Practically Classics Forum

Had to do a very quick preparation of the MGB ( 1967 wire wheel roadster ) to meet a forgotten MoT deadline and noticed significant play on the left front wheel. Not having time or shims, I was able to 'fix' it by tweaking up the main bearing nut by one flat. There's now no discernible play and the wheel still turns freely and didn't complain or got hot on the (successful!) trip to the MoT man.

However, I did need about 100ft lb torque to take the nut round to the next point where I could refit the cotter pin, higher than the quoted 70lb ft maximum. There seem to be as many opinions on mgb wheel bearings as there are bearing sets out there ( shims, no shims, torque 'till it binds then back off etc etc ) but does anyone have a view on my current set up. Do I need to add a shim, maybe just add more grease, or is the set up inherently strong enough to run like this?

Thanks in advance - Jez

They're taper-roller bearings, as such they shouldn't be remotely tight and if you had to apply that sort of effort to take out enough play for the test - bearing in mind that there must be some - then something's very wrong.

The same bearings are used in many other cars, I've never come across anyone who wouldn't simply tighten them to the point where there wasn't any radial play at the rim, then back them off to the next position where the pin would enter, which should equate to a detectable amount of play.

They're cheap enough, I'd change the bearings rather than risk the potential consequences of taking a torque wrench to their castellated nuts!


It's also possible that, if you didn't back the nut off and clean the thread on the stub axle before adjusting it, some debris could have been preventing your taking the nut up with finger pressure alone. Failing that, I'd also look at swapping the nuts side for side, that way, the notches you need might line up with the pins on both sides, though after you've put that sort of torque into it, there's almost sure to be some damage now so go with the new bearing idea.

JPB wrote:They're taper-roller bearings, as such they shouldn't be remotely tight and if you had to apply that sort of effort to take out enough play for the test - bearing in mind that there must be some - then something's very wrong.

The same bearings are used in many other cars, I've never come across anyone who wouldn't simply tighten them to the point where there wasn't any radial play at the rim, then back them off to the next position where the pin would enter, which should equate to a detectable amount of play.

They're cheap enough, I'd change the bearings rather than risk the potential consequences of taking a torque wrench to their castellated nuts!


It's also possible that, if you didn't back the nut off and clean the thread on the stub axle before adjusting it, some debris could have been preventing your taking the nut up with finger pressure alone. Failing that, I'd also look at swapping the nuts side for side, that way, the notches you need might line up with the pins on both sides, though after you've put that sort of torque into it, there's almost sure to be some damage now so go with the new bearing idea.

JPB, I am afraid that you do not understand MGB front hubs, as they are set up requiring the hub bearing spacer be under compression, and the rear seal will not when the spacer and shims are left out.
Jez, if the hub turns freely with no notchiness and was greased recently it should be safe to use.
Matthew

Strange, I understand simple taper roller bearings' M.O. well enough and have never heard of them being used in this way on any of the other cars that use exactly the same stub axles and bearings; various Triumphs, Reliant Rebel, kitten and Fox, A60, etc.
Even stranger, the manual covering cars current between 1981 & 1991 says only this:

Autodata, 1991, ISBN: 0-85666-601-7, pages AUS42-AUS43 wrote:11: After tightening the nut to the correct torque, this is only a little over fingertight, mount a dial gauge sp that the stylus touches the washer. Zero the gauge and adjust the nut to give an end float of between 0.002" and 0.008" (0.051 and 0.203mm). If the nut has been tightened to the correct torque, this will mean slackening the nut approximately one flat only.12: Fit a new split pin, fill the hub cap with fresh grease and press it into position.

And no, I don't know anyone who'd use a dial gauge for this either, but in an ideal world maybe...

Gotta agree with John on this, these are set up finger-tight only. There is a centre collar that goes between the inner and outer bearings IIRC, and it sounds as if something's amiss and your inner bearing is limiting on this, so you're having to give the nut a huge torque to tighten up against this to take the play out. It'll work OK like this for a while I suppose, but it does sound like something is amiss in the hub, so personally I'd strip it down and investigate - with the correct workshop manual to hand if you don't believe us! The carnage that could be caused to yourself and others if the bearing, nut or stub gave way doesn't "bear" thinking about, so better safe than sorry.

Never heard of shims being used on these, just the method John quotes. Easy Peasy.

Cheers

Thanks for the input guys. The manual states that up to 70lb torque may be needed, rather more than finger tight, so it seems the MGB set up with shims etc is different from some other taper bearing applications. There is a school of thought that the shims can be omitted, maybe making them behave more like a conventional set up, but the counter to this is that the intended design makes the whole arrangement stronger by keeping the stub axle itself under tension.

As the bearing is running freely, I'm not going to panic right now, but I will get hold of some new shims prior to removing the hub and taking a look around. From what I've read, I need to reduce the amount of shim in order to get rid of the slop at the official torque settings. The tip on cleaning the thread is also a good thought, as the dust cap doesn't make the best seal you've ever seen.

Wonder if I'll get time to play over the Easter break.........

Cheers - Jez

The idea of this sort of set up is that nut should be done up tightly, with the spacer between the two taper races being of the precise length to give the correct preload when the nut is done up to the correct torque, although I've never heard of them being adjusted by shims before. If everything is set up correctly there should be just perceptible play with no roughness or binding. I wouldn't advocate dispensing with the shims, all you'd be doing would be simulating worn bearings.

JPB wrote:Strange, I understand simple taper roller bearings' M.O. well enough and have never heard of them being used in this way on any of the other cars that use exactly the same stub axles and bearings; various Triumphs, Reliant Rebel, kitten and Fox, A60, etc.

A60s don't have taper roller bearings, but an opposing pair of angular contact ball bearings. As such you cannot really adjust out play in them in the same way as with taper-rollers.

From what I can see though, MGBs do have taper rollers...

Here's an interesting video.

http://www.youtube.com/watch?v=RJYIXZtnIiw

The majority of mgbs on the road have incorrectly assembled wheel bearing assemblies.

The way they are designed the shims are integral to the function of the wheel bearing. Any play must be taken up by the removal of one or more shims. There are a 30 thou, 10 thou, 5 thou and a 3 thou shims. if there is excessive play then remove the thinnest shim and torque to 60lb. You should end up with 2 thou of free play. Leyland used to use a guage to measure this, but just check side to side movement on the wheel. Shims and torque are the way this type of stub axle works. When you regrease there is no need to remove the rear bearing as this never ever runs dry.

All other methods suggested to adjust play on a mgb wheel bearing are wrong.

carlp wrote:The majority of mgbs on the road have incorrectly assembled wheel bearing assemblies.

The way they are designed the shims are integral to the function of the wheel bearing. Any play must be taken up by the removal of one or more shims. There are a 30 thou, 10 thou, 5 thou and a 3 thou shims. if there is excessive play then remove the thinnest shim and torque to 60lb. You should end up with 2 thou of free play. Leyland used to use a guage to measure this, but just check side to side movement on the wheel. Shims and torque are the way this type of stub axle works. When you regrease there is no need to remove the rear bearing as this never ever runs dry.

All other methods suggested to adjust play on a mgb wheel bearing are wrong.

MGC is the same