Adjustable rear hub seals..Whaaaaat????

[philthehill]

Whilst not everyone has access to different thickness gasket paper and therefore has to accept the thickness of hub gasket supplied by the Minor spares suppliers (I have at least two supplied thicknesses of 0.030" & 0.0255") - if you have this is how to determine the thickness of gasket paper required for the Minor rear hub.

Reference:-
BMC wksp manual Section HH2.

Best done with the hub removed from the axle.

1. Ensure that the hub bearing is pressed fully home into the hub.

2. Place square (true) steel block across the bearing and hub gasket faces. The steel block should be above and not touch the hub gasket face.

3. Holding the steel block down hard against the bearing outer face measure (feeler gauges) the gap between square steel block and hub gasket face.

4. Subtract the specified amount 0.001" - 0.004" (see Section HH2) from the measured gap and the remaining measurement will give the thickness of the gasket required.

The above will give the correct factory specified clamping effect on the bearing between hub and half-shaft.

[BLOWNMM]

This is exactly what I did to determine the gasket thickness. I had some 0.007" material at hand and made the gaskets from this. This resulted in the protrusion of the bearing outer race from the hub AND gasket at one side 0.002" and the other 0.003". These figures comply with the manual and ensure the outer bearing race is properly clamped between the abutment shoulder of the hub and the axle driving flange.
Bob

[RobThomas]

Just to add some more data, I bought some KOYO 6207-2RS-CN bearings, 6207 (the right dimensions), 2RS (2 rubber seals, neoprene in this case), CN (normal spec rather than the looser C3 spec, and thus they don't have an C-mark on them) for about £8, inc postage. CN is about C2.5 so C2 bearings are more precise and C3 are rather sloppy. They go from C1 to C5, I think. I can feel no radial play but there is a little lateral play (half shaft in-out) play from new.

The seals covering the balls are fixed to the outer ring and make it fairly water-tight. The 'upstand' out of the hub is 11 thou on the first bearing, the standard gasket was 18 thou so it would need to compress the gasket by 7 thou if everything worked out alright. Might be a bit optimistic and suggests that the 14 thou that Mick mentioned a few years ao would be about right for this hub. It will be interesting to test the other hubs I have here in boxes in the garage.

I removed the old bearings and seals from the hubs, washed them in degreaser, boiled them in water to loosen any remaining goo, stuck them overnight in a tub of hot water and Citric Acid and the came out this morning looking like new. Rather than paint them I covered them in a smear of military surplus (ie nicked from the RAF) preservative and then assembled.

The first hub is marked as being EN8 material. The bottom of the bearing hole is a tight 90 degree cut rather than the small radius I found on the bottom of the hole on the other axle I rebuilt a few years ago.

[les]

SKF do an equivalent bearing, which would, no doubt, be top quality.

[RobThomas]

SKF-62072RS1 seems to be about twice the price and they are listed as being of the same quality as Koyo, but who knows??? Koyo seems to be rated to a higher load and a higher speed, but that may well be advertising blurb rather than a real indication of quality. Mind you, we aren't talking about using them in a Space Shuttle, are we. 10,000 miles per annum at max 60 mph should be OK.

Can't fit them today due to me still having a load of stitches in my shoulder.

Rob 1: Basal Cell Carcinoma 0

[Declan_Burns]

Rob,

Less than 10 quid!
http://www.ebay.co.uk/itm/6207-2RS1-Sin ... SwKtVWzX1J

Regards
Declan

[philthehill]

Declan/Rob
I have one of the above SKF bearings but it is marked up as C3

Full part number:- 6207-2RS1 / C3.


Phil

[les]

I found this.
http://www.qualitybearingsonline.com/ko ... GwodLT0ACQ

[philthehill]

Les
Many thanks for the interesting link with specifications / comparisons attached.
It appears that MG Rover were not adverse to supplying C3 clearance bearings for use in the Minor rear hub.
I obtained a NOS MG Rover rear wheel bearing Pt No: RFM001143EVA which is marked up as a C3 clearance bearing.
Phil

[Declan_Burns]

I fitted a new C3 bearing and there was more play rocking the wheel than beforehand. I binned it.

Regards
Declan

[RobThomas]

The ones I bought had no 'C' marking on them so I read up on the subject. If it doesn't have a 'C-number' on it then allegedly it is a C-normal size, the ones we want. 6207-2RS or 6207-2RS-CN is what you'd want written on the box, I guess. The more unscrupulous might just not bother to write 'C3' on there?

How long have SKF been made in Malaysia?

[philthehill]

Bearings made in Malaysia since 1992. (See history section of below link)

http://www.skf.com/uk/products/bearings ... index.html

[les]

There seems to be more to this internal clearance business than first meets the eye, well meets mine anyway!
If I'm reading Phil's link correctly, apparently the c value, will largely depend on the application, temperature and fit.
There's always another stage of neurosis to aspire to if you dig deep enough into a subject!

[BLOWNMM]

C3 and C4 bearings are usually used in electric motors which are subject to full load when started. In the case of an AC synchronous motor this results in the rotor heating up very quickly and in the case of a DC motor the armature also heating up quickly. This heat is transferred along the motor shaft to the inside bearing race causing it to also heat up quickly. The outer race remains relatively cool because the motor end shields do not heat up quickly. Net result is that the bearing clearance rapidly decreases, and if a CN or C2 bearing were used it would most likely gall or fret destroying the bearing. As far as quality I prefer FAG although they are somewhat more expensive.
Bob

[smithskids]

I have just fitted new hub bearings to my pickup. As it was a bank holiday weekend I had to get them from local bearing supplier in Hull so these should be OK. They were twice the price of my usual south coast supplier of Moggy bits. Timkin 6207. the only other numbers on the box were 01G 79 =AER. The old ones were RHP about 20 years old. Didn't see any reference to "C".

[philthehill]

The MG Rover supplied bearing as quoted above only had the reference to C3 on the actual bearing.

Details etched on MG Rover supplied bearing:- NSK 6207 C3 England.

The original Minor bearings do not carry any details for some reason.

[RobThomas]

The Koyo website says that if it doesn't have a "C" marking then it is to be assumed to be "C-normal". It might be a universal rule? Linda like pistons being assumed to be STD if they have no oversize marks.

[RobThomas]

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[philthehill]

Rob
Is it the angle of the picture? - the seal looks to be deformed in two places where it fits to the inner race.
Before mounting the hub I would suggest filling 50% of the void between oil seal and sealed bearing with LM grease or similar otherwise the seal is going to pick up and get ruined.
The rear hub seal will then act just like a front hub seal.
Phil

[RobThomas]

Just an optical illusion, Phil.

Good call on the grease. I've gone round the ends of the axle tube with Scotch-Brite to get them back to bare steel and slapped some of this NO-OX-ID preservative that seems to be quite resilient. Maybe red rubber grease will do the job?

Stitches out tomorrow so I should be permitted by management to go outside to play. Finished the first Alta head this moring and managed to get the OD and ID centrelines of the guides parallel to just 2 thou, 1 thou either side, after packing the bed of the lathe a tiny amount in one corner. Surprised how flexible the lathe bed was.