Sprint Diff Whine

[Dolly-Nut]

I have a known whiney diff which has previously been ran low on oil. I imagine the lack of oil has roughened the pinion bearings to the point of singing. It's the collapsible spacer type. Now I've never tacked a diff rebuild before but what do I need to look out for?
Is a spreader necessary or are lever bars and a steady hand enough? Setting the pinion nut torque seems to be a sticky one, how do others set this? Research suggests torturing to 90lbft then increasing to 120 until a torque of 26-29lbft is require to rotate the pinion, does this sound right? I want to be confident in the procedure before tacking it.
My aim is to replace both pinion and diff side bearings, reset the pinion preload and see how it goes.

[cliftyhanger]

I too have never done a diff, but I have a good friend who has done loads.
He uses no special spreaders, just the usual pullers and punches etc. And a wealth of experience!

The whine may be down to CWP damage, in which case nothing can be done. The mesh of the CWP is the main thing to get correct. With the collapsible spacer you do the pinion up until the mesh is correct, and that is it.

I have oversimplified that a lot I think but advice from somebody who has done the job is invaluable.

[Dolly-Nut]

How the CW is centred in the casing should also affect the meshing.
Mart has offered his services so hopefully we can work it out together and pass down the procedure!

[cliftyhanger]

Yes indeed. I meant that the spacer is collapsed to set that distance.

I think you can replace the collapsible spacer with a solid one and shims. Or use a shim with your old spacer and re-use. I prefer a solid spacer when I get diffs "done"

[soe8m]

Not using a spreader is not doing the job right. People who do and say they don't need to are not getting the clue. The collapsible spacer is only for the bearing preload. Not the gear setup.

Jeroen

[79Inca]

In nearly 40 years with Sprints I had two rear axles and diffs rebuilt. The guy who did them said that the collapsible spacer is the problem - he says that in in his experience, supported by measurements, that they collapse a bit more in use and throw everything out. Both my diffs (Standard and LSD) were done the solid way and it seems to work well. I find the tab on the LSD plates fret the slots and they need building up again every 10,000 miles or so. I use a place in Coventry for axles as they do a good job and much quicker than I can do myself (I just took a year on a top-end overhaul as work interferes!).

[tonybsa]

Bin the collapsible spacer,it was fitted as a way of cheapening production(dont need multiple spacer sizes on the assembly line),and there crap.
I did an axle rebuild last year.Lots of good vids on youtube,mainly from American muscle car builders,also Practical Classics recently did a guide.You dont need a spreader,but its easier if you can get one.You will also need a Dial Test Indicator with a magnetic base,and some engineers blue,and a LOT of patience.
I made my own solid spacers and case hardened and ground them,I made variuos lenghts slightly longer than the collapsed spacer I removed,and kept fitting different lengths until I got the correct preload on the pinion,this is the first job when rebuilding the axle.Hope this helps.