I've rebuilt the rear axle of my Opal - new half shafts and outer hubs and mostly new bearings. I set it all up in line with Woodrows instructions, using engineers blue to get the teeth contacting in the right places and I thought everything would be fine. But it wasn't because I got a lot of axle noise that sounded very much like a car going over a cattlegrid at speed. And yes, I had remembered to put oil in.
So back to the drawing board!.I dismantled it all again, checked clearances etc and reassembled it. I got 1/16th backlash at 7" radius and again thought I'd cracked the problem. However, on driving the rear wheels with the car on axle stands the cattlegrid noise is still very apparent.
So what to do? My question to those who've had similar problems of noisy axles is this - "Will increasing the tooth clearance using the screw adjusters be likely to lead to a quieter axle? If not that, what else should I try?
Your thoughts would be welcomed.

Location: Sheffield

There is a very useful article by Jack French on rebuilding the axle in the green 750 Companion.
Over the years the CWP wears and after running with far from standard settings they get used to it. When this happens the theoretical mesh set up may well no longer be what it wants. Difficult to say what settings it should have but from your description it may well be 'cogging' which, as you suggest, would be the mesh is too close. Difficult to tell if the crown wheel or the pinion should be moved. I expect trial and error is the way to go and slackening the screw adjusters is worth a try.
Trying it on axle stands seems a very good idea and the lack of load would minimise any potential damage from incorrect mesh.
Jack French's article does give a rule of thumb for adjusting the pinion. Whether it is noisy on load or overrun determines whether shims should be added to or removed from the torque tube flange - can't remember which though!

Chris,
was the axle noisy before you rebuilt it with new halfshafts?

Location: Deepest darkest Kent

How does it feel to turn by hand? If teeth not contacting at ends or running on a wear step( blueing OK) and some backlash should be reasonable.
Is the roughness at tooth contact frequency? I dunno what happens if the a.c side gears are fitted reversed. Mention recently of wrong sized axle shaft for side bushes. (I don’t know if this applies to long shaft models, but perhaps may lead to noises from the planet gears).

Location: Auckland, NZ

fill it with a mixture of oil and timesaver and go for a spin.

Kill or cure

Hi Robert,
I've no idea how the axle ran before I took it to bits. The car had only done 100 miles in the last 20 years and was in no fit state for any mileage before being stripped and refettled.

Location: Sheffield

Hi Bob,
Doesn't feel too bad turning by hand - allowing for tightness of all the new oil seals. The crown wheel and pinion also look in pretty good condition - no obvious worn or rough areas. However, although the new half shafts looked to be a good fit - neither noticeably tight nor sloppy - I didn't give them a lot of close attention. So if increasing clearances doesn't effect an improvement maybe I need to look closer in the diff area itself.

Location: Sheffield

Thanks Jim, I'll dig out the Jack French article. Sounds interesting.
Regards
Chris

Location: Sheffield

A universal joint problem possibly most likely. Is the uj somehow causing a loose torque tube ball joint to chatter?
I dont know if long axles were ever thin or now available new, so that may not be a possibilty. Anyway, seem to have covered that.
When pinion is turned by hand, should not or barely feel the individual teeth.

If you obtained a genuinely good mesh pattern that is no mean feat with used parts. Often the wear ridge on the pinion needs to be stoned away. And the fact that the 5.25 diff teeth do not hunt can create two mesh patterns and confusion. But hardly likely to cause the effect described.

Any post assembly adj is usually to try and reduce drone or whine.

Location: Auckland, NZ