BW78 diff gear backlash

[Charlescrown]

slewinson you hit the nail on the head with poor assembly and I agree with the unknown torque value on the pinion nut. I have also seen so many failed components caused by poor assembly. Many mechanics/technicians don't understand the consequences of dirt etc. As far as the pinion nut torque I have been stunned with the amount of torque required to compress a crush tube to reach the required rotating torque. I know manufacturers make several sizes available and some measuring must be done for the correct selection. I think too many don't understand the process and never get the preload correct in the first place. How many diffs have you seen fail after the pinion oil seal has been replaced. All the more reason to have it done by a competent specialist. I still believe that if a crush tube is assembled correctly you wont have any problems.

[immortality]

absolutely a misconception. they would probably be worse as autos have a filter and heaps of fluid, diffs and manuals have none and the low amount of oils unsure dirt and wear particles recirculate much more often doing progressive damage.

Although I totally agree with this sentiment when you have wearing parts in a diff that create debris sometimes I wonder if you're chasing your own tail.

Take the OEM Holden LSD. When the cones wear they create particulate matter which contaminate the oil and the entire diff and it's for this exact reason I advocate that LSD diffs should have much more frequent oil changes compared with a standard open type diff. Having said that, LSD diffs don't tend to wear out any quicker than standard diffs when looking at things like bearings and gear sets as far as I have seen.

Diffs are probably one of the most under-serviced parts of any motor vehicle, performance or otherwise.

[vlad01]

I service my diffs all the time for this reason. Generally every year for a daily driver.

manuals every 20k or less I do my changes which is far more often than I'd do an auto, well if i had an auto lol

[Charlescrown]

Interesting point about the LSD wear. The housing is cast iron (not sure about the cones) which contains a high level of graphite. I wonder if this powder helps lubricate gears?

[vlad01]

actually the housing is cast steel. you can weld it

[Charlescrown]

Not going to argue that one. I have seen many hemispheres busted apart and they are cast iron but yes it might be with a LSD. I didn't know they used cast steel for that type of construction. You can also weld some types of cast iron. I just use my MIG with steel wire to weld exhaust manifolds and they don't crack.