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MG MGB Technical - front wheel bearing - is this a shim?
|I had to remove the hub to change the brake disc and found this inside. I presume its a mangled shim but something must have been done up really tight to flatten one half of it. I can't get 3 thou end float with a torque of 40 ft/lbs unless I turn the hub nut back one 'slot'. Maybe this shim (measures about 9 thou) would have been enough. I must get me a stock of shims. I'll probably find the other hub also won't be in spec when I come to do that.|
this is the first time I've had to do this and its really fiddley to do inside a wire wheel hub.
|Hello Steve, That shim is in a bit of a sorry state, just a new pack from MGOC. You are right what you said about tightening up the nut, it's easier the get the proper clearance if you do it with no grease on the bearings. There are plenty of video's on the web how to do every day tasks.|
|I made up a pair of "hooker-outers" from pieces of wire coathanger with a small hook bent and filed flat at the end. It's still fiddley, but a bit easier!|
|Standard shims are 3, 5 and 10 thou in varying quantities, plus a standard 30 thou. You are aiming for 2 to 4 thou end-float. Juggle shims until you get two sets 1 thou different where one set just gives perceptible play, and the other none, then use the thinner set plus a 3 thou. They aren't marked (IME) but if you use one to bend another it's easy to see which is the thicker, so easy to work out all three. 40 ft lb is the *minimum* torque, you then need to tighten until the first split pin hole lines up. Definitely needs to be done before greasing when fitting new bearings, but if doing older, greased bearings you will need to tighten to that split-pin hole before you can finalise the shimming, as you may find the end-float vanishes between 40 ft lb and 70 ft lb.|
Speaking of shims I recently ordered a set of king-pin shims. These *did* have sizing numbers on them, and came in separate bags with the correct sizing information on them, but no amount of juggling made any difference. Measuring them I found they were all the same size! Oh how I chuckled ...
|I eventually bought a dial gauge and magnetic clamp to do this job. Using this and not greasing the bearings (per Paul H above) until you are finished makes it easier. The manual specifically tells you not to pack the area between the bearings with grease.|
|Unfortunately I'm not changing the bearings so have fully greased bearings. Where did you clamp the magnetic base too Stan?|
|Just to inject a little fun into the post, has anyone taken out the shims and used the axel nut to preload the bearings? Ric|
|Thats a good question. I remember it was a problem. I might have got it somwhere on the wishbones. Sorry should have taken a pic. I could post one of the gauge and clamp if you like|
|I've heard of no shims and 'pre-load' which some Americans insist is the right way to do it 'cos that's the way it is on American cars, and no shims and end-float i.e. a slack nut ditto. After a comment on the MOT that one front wheel on my V8 had a bit too much end-float after 15 years and 85k I discovered it had yet another combination, that of some shims and a slack nut! I had to add shims to get the correct end-float with the nut tightened, presumably the last person to work on it, possibly changing bearings, had no spare shims. I consider myself fortunate that the bearing inners hadn't spun on the stub-axle.|
|Most American cars don't have quite the same configuration as MGBs. The advantages of the shim stack on your car are many. First, compressing the outer spacers / races into a single unit strengthens the entire spindle assembly. It also prevents the inner spacer, where the grease seal runs, from spinning on the spindle and creating wear. It does the same for the inner bearing races. Additionally the shims allow precise setting of bearing play which lengthens their service life and (arguably) increases steering precision. The spindle is strong enough to run without them in normal use, but I've never seen a valid argument for leaving them out other than just being lazy.|
This thread was discussed between 02/10/2010 and 09/10/2010
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