Mk8 RWD rear wheel bearings, grease or not?

[Sam123]

Bit of an update, I've just finished this job. Few potentially useful thoughts below:

I initially bought new bearings, but in the end bought brand new FoMo hubs. That was mainly because my bearing press kit didn't include the size of drift needed to press out the old outer races; presumably it's an unusually large size. And I just couldn't be bothered faffing about. The hubs were £150 each. But if you do the same, irritatingly the new hubs include the inner bearing complete, but not the outer bearing cage (the hub already has the outer bearing race pressed in), so you'll need to buy the outer bearing separately. I don't think you can buy it separately, at least not from Ford, and you certainly can't but just the bearing cage. So you'll probably have to buy a full bearing kit just for the single bearing cage.

My existing bearings looked absolutely fine. The van's 10 years old and on 100k miles, and the existing bearings showed no wear at all, so replacing the bearings was probably unnecessary in truth. Had I not already got it in my head that I was replacing bearings I probably wouldn't have bothered.

The sealing surface on the axle stub (against which the hub inner seal seals) was quite badly corroded, particularly on the OS. So get hold of some rust remover gel, like BiltHamber Deox gel, and wires brushes, and budget ideally half a day of faffing around putting the gel on and letting it soak and agitating etc. After removing the rust, my sealing surface is fairly pitted, there's probably only half the depth of the sealing surface still looking good. So ideally you'd probably try and repair the pitting. I didn't, so let's hope the remaining sealing surface is sufficient.

But on the 'sealing' point, what's the point of oil bath bearings? All the sealing challenges with containing the oil and risk of running dry if the diff level drops, why not just greased or sealed bearings?

I didn't grease in the end, just pre-oiled. Again, fingers crossed.

At a guess, removing the shafts probably loses a third of a litre of diff oil.

The final torque for the hub nut is 30Nm, and I imagine that's fairly critical, so probably worth buying an accurate low-torque torque wrench.

All that work to replace a pissing tone ring!

[dumper]

Usually I knock the bearing outer race out with a punch if they haven’t got a lip to hit it on you can get a mig or stick welder put a small run of weld on the ring in 4 or 6 places being careful not to get it on the hub then throw some cold water on it and as it cools down they shrink and will fall out or need a slight tap this method will also work on brass and steel bushes.
If you find that the hub seals leek in the future you can possibly get a speed sleeve that taps onto the axle tube and is a very thin metal ring we used them a lot on a Cummings engine crank seals if you found you did need them a HGV motorfactor would probably help .

[Sam123]

Yeah, in hindsight I should have just replaced the bearings not the hub, a bit of a waste of money.

I suspect I will need to use the speed sleeve option in future. For posterity, the speed sleeve would need to be 75mm ID to fit over the existing sealing surface, and a maximum of 15mm wide which would overlap the existing taper, or 12mm wide leaving the existing taper clear. (that's on the SRW version that uses Ford axle seal 5563805)

[metalworker0]

Never seen one of these used .. would be interesting to see, i suppose it would be an interference fit.. maybe requiring it to be slightly smaller than your 75mm .. or glued on with bearing retainer...

all the best.mark

[Airthies]

Mk8 shouldn't need a speedy sleeve and doubt you'd get one to fit between the axle and seal body.

Mk8 are a cartridge seal so it comes with it's own inner seal surface (basically it's own speedy sleeve) and the rubber on the inner diameter is to hold it onto the axle stub in one position rather than being a rotating part on the axle. (unlike the Mk7 that runs a radial lip seal directly on the axle stub and which wears a set of grooves in the original seal surface, to the point it won't seal properly even with new seals).

Fitting a Mk8 hub and seal needs very little clean surface on the stub, as long as there's enough to create a joint between the seal and the axle.
Just making sure there's no loose debris or excessive rust build up so the seal sits evenly should be enough.


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[dumper]

Mk8 shouldn't need a speedy sleeve and doubt you'd get one to fit between the axle and seal body.

Mk8 are a cartridge seal so it comes with it's own inner seal surface (basically it's own speedy sleeve) and the rubber on the inner diameter is to hold it onto the axle stub in one position rather than being a rotating part on the axle. (unlike the Mk7 that runs a radial lip seal directly on the axle stub and which wears a set of grooves in the original seal surface, to the point it won't seal properly even with new seals).

Fitting a Mk8 hub and seal needs very little clean surface on the stub, as long as there's enough to create a joint between the seal and the axle.
Just making sure there's no loose debris or excessive rust build up so the seal sits evenly should be enough.

That’s interesting as a said I didn’t do mine myself at 73 I let the local garage do the bigger jobs but I got the seal kit from Ford and you have to buy a pair so still have one at home will have a look when back off Hoiday also they can leak as one did after new discs fitted that how I ended up with a spare seal

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[Sam123]

Mk8 shouldn't need a speedy sleeve and doubt you'd get one to fit between the axle and seal body.

Mk8 are a cartridge seal so it comes with it's own inner seal surface (basically it's own speedy sleeve) and the rubber on the inner diameter is to hold it onto the axle stub in one position rather than being a rotating part on the axle. (unlike the Mk7 that runs a radial lip seal directly on the axle stub and which wears a set of grooves in the original seal surface, to the point it won't seal properly even with new seals).

Fitting a Mk8 hub and seal needs very little clean surface on the stub, as long as there's enough to create a joint between the seal and the axle.
Just making sure there's no loose debris or excessive rust build up so the seal sits evenly should be enough.


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Oh yeah, you're right about the cartridge seal. I just looked at the old one, and the inner rubber does indeed rotate separately to the fixed outer. That was a waste of time all the rust removal I did.

Related topic, does anyone have any opinions on the correct torque for the 5 half shaft bolts (SRW). It's a weird one, I'm getting different figures from everywhere.

The Ford workshop manual seems to say 68Nm + 90 degrees. Although there's then another page of the manual which seems to just say straight 110Nm. But then several other fairly respectable sources say 30Nm +70-90 degrees. And when I removed the old (factory original) bolts, they seemed not much more than hand tight.

I've gone for the 68Nm+90 degrees, because that's what the manual says, and they're supposed to be torque-to-yield, and I can't imagine the lower figure would get anywhere near stretching the fairly chunky bolts. Does anyone else have any idea why there's differing values floating around?

[dumper]

For some reason my reply to Airthies post it only put the quote on I seem to be having trouble on holiday in Ireland I tried to put on the reply that it was interesting that the seal was a cartridge I didn’t fit it myself being 73 I let local garage do it but I got the seal from Fords and they came as a pair and only one leaked after the disc was changed but I think that was the side that had two reluctor rings replaced so came off three times and refitted three times it also needed a new nut as it let go torquing it up and would have a look at the one I have at home but Sam as confirmed it so no need now
If possible can a moderator remove the redundant post?

[Airthies]

For some reason my reply to Airthies post it only put the quote on I seem to be having trouble on holiday in Ireland I tried to put on the reply that it was interesting that the seal was a cartridge I didn’t fit it myself being 73 I let local garage do it but I got the seal from Fords and they came as a pair and only one leaked after the disc was changed but I think that was the side that had two reluctor rings replaced so came off three times and refitted three times it also needed a new nut as it let go torquing it up and would have a look at the one I have at home but Sam as confirmed it so no need now
If possible can a moderator remove the redundant post?

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[dumper]

Cheers Airthies just had a look was expecting it separate underneath the quote box I should have looked better