Outer Limits 4x4 Board

murcod wrote:I know I haven't got an LSD from going off road in 2WD and getting stuck with one rear wheel in the air spinning uselessly. Anyone who's gone off road a bit should know from the amount of wheel spin they get from the rear (either you've got an open diff or your LSD is shagged if one rear wheel spins when lifted.)

Not necessarilly. With one wheel in the air the tailshaft drives the pinion, which turns the ring gear to drive the diff carrier. The two axle shafts are connected to the diff carrier by clutch packs (one clutch pack per axle.) A certain amount of torque is required to overcome the friction in the clutch packs, after which that axle will spin. If one wheel is in the air and the other on the ground, the clutch pack on the grounded axle will give in at relatively low torque, allowing the carrier to spin and the opposite wheel will spin with it (twice the speed actually, but lets not complicate matters too much.)

Thus, with one wheel off the ground the other wheel can only receive as much torque as is required to make the clutch packs spin - not normally enough to actually drive the car, particularly up hill.

This is where the handbrake becomes useful! By pulling on the handbrake a few notches you are adding resistance to the spinning wheel. There is a wedge type of mechanism in the diff which compresses the springs on the clutch packs as the drive torque increases, so not only do you add some "drive" resistance to the spinning wheel, you add extra grip to both clutch packs. This means more torque is required to get the clutches slipping - hopefully more torque than is required to get the car moving.

I've found my Paj spinning wheels and going nowhere, but three clicks on the handbrake allows it to drive out like there was never a problem. I think the key to it all is to be gentle on the accelerator. Too much throttle feeds in too much torque, overwhelming the clutch packs and allowing one wheel to spin. Once that wheel starts spinning the drive torque drops, releasing pressure on the clutch packs and you'll go nowhere.

If a wheel is spinning you're doing it wrong.

Scott

NJ SWB wrote:If a wheel is spinning you're doing it wrong.

Or you haven't got an LSD! I was trying to gently drive out when I got stuck- not using all the power from the mighty 1600cc fire breathing engine.

LSD's are very rare on Ferozas. I will try the handbrake trick next time it happens and see how I go.

I spoke 2 ben today and hes still gotta find a few bits so it could be looking good
He said I could have it for $350

How much would it cost 2 get overhauld just 2 make sure it's in good nick

Wouldn't using a bit of brake presure work the same way as using the handbrake

rocknferoza wrote:Wouldn't using a bit of brake presure work the same way as using the handbrake

It may help tighten up the rear LSD, but it will also be adding drag to the front wheels too, sapping up some of the drive torque, i.e. more torque is used overcoming the friction of the front brakes, so less is available to push the car.

Of course, if you have LSDs front and rear, then go for it!

Got both good and bad news


Good news is the LSD is complete

Bad news is that theres a couple of damaged/broken bits




What should I do

Try and find another LSD in good nick if possible or see if this one can be fixed

What's broken, and more importantly, what's he want for it?!

Sounds like he should be giving it to you.

murcod wrote:What's brokendont know, and more importantly, what's he want for it?! he wanted $350 for it before he found the broken bits

Sounds like he should be giving it to you.

Was thinking of ringing up a few places before ringing him again. See if I can find one elsewhere.