Salisbury diff - pinion nut torque

[Snagger]

Hi folks, hope you had a good Christmas!

I have replaced the pinion seal on a 110 Salisbury axle to be fitted to my 109. I marked the nut and pinion prior to removal so that the nut could be refitted to the original position, but while cleaning the parts for reassembly, the marks were washed off.

So,I have checked the LR green bible, and it says that when fitting a new crush tube and setting the pinion bearing preloads, the crush tube needs a torque on the nut of approx. 250'lbs to start crushing, with the required torque rapidly increasing to continue crushing the tube until the preload is correct.

I am reusing the original bearings and crush tube, and so far have just torqued the nut to 150'lbs. This seems tight enough to prevent it from undoing and to make sure that there is no play in the bearings (both bearings tightened right up against the crush tube), but should not have crushed the tube any more.

The worry is that the tube may have a little hysteresis in it, expanding a touch as the nut was undone, and may not have gone back to the same length as before the nut was undone. However, after 20-odd years and well over a hundred thousand miles in place, I would hope that the heat and vibration in service would have relieved the compression stresses and set the tube length permanently.

Does anyone know if leaving the nut at this 150'lb setting will be sufficient, or will it cause problems?

[Phil Hancock]

Nick try the feel of the pinion for preload with your hand. If you feel uncomfortable with this, pull the halfshafts and as the bearings are used then following the manual set the preload to the max poundage for used bearings. Or you could slacken the pinion nut to just get a minute whisker of pinion bearing play and then take a preload reading on the pinion, then add the book figure for used bearings(minimum) and finally set the pinion to the sum of the two. Then refit halfshafts.

[Timmy511]

measure the length of the crush tube, get one machined up out of tube (thicker than the crush tube of course) and then tighten it FT.

standard rover diffs are preloaded using spacers and shims, this method would be pretty much the same and imo alot better as you know you can really tighten it without destroying the bearings.

[Snagger]

Thanks, guys. I'll check the preload against the other axle's once I remove the half shafts, then. I don't think the difference in the 4.71 and 3.54 gearing will make much difference, but I'll try to allow for it (stiffer on the 3.54). It feels pretty good by hand, though, at 150'lbs.

Phil - I sent you a PM on LRNet - no real need to bother, since you have already answered my question, though I'd always be glad to speak to you anyway!.

[Snagger]

Well, I pulled the half shafts and tested the pinion preload with it driving the diff carrier only. It's exactly the same as on the other stripped axle (I suppose the gear ratio doesn't make much difference when there is no resistance from the hubs and road wheels). So, it would seem that using about 150'lbs on the main nut if you lose the markings works well enough.

[Snagger]

I never came back with the driving results.  Sorry.  It works fine, with no noise, backlash, heat or wear issues after another 40,000 miles in every day use.  It also works fine when swapping back and forth with different pinions and ring gear ratios, retaining the original crush tube.  Sounds like a botch, but when you think about how it works, it isn’t.