Rear Wheel bearing or UV Joint ?

[all mod cons]

For a while now I've heard a 'knock, knock, knock' from the rear nearside wheel of my 1200 Herald. The noise is similar to that I've known in other cars to be a wheel bearing, however today when I mentioned it to another Triumph guy, he suggested it may be a UV joint.

I jacked up the car, held the wheel at either side and rocked it to check for play. There was play there but the whole axle shart moved and the noise I heard seemed to be near the diff.

I then took the wheel off to get a better view and did the same. The axle shaft was definitely moving. From this I gather that the play cannot be a wheel bearing, but must be at the UV joint ????   Can anyone confirm my thinking?

If it is a UV joint is this difficult  to replace? Is it something I could live with for now? I imagine it's not as 'dangerous' as a failing wheel bearing which could, of course, eventually seize ?
Thanks,
Richard

[Ben Baxter]

Just have a quick check that it's not the nuts holding the driveshaft flange onto the diff that have come loose - that's what it was on mine, only discovered it after a lot of effort so thought prudent to change the UJ's while I was at it though.

And when I say loose I mean loose, they'd come about 12mm down the thread, and this was discovered at the end of a 700mile motorway drive  :-/

Sounds like the universal joints otherwise, though someone around here should be able to point you in other directions if not.

[Bob Bowling]

These cars are prone to wearing out the joints on the swing axle, so I would say that is your most likely problem. A failing universal joint on the swing axle is not too dangerous as long as you don't consider the joint coming apart and your back wheel dropping off. Happened to me in 1979 so I do know it happens. You also run the risk of damaging the yoke on the half shaft which means you have to find another. Best get it sorted sooner rather than later.
Not too hard to fix, lots of advice on here about it.

[all mod cons]

Thanks both. I'll check these points out today and also spend some time searching the threads for info on the joints.

[Richard B]

Bill of Rarebits has an article on it on his site;

http://www.rarebits4classics.co.uk/Hints%20and%20Tips/UJ%20Replacement.htm

[all mod cons]

Thanks for the link.

I did a bit more investigation today with the car on axle stands.
I held one side of the UV joint in place (with a screw driver) and attempted to move the other. There's no play at all in either side UV joint, or the one for the propshaft to the diff.

However I did make a discovery - as I could see everthing a bit clearer under the car. If I turn (rock) the rear wheel back and forth I can see the drive shaft and UV joint all moving, but the play appears to be inside the diff.

If I turn the propshaft by hand I can rock it a few degrees backwards and forwards before the 'drive' is taken up on the rear wheels. I hear the knocking noise as I do this.
So, after all this I think the play (and the noise I first heard thinking it was a bearing) is inside the differential.
Anyone seen this before or got any advice?

[Bob Bowling]

Read Bills article on replacing the joints - they will knock even when no play is apparent.

If the knocking sound is quite loud and occurs on the over run, a joint is going. For the small cost of a replacement joint (about £10.00) you can save yourself a load of trouble.
If it is a joint, and you ignore it, it will fail and probably end up costing an awful lot more.

[Nick Moore]

all_mod_cons wrote:

Thanks for the link.

I did a bit more investigation today with the car on axle stands.
I held one side of the UV joint in place (with a screw driver) and attempted to move the other. There's no play at all in either side UV joint, or the one for the propshaft to the diff.

However I did make a discovery - as I could see everthing a bit clearer under the car. If I turn (rock) the rear wheel back and forth I can see the drive shaft and UV joint all moving, but the play appears to be inside the diff.

If I turn the propshaft by hand I can rock it a few degrees backwards and forwards before the 'drive' is taken up on the rear wheels. I hear the knocking noise as I do this.
So, after all this I think the play (and the noise I first heard thinking it was a bearing) is inside the differential.
Anyone seen this before or got any advice?

There's always a bit of play in a diff, so that may or may not be related to the clonks. The shaft shouldn't be free to move in and out - are the cap head bolts holding the halfshaft bearing carriers tight? On second thoughts, if they're coming loose you won't have much oil left in the diff!

A good test to see if your UJs do have free play is whether the knocking is more pronounced on corners. A little free play won't hurt, though - in Heralds the UJ acts as a suspension joint and is subject to loads it's not really designed for. As soon as they develop a couple of thou endfloat they start clonking. It's a Triumph thing.

[heraldcoupe]

Excessive backlash in the diff will be evident as a single clonk on takeup of drive, change of direction, or (possibly) changine gear. There is no way that play in the diff can result in a rhythmic clunk.
UJs will make a hell of a racket before you are able to physically detect the play on the car. By the time you can detect play, the joint is so bad it is in imminent danger of disintegrating. We are talking of no more than 0.010" play when you can hear ticking from the UJs,
Cheers,
Bill.

[all mod cons]

Thanks Bill - mine has to be the UV joints then.
I'll do the tests that you mentioned in your article to work to out which one.
I'll reread it and check the Haynes book to see if it something I think I could tackle, otherwise TRGB are quite local - I might ask them for a quote.
Richard