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MG Midget and Sprite Technical - Rear bearing question

Hi All, I'm working on the rear axle of my Frogeye and upon taking off the RHS rear drum I'm greeted with the usual leakage of axle fluid despite my last attempts (many years ago I should add) of using a RTV type sealant as well as the O ring and the paper gasket.
I pulled the hub carrier and bearing apart and found the bearing was not as tight a fit as it should be in the carrier and the carrier could be moved in and out on the axle. I also had a slither of metal come out from the bearing indicating the hub had been rotating without the bearing I think.
I didn't feel the half shaft was mating with the hub carrier fully when installed, I measured the depth of the carrier's bearing housing and the bearing and was surprised the bearing was marginally wider than the housing so no surprise the half shaft wouldn't get that good seal with the gasket & O ring.
I spent some time Googling this yesterday and learned it is normal the bearing sits proud by a fraction and is potentially due to the differences with modern metric sized bearing as opposed to what would have been installed originally? Is this correct?

I know in the past when installing new O rings and gaskets I've tightened up the half shaft with the road wheel nuts and then inserted the countersunk screw that holds the shaft in place but I've had this leak several times now, given the low mileage I do I'm looking for any better suggestions? Thicker gasket? machine the carrier that extra fraction?
New bearings and seals etc all on order but I can't help feeling I'm just postponing this by a short period before my brakes get oiled up again.

By the way, I'm sure I'm not helping the situation with having a modified engine with higher output and steel half shafts, should I consider going back to original halfshafts?
Any guidance welcomed!

Mark
Mark M

I think you'll find that the bearings have always been metric.

The bearing will sit slightly proud, not much, as the bearing has to be clamped between the halfshaft and the hub. Fitting a thicker gasket could leave the bearing unclamped.

If the bearing is loose in the hub, you should probably be looking at replacing the hub.

Also, with a properly specced gasket and o-ring, you shouldn't need any sealant.

I have some used ones available, if you need one.

daveo138 yahoo co uk
Dave O'Neill 2

Thanks Dave, Used hubs you mean? It looks like I probably do need to consider these, what would you want for these?
Mark M

You seem to be doing everything right. It follows exactly what I do and mine never leaks.
Are you using the Peter May halfshafts? Mine were a binding fit into the diff and had to be literally drifted home to seat properly. So you might want to check that without the gasket and O ring its able to go fully home. Also check the diff vent tube is clear as any pressurisation will force a leak. Don't use bearing Loctite to fix the rotation as it may never come out again,suggest you try Wellseal instead.
f pollock

Yes, the Peter May halfshafts, good point on checking they go fully home, I will do that.
Breather is on the list to clean/replace.
I have just ordered some bearing loctite! I' will look up Wellseal, thanks for the tip.
Mark M

Mark

Yes, I meant hubs. I added a line of text there, which kind of upset the context.

A tenner each, plus post.
Dave O'Neill 2

Mark, I've recently rebuilt my frogeye axle with later half shafts. I did a lot of archive reading about sealing and several people said to cut the inner diameter of the paper gaskets so they didn't overlap the rubber rings so this I did. The rings do the sealing but must be compressed which is why you bolt the half shaft against the hub initially then tighten the half shaft to hub screw. - I think some leave out the paper gaskets. The slight protrusion of the bearings is normal as Dave says and the half driven flange curves out to accomodate this (I think that's why anyway). One of my half shafts was tight on the studs and had to be bolted up snug to the hub. Not on the road yet btw.
Bill Bretherton

Mark, I've recently rebuilt my frogeye axle with later half shafts. I did a lot of archive reading about sealing and several people said to cut the inner diameter of the paper gaskets so they didn't overlap the rubber rings so this I did. The rings do the sealing but must be compressed which is why you bolt the half shaft against the hub initially then tighten the half shaft to hub screw. - I think some leave out the paper gaskets. The slight protrusion of the bearings is normal as Dave says and the half driven flange curves out to accomodate this (I think that's why anyway). One of my half shafts was tight on the studs and had to be bolted up snug to the hub.
Bill Bretherton

The bearings should sit about 8 thou proud of the hub. The gasket will crush approximately 50% when the wheel nuts are torqued up. So if the gasket is the correct 0.4mm/16 thou thickness, it will compress to 8 thou and there will be zero gap between the bearing/hub/shaft. I did all the measurements on this four or five years ago.

Cheapo bearing kits were supplying too thick gaskets for ages. Which I reckon is what leads to knackered hubs and snapped half shafts (If the hub is moving about a little, the other end will be in the diff too!).

I used to do a rear bearing/seal kit, with "proper" parts and a range of gasket thickness to allow the user to ensure a correct fit. I still do if people are nice to me :-)

The new issue now is suppliers selling C3 clearance (i.e. sloppy fit) bearings when they should be standard fit I believe.

Happy hunting.
Malc.
Malcolm Le Chevalier

Another thing to add... make sure your hub studs are nice and straight, otherwise it makes the shafts a pain to get in and out :-) It's a good time to upgrade to longer studs whilst everything is apart.
Malcolm Le Chevalier

I'd not recommend omitting the paper gasket, or trimming it. It's supposed to overlap the O-ring. Malcolm Chev did a lot of research on this issue and discovered that thickness of the gasket is critical, check archives. A lot of new gaskets are the wrong thickness which doesn't help. Also I think modern O-rings may be metric equivalents which also won't help. Malc was selling some carefully specced and sourced ones a while ago, may have some still left?
David Smith

Thanks for the recommendation David :-)
Malcolm Le Chevalier

Malcolm, oh dear, looks like I was persuaded to go the wrong way by the archives! It could be that people were trimming gaskets as they were too thick? I still don't see why the O ring alone cannot seal though. Not on the road yet so I need to make a decision!
Bill Bretherton

Bill

I do suggest revisiting the hub seal. If assembled carefully with the correct thickness gasket and 'o' ring, then all should be well. As Malcolm pointed out some of the rear bearings are C3 standard which leads to a sloppy fit and potential 1/2 shaft failure. The bearings of the correct standard are easily available.

They are not as problematic at the FWB's!!
Bob Beaumont

I use Malcolm's rear seal kit. Mine don't leak, even under such provocation as in this image. Believe everything he says about rear bearings.

Rob Armstrong

The only way to do it is put it together without the gasket and 'O' ring and with the nuts done up finger tight ,then measure the gap between the two flanges with feeler gauges and select a gasket only few though thicker to allow for compression which will then result in the bearing being held firmly without any stress on the flanges when it's finally assembled complete with the o ring and selected gasket size
William Revit

Thanks for all the comments, comforting to know I'm not going crazy trying to understand this better.

Dave O'Neill, yes I'd like to buy 2 please, can you email me? marktmaguire at gmail dot com

Malcolm, How do I know if the parts I've ordered are good or cheap? I'd happily buy a good set from you if you are willing and able to supply them.

Thanks

Mark
Mark M

This has opened an old can of worms! Bob, I will revisit mine with regard to the above posts. You think you've done the right thing then it rears its ugly head again!
Bill Bretherton

Your right Bill, with old cars even the simplest procedure can be fraught with issues. I have to say quite a lot is down to poor quality/incorrect sizing of replacement parts.
Bob Beaumont

Thanks Rob. Damn, that picture has me yearning to get out in my car! I am so bogged down in my "project" right now :-(

Mark, drop me a message to chevalierclassics@gmail.com I will have a look what stock I have tonight.

Cheers,
Malcolm
Malcolm Le Chevalier

This thread was discussed between 14/04/2020 and 15/04/2020

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