Outer Limits 4x4 Board

How much diff backlash should be felt in the rear tailshaft. At what point will it start to do damage to the diff.

Cheers

definately NOT the way to judge backlash. if your wondering about the ring and pinion your better off pulling the diff out, otherwise your taking up all the slop in the side gears aswell.

you can have a lot of slop in the tailshaft without anything being actually wrong. when you turn the tailshaft with the wheels stationary, before it stops you have to take up multiple small clearances that can all add up to a significant quarter turn or more of the tailshaft. there is backlash between the axle and side gear splines, between the spider and side gears, between the spider gears and the cross shaft(s), and between the crwonwheel and pinion. crownwheel/pinion backlash can only be measured at the crownwheel with the pinion held motionless, and usually more disassembly is required to measure/adjust spider/side gear backlash. if it works and doesn't make any bad noises, it's probably ok. Unless you're set up to do diff work (ie you have the special skillz and special tools) then there's nothing you can do about it anyway.

If you can reach in via the filler hole and jam the crown wheel somehow (relatively gently, don't drive a piece of 12mm deformed bar in ) then you should be able to guage how much play between crown wheel and pinion. An experienced hand will be able to tell if it's bad or not. Sorry DD, if you've got a 1/4 turn worth of play in the diff/axle, it's fkd.....

RED60 wrote:If you can reach in via the filler hole and jam the crown wheel somehow (relatively gently, don't drive a piece of 12mm deformed bar in ) then you should be able to guage how much play between crown wheel and pinion. An experienced hand will be able to tell if it's bad or not. Sorry DD, if you've got a 1/4 turn worth of play in the diff/axle, it's fkd.....

the spec for landcruiser gears is about 0.010" measured at the crownwheel. due to the screwing action of the pinion in the crownwheel and the preload on he pinion bearings it is impossible to get an accurate idea of backlash at the pinion flange. a quarter turn between the pinion and crownwheel is impossible, however the cumulative effect of all the available slop in the final drive can easily add up to a quarter turn of the tailshaft without anything being specifically bad.

I have to confess, i'm a backlash nazi.

All of the 4x4's i've had i have completely removed the centres, stripped them, then reassembled back to (as close to) factory spec as posible. I cannot stand uni/tailshaft/diff slop - it drives me insane.

I pulled the rear centre out on the GQ a few weeks back just for a general inspection (it had too much slop), and found that it was actually the axle splines & receivers causing the play.

I hastily reassembled the diff, and i wont worry about it until it a) breaks; b) a cheap disc rear diff appears.

Playing with diffs is definately NOT for the untrained (grind crunch grind squeel).

ENJOY!