Really Urgent request...

[Jonathan]

Pre-loading the diff 'correctly' this time as the p/o's mechanic had really screwed this up and nearly mashed the whole gearbox becuase of it.

Draw weight on the diff needs to be ~35nm, with the little tool I made I thought I could achieve this but I cannot, need to turn the castle nut about another 1/20th turn to achieve the pre-load on the bearings and I desperatly need the correct tool which has a socket attachment to get the leverage.

Has anyone got this or can lay hands on it on a hire fee ?

New one will set me back

[Vulcan Grey]

I use a piece of wood and a fish scale...

Use the piece of wood (like a wire brush handle) to gently pound the differential preload castellated nut around. Don't brake off the teeth. I never had a problem with the wood hurting the nut fingers.

[Jonathan]

Cheers, I have tried that but I'll give it another go - perhaps in the light I can find some harder wood, the wood I tried with could have been too soft, it simply splintered against the castalations too easily.

I used something like a C spanner to get to it's current place which is really tight on the case (as tight as I can physically turn it, needs hammering) but the pre-load on the thrust bearings isn't enough yet.

[molemot]

Could try a brass drift, or aluminium, something harder than wood but softer than the nut...I used angler's spring balance and an old brass drift inherited from my Grandfather, so I know it'll work. Also use the spring balance to set cambelt tension!

[Jonathan]

Did think of that but didn't wanna bash off any lugs

If the wood fails I'll have to slide back into work and get me a piece of ali and give it another go.

When you did the torque the diff should be turning at ~3-4kg pull right ? 1kg + 10nm force roughly.

Hard to gauge becuase the harder/faster you pull it the more force is excerted.

Currently mine is about 4kg frictional load then once it spins it's about 2kg at approx 120rpm on the diff.

Just wanna get this right, no-one seems to have done it in the workshops I frequent so any help is a big bonus

EDIT : 1 lug down

It is ever so tight but I still haven't got anywhere near the pre-load.

Further Edit :

Made a jig for this using the old castle nut, drilled some holes and put bolts into it and managed to safely get another 2/3 of a turn, no way in a million years was thing going to go hammering with a punch its SO tight. The initial friction is almost too hard to turn by hand but once it's spinning it's quite free ~ 20nm, problem is both the old man and myself simply cannot hold the box to turn that nut anymore - any tighter and I am convince I might break something expensive...

[Vulcan Grey]

Did you lube the threads on the nut? They shouldn't be dry, the aluminum will gall, and make it much harder to get to proper compression (remember you're not torquing a bolt, your comprerssing the diff bearing).

The service manual says this BTW (didn't know if you had it)

[Jonathan]

Thanks Travis,

Yerp - oiled the threads + cleaned them (its a new castle nut as well).

Just spoke to the UN1 God Derek Bell who seems to have corrected the errors of my ways

He was under the impression this torquing of the diff only needs to be done with new bearings - infact if you look at the page it does say 'if new bearings and/or crown wheel are being fitted'.

Prob is I naturally assumed this would be OK for re-setting the diff as I had no reference of where the original nut was set to thanks to the p/o's mechanic who took it off

Derek encountered the same issue and suggested backing it off and nipping it + 1/8th turn - there's no play in the diff at all - be nice to get it back in the car once and for all !

BTW if anyone needs the tool for undoing this in the future - giz a shout, my ruined castle nut and a few bolts worked a bloody treat and no bashing required B)