Quote:
Originally Posted by moltuae
Also, if all the wheels are free turn (such as when the car is on a lift), I understand why turning the wheels by hand will result in wheels turning in opposite directions, due the way diffs work. However, I don't understand why it would be necessary to have them turning in opposite directions on a brake tester. After all, they turn the same way on the road.
|
Because turning the wheels in opposite directions will result in zero rotation of the output shaft of the diff. Turning the wheels in the same direction results in the output of the diff turning. With Torsen it makes no difference as the geared centre diff will just be driven by one axle instead of the engine. No big deal for a short time. Something with a viscous centre diff (Subaru?) would probably also be fine.
Think of a TT though, where the rear wheels are directly coupled to the front wheels by way of a clutch pack, or indeed a Land Rover where they are directly coupled by the transfer box. If you turn one axle forwards the output from that diff must turn the other axle forwards. If that other axle is on the ground something has to give. In a TT the clutch pack breaks - what happened to my MoT guy. I expect a Landy would either drive off the rollers, stall them, or just lose traction.