|Posted: 12†November†2004 at 5:19am | IP Logged
A LSD is not the ideal for offroad situations, a locked unit does work better there. Where a LSD comes into its element is on high speed driving on tar and hard dirt roads. Its operation is not as harsh as a locked diff and it 'comes in' much more gently.
In rain, if you pull away fast at an intersection and want to go left or right, your vehicle picks up its inside wheel. The vehicle hardly moves, but the inside wheel spins uselessly. With a LSD, this does not happen and you can safely 'nip' into the traffic.
In track racing, a LSD has a similar function. Whist cornering hard, your inside wheel picks up into the air, spins wildly, and because of the way open diffs work, all traction is lost and the vehicle slows down. In this situation, a LSD will 'pull you through the corner' without loss of traction (and thus without losing speed). In a motor racing stiuation a LSD is superior to a locked unit, as the car's steering around corners is not affected. One can get LSD unit for front or rear axles.
Lets look at a selectivly switched locked diff. This is either something liked a local Gearmax or the expensive imported ARB locker. Geramax only makes a locking unit for rear axles, whereas ARB units can be fitted to front or rear diffs. A vehicle with a locked diff does not want to go around corners because of the rear wheels rotating at the same speed. You just have to watch a 4x2 with a locked diff in sand; it wants to go straight even with the front wheels turned to one side. The wheels will plough on until power is stopped, then only it will turn. It is a bit better on a 4x4, the front wheels will 'pull themselves reluctantly' around the corner.
Then there is another animal; an automated selective locked diff such a a Detriot Locker, that locks the diff in a straight line but unlocks it when the diff senses that you are going through a corner. From the examples mentioned above, you can work out that it works better for offroad situations. It is gernerally cheaper than a full locker, activates automatically and activates with an audible (and sometimes annoyingly) loud 'clunk'. Unit for front and read axles are available.
You can work out from this what will suit you the best for the conditions you are going to drive under. It will also differ according to you specific 4x4. A permanent 4 wheel drive's requirements will differ from a part time 4 wheels drive system's.
Personally, I like the LSD unit in the back of my Terrano. I would also have liked a selectable unit (such as the ARB) for the front for when I go into the really rough stuff. A LSD unit in the front (as Andre, this site's Webmaster has recently fitted) may be my only option because the the cost of an ARB (R12K plus)
I hope this explains the options out there a bit more.
Edited by mvcoller on 12†November†2004 at 6:08am