Mk8 RWD rear wheel bearings, grease or not?

[Sam123]

I'm planning to replace the rear wheel bearings on my 2015 mk8 RWD. These are the open-cage type thrust bearings.

What is the consensus on whether they need to be greased?

As I understand it, they are oiled by the diff oil, and the seal is on the other side of the bearing. So I *think* that they come ungreased from the factory (haven't yet disassembled to check). However, seems to me that risks insufficient lubrication, particularly if the diff oil level drops even a bit low. Also, it would feel weird putting in open bearings without grease.

There seems to be conflicting approaches in YT vids, some grease, some don't. Any reliable views here? Thanks

[metalworker0]

Looking at the diagram, the rear innermost seal is to stop oil leaking out of the back, down the back of the brake backing-plate, seals the whole of the cast iron outer tube has a gasket on the front .. so i would say oil only..

notice: how large the hole is on the inner most seal

http://www.catcar.info/ford/?lang=en&l= ... QyNTYrMTMx

under normal circumstances the diff oil will never drop ... and will only do if you have other leaks.


all the best.mark

[dumper]

50 years of fitting bearings to hgvs/ psvs/vans and cars yes definitely grease the bearings they need to be lubricated before the oil gets to them if you don’t grease them before you put the outer bearings in pump some oil into the void between the bearings.
The grease will mix with the oil and will not give any problems the only bearings I definitely wouldn’t grease is for an automatic gearbox
A breakdownI went to years ago the fitter had put the a bearings in dry no oil or grease it did not do many miles before it welded its self together and the hub had to be cutoff luckily it didn’t destroy the axle

[Airthies]

There's two schools of thought here as you rightly say.

One is as dumper suggests grease them and the other is don't grease oil bath bearings!

I'm of the "DO NOT PACK OIL BATH BEARINGS" persuasion (35+ years of being a fitter).

Oil the bearings when you fit them so they're not dry, then top up axle oil.
Once one side is done, set the axle at an angle to let the oil fill the hub void.
Do the other side and set the axle the opposite way so oil goes to the opposite side.
The length of time it takes to fit the wheels is enough to get the oil to the bearings.

Set it on its wheels or at least level and recheck oil level after it's had time to settle.
Never had a failure yet....

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[Sam123]

Thanks all for replies. I think I'll disassemble and see what they're currently look like (bearings not failed, only doing for completeness as I need to change tone rings and discs).

If they look ungreased I won't grease the new ones. I've only ever worked on non-live axle passenger cars before, so I'd never seen open bearings that weren't greased before.

[dumper]

You probably will not see any grease it will have mixed with the oil I doubt Ford would do it back in the days of mk 1 transits the front wheel bearings had very little grease from new at work it was standard practice to remove the outer bearing re,grease it and pump some grease into the void in the hub if you don’t want to grease them make sure you oil the bearings and pump some oil in the void between the bearings the idea of greasing them is to make double sure they are lubricated it’s easier than jacking it up both sides to run oil in .

[Airthies]

I'm pretty sure it wouldn't take me any longer to tip an axle one notch on the axle stands than to pack oil bath bearings with grease... and is less messy

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[dumper]

Some axles you would have no option it to get your hands messy t think it was the Ford D series the inner bearing was packed with grease with a internal seal and the outer was oil fed and another set up that was all grease with a outer seal on a plate that located on the half shaft bolts and sealed on the axle tube

[Airthies]

Some axles you would have no option it to get your hands messy t think it was the Ford D series the inner bearing was packed with grease with a internal seal and the outer was oil fed and another set up that was all grease with a outer seal on a plate that located on the half shaft bolts and sealed on the axle tube

I'm all for a grease packed bearing if that is what's required.
BUT... this isn't a MK1 axle, a HGV, a D series, or anything else in-between.

It's a Mk8.
That is an oil bath axle.
That uses a lower viscosity oil than older axles.

I don't see why just because it was done 50/35/20 years ago, that it's a reason to do the same today in an application that it's not required.

Do not go blindly forward without asking why...
I will continue to question old practices if they are still relevant and question new practices if I feel they are not the best process.

There is no "one size fits all"


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[dumper]

You know all about live axles with your 4x4 conversion but the only change to axels since the 60s is the oil specification we will have to agree to disagree on this one.

[metalworker0]

OP - this is just an alternative thought - If you are uncomfortable with grease you could try Vaseline ,, has a very low melting point, so when the oil reaches and gets to anything more than a little warm .. it will melt and disperse completely into the oil .. this idea was given to me by a couple of sources... 1, the genuine rover v8 manual tells you to fill the oil pump up with Vaseline when you assemble the engine, 2 . its quite durable for your application (time wise),, Alexander 3D die sinking machines / Pantograph engravers have bearings in the spindles that spin at 20,000 rpm and above .. and Vaseline is what the recommended lube is.
So perhaps an alternative method.


all the best.mark

[Sam123]

Thanks Mark. I haven't actually yet done the job yet, keep putting it off. Interesting thought, still not decided what I'll do. I think I'm erring towards just pre-lubing the bearings with a bit of gearbox oil. Just feels very odd to me not greasing open bearings.

[dumper]

If you’re going to use oil before you fit the outer bearing put some oil in the void in the hub

[bortaf]

i don't grease but i do prelube with lucas oil stabiliser, in the same way i use it as assembly lube when i build an engine, when you drop the axle back onto the wheels the oil should flow in the hub doing all the lubing the bearing needs but if the oil is very low you must fill the diff before driving it, hense i pre lube just as an extra protection, no real idea or any evidence as to why not grease it's just the way i was taught years ago, i don't come from a HGV background like dumper so use a differant method.
In short no need to but i do just in case
not sure that helped at all

[dumper]

i don't grease but i do prelube with lucas oil stabiliser, in the same way i use it as assembly lube when i build an engine, when you drop the axle back onto the wheels the oil should flow in the hub doing all the lubing the bearing needs but if the oil is very low you must fill the diff before driving it, hense i pre lube just as an extra protection, no real idea or any evidence as to why not grease it's just the way i was taught years ago, i don't come from a HGV background like dumper so use a differant method.
In short no need to but i do just in case
not sure that helped at all

Yes there is more then one way to skin a cat as they say what ever method you use they have to be lubricated if not what happened I’ve seen first hand

Just for people who think greasing the bearings could be bad at work we stocked front wheel bearing sets that we’re the same for a Scania and a Volvo Scania was greased and the Volvo running oil, same bearings different application of how they are lubricated