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MG Midget and Sprite Technical - Moving on!

After nearly a year searching for my front wheel bearings success came my way and I found the proper bearings. The front suspension is completed with new bushings, bearings, springs, rebuilt shocks from Peter C, brake lines, hoses, tie rod ends, and many other things. Not to mention the new paint in the engine bay and other places.

I now have the rear of the car disassembled and the new spring bushing kit on the kitchen table. Many other parts on the way including a new SU solid state fuel pump. I have a new Facet pump that has been on my shelf for a few years which will become a permanent installed backup pump. Tuesday I will stop in at Peter C's and pick up rebuilt shocks and new links. New brake lines are included in the project. The PO had replaced the wheel cylinders and shoes so I will have not replace them. But I will replace the hub seals and inspect the bearings. I have decided to leave the pinion alone since there is no sign of leaking and that would not be a big deal to do later if needed. The fuel tank will also be removed so I can inspect it and repair or replace if needed.

It is a great feeling to be past the front end and that bearing mess.
tomshobby

Great news, Tom, and thanks for the update. And of course, thanks as well for all the digging you did for bearing info. 'Tis much appreciated,

-:G:-
Gryf Ketcherside

Would you share your source of front bearings? Thanks for all of your time devoted to this and sharing it with others.
J Bubela

Is it going to be a subject in the tech wiki orso?
'Cause searching the archives can take a while
Alex G Matla

Alex the Wiki has a section (two actually) to enable all available info on wheel bearings to be placed in it

It is waiting for Tom to post when he feels up to it

he must be worn out after his marathon search :)

It was a major task to complete it, I know I am going to be sorting out my "new bearing slop" problems this year

http://taratec.org/mediawiki/index.php?title=Main_Page
bill sdgpm

I actually did not know we had a Wiki site. Someone mentioned that one was being set up but that was all I knew.

I am more than happy to contribute what I found. I have posted the findings on this page; http://smithtr6.com/bearings.htm It is not complete because at the end I have not included the finding of the bearings and related information.

Bill, what would you suggest for a location and title for this?

The last week or so I have spent time just enjoying working on my car. I am trying to get some things done before my wife goes in for a knee replacement on the 6th. Also, my health is not the best. When I retired I applied for SS disability and they sent me a letter saying I "easily qualified". Now, actually last week, I was diagnosed with Parkinson's. And while I was being checked out for that the doctor decided I needed an MRI and a few other tests to see if they can find why I have so much trouble walking.

All I am saying is that the next few weeks will be a little hectic. So, let me know how to list it and I will work on it. Probably be a few weeks before I can put a lot of effort into it though.
tomshobby

Tom

bad news medically but, on the brighter side I had a new knee a few years ago and it has changed my life from permapain to occasional aches and slightly slower "off the mark" responses

I can even jog (slowly) so your wife should not worry about the new parts going in

I hope your quack can get you back on the ball too

The Wiki has sections for Axle and Suspension

I went to Suspension

I opened a page in it to take your and anyone else's notes for wheel bearings , both ball bearing and taper roillers, whatever

Just open the website, then register and then you will be eligible to add or amend the info in its pages

Good luck I'll be "fingers crossed" for you both for the next few weeks
bill sdgpm

Hi Tom

I am now back in the UK and have contacted my friend (Director of NSK who took over RHP the original manufacturers and the guy who supplied me with our original drawings). He has put me in touch with a company that they deal with who can manufacture obsolete bearings to original drawings (not a problem) or can modify new bearings.

Of course the issue is cost and I suspect manufacturing a 20 degree face adjusted angular contact bearing with large radius on the inner race would be cheaper than to purchase an expensive 40 degree face adjusted bearing and modify it by machining a larger radius as described. However it will be interesting to find out.

If that is possible I suspect that having a major MG supplier stock these would be the only way to progress. At least it would cure both the wheel bearing play problem plus the strength issue that the radius problem could cause.

Let you know how it goes obviously NOS will not last too long. :)
Robert (Bob) Midget Turbo

I didn't know there was a Wiki! I remember there being some discussion but didn't realise that anything had been set up. How long has that been around?

I have just followed Bill's link for a quick look and will follow it up again later. I see it is partly written in the first person, but I don't immediately see who that is.

Guy
Guy Weller

I gather from Tom's writings on the front wheel bearings, that it is not possible to retrospectively re-grind a radius on the inner bearing. Apparently the grinding causes the bearings to chatter and this damages the running surfaces of the races.

I think I appreciate what is being said, but I find it surprising that the bearings cannot be prevented from hammering the surfaces by either embedding in a heavy grease or being held by a strong magnetic field sufficient to counteract this problem during the machining process.

Too simple?

Guy
Guy Weller

One of the things I looked into was re-machining the radius. BTW, the radius is machined not ground.

The following paragraph is from my web page;
Machining the bearing radius. I have had several say why not just grind or machine the radius on the new bearing. I did ask the Timken engineer if that could be done. He flatly recommended against it. He said that it would likely create stress fractures in the bearing race. By that time I had chased this dog around the bush so many times that I was getting a little cynical and although I respected him I did not believe it could be true.

Then I had the opportunity to ask specific questions of Jeff Weiss of LMS Bearings, Inc. LMS makes custom bearings. Jeff was very patient and explained that bearing races can only be machined before the bearings are assembled. In fact that is how and when the radii on bearings are applied. Finally the question became clear and the answer was soon to follow. The machining does not damage the radius area of the race. The machining causes the balls or rollers to bounce around and produce a brinelling effect on the inside of the race. Even though the marks may be invisible to the naked eye these small dimples or creators caused by this brinelling effect on the race surface from the movement of the balls or rollers during machining can dramatically decrease bearing life.
You can Google "brinelling effect" to better understand.

But that does not mean it cannot be done. The thing is that the bearing needs to be either disassembled or made so the balls/rollers cannot rattle around.

In my search I did find a company that would re-machine them for about $5. That would need to be in lots of 40 or 50 and they would be done as is.

I have worked out a method for doing it that would work for ball bearings. But I would not touch taper bearings.

I can write more about it but Shirley just got home and wants to go for a ride in the TR6. First things first!
tomshobby

Yes I preciate that Tom but this company works closely with NSK and will only do what is correct and acceptable to NSK. In fact NSK supply them with all of the original RHP (Ransome, Hoffman and Pollard) engineering drawing to ensure their modified or manufactured bearings are perfect.

As you are aware I am personally more concerned with the face adjustment which is the bane of us poor Brits but if the radius can be resolved just as easily then that is great. :)
Robert (Bob) Midget Turbo

Tom,
Yes those are the paragraphs I was referring to. I am not an engineer - hence not distinguishing the difference between grinding and machining.

Your references describes the "brinelling effect" causing micro-dimples from the balls bouncing around. My simplistic comment was to control the bouncing effect by use of a heavy grease or by "fixing" them with a magnetic field.
Guy Weller

Guy, the grease might work but anything that might cause residual magnetism in the bearings might not be so good.

Bob, I agree about face adjusted bearings being important. I think where we differ is that I would use a shim between the inner bearing and the stub axle face if the radius caused a space there. When I was searching I was looking for both conditions. In fact before ordering my bearings I requested clarification on both conditions. Then when I received the bearings I did my own check to verify the face condition.

It is no wonder that most companies quit responding.

Bob, your opinion please. And from others as well.
Is it time to approach suppliers like Moss for example and see if we can find at least one that would be interested in stocking what we need?
tomshobby

Tom, about residual magnetism, what happens with that when you heat the bearings with an induction heater? That's a magnetic field to considerate! I've never heard of trouble after fitting bearings wich where fitted this way.

Maybe more something for MGOC spares?
Alex G Matla

Heat them beyond the Curie point, and there's no residual magnetism.

A
Anthony Cutler

Hi Alex, I have used a heater also and not noticed any magnetic condition in the bearings or any movement in the bearing while it is being heated. Maybe someone might know why. My comment was more to be sure the bearing would not become magnetic, even a small amount, and attract metal pieces to it. I was not saying it would happen, just that it might.
tomshobby

Anthony,

You're having a laugh aren't you?. The bearings wouldn't be much use after heating to the Curie point!, well not their intended use anyway. Probably in excess of 800C.
David Billington

As I think I mentioned in the previous thread it is possible to machine the radius but not recommmended. There is a high chance of small stress fractures which will only show up on x rays but will result in premature failure. We used to hard turn some special non corrosive bearings with very hard carbide tips but it is slow and puts immense pressure on the race and therefore there is a very high scrap rate (this was in an unassembled state).

Guy - you could grind them but again not recommended as the grease would attract the grit so they would need very thorough washing out to ensure no grit remained. Normal grinding causes some magnetism and bearings are demagnetised before assembly.

As Tom says the radius is formed at the turning stage while still soft and after hardening is not ground like the faces and diameters are.

In terms of damage to the track (the bit the balls run in), this is very small but again will result in failure. The tracks are ground and then honed to a mirror like finish which is measured in microns. Finished bearings are noise tested and testing a new one against one only slightly dulled will show how much difference this will make (not audible to the ear but very noticeable on the testing machine)so you can see the difference dimples would make.

The small company Bob refers to is I suspect one of those that I referred to before probably started by ex RHP employees and probably using some NSK components such as balls.

Trev
T Mason

Just for info, i'm sure bearing heaters are a.c. therfore the magnetic field is constantly changing, this therefore does not leave a permanent magnetic field in the bearing part. Using a.c. coils is in fact how 'magnetic' components can be de-magnetized.

Also at work in my 'previous life' induction bearing heaters were used successfully following the common sense logic of only heating the bearing to the expansion you require to enable them to fit, they also have some advantages as the heating is uniform. That said for a midget I'm sure gas mark 7 for 20 minutes in the oven would suffice.
Regards
s.lowiss
s lowiss

This thread was discussed between 24/04/2010 and 01/05/2010

MG Midget and Sprite Technical index

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