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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Front Wheel Bearings....... a question?

First of all, I apologise profusely for raising this again.

I was wondering earlier today whether the MGA suffers from the same bearing issues as the Spridgets. Much of the engineering is very similar except that the MGA is heavier. So, I looked in the workshop manual.

First of all, the A has the same problem of the radius at the root of the stub axle. However, the engineers got around the problem by placing a spacer (with an appropriate chamfer) between the bearing and the stub root. What's more it is a thick spacer - sufficient for the lip seal to run on its outer rim. One of the difficulties with the early suggestions of a thin spacer on the Spridget was that it pulled the lip off the running face on the stub axle, rendering the seal ineffective. Not a problem on the A.

No call for face adjusted bearings - they used conventional deep-groove ball bearings so no need to worry about precise axial adjustment in order to prevent the introduction of end-float. I would have thought the reason to use angular contact bearings on the spridget was to provide a capability of withstanding axial loadings Clearly the A is a heavier car but the designers felt deep groove would be adequate.

The design of the A predates the Spridgets so the engineering is not a result of finding a solution to the complexity of the face adjusted, angular contact. Perhaps the opposite applies and the Spridget solution was regarded as an improvement, but I am not aware of regular wheel bearing failures on the A.

Just a thought!





Graeme Williams

The MGA may predate the Spridget, but Spridget bearings are the same as those used on Morris Minors (1948) and Austin a30 (1951). In fact, virtually the complete front suspension was borrowed from the A30.
Dave O'Neill 2

Graeme

Im sorry buddy, I dont understand the question.

Are you asking if face adjusted angular contact earings will work on a MGA?

Steven devine is going to be your bed buddy on this one... theres not much he dosnt know about the A

Prop
Prop and the Blackhole Midget

Also. for the Deluxe and Twin Cam, BMC/MG felt the need to use needle roller bearings.
Dave O'Neill 2

That should be tapered roller bearings.
Dave O'Neill 2

Exactly the opposite Prop. I am wondering why the MGA used a pair of bog-standard deep groove ball bearings, but the Sprite had to have such a comparatively complex solution which has, on its own, been the cause of several hundred posts on this BBS and a lot of heartache for owners. I am not proposing fitting deep groove bb's to a sprite, it was more one of engineering interests as to why sprite designers did what they did when the root of the design philosophy was the same.
Graeme Williams

Prop do you need pierced ears for face adjusted angular contact earings. lol
mark 1500 on the road Preston Lancs

Lol! Missed that one Mark!
Graeme Williams

Maybe Prop's tongue's pierced. Maybe that's why it isn't always clear what he says. ;).

Interesting Graeme. They do use a spacer, so I assume the nut is torqued up too. I would also assume the deep groove bearings they used(use) must be to quite a close tolerance, otherwise there would be wheel wobble.

How long before we reach 100, and mention the war and Hitler?

Oh well, only the 100 target to get to now. LOL.
Lawrence Slater

I can't see any reference to a torque setting.
I don't think there is enough free play in a dgbb to pose a problem, unlike angular contact which get very floppy if not tightened up.
It could be - and I don't know the information - that the ball bearings are much larger in the A and therefore capable of standing sufficient axial loadings where as with the small spridget hub, the equivalent small sized ball bearings would be inadequate.
Graeme Williams

Heck I I wrote it, and I didnt even catch it.... haha

My thumbs have gotten fat, I cant seem to hit the correct keys any more

So why the spridet went cheep and the A went advanced

I think (just guessing) the midget was.supposed to be a throw away entry level sports car...I think BL, always thought the car would.hit 70,000 miles and go to the crusher it was never meant to be what the car turned out to become

I think thats why the odometer only goes to 99,999 miles and no electrical relays, plus lever shocks
Prop and the Blackhole Midget

Good call Prop.

You nailed it exactly.

These cars were never meant to last as long as they have.
Greybeard

Prop: I think the A is the cheaper solution! Two stock ball races must be "10 a penny" compared with face adjusted angular contacts with an "extra" radius machined on.

Perhaps the wheels on the A fall off regularly due to premature bearing failure.
Graeme Williams

MGA bearings never seem to wear out, and if assembled correctly the stub axles are really strong too.

dominic clancy

IIRC Andy Phillips in Thailand mentioned his sprite had been fitted with deep groove ball bearings in the front hubs instead of angular contact bearings, standard deep groove bearing come in the same envelope size
David Billington

Hmmm....Ive packed a few bearings in my day....and on the MGAs and Midgets. Ive never seen an MGA bearing fail....and Ive put a lot of miles on em. Im not sure what the required time to repack bearings is but every few years when the mechanics check the front end for safety...I usually have to repack the front bearings to get the car to pass. It seems to take the slop out after a fresh greasing.


I cant say really anything about the midgets..I havent driven it on the road long enough to have an opinion. I did however have to change out the drivers side bearings as they were wiped out. I was lucky and found a car at the breakers and changed the whole disk brake and bearings at once.

I do have to admit being completely shocked at what it cost to rebuild a midget front end. $1000 dollors gone in a blink of an eye...and really no other solution thats cheaper. I still cant get over what that costs.

I was surprized to learn that ford had run angular bearings in the front ends since they built the model A in 1929.

You have to go back to the Model T days to see a set up like the MGs...

Ford I guess back in the day was ahead of the curve that way as the GM and all the rest were still using roller bearings up into the late 1950s.

It was just standard practice to have them that way. (Thats what the old timers always told me....and the ford guys always love to rub your face that Ford did it first!)
And then the whole we got a v8 and everything else isnt worthy. Bla Bla Bla

I think in the A30 days the engineers probably just used what they could get a hold of figuired out what they needed for tolerence and price...and you see what
they arrived at.

Mr Sloan....has a whole school built in to M.I.T. out here in Massachusetts...Ive heard his name but could never really get a good understanding of who he was until you see how he is attached to the old time car world. Bearings!

http://en.wikipedia.org/wiki/Hyatt_Roller_Bearing_Company

Just my 2cents! :-)


Steven Devine

Good memory David...

Yes my car had deep groove bearings fitted when i got it, as david says that are the same physical dimensions as the modern angular contact ones. and very cheap.

I did a quick fag packet calc at the time, based on the SKF data for the bearings, and they looked like they would be fine to use, plenty of safety margin based on a full weight car cornering at 1G...

Problem is you would still have the same issue with the stub axle radius...
Andy Phillips (frankenfrog)

Couldn't you go back to your original idea for a spacer between the bearing and the stepped end of the shaft?
It's all academic since we now have a reliable supply of the correct bearings and these are becoming available through the usual retailers as well as direct. As I said in my original post, I had checked on the MGA system out of interest and felt it worthwhile making the comment. I know how much this BBS enjoys a regular FWB thread!

I must check whether the MGA sucks up oil and what torque is used on the rear hub nuts.
Graeme Williams

I remember you mentioning you ran deep groove bearings too Andy. I thought it interesting when you mentioned it at the time as I had put some thought into the idea of deep grooves too.

I had found inner bearing with the correct radius for about 30 quid each.

The outer bearings where also about ~30 quid. But as they had no special radius requirements I looked at deep groove bearings of similar dimensions for a fiver.

A back of an envelope calc (I don't smoke) showed they would be OK for axial load (I think I considered 1G too). Also (please correct me if I am wrong) when you are cornering hard the biggest load would be on the outside wheel inward toward the centre of the car. Therefore the cornering load would be translated into axial load on the inner (larger) bearing.

The inner wheel would only be lightly loaded due to the weight transfer and there would be a relatively small force acting to pull the wheel off the axle, which would have to be resisted by the outer (hypothetically deep groove) bearing.

Malcolm
M Le Chevalier

"I must check whether the MGA sucks up oil and what torque is used on the rear hub nuts."

Yes, I strongly agree. You must, and then report the findings here. -- In-depth, and with no detail omitted ;).

Lawrence Slater

Malcolm
Great minds think alike....
Andy Phillips (frankenfrog)

do you still have the deep groove bearings on your car Andy?

dunno about great mind, maybe more 1000 monkeys on 1000 typewriters
M Le Chevalier

No, i made spacers and bought the SKF angular contact bearings.
3 years and going strong, though i do very little milage...
Andy Phillips (frankenfrog)

There's a new film being made. It's a massive production with an all star cast.

The working title is ----

"FWBs. The subject that wouldn't die".

But they are open to further suggestions.
Lawrence Slater

Whose in it!

I want to see this soon!

http://www.youtube.com/watch?v=n0dZ_2ICpJE

Before I get blacklisted!
Steven Devine

NOBODY has the right, to tell you that 40 degrees is superior to 20 degrees!
Lawrence Slater

Ha ha L!....but would they have too!
Steven Devine

How about, ---

--- " Tapers have an angle too. " ?

;)
Lawrence Slater

Time for the hitler skit in the FWB thread.

http://www.youtube.com/watch?v=VuVFFNvyUT8

Code word: Habeneer!
Steven Devine

This thread was discussed between 22/11/2015 and 29/11/2015

MG Midget and Sprite Technical index

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