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LSD Diffs


pete300tdi90
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Ho Ho How do people find LSD diffs?

I have a KAM locker with areo space shafts in the rear... love it! and I want one for the front as when I compete running 2 winches and 1 locker puts me in the big boy class :S so without a front locker I might struggle, but by the time you put in a locker, HD shafts and CVs you need to rob a bank...

I was thinking LSD as the shafts/CVs could wait as their would be less strain, but I have a friend running true tracs front and rear and tbh, they are crud! in think mud when he is stuck, all 4 wheels spin, but he is still stuck, when he cross axles it, it goes no where and they dont seem to work...

What do people think about...

a) putting LSDs in the front axle?

b) what LSDs work as true tracs seem naff

c) would it make such difference, or shall i twin motor my 8274/get a 3rd winch...

thanks,

Pete

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Truetracs do work in cross-axled situations, if you push gently on the brakes with power on you will get them working. Truetracs are not actually a limited slip diff, they are torque biasing, which is slightly different, and need SOME resistance on the loose wheel to work.  I too have a mate with Truetracs front and rear and yes they do work :)

All 4 wheels spinning in thick mud? You'd get the same with 2 lockers if you are beached. 

I suspect you thinking they are pants in a cross axle is down to the driver not knowing how to use them, they are well regarded by many, and are, for a LR diff, virtually bullit proof.

TBH I would put the money towards the winch upgrade, if you are in winch challenges that is....

Other option, is to locker the front axle, and put those 'slipper hubs' on, can't remember the name, but they take the shock loading out of the drive train.

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another vote for winch upgrade If you must spend the money.

Horses for courses really.

If you were competing in comp safari I think I would encourage the use of a lsd.

For winch challenge sometimes you need good maneuverability, turning around in gated areas or turning in amongst trees/obstacles.

For this you are better with an open diff. So being able to switch it on and off becomes important.

If you already have one locking diff and you use your vehicle for winch challenge I am confident that (for winch challenge) the best place for your locking diff is in the front axle.

I would rather loose my rear locking diff than front during a winch competition.

Having a locked front diff whilst winching (forward) over obstacles in my experience can quite often more than double the speed I can get over the obstacle.

Both wheels drive lifting the vehicle rather than one wheel acting as an anchor and the other digging a hole.....

obviously mechanical sympathy must be a consideration.

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I havn't come accross LSDs in Land Rovers, not like you find in road cars (like the old Capri 2.8 special), LSDs use friction clutches and lock up under power (or engine braking) due to a cam action in the planetary gears.

Truetracs you seem to know about, they are Auto Torque Biasing with either 3:1 or 5:1 ratios and as said need some grip on either wheel but will transfer 3 or 5 times the torque to the slower wheel. These are suitable for the front axle.

Detroit lockers are poular (cheaper than an air locker) and these work by a clever mechanism that is part cam, part freewheel. The diff is actually locked and if there is enough grip to drive the mechanicsm the diff unlocks (with a noticeable sound) and the faster wheel then becomes undriven. I've had one and I'm not a big fan. When you're in mud the diff is locked like it or not, sometimes that's a handicap. When on the road the car becomes 1 wheel drive in corners, promoting understeer. To make things worse they increase the speed differential between the front and back which is bad for a B-W centre diff.

I've got Air lockers front and rear, I have control, it's my favourite set-up. I have a B-W in the middle and it's not ideal, no use when you are parked as I only have 2 wheel handbrake, though it's nice on the move and in snow etc.

In a later car with brake-intervention traction control an ATB would be a usefull addition, if I could afford it I'd put one in the LSE.

You're probably aware that most if not all trick diffs are stronger than a Rover 2 pin diff.

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I've got Air lockers front and rear, I have control, it's my favourite set-up. I have a B-W in the middle and it's not ideal, no use when you are parked as I only have 2 wheel handbrake, though it's nice on the move and in snow etc.

Erm... pretty sure the BW is locked when it's standing still. I sure as hell can't spin a wheel when I jack one up (well, I can, with the appropriate amount of force as is listed in the manual to test the viscous coupling).

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LSD's are superb for racing ie comp safari but are not really designed for winch challenge use. I have LSD locker combination diffs in my 90" and they are brilliant for greasy roads and loose surface driving which was really useful when we were racing at TAT earlier this year (lots of high speed driving across open grassland) BUT fairly useless when you get completely cross axled. As such i'm fortunate enough to have a locker to over ride the LSD. The best of both worlds, but an expensive option for most people.

For serious 'challenge' type stuff you really want a locker up front.

I also wouldnt advise having an LSD in the front axle only.

Our Lsd's for the front axle have different friction levels to a rear diff set up so as not to upset the handling.

A front LSD works well when used in conjunction with a rear.

For road use i have found that from extensive testing of our own diffs you really need one front and back to get the full benefits. My reason for saying this is follows. Land Rovers (of the type were talking about ie: defender) are permanent 4 wheel drive, BUT if you were to pull away hard on a hill or traffic lights etc then for the most part you will always spin a front wheel as you pull away due to the front of the vehicle going light. Now on your landy this means that all your drive is being lost through that spinning wheel and therefore not even getting to your rear diff! To ensure drive to the rear in this scenario you would need to have either your centre diff locked to force drive to the back regardless OR have an LSD in the front thus restricting wheel spin and ensuring drive gets sent to the rear.

I'm not sure what i'm trying to say anymore as i think ive confused myself :blink::lol:

Maybe a better solution for enthusiastic driving would be an LSD centre diff?

I think you can get them from quaiffe but they are expensive.

Steve

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Erm... pretty sure the BW is locked when it's standing still. I sure as hell can't spin a wheel when I jack one up (well, I can, with the appropriate amount of force as is listed in the manual to test the viscous coupling).

The Borg-Warner is yet another type of LSD, a Viscous locking diff. Inside it has a bunch of textured/perforated plates surrounded by a silicone fluid that thickens when heated. Any slipping between the plates (alternate plates connected to either end)heats up the fluid and locks the diff.

Now a B-W is about stiff enough to loosen the wheelnuts against if you shock the wrench but if you lean slowly then the wheel should turn, that's a good indicator that it's working.

So that means that when you're travelling over a loose surface it works really well, it's good on the road and pretty much got rid of the power understeer that RRC used to suffer. When parked however the locking element can slip, it has to in order to still be a diff.

As an aside, very early RRC with the LT95 4 speed had a friction plate LSD (a proper LSD) and a diff lock operated by vacuum. Very early SI had a sprag clutch like the Willys jeep (not the far more numerous Ford & GM jeeps) which locks up 100% when the back wheels try to spin faster than the front. The Willys jeep also sported very clever CV joins rather than Hookes's joints in the swivels.

But anyway there are different types of "limited slip" diffs, these probably work better on tarmac or fast loose surfaces. Slow speed thick mud and borderline winching situations, excessively slippery surfaces etc you're perhaps better off with a switchable full lock on the diff, but we all drive a bit differently and prefer our own set-up.

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