rear brakes / hubs

[dellerie]

evening gents, i have a leaking rear hub/seal. it the o/s (i guess that doesn't matter).

i have changed the halfshaft seal (paper) around 4 times and it still continues to leak at the bottom where the drum fits against the backplate.... the lowest point. the only thing i haven't changed is the oil seal. is it likely to be this? at the same time i will change the bearings as well. i also don't have that rubber ring on the hub.

could someone explain as to how the oil seal would fail and how it stops the axle oil reaching the brakes. it's puzzled me the more i look at it.

thanks.

[chickenjohn]

You can get the rubber O ring, paper gasket and bearing oil seal as a kit from the usual suppliers.

There is another oil seal that you cant see, in the hub behind the bearing. You'll have to undo the big nut and use a hub puller to pull the hub off then drive the bearing out and remove the seal.

[chrisryder]

indeed, the way it works is the seal behind the bearing is a force fit into the hub. so the seal spins with the hub/wheel. the seal seals onto the same stub that the bearing sits on, which is all retained by the hub nut.

as CJ says, you have to remove the bearing to fit a new seal behind it. it's just as much work to replace the old bearing as it is to fit a new one, so it's a good idea to replace while it's off to save doing it all again!

corrosioon the stub can mean that the seal doesn't seal properly on there, it's a good idea to check it out while the hubs are off. if it's very corroded you can get 'seal track repair kits' that come with a sleeve for the seal to run on instead.

do remember to replace any brake parts contaminated with axle oil. new shoes ideally, and dry out the drum with heat if you can.

[dellerie]

indeed, the way it works is the seal behind the bearing is a force fit into the hub. so the seal spins with the hub/wheel. the seal seals onto the same stub that the bearing sits on, which is all retained by the hub nut.

as CJ says, you have to remove the bearing to fit a new seal behind it. it's just as much work to replace the old bearing as it is to fit a new one, so it's a good idea to replace while it's off to save doing it all again!

corrosioon the stub can mean that the seal doesn't seal properly on there, it's a good idea to check it out while the hubs are off. if it's very corroded you can get 'seal track repair kits' that come with a sleeve for the seal to run on instead.

do remember to replace any brake parts contaminated with axle oil. new shoes ideally, and dry out the drum with heat if you can.

i presume the oil seal is similar in design to the front one? i guess it goes a particular way as well. would that be the spring side 1st?

[bmcecosse]

Check the breather on the top of the final drive casing isn't blocked - and the axle not overfilled.

[chrisryder]

i cant recall which way around it fits, just fit it the way the old one comes out!

[bmcecosse]

There was a thread with very 'divided' opinions on the subject recently!

[IslipMinor]

i guess it goes a particular way as well. would that be the spring side 1st?

The 'spring side' of the bearing oil seal faces the bearing itself, i.e the source of the oil that you are trying to prevent from escaping!

The 'O' in the hub to half shaft joint is generally reckoned to be essential to a satisfactory seal. Does your hub have the 'O' ring groove in it? If not, it might be worth getting hold of a couple of the later hubs, with the groove, and swap them over at the same time as fitting the new seals and gasket.

[dellerie]

no i don't have the O ring grooves in my hubs. i have changed the n/s hub gaskets with blue gasket sealant and that seems to have cured that side. but the o/s keeps on leaking.

[taupe]

The old oil seals on my hubs were very brittle and broke up when removed... it wasnt sealing at all on one side and the drum was full of oil.

The new seals have a double lip seal on them (at least the ones I got from DSN do) they are remarkably cheap to buy.

The side of the seal with the spring should face the bearing (as Islip says above) and the other smaller lip acts as a dirt/brake dust seal.

If you can get good quality bearings its well worth replacing them at the same time and replacement hubs with an O ring groove are worth considering... but a gasket with hylomar on should be ok if you keep your original hubs.

Taupe

[dellerie]

Check the breather on the top of the final drive casing isn't blocked - and the axle not overfilled.

i have replaced that with a new plastic one from a MGB, they are the same. i have filled with 1 litre of EP90.

i am off to the garage to take the hub off now anyway.

[dellerie]

i have removed the hub and the bearing fell out. thats not right surely? the oil seal was crumbling and also fell out.

i've fitted a new oil seal and bearing. in the hub, there are 2 steps. 1 for the seal and 1 for the bearing. when both fitted, there is a gap between the 2. the bearing is flat with the halfshaft surface and there's no gap between the seal and the rear of the hub.

is that right?

[MarkyB]

Was the new bearing a tight fit?
The old one shouldn't have just dropped out.

[dellerie]

Was the new bearing a tight fit?
The old one shouldn't have just dropped out.

i tapped it in with a hammer. it wasn't loose, but i wasn't difficult to fit in. is that wrong?

[MarkyB]

Sounds OK then.
I was concerned that the old bearing has seized at some time and started to wear the casing.

[dellerie]

new bearing has fallen out before i tried to fit it to the car.

with the play in the hub, i tried to tighten the nut up as far as i could. i think i now have stripped the thread. does that sound like i need another axle?

[taupe]

If youve stripped the thread on the axle then yes I would think its scrap!

[chrisryder]

i would hope the thread would strip on the nut before the axle. is it the nut you've stripped?

the bearing falling out suggests, as MarkyB suggested, that a bearing could have seized in the past and caused the whole hub to turn on the bearing. you can get 2nd hand hubs to get a hub that a bearing will stay in! be sure to look for a hub with the groove for the big o-ring.

[bmcecosse]

Would take some effort to strip that thread!!!!!!!!!!!!!! Inspect carefully. You may indeed be lucky and it's just the nut - but hard to imagine that could happen without damaging the shaft threads.

[Neil MG]

Sometimes it feels like the threads are stripped as the hub is pushed on by the nut, suddenly no resistance, no gap and a lot of turns. If that's the case, you will see immediately if you undo the nut a couple of turns.