Anyone who's bought rear discs/hubs in 2023 - PLEASE READ

[dapinky]

This is a bit of a heads-up for anyone who has bought any new discs/hubs since 2022 - maybe before that, but they were unobtainable for along time, and then all the usual specialist suppliers seemed to advertise new items at the same time, at the same price.....

.... I may well be wrong, but I suspect that they all come/came from the same engineering place - hence it is not relevant where I got mine from (for the purpose of this warning post!).

I noticed that my car was driving like it had a square wheel when I went for the MOT (my first ever drive of it, and the first time it's been driven in 8 years).....

...I tried the wheels off my own car and it was identical, so i adjusted the bearings a bit and it made some difference, but nowhere near correct.

... as "good fortune" would have it, there was a post on Facebook by John Whelton who had fitted a brand new pair of rear hubs, and found that they were not running true. He posted some videos to show how much run-out there was, and it looked quite substantial. Whilst he didn't "name & shame" the supplier as it is an ongoing negotiation, he was quite happy to provide me the details privately.

Suffice to say, mine came from the same supplier, and I'm pretty sure that whoever the supplier had been, they would have the same potential issue.

Like John, I then set about measuring mine, but my dial gauge was broken, so I had to wait for a new one to arrive (next day, thank to ebay!!).

So, I measured the ROS and found it had about 0.15mm run-out... and it didn't matter if the bearings were let out a tad, or tightened up to needing a pull to rotate the hub, but no chance of 'freewheeling' - all readings were pretty similar.

With nowt to compare that to, I dug out the old hub, cleaned off the outer face with a flap wheel in an angle grinder, stuck it on the hub and (even with a fairly rough surface, and old bearings) it had a run-out of less than 0.05mm....not too much different than the new one, but it clearly is more on the new one, especially if you consider that the disc face is dead smooth on the new one.

Okay, so looked at the NS one, and first measurement showed it to be 0.80mm out! - now that is pretty significant in my book! Again, with bearings loose, normal and tight it was the same.

I put the disc that had been on the OS on and it was still 0.15mm out of true, so dug out the other old disc (which is pretty knackered to look at, with one bolt-hole useless as it has been drilled and tapped to M14!!!) Anyway, with the face cleaned up I was amazed to find that the run-out was less than 0.02mm - so better than the "good" old disc, and far, far better than the new ones.

I kept that one on for now, but wouldn't be doing a long drive with it.

Anyway, a quick phone call to the supplier, and was told that there have been a few issues with these items, and they have removed their stock from sale for now. It will be sorted out with a new pair when they get some accurate ones in.... this could be about a month or more

In the meantime, I would urge anyone who has bought a rear hub (or two) since Christmas 2022 to get an accurate check of the disc face, and if it is more than 0.05mm out of true, see if it is one of the 'defective' batch, and get hold of whoever supplied it to you.

Okay, it is annoying, but it isn't really going to make a big difference to my planned use of the car - it could be so much more devastating if it was needed for a Grand Tour of Europe or a daily commute.

I shall not be naming the supplier, because clearly it is a fault of their supplier - and they are addressing the matter as best as they can.... so no problem with them at this stage.

Obviously, I have been considering the way forward, and have been in contact with Ron about the Astra Hubs...... I am prepared to give the company a chance to sort out the duff parts (machined by Stevie Wonder using a cubit as a measurement device when setting up the lathe), but if they can't get me a suitable pair in a reasonable timescale, I shall be looking for a different resolution, which will involve Astra Hubs!

[Welly70]

Cheers dave, glad my videos helped and just glad I wasn't going mad.

[Tuga2112]

this is the same issue john whelpton was discussing on facebook isnt it ?

[FunElan]

That's a damn shame.

If someone can well document the replacement "custom" hub/disc conversion, I think we'll all be better for it. It should be in the wiki.

[dapinky]

this is the same issue john whelpton was discussing on facebook isnt it ?

Yes Joao - like I said in my post!!!! (and he replied under his pseudonym of Welly70).

Anyway, the point is that it isn't an isolated case, and I (we?) don't know how many are out there - it could be that the only 2 bad ones have been sent to John and I, and the rest are okay (or okay enough to not notice), or there could be a whole load of them.

FunElan - there is no 'off-the-shelf' hub conversion, and the closest that has been done involves an Astra hub (with sealed-for-life bearings) and a separate disc. It does require some modifications to the rear upright of the Elan, and although the mod is somewhat reversable, I can't think why anyone would want to do so..... but it may be that by reversing it, things are not quite right.

I am not the man who has done the work - but I have been speaking to him (and actually saw his prototype unit earlier in the year). It may well be the way forward, but it may just be the start of a quest to find a 'perfect' solution..... I'm sure that once it is sorted, details will be made available, but at the moment, it is still 'work in progress'.

[Tuga2112]

further question (this time after ctually reading the whole shebang)

would skimming the disk in situ resolve the issue ?
i mean this as i am gessing it depends if the axle of rotation is true with a disc cut out of shape. or the opppoiste

alternatively, re-machining the inner side (and using a bearing with larger diameter as result) could make these faulty units to work safely ?

certainly more interested in the hub change that RonR was talking about in he's project thread. but hoping that whatever comes from it its reasonably priced

[dapinky]

I don't know if the machining is due to a faulty flat bit where the bearing sits, throwing its axis out of true, if the whole inner 'hole' is out of true, or if the disc is badly machined.....

..... I didn't bother putting a dial gauge on the actual outer hub where the wheel fits, as it isn't really my problem!

That said, it *could* be machined, but to get 0.8mm of run-out removed from the disc it would mean taking about 1mm off the thickness (and that may be on both faces - again, I never put a gauge on the inner face) - and that would put it close to the minimum thickness of 10.7mm allowed......

..... refacing the inner lip where the bearing sits may be all that is needed, but care needs to be taken that it doesn't sit too far into the hub as that would throw the taper bearing fit out.

..... and then you'd need to (possibly) machine the hub face so that the wheel runs true.....

Whatever happens, the items are unfit for use as they are, and it may well be that the engineering company that made them cannot make them to the required tolerances, and we end up in a situation where the parts cannot be supplied. Or it may be a couple of bad units in a batch, and with a bit of added care in the setting up of the machinery - tools all is well in the world.

Only time will tell.

[Simon_P]

Good post dapinky.
I saw the video and wondered if the disc face was turned or ground?

the axle of rotation

that'll be it!

Only time will tell.

combined with the man (or woman for the politically correct) with the correct tools, equipment and experience.

[Welly70]

Hi all.
Thanks again dave for showing i hadn't gone bonkers. Fingers crossed no one else has the same fitted. Unfortunately had to fit a used pair which have gone on without grief whilst we wait for hopefully some new to surface.

[dapinky]

Just noticed that this is all a bit 'wordy' and may benefit from a 'visual' element......