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MG MGB Technical - Tube axle hub seals

I have had problems with leaking seals--pinion and hub--on the 1970 MGB. Wet brake shoes are a problem. I am currently carrying out the third hub seal replacement.

There is ongoing discussion regarding GL4 and GL5 80w-90 gear oils. If there is a brand or oil formulation currently available in the U.S. that is kind to seals, I would appreciate a recommendation.

I am tempted to add a seal expander/stop leak for good measure. If there is any experience with this, please comment as well.

The breather is clear, the diff has never been overfilled and the collars on the axle shafts do not show grooves or damage. The car is driven regularly, mostly on extended cross-country trips.
Glenn Mallory

Bearing wear? Hubs tight on the half-shafts? There is also the question of quality and fit, which is the biggest problem with replacement parts these days. have you tried different sources/products?

Opinions vary, but I have Castrol oils and the container with the picture of a gear lever on is GL4 (used in the V8 gearbox) and the one with the picture of an axle is GL5 for V8 and roadster, the V8 manual does show different grades for the two. However with the loading and use most MGBs get I doubt GL4 would cause a problem from a wear point of view. Replacement of either seems to be pretty unusual on the tube axle.
paulh4

Glenn,
I would very much doubt if any oil is causing your problem.

GL5 for the rear axle has been for sale from mg specialist supplies in the UK for very many years, possibly decades, I can't remember. Many may say it must only be GL4, they are wrong and totally out of date (same with the gearboxes but that's a different subject).

The better more modern 'synthetic' oils would probably contain better additives and better for seals but as the USA market has different oils to the UK (and much lower costs) you'd have to ask the manufacturers. The MGA and T-series blokes often mention the likes of Redline, they're not as stuck in the past and/or misinformed as many B owners are and they seem to actually use and drive their cars as designed unlike many B owners.

Might be a good idea to try an additive to your existing oil, if it's not old oil, check out ATP AT-205 Re-Seal (a polymer oil that mixes with oils) you add it and then need to drive the vehicle to get it to work. It might take a number of hours of driving to get it to work but possibly not many. You won't need much for the axle so could also use it on other leaking/weeping seals or perhaps as a preventative if you're not using good oils elsewhere.

It only rejuvenates the seals and will only work if that is your problem.
Nigel Atkins

I pulled the hubs off last night and found that they came off all too easily. One came off in my hand when I removed the castle nut and the other with a slight ding with the slide hammer. Torques to 150 lbs/ft? I can't imagine that when the axle was last reassembled that these nuts were tightened sufficiently.

The pinion seal is also leaking (it has been replaced) so I had suspected oil. The oil level had not gone down appreciably. A little 90w goes a long way, especially on brake shoes.
Glenn Mallory

Perhaps if you clean and put everything back correctly it'll all be sorted, new shoes obviously.

One drop of any oil where it shouldn't be looks like a puddle.

Willy and Paul will know correct fitting procedure.
Nigel Atkins

Hmm Unfortunately the rear axle seals aren't effected at all by the tightness of the centre axle nut-The seal is in a separate housing behind the brake backing plate and runs on the axle shaft-
It's not unusual for the hub to just pull off after the nut has been removed, but usually you do have to give them a gentle whack to release the outer tapered colet first to get them to move -
On the seal softeners, usually they only work on old seals that have gone hard--but--years ago working on Ford F series ambulances we used to have to run transmission additives in the autos to keep the fluid in them, but that was more of an anti frothing , blowing out the breather issue. But frothing isn't your problem---
Just make sure you get good quality seals, preferably the double lipped dust proof style-
I've heard but don't know really, that if you change from mineral oil to a synthetic that sometimes if the seals were the originals that the change of oil type can affect the seals --don't know, I've heard of it with brake fluids, but axle oils--??
GL5 is fine for the axle-
The difference between GL4 and GL5 is GL5 will take more punishment - both are ok for hypoid drives but GL5 has different additives and will take more shock before it'll get squeezed out between meeting parts and that's the basic reason GL5 isn't deemed suitable for gearboxes with synchro rings, it retains it's lubricating film too well to allow the syncro to do it's friction thing where the GL4 will allow more friction there
With the oils, i'm a bit of a Castrol nerd when it comes to diff oil and poke Castrol SAFXA 80/140 in everything ,it's got all the goodies in it for lsd's of all types and was originally built for hob cut high performance gearsets that are noisy with normal gear oils-It's a magic high performance oil that does the job well
William Revit

Found this, there's an interesting note about seals down the bottom in product info---
Also called Syntrax 80W-140 now apparently but i'm sticking to SAF XA -don't know why they're changing the name


https://www.supercheapauto.com.au/p/castrol-saf-xa-limited-slip-rear-axle-oil---80w-140-1-litre/66663.html
William Revit

My hubs needed a bit of a whack as well, it's wedged between two tapers.

A hub nut can come loose if the bearing isn't pressed onto the half-shaft enough leaving a gap between it and the oil seal collar stroke collar and half-shaft as in the attached, such that the bearing subsequently moves. I've also heard of a case where even with the hub nut fully tightened the hub was still a bit loose, they never came back with the resolution. 150 ft lb then to the next split-pin hole. Can't remember how many there are on a half-shaft, most front hub stub axles seem to have two although new units only have one according to some purchasers.



paulh4

Willy
some modern GL5 can be used with syncho rings according to the blenders, of course time may tell differently and my gearbox falls apart but it'd be decades for the average MGB use (not Glenn's). I remember being told 20+ years back that Mobil 1 would ruin my classic's engines - particularly by those who hardly drove their classics. 🤣

Would it be more likely now clearing out the crud and muck rather than type or marketing description of oil as the seals thing tends to go back many decades, unless decades old oils are being used.

I don't know about USA oil seal parts quality, oil and seal additive I strongly doubt will actually do anything to sort the problem - better oil in Glenn's type of use will help and perhaps the added polymer as belt, braces, chewing-gum and bit of string reassurance but not worth the effort unless using it elsewhere and the bottle still has some left.
Nigel Atkins

Nigel
I reckon the 80-140 would help Glenn maybe as it doesn't thin out so much when it's all hot and toasty

With the GL5 in your own gearbox, if the synchros are working ok then I can't see a problem with using it, and it works great in the old Mustang toploader boxes as well--they had an issue with baulking causing it impossible to change gears fast at higher revs but with GL5 they change fine----------

Paul-The axle shaft usually has a single split pin hole and the wire wheel type splined hub has two holes at roughly 90deg. which are roughly half an axle spline out from each other so that you can rotate/fit the hub on a spline to line a hole up with the pin hole.
William Revit

Willy,
I'm with you but it always depends who's and what GL5 oil. I barely now do possibly double (or more?) average(?) than the MGB mileage in the UK so my type 9 could fall apart at any moment as I have no proof of longevity, I've only done about 16k-miles in 5 years because of piss-poor parts and piss poor people in the UK motor trade, for the rest of the car, let alone a couple of years of Covid.

But don't let me pull anyone down as the garden of classic cars in the UK smells of sweet, sweet roses especially if you're selling or your mind is in a distant decade that never really existed.
Nigel Atkins

Your type 9 will be fine-and easily repaired if not-
Something that might interest you, I put an ultra close (circa 2.1:1) first gear close ratio gearset in a friends rally replica RS1800 Escort, magic ratios but mate, the noise was unbearable being a road car, 4th was silent being direct drive and 5th screamed at cruising speed so he ended up driving around in 4th most of the time and wanted to go back to normal gears--Then noticed R/F were doing a semi helical c/r set with almost the same ratios--got a set of them and a noticeable improvement, specially in 5th as the gears for 5th in this set are at more of an angle than the others in this set--but still annoyingly whirring in 5th on the highway
Pulled the oil out and refilled with the SAF-XA 80/140
Noticeably quieter out the road and now user friendly, a little bit stiff in the gearchange when it's dead cold but a couple of laps round the block and he's good
Like you, it's fingers crossed but all seems fine just now-
Cheers
willy
William Revit

Willy - I was talking about split-pin holes in the shaft - just checked my old one and it does have two. So presumably one should line up the WW hub on the splines so that either can be used to insert the split-pin as you won't know which one you are going to need until the nut has been tightened.
paulh4

Cheers Paul--I think we're both saying the same thing ,but differently--all good
willy
William Revit

Willy,
by coincidence a mate has just used some Millers CRX LS 75w-90 NT I gave him a few years back as it was sent to me by mistake. He said the outside of the tin rusted and so 5 litres became a lot less. It went in a Sierra(?) LS diff, just changed the CVs off it. - https://www.millersoils.co.uk/products/crx-ls-75w90-nt-2/

Anything old Ford and especially motorsport is stupid pricing and value over here, lots of Ford fanatics. Unless you have good contacts any work on a Type 9 would not be cheap (apart from perhaps quality of new parts?).

I'm not at all worried about the GL5 oil in my gearbox, I let others do that same as when I put the Mobil 1 in the engines that done fleet mileage compared to the average UK classic. I know at least one engine continued to run fine after I moved the car on as years later I was asked if I wanted to buy the car back. Shortly after the chap first bought the car from me he asked about any brake issues and I told him the brakes were fine, he was a motorcyclist and bought the car to give his girlfriend more than the bike's back box for shopping and to help him avoid more speeding tickets as IIRC he had 11 points on his licence and 12 and you loose it for a while.

The car was a B roadster with a Rover V8 and when I first got the car it still had the 3.9 diff which would turn the speedo but no good for my use so I had it swapped for the 3.07.


Nigel Atkins

Done a few v8 conversions over the years, joined forces with a mate and did 2 last year for him, Easy job nowadays with everything available, there's even a 3.07 cw/p set now with the correct offset to suit the MGB 3.9 cw. carrier- more or less a bolt in job- did my first v8 back in 1976 (last century)with a 4.4 Leyland engine and c/r gearbox-- tried every ratio from 3.9- 2.7 in them and for me i reckon 3.2 is the magic ratio for getting the best out of them
Keep em spinning
willy
William Revit

In the UK petrol wasn't cheap even 25+ years ago and touring foreign lands like Scotland and Wales the petrol and petrol stations were less available, good ale even less so in Scotland, so you had to travel to find it so mpg was a consideration.

Mine was r/b so more about comfort than speed though it did have an (oversized) Holly and Offy so it liked a drink even more than the owner.


>> Thread drift awaiting Glenn's return. <<


Nigel Atkins

This thread was discussed between 09/07/2022 and 12/07/2022

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