thats a good trick snotrag. I do have a problem though. I have the stupid Mercedes 2 handbrake/footbrake nonsense. But i'm tempted to give it a go. As for the winter tyres, it was on my mind a couple of weeks back, but can i justify getting them because of a few days in a year (although i will not be outdone by little fwd hatches. Grrrrr)

[snorkel sucker]

snotrag said:

urmm said:

- When they get stuck they both spin one wheel. Would an LSD help as I would assume they would prevent this and give more traction?

a clutch type LSD will help but a torsen will only help if there is some grip on both wheels.

But there's an obvious trick which I thought all phers would know - in a rwd car with one wildly spinning wheel, you use the handbrake. One hand on the wheel, one on the handbrake. As you pull away and feel one wheel light up and spin the power away, you feather the handbrake to work as a diff lock, which speads the torque more evenly between the wheels and often is enough to drive you forward. You can do it in a fwd car too if your good enough and quick enough to do some very gentle left foot braking.

well bugger me i didnt know that. nice tip. may come in handy on the beemer...

[fridaypassion]

Might try that if our RX8 is still stuck here in a few days!

[Graebob]

snotrag said:

urmm said:

- When they get stuck they both spin one wheel. Would an LSD help as I would assume they would prevent this and give more traction?

a clutch type LSD will help but a torsen will only help if there is some grip on both wheels.

But there's an obvious trick which I thought all phers would know - in a rwd car with one wildly spinning wheel, you use the handbrake. One hand on the wheel, one on the handbrake. As you pull away and feel one wheel light up and spin the power away, you feather the handbrake to work as a diff lock, which speads the torque more evenly between the wheels and often is enough to drive you forward. You can do it in a fwd car too if your good enough and quick enough to do some very gentle left foot braking.

Excellent tip and really works. I've been using it in the crap weather while couriering in the Sprinter. 2nd gear, clutch and handbrake feathered in unison means a slick getaway almost every time.

[coley20]

DickyC said:

The most impotant thing governing a two wheel drive car's ability in the snow, before any form of traction control, to my mind, is having the weight of the engine over the driving wheels.

Front engined, front wheel drive is best. Rear engined, rear wheel drive is a poor second. Front engined, rear wheel drive is bad. My step daughter's MGF is poor in the snow but so much better than my wife's SLK. The SLK has traction control and gizmos aplenty but I'd go so far as to say it's the worst car I have ever experienced in slippery conditions.

Well said, traction control cannot change the laws of physics

[FesterNath]

coley20 said:

DickyC said:

The most impotant thing governing a two wheel drive car's ability in the snow, before any form of traction control, to my mind, is having the weight of the engine over the driving wheels.

Front engined, front wheel drive is best. Rear engined, rear wheel drive is a poor second. Front engined, rear wheel drive is bad. My step daughter's MGF is poor in the snow but so much better than my wife's SLK. The SLK has traction control and gizmos aplenty but I'd go so far as to say it's the worst car I have ever experienced in slippery conditions.

Well said, traction control cannot change the laws of physics

But neither does snow. So, how come RWD generally has better traction in the dry, but not the snow?

I'd say your problems with an SLK are more tyre related, and that generally FWD cars have narrower tyres.

[varsas]

DickyC said:

The most impotant thing governing a two wheel drive car's ability in the snow, before any form of traction control, to my mind, is having the weight of the engine over the driving wheels.

Front engined, front wheel drive is best. Rear engined, rear wheel drive is a poor second. Front engined, rear wheel drive is bad. My step daughter's MGF is poor in the snow but so much better than my wife's SLK. The SLK has traction control and gizmos aplenty but I'd go so far as to say it's the worst car I have ever experienced in slippery conditions.

I disagree.

Assuming the biggest problem you have is going up hills, you need a car which will work best in that situation. When you go up a hill the weight transfer is toward the back of the car, so to get the most weight over the driven wheels (more weight = more traction) you'll be wanting the engine at the back, and the rear wheels driven.

In practice cars with that arrangment have wider tyres/other things that make them unsuitible for snow but in theory, if you wanted to build some kind of snowey hill climbing 2WD special that's what you would do. That or reverse a FWD car up. FWD cars also need to steer, which means the driven wheels aren't always pointing straight up the hill, which is another disadvantage for them.

I agree that front engined RWD is the worst, not sure where rear engined RWD comes in, but I imagine it would be very good indeed, probably better then front engine FWD, I imagine a beetle would be great fun (and quite capable) in the snow?

Edited by varsas on Saturday 26th December 13:18

[SmoothRB]

FesterNath said:

But neither does snow. So, how come RWD generally has better traction in the dry, but not the snow?

I'd say your problems with an SLK are more tyre related, and that generally FWD cars have narrower tyres.

As the car accelerates you get weight transfer towards the rear axle. This gives a RWD more grip and a FWD less grip. One reason FWD drag cars suck.

But that is a dynamic condition. Driving on ice is slow speeds/accelerations, moving off from stationary etc. So weights transfer is not a significant factor.

[varsas]

SmoothRB said:

FesterNath said:

But neither does snow. So, how come RWD generally has better traction in the dry, but not the snow?

I'd say your problems with an SLK are more tyre related, and that generally FWD cars have narrower tyres.

As the car accelerates you get weight transfer towards the rear axle. This gives a RWD more grip and a FWD less grip. One reason FWD drag cars suck.

But that is a dynamic condition. Driving on ice is slow speeds/accelerations, moving off from stationary etc. So weights transfer is not a significant factor.

Except for going up hills, where you still get weight transfer, and where you get most of the problems. You are correct though, on the flat, on ice, it doesn't make any difference. I wonder which is best going down a hill, I would guess FWD is.

[SmoothRB]

varsas said:

SmoothRB said:

FesterNath said:

But neither does snow. So, how come RWD generally has better traction in the dry, but not the snow?

I'd say your problems with an SLK are more tyre related, and that generally FWD cars have narrower tyres.

As the car accelerates you get weight transfer towards the rear axle. This gives a RWD more grip and a FWD less grip. One reason FWD drag cars suck.

But that is a dynamic condition. Driving on ice is slow speeds/accelerations, moving off from stationary etc. So weights transfer is not a significant factor.

Except for going up hills, where you still get weight transfer, and where you get most of the problems. You are correct though, on the flat, on ice, it doesn't make any difference. I wonder which is best going down a hill, I would guess FWD is.

Downhill you would be braking. I'd rather have RWD 'cos you can engine brake with the rears and normal brake with the front.

[Zad]

What you need is one of the older type progressively locking viscous diffs. They are rather good in the snow.

Or one of these.

[wolves_wanderer]

fridaypassion said:

Might try that if our RX8 is still stuck here in a few days!

The handbrake trick works a treat, it has got me out of a couple of situations where the rears were spinning up in second with no accelerator pressure. I haven't got my Rex stuck yet (famous last words).

[Mound Dawg]

My Alfa 75 has a ZF plate tyre LSD and yes, it does help. Yes, the tail can kick out but generally that's because the car's actually MOVING rather than standing still with one wheel spinning away uselessly.

Also helps that the 75 has a naffing great gearbox sat over the rear axle so in most conditions has all the traction you're going to need. When the snow came down mine was wearing R888s which weren't exactly the best footwear for the occasion but I still got home ok.