Originally Posted by
wagoo
I have no personal commercial barrow to push with the following comments, which are my personal experiences from owning a twin Salisbury diffed LandRover fitted with first 2, then 1 and then no Detroit lockers.
Constant 4wd may to a degree mask the handling quirks and foibles of Detroit Lockers,which are influenced by unequal tyre pressures, diameters, road camber etc when on hard surfaces, but in my experience they are still there and become apparent on medium speed wet slippery 4wd tracks.
Also from a mechanical durabilty viewpoint, not only of the locker itself, but the whole drivetrain, they are less than ideal.
To be capable of unlocking when making a turn, they depend on backlash between the dog teeth of the central driver and the teeth of each side gear.According to specs this backlash is 13 degrees.Multiply that by the crownwheel and pinion ratio of 3.54:1 and add a few degrees for axle spline clearances and crownwheel /pinion backlash and we end up with around 50 degrees of free movement at the propshaft before drive reaches the wheels. Constant 4wd LandRovers have enough annoying backlash as they are.Add a loosish centre diff to the equation and we have a very sloppy drivetrain indeed.
Whilst a mechanically sympathetic driver can compensate for some of this slack by adopting a modified clutch operating practice during gearchanging, this backlash is pontentially destructive in more challenging offroad terrain where the wheels can be alternately gripping and scrabbling for traction. The impact forces that can be generated by backlash could be likened to the analogy of a hammer and nail. If you rest the hammer head on the head of the nail ,(no backlash) you can push down with all your might and the nail won't penetrate the wood to any degree. Lift the hammer head several centimetres before striking the nail and things start to happen.
These impact forces not only place extra stress on the halfshafts in a grip and scrabble scenario, but also feeds back through the whole driveline.
Quite aside from all that, it is well documented that the quality of materials and manufacture of later Detroit lockers is quite inferior to their earlier efforts and small design changes have resulted in a unit that generally rips the dog teeth of the side and cam gears when a halfshaft fails. A search on American 4wd forums such as Pirate 4x4,com where Detroits are much more common will back up this claim.
Bill.