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MG MGB Technical - Wheel bearings (NO SHIMS?)

I copied the below from the web site Weimerology . This makes perfect since to me and was woundering if any one can disagree with leaving out the shims. They are really a pain to get right.



MGB's have a spacer and some shims that go in the hub between the bearings. Use them if you must, but you don't have to. These items are engineering overkill, not really needed, and not likely to fit properly with new bearings, so we'll leave them out and do this like it's done on a billion other cars. Tighten the spindle nut good and snug, rotate the hub or hub/wheel assembly a couple of turns, back the nut off until slack, and re-tighten lightly.
If a cotter pin hole lines up with the slots in the nut you're set. If not tighten the nut ever-so slightly and check again, if the pin will go in, do it. If still not back the nut off until it will. Give the hub/wheel a couple of turns, press/shake it sidewise and up and down to detect any looseness. No looseness? Bend the cotter pin to secure it. Looseness? Remove the pin, tighten the nut to the next slot. Some spindles have two cotter pin holes, one vertical and one horizontal. Look for this and use whichever one makes the hub fit best.


Writen by:
"John Dandy"
(theAutoist NOTE: John Weimer's new "nom de plume")

Kevin Pearce


http://www.theautoist.com/weimerisms.htm
Kevin Pearce

US cars have been without shims and spacers as far back as I can remember. Never saw any damage that I could attribute to this setup. On the other hand, Abbington must have had some reason for using them. But of course, they did stick the tranny dipstick in a nearly unreachable location, use two 6V batteries instead of a single 12V and design that cursed rear engine mount, too. I can see nothing wrong with what John Weimer, a lifelong mechanic by the way, says in his write up. Leaving the shims and spacer out makes a rearing replacement job a bit faster, too.
gerry masterman

Kevin, I do as John does and have not experienced any bearing problems. Of course the MGB shop manual says to use them. Clifton
Clifton Gordon

Following the MG manual will earn your MG mechanic an extra $150 bucks or so. These guys gotta eat to ;-)

Pete
Pete

Let's see--last time I did this job it took about an extra five minutes to shim and check the play. In 1970 I had a front wheel bearing seize on my '64 and the short out of control ride was unsettling to say the least. I think I'll keep maintaining my car the way Abingdon intended.
R. L Carleen

IMO if you leave out the shims and spacer, you run the risk of spinning the inner races of the bearings round the stub axle.
When assembled as the factory intended, the inner races, spacer and shims are made into a solid assembly by torqueing the nut.
In 99.999% of the cases you will probably never notice any problem with leaving the shims and spacer out, but a wheel bearing on a friends B failed once and here we found that the inner race of the inner bearing had almost welded itself to the axle by spinning round.
A simple bearing replacemnt job turned into a complete kingpin replacement. Thanks PO!
I say yes to shims and spacer.
Rufus
R Pool

Some cars were designed to run taper bearings without spacers and shims - MGs were designed to run with them.

If you reckon you know more about engineering design than the manufacturer then leave out the spacer and shims.

But what if you have an accident that kills others and the cause was found to be that "you failed to maintain the vehicle in a safe and roadworthy state" not only might your insurance be void but you would have to live with the consequences.
Chris at Octarine Services

I have had mine set up both ways but eventually decided that the little extra work required to fit the shims is worth the peace of mind.

The job is really not that hard if follow some excellent recommendations made in the archives.

I think that using the spacer and shims, stabilises the stub axle, ie the extra thickness achieved by have the nut 'tight' creates a more robust axle for the bearings to rotate from?

Ian Buckley

Ian--I think you've got the right idea. Extra stability and strength,
R. L Carleen

There are LOTS of proceedures you can do by an alternative method with fair to good results.

Rather than think the MG engineers were God-like in their reasoning ability, I prefer to assume they were working in an environment that rewarded the ability to adjust for wildly out of spec parts. This was England at the height of the Socialist movement after all and their version of a "slow down" was to mis-assemble stuff or bollux the tolerances, or such.

Not, perhaps, at Abingdon, but at their suppliers.

In any event, having a fully stressed assembly gives you at least two advantages that I can think of.

One, clearances can be larger between the stub and the inner race to help alleviate siezing from corrosion and the resultant nightmare of trying to get that bugger off.
Two, the end-play is held to a close tolerance and is entirely within the bearing. No hammering or chatering as the assembly slops back and forth. No "unscrewing" of axle nuts, etc...

p.s. I LIKE the method.

Mike!
Mike!

Hey all, I thought since someone out there was suggesting you can leave out the shims it might be a good thing to prove or disprove for the novice mechanics. (myself included) I have though been servicing all the vehicles in my personal collection and my construction company for around 35 years. I have never had a wheel bearing seize but I try to keep everything "maintained". This MG is the first vehicle I've worked on that uses shims and after reading the article saying you could leave them out I had to question the necessity of them.
After spending around 1500 hours working on a car that has only 69000 miles on it I am inclined to question the engineering just a bit. This car has been in the family from day one and I know its history. From 1977 to 1996 (96 to 04 stored) it was driven by my father in-law and was never driven hard. In that time we replaced the clutch 3 times, ring gear twice, flywheel once, starter 4 times, alternator three times, rebuilt all brake and clutch cylinders three times, replaced seat covers and top once, ignitor 2 times, replaced all engine gaskets once, rack assembly once, front suspension grommets twice, fuel pump 2 times, carb rebuilt 2 times. We are on the third set of tires and 3rd set of brake shoes and pads, still running original exhaust pipe and catalytic converter, replaced mufflers and tail pipes once. I think the rotors and drums are original. The clock is original but can't remember the last time it worked. The wheel bearings by the way were just replaced for the first time during this restoration. This restoration included major rust repair, engine tune up, alternator, all clutch and brake hydraulics, brake pads and shoes, hazard switch, turn signal switch repair, carpets, tail lights, carb rebuild, gas tank sealed, fuel pump, hoses, fan belt, elect fan repair, front springs, all suspension grommets, axle straps and mounting post and a host of other parts I can't recall.

The only reason I would question the engineering of the MGB is because I've driven some cars 69000 miles and only opened the hood (bonnet) to change oil and check the fluid levels.
After reviewing my history report it seems the wheel bearings have not been a weak point in engineering. I agree using the shims and spacer can only "add" to the strength of the assembly but it is nice to know that if one finds himself in a jam without the proper tools or shims, you might be better off to leave them out until a dial indicator and shims are available. I guess I'm off to find a dial indicator to add to my collection of tools I only use once a year.

Thank you,
Kevin
Kevin Pearce

Bummer on that record, man.

My '67 (umpteen thousand miles) has had one new clutch, three engines (the third was because I "overbuilt" the second for SCCA autocrossing rules), one set of wheel bearings all the way around (did stupid thing on rears and had to do it over) but they weren't bad, rebuilt calipers once (didn't really need it) and the clutch slave cylinder once (it did need it) three starters, one generator, went to alternator, went to Mallory unilite dizzy, one ring-gear, two sets of brake pads, one set of rotors, one set of shoes. Replaced driver's seat because high g-forces caused seat to tear out :O, went with 3/4" front sway-bar and tube-shocks all around.

You should know that I auto-x in DSP with wide-sticky rubber and put a Qauife in the rear.

Gave up on the soft-top ;)

Other than retiring it due to excessive rust (really hard to dial in the suspension when it flexes that much!) it has been dead reliable.

As I said above, there are lots of alternative methods that will "work" but then again...

Mike!
mike!

Kevin,

Not so much an issue with the engineering, but the fact that things deteriorate when the car is not used much - especially if the use is all local stop start driving with the engine never really getting up to temperature. Storage in a garage can also contribute to decline.

My car has done over 300,000 miles on two engine builds, 4 clutches, one set of brake lines, one set of king pins, 3 sets of dampers and 5 sets of tyres. It has had one rebuild with new sills and front wings. Pretty well everything else is original, including the wheel bearings.

But then it gets lubricated every 1000 miles.....
Chris at Octarine Services

I like that, what a service record, but then link that with the thread "what is originality" My cars are the same and much like the original hammer that's had two new heads and three new shafts !!
Iain MacKintosh

This thread was discussed between 28/08/2004 and 31/08/2004

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