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**RS2000&MEXICO** · 21-01-2005, 18:44

kevin curtis has got some lee..

**M11RF** · 21-01-2005, 18:59

You can get poly bushes that look std-ish Lee. All in black.
I could have sent you my old ones but they are long gone!!
They were ok too

sorry!!

**Kel** · 21-01-2005, 18:59

I'm sure burtons or rally design do new items

**lee bishop** · 21-01-2005, 19:03

not an issue of looking std, you shouldnt mix poly and rubber bushes, and i dont want to have to fit polys everywhere, just cos two have gone crumbly, what about the LSD issue, no one has answered that one.....

**Tim** · 21-01-2005, 19:03

sounds like u got a lsd

**RS2000&MEXICO** · 21-01-2005, 19:16

do a nice big wheelspin lee ... if there are two black lines left behind then you have got a lsd if only one then its standard thats the way i test to see if there is a nice lsd in the axle....

**lee bishop** · 21-01-2005, 19:19

anybody got any more bright ideas?

**RS2000&MEXICO** · 21-01-2005, 19:20

whats wrong with that lee.....lol

**lee bishop** · 21-01-2005, 19:24

nothing if you dont care for your car......lol

**RS2000&MEXICO** · 21-01-2005, 19:26

allright then just do a small wheelspin then

you know you want to.....pmsl

**lee bishop** · 21-01-2005, 19:29

i have a standard engine, with 7" wheels! it doesnt wheelspin! it just goes....... only in fast corners does it let go

**M11RF** · 21-01-2005, 19:34

Shamelessly stolen from TurboSport and passed off as my own work!! hehehehe... :laughing6:

No need to elaborate on that bit, Gary was spot on. A full locked diff, i.e. welded up would in effect be 100% LSD - but its not actually an LSD then so to call it a 100% LSD is a bit confusing for my little, slightly pickled brain.

Imagine this, youve got one wheel in the air (no grip at all) and one on the ground with lots of grip. With a free diff (i.e. not an LSD, or 0% LSD) All the drive would go to the wheel in the air. With a (metaphorical) 100% LSD - then both wheels will turn the same amount - even though one is in the air.

Theres loads of other variables with an LSD though - preload for a start - this is how hard the clutch plates are pressed against each other when at rest, so even when you are driving in a straight line, there is some load on the plates. This is adjustable by fitting stronger springs, and/or fitting thin shims behind the spring to compress it more. You know how most people check for an LSD - jack the wheels up and see which direction one wheel turns relative to the other? Well what you are actually checking is pre-load - if it didnt have any preload, the other wheel would just stay still, but its still and LSD. This is not the same "preload" that holds the taper roller bearings in contact with each other. Typically, a gravel car will have higher preload than a tarmac car.

Incidentally, automatic torque biasing diffs dont have any preload (they dont have any clutch plates actually) - they work on a different principle, and progressivley wind up as you go round a corner. I have to admit i don't fully understand them, but to be honest i don't plan on using one either so it doesnt really matter!

Then you've got ramp angles - the "V" shaped groove in which the sun pin's ride. Typically these are a 90% groove, i seem to remember - which means you have a 45 degree ramp angle for braking, and the same for acceleration. To get an idea of what the ramp angle does, think about rolling a log up a hill - the steeper the hill, the harder it is to push, therefore you need to get a bigger torque gap between the 2 wheels to get the sun pin to ride up the ramp and start pressing the clutch plates together... This feature is not exactly adjustable - unless you start machining out the ramps, which is a whole new ball game.

Just to complicate things a little bit more... anyone ever used a "detroit locker"? Exact opposite of an LSD - it is locked when you go in a straight line, but frees up when you go round a corner. Dragsters are about the only thing that would use these, unless im mistaken.

So what diff should you be using on the road? If you are arsing about doing donuts, and/or going round roundabouts backwards then you will find a standard LSD not quite up to it, i would suggest. However a full-on gravel spec rally LSD will clunk and bang and generally make the car a bitch to drive round town, not to mention make it understeer. So really you want something in the middle. Our rally car has what i would describe as a tarmac spec LSD - full set of plates but not too much preload - and it is perfectly civilised on the odd occasion its used on the road.

Right i'm sick of writing, any more questions just fire away, i'll try my best.

http://forums.turbosport.co.uk/bbs/showflat.php?Cat=0&Number=329551&an=0&page=0#329551

**lee bishop** · 21-01-2005, 19:41

i am no better off mark.......wheres that whisky......

**M11RF** · 21-01-2005, 19:49

Looks like you`re going have to get the spanners out and take it to bits mate... Dont ask me how you tell when its out though!! :laughing6:

Brian, or should i say Brain... Will come up with the answer i`m sure

Announcement

MOT FAILURE!!! (and LSD question)

MOT FAILURE!!! (and LSD question)

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