Tread depth and LSD ?

[Tom_S14]

Hi,
As geoff and ripper will testify, one of my rear tyres is bald http://300zx.co.uk/200sx/ubb/smile.gif Unfortunately the other one is only half worn.
Qusetion is, how well does the LSD work if there's a different radius on each wheel because the tread depth is different ?
And should I buy two new tyres and not be such a cheapskate ?
Heard all these horror stories about transfer boxes in 4wd cars and tyre wear, so I'm thinking the same must apply with an LSD ?

Tom

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1996 Blue/Green S14 (manual)
K&N cone filter
2.5" Tube-torque Cat Back Exhaust.
TechTom MDM-100
Race-Technology AP-22
http://tom.marshall.tripod.com

[JohnD76]

Don't be a cheapskate. http://300zx.co.uk/200sx/ubb/biggrin.gif

Try http://www.micheldever.co.uk

John.

[geoff_s14]

Tom,

As far as I'm aware, there isn't a problem with the LSD on the 200sx, but you're right about the succeptability of 4WD transfer boxes to knackering as a result of differences in rolling radius across axles. The calibra was particularly prone to this problem I understand. However, I can't believe you are still running around on that hoop of canvas I saw at Donnington. I wouldn't worry as much about having different tread depths as much as I would about the effects of a blow out at 120.



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Geoff
Emerald S14a

http://www.animfactory.com/animations/transportation/cars/mirror_md_clr.gif

[Tom_S14]

Goeff,
I'll grant you that the "hoop of canvas" on my wheel isn't the best at water dispersal. I aim to run in the dry strip left by the front left tyre http://300zx.co.uk/200sx/ubb/biggrin.gif
It spices up the driving experience, it tends to slide a little more on that side through corners http://300zx.co.uk/200sx/ubb/smile.gif
Good news that I won't knacker the LSD.... but can the LSD work properly with different radii ? Putting it into simple language, won't the LSD "think" I'm going round a slight corner even when I'm going in a straight line, thus providing less lockup ? If you see what I mean ?

tom

[goosegog]

The usual problem with using an LSD with tyres of different circunferances is that under power, the diff will lock and with both wheels turning at the same speed but different sizes, will cause the rear of the car to steer under acceleration.

I am a mechanic for an Aston Martin specialist and we have to measure tyre circumferance and put the closest pair on the rear. I allow a maximum of 1cm difference. More than that and rear end steer is quite noticeable.

Ferg

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[Marcos]

Yeah, i get that on my kart (no diff)

Have you started getting dizzy yet?!

[Tom_S14]

Quite dizzy, spinning around because she likes it like that. But enough of my taste in music.
Well, don't get any accelleration steer - so either my lsd is more s than l or I'm not accellerating hard enough http://300zx.co.uk/200sx/ubb/biggrin.gif
I think I'll get a pair of decent tyres on the back with some tread on 'em. When it starts to snow I'll be righteously stuffed otherwise.

Tom

[goosegog]

One good method I found to test LSD operation is in the wet:

You know when they dig up the road to lay cables and leave a narrow strip of new tarmac sealed with tar. This is usually more slippery than the original road surface

In a non-LSD car, it will spin just the one wheel on the slippery tarmac but in an LSD car it should, given enough power, spin both wheels. If you're not sure, the back should snake around nicely and accelerate well if both are spinning! If just one is spinning all you will really notice is mild acceleration and the revs going sky high

Ferg

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[Tom_S14]

Ferg,
Yeah, it's definitely LSD, both wheels go together. They didn't make non lsd S14s did they ?
Maybe the tread difference just isn't enough to cause much of an effect or something ? In this weather the back end is all over the place anyway (or it wants to be !). Thinking about it, when I boot it in a straight line it nearly always goes out to the left... and my dodgy tyre is on the left, so maybe that's it ?

Tom