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MG MGB Technical - Front wheel bearings

You will think me a right ding dong. After all the front suspension rebuild I did not pay close attention to the re assembly of the hubs. And these stub axles are rebuilt units. So as I had mentioned before, there must be some individual variation. Anyway, I put the hubs on with the old shims but, you guessed it, did do any measuring. So a quick drive round the block I thought. I bearly got 100 yards up the road when I could hear an awful grinding sound from the front, in the vecinity of the wheels. Limp very gently back. Jack up the vehicle. Wow, now I have collosal play at both front wheels. I take the hubs appart and find the inside top edge of the discs scored quite badly. The bearings, after thorough cleaning APEAR to be ok no pits, no cracks, or flats. I guess I had too much endfloat, when I loaded the hubs with all the old shims. Now here is the question; the book, says measure end float, from where? I have a dial gauge. should I get new bearings or risk these. I will have to get the discs skimmed any other tips? Mike
J.M. Doust

You measure the endfloat from any fixed point on the front suspension, such as he lower spring pan, using a magnetic base. I still have the original Timken bearings, in my '67. I've cleaned and repacked them 3 times in 39 years of ownership. If yours appear to be in good shape and show no wear or pitting, you should be able to re-use them. You should measure the endfloat with the bearings freshly cleaned, so as not to throw off the clearance values with grease. RAY
rjm RAY

Right Ray, thanks very much. I guessed you or Paul would come through with an answer. I shall make sure everything is spotless, and do som proper measuring. These Timken indeed must be original, 38 years old they really look good. Pity I was a dumb ar*e, I have to sort the discs. Mike
J.M. Doust

Back up here!

The stub axles have nothing to do with the adjustment, The whole adjusting process us to do with the relationship of the bearings to the hubs, so if you have not changed any of those parts (hub, bearings, spacer, shims), nothing should be different.

What you are describing is extreme looseness, which can only have two causes:
1) you left the nuts very loose.
2) parts are missing. The only part likely to cause this AND be missing is the inner bearing spacer at the base of the spindle, on which the oil seal runs. It is easy to think that this is a part of the stub axle, and either leave them on the exchanged units, or drop them in the cleaning tank.

If the discs are scored only on the outer 1/4" or so, you are better off smoothing the edge up with a file or hand grinder. The discs are thin enough to make skimming not good, especially if you plan hard usage; and cheap enough that replacing them is not a lot more than paying to skim.

FRM
FR Millmore

Damn and double blast, That I never knew there was! An inner spacer. So you say this is between the Oil or grease seal and the base or back of the spindle? I certainly don't think I have this Thanks FRM, I'll have to look at the old spindles, still have them. Mike
J.M. Doust

WSM: "collar, oil seal"
Also what the inner bearing leans on.
The ID has a large chamfer to clear the stub axle root radius, be certain you fit it right way round!

FRM
FR Millmore

And, Mike, If it's any consolation, I did exactly the same thing a few years ago-so you are not alone!! I expect others have done it too! I left it on the old unit but luckily had not returned it for exchange.
Michael Beswick

Even with new bearings I've found in the past the shim set was the same.

Personally I find setting end-float by feel easier than with a dial gauge - especially not having a dial gauge. Assemble the hub before greasing the bearings, then juggle shims - which go between the spacer tube and the outer bearing - until you have two sets 1 thou apart, where one gives no perceptible play and the other (larger) gives just perceptible play. Use the larger set, and add a .002 shim.
PaulH Solihull

Then of course you find that the castle nut does not line up with the hole in the stub axle when you torque it up. Then you have to shim between the bearing and the outer washer.
Steve Church

Thanks All. I feel somewhat better knowing that I was not the only one to commit this boo-boo. Yes, the collars were still on the old shafts which I had no cleaned, yet to return. Thanks Paul, for the try-it-by feel method, that's the way I had done it before on other cars. I am all set up for another go this week-end! Mike
J.M. Doust

"Then of course you find that the castle nut does not line up with the hole in the stub axle when you torque it up"

The torque spec for the front hub nut is 40 ft lb minimum, then tighten to the next split-pin hole (there are two), which should happen before 70 ft lb. This *shouldn't* affect the end-float on the bearings, but if it does then you will just have to rejuggle and add a thou as you have probably squeezed some grease out of faces elsewhere. It is a bad idea to put shims between washer and bearing. When tightening the nut you can shave slivers off the edges of the hole in the shim, not what you want inside your hub.
PaulH Solihull

Good point Paul. However it is awefully tempting to do when you have been fiddling with shims for a wire wheel hub. So much easier with a steel wheel hub.
Steve Church

"The torque spec for the front hub nut is 40 ft lb minimum, then tighten to the next split-pin hole (there are two), which should happen before 70 ft lb. This *shouldn't* affect the end-float on the bearings, but if it does..."

It does. When I adjust these, I torque the nut to low spec, then until the pin lines up. Do my shimming, always with the pin aligned and the nut torque in range, and when it is correct, I mark the nut as to exactly what position it is in and which split pin hole is used. Once you grease the bearings and fit the seal, you cannot feel the end float, so the marks are critical; final assembly is by the marks.

FRM
FR Millmore

Thanks folks I have the sequence now. Let's give it a go! Mike
J.M. Doust

It certainly helps to do the full torque and split-pin thing while determining the shims required, but speaking personally I've always been able to still feel end-float after the bearings have been greased.
PaulH Solihull

Paul-
The generally accepted convention is that .002-.005 is the minimum end float a person can feel, with more experienced mechanics tending toward the lower end; I have done a lot of measuring of this, both with my feel and others, and it is consistent. I can personally feel .002 reliably, and .001 clearly on on dry or slightly "iffy" on light oil lubricated parts. On bearings so set, I cannot feel .002 after greasing; if you can, then either you are superman (and thereby cause the grease films to migrate off of the bearing surfaces), or you have more endfloat than you think.

I once spent a day doing nothing but playing with these measurements for the express purpose of seeing what the limits were. Used a bridge on the hub with an .0001 indicator on the spindle end, and pristine spacers and shims. My "check at torque" recommendation is based on these measurements. A hub set at .002/40lbft will have zero endfloat before you get to 70lbft. Damaged or dinged shims and spacers could well result in substantial preload as torque is increased within the range.

FRM
FR Millmore

Well there we are, superhuman then :o)
PaulH Solihull

Very interesting FRM. And I am in agreement. In all walks of life, as humans we can become quite specialised, and learn to 'develop' a sense. So in your case the sense of touch can become very acute. Look at the person with impared vision. I marvel at the ability to read Braille, I have tried it. I could not feel the gaps between the dots. etc In Dentistry, we develop a 'feel' eg in Root canal Therapy. (Sorry, this may be scary stuff to some.) In these procedures we use very small files and reamers down to 0.010 of a mm!I try to teach my students how to feel for an apical foramen (forget the jargon.)Or another example, stripping a firearm without looking at it, (a 1911 Colt inside a bag!) Bottom line, you and Paul can tell by feel alone if a tolerance is off, marvellous. Mike
J.M. Doust

The same applies to the use of lifting pins on SU carbs. The difference of just right to fractionally weak and fractionally rich has to be learnt on HSs, but on HIFs it's practically subliminal.
PaulH Solihull

Thanks Paul, Now then folks, I have the front bearings all in and correct. Boy what a feeling. The wheels revolve lovely, not like a can half full of coffee beans, as it did before.! and with the handbreak off, an on level I can push the car in and out of the garage, I could not do that before. Now, I wonder how the engine works? Mike
J.M. Doust

One thing at a time. RAY
rjm RAY

Just a quick up-date in case anyone is interested; Car now back on the road. Took it down to have the alignment re-set, all went well and it drives beautifully. The young lads at the tyre shop had not seen an MG before! (Oh whow, that a generation of young people don't know these cars!) But it was interserting to watch them use this electronic gear and a computer to help align. Then, they test drove, came back and continued, saying wasn't quite right? It might have been bull, but they appeared to be genuinely interested. The commented it was more interesting than the mundane cars they have to work on. From there I took it to the exhaust place, to have the plug put into the exhaust down pipe for the Air/fuel oxygen sensor that I am about to fit (old thread.)That is the next project. Thanks folks. Mike
J.M. Doust

Mike, it seems that most interested observers of my MG are children under the age of 14. They've never seen another car quite like it and since everyone has a cellphone, with a built in camera, they all want to take a picture of the little yellow car that's older than their parents. RAY
rjm RAY

Do you know, that is pleasing. Actually, while on my jaunts I stopped off at the fuel station. Did not put fuel in the car, as I want the tank to be as low as possible for the fuel sender change,put some in the jerry can for later.But again a young 20 year old, says,' Oh that must be fun.' He was in a 'Hot utility truck! I was about to say, yours must be fun also,,, in the wet! But I did not. Somewhat similar to Christianity, we need to bring the Good News to the young generation. We can do both! Mike
J.M. Doust

This thread was discussed between 23/10/2011 and 04/11/2011

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