Wheel wobble

[ndevans]

Good run from Bristol to Holyhead on Tuesday, followed by an equally good run home today. Car ran well, fuel consumption good, all felt fine.
Then, near Shrewsbury on the way home, a strange thing happened. We pulled up at lights and two lads in a pickup drew up alongside and said "your rear offside wheel has a heck of a kick on it".

So I stopped at the next lay-by and checked the wheel nuts -all OK. I then raised the o/s wheel off the ground and turned it by hand. Sure enough there is a slight wobble. The wheel feels solid when I try to rock it top to bottom and left to right. I raised the other rear wheel and that looks perfectly straight and true when turned. At speed there is no vibration or noise coming from the rear, and the bearing does not feel or sound like it's on its way out when i turn it by hand (it shouldn't be, it was brand new C3 type 1000 miles back). I couldn't get the drum off as I did not have the correct screwdriver with me to remove the screws (note to self-put one in the toolbox).

I continued my journey and got home without issue.

No video, I will try to get some tomorrow. This is not the wheel that came off a few weeks ago.

It is not a very pronounced wobble but is definitely there compared to the other side, but as I say, there is no unusual vibration or noise at speed. Should I be concerned? What could it be?

[Bill_qaz]

Use a pointer such as a screwdriver on an axle stand or block of wood and with tip on wheel rim and jacked up rotate the wheel by hand and check run out to see if you have a buckled wheel. If it ok repeat test against the tyre in case its not seated on rim correctly or the tyre is defective. Check inner and outer tyre wall for any bulges.

[ndevans]

I'm pretty sure the wheel itself was not running true, but that was only by eye and it's easy to be distracted by slight variations on the tyre.
I will try the wheel rim test tomorrow, will also swap the two rear wheels over to see if the problem moves.

[mike1864]

Wouldn't it be less effort to start with trying the spare wheel? (if you have one!)

[ndevans]

Could do, but that is a standard steel rim, the others are alloys. I'd rather compare like with like.

[ndevans]

I have measured the run in, it's about 2-2.5 mm on the o/s, bit under 1mm on the n/s. When I swap the wheels over, it's about 0.6mm on the n/s, but still about 2mm on the o/s.

[Bill_qaz]

Do the same check on the drum face where the wheel sits.
Does the wheel fit over the centre hub ok and sit flat against the drum face.
You can smear thin layer of grease on contact face, bolt up wheel, then remove and see contact points, to ensure full contact.

[ndevans]

I checked the drum face with an engineer's straight edge, and as far as I can tell it is square diagonally across each pair of bolt holes. It looks clean, as does the inner surface of the wheel. There is plenty of room between the halfshaft centre and the wheel.

[Bill_qaz]

Although the contact face is flat it must have run out as the problem stays on offside even when wheel is swapped.
You need to check run out on mounting faces.
You could also check for camber on rear mounting face with spirit level. Also tracking, measuring inner rim to inner rim, in front and behind axle. To insure axle is not damaged.

[ndevans]

Swapped the half shaft for the spare, cleaned all up and put it back together. Now down to about 0.6mm wobble on that side with the original wheel . Whether that is due to the half shaft change or just the clean up and reseating I don't know.
My only reservation is that the spare half shaft is not hardened, therefore I run the risk of breaking it (I have a 3.9 diff and a 1275 putting out about 65-70bhp).

[Bill_qaz]

So surely if same hub and wheel studs but different halfshaft cures it then it can only be the mating face of the halfshaft, either to hub face or wheel face.

Screenshot_20250803-180011_M365 Copilot.jpg (97.62 KiB) Viewed 4923 times

[ndevans]

Here are the videos of the measurements.

1 o/s with original wheel
https://drive.google.com/file/d/1BCZqLT ... p=drivesdk

2 n/s with original wheel
https://drive.google.com/file/d/1BS3Nh2 ... p=drivesdk

3 o/s with wheel from n/s
https://drive.google.com/file/d/1BSPiPB ... p=drivesdk

4 n/s with wheel from o/s
https://drive.google.com/file/d/1BOz3M2 ... p=drivesdk

[les]

It might be an idea to try that with the wheel off, using the gauge directly on the fully home and securely tightened brake drum.

[Bill_qaz]

Run your dti on the halfshaft just inside wheel studs with current replacement shaft and refit original and compare, and as Les suggested on the drum face. The run out will be amplified at the wheel rim.
Just another thought are your wheel nut bottoming out on studs and not fully clamping wheel.
Was anything trapped between surfaces rust flake etc.
Did you try the grease trick to check full face contact wheel to mating face.
Interesting puzzle

[ndevans]

Dial indicator on the original halfshaft before I disturbed it.

https://drive.google.com/file/d/1a_CvAE ... p=drivesdk

I couldn't get it to run inside the studs, they are long studs and kept fouling the body of the indicator. I did the same thing on the drum, no video but it was a similar figure on the indicator.

[ndevans]

How much run-out is acceptable on the wheels? I'd expect a bit, as it's difficult to get all the mating surfaces mirror smooth, but I do think 2-2.5mm is a bit excessive.

[les]

I’m wondering if the wheel wobble is as bad as those lads were saying, get another person to follow you to get a second opinion.
Can’t be too bad if you don’t feel any symptoms.

[ndevans]

The wheel seems firmly clamped, there was no movement when I tried rocking it n-s & e-w, so I don't think the nuts are bottoming out on the studs. I am also coming to the conclusion that it may have looked worse than it is. I guess a ½mm of crud between wheel & drum or drum & halfshaft could result in a couple of mm displacement measured at the wheelrim.

The question remains though, what is acceptable?

[philthehill]

If you have wear on the inner end of the half-shaft coupled with wear in the diff sun gears you will get wheel rock.
The rear wheel bearing being a single race will not contain any play in the bearing.
The inner end of the half-shaft supports the bearing and should eliminate the rocking play.
If C3 wheel bearings are fitted the wheel rock will be compounded because of the extra clearances found in a C3 bearing.

[svenedin]

Was this anything to do with your wheel falling off on the M4 on the way to Minors on Tour to France?

Stephen