Sealed wheel bearings

[David53]

Just fitted the sealed bearings to the front hubs (MM Style). Hubs are quite firm to turn when nut tightened. The wheelss do not spin as freely as the old bearings. In fact they don't really spin freely at all. Car drives ok, no noise from the hubs. Is this normal? Will they free up?

[mike.perry]

I have sealed bearings on my hubs, MM modified for M1000 swivel pins, no problems at all. Did you try spinning the bearings before you fitted them? Check that the new bearings are exactly the same width, not a metic equivelent of an imperial size, if necessary take the old bearings to the store and compare them with a micrometer
When tightened the load should be from the hub nut transmitted through the inside of the outer ball race, through the spacer which presses on the inside of the inner ball race to the stop on the stub axle. The hub should then spin freely on the outside of the bearings.
If the bearings are the wrong width then when you tighten them the load will be transmitted from the inside to the outside of the bearing which will put a stress on the ball bearings

[David53]

Thanks Mike. I used the numbers advised by Oliver in an earlier thread. They seem to be the same as the old ones but have not measured with a micrometer. They are RS bearings. Once the hub is seated all the way onto to the stub axle the stiffness is there, even with Hub nut not tightened. That is, I pushed the hub firmly onto stub axle then tightened nut right up to seat them. Then, with nut removed the tightness was still there.

[David53]

The width of the sealed inner bearing is 14.288 mm according to the website. I do not have a micrometer but measuring the old bearing with a ruler it seems to be just a tad over 14mm so I think widths are ok. I think it must just be the nature of the sealed bearings to be very firm, especially when first fitted. Hub nuts are tightened as tight as possible with a standard socket then backed off just enough to fit split pin. I also fitted new seals which I guess is not required but I had them so used them anyway.

[mike.perry]

If the wheels are only turning once then you are in danger of overheating the bearings.
I have sealed bearings on both hubs and they spin freely. Have you got Series MM swivel pins or have your drums been modified to fit M1000 swivel pins (the bearings are different sizes)?
I think that you are going to have to do some tests. Fit old bearings and test. Fit old inner and new outer and test. Fit new outer and old inner and test. You should be able to find out which bearings are faulty.

[David53]

Original MM pins and hub/drums. The part numbers came from Oliver on the forum here and were for MM hubs. I will see how they go for a week or so and see if they free up at all. If not
I will experiment as you suggest. I also ordered new rear wheel bearings of the same type which I have not yet fitted and comparing these to standard bearings they are quite firm to turn.

[mike.perry]

Even if the bearings are stiff, the weight of the wheel should act as a flywheel and keep the wheel spinning.

[David53]

I have ordered a micrometer (Gotta love ebay) and will check the dimensions of the sealed units against the old bearings to see how much they differ. I am wondering if the internal diameter of the sealed ones is slightly smaller, and once pushed home on the stub they are being stretched outwards slightly thus compressing the bearing?

[David53]

Have checked the specs of the sealed bearIngs against the originals measured with a digital micrometer and they are exactly the same dimensions. So, assuming the old bearings (supplied by ESM) are correct then all is good. I will see how they go for the first hundred miles - hopefully they will loosen up.

[katy]

Drive 5 or 10 miles and then check the temperature on them, repeat as necessary to find out if they're overheating. A non-contact thermometer would be helpful.

[mike.perry]

Did you turn the bearings before you fitted them? How did they feel compared with the old bearings? Were any stiffer than the others?
Do not over tighten them when you fit them.

[David53]

Yes, the sealed bearings were quite firm to turn, unlike the old bearings which were very loose. I feel pretty confident it will loosen up with a bit of driving. Hub Nut is hand tight with socket then turned back enough for split pin.

[David53]

All good. Wheels spin 3-4 times, firm but spinning freely. There is a slight rubbing noise which at first I thought was brake linings but now think it is the oil seals rubbing against the stub axle base. They were a little proud when fitted. If course, totally uneccessary with sealed bearings anyway so don't really know why I bothered...

[David53]

May have spomen too soon After a drive of about 45 minutes today the front wheels were quite hot to the touch. I guess a certain amount of heat is normal due to brake activity but they were both rather hot. I'm at a bit of a loss as to why - bearings are exact dimensions of the old bearings, so are they just too firm for this purpose?

[mike.perry]

Can't think why you are having problems. Were your old bearings worn? If they are OK you could try fitting just the new inners and seeing if they bed in before fitting the outers

[katy]

David, does your car have the spacer between the front wheel bearings? If so, I'm wondering if some PO has shortened it (them) up slightly to compensate for wear in the bearings. Then w/new bearings and the nut tightened it would be putting too much preload on the new bearings.
Anyone have a spec for the proper length of the spacer?

[mike.perry]

I have some original MM spacers

[katy]

Can you measure the length and post it?
TIA, Ken

[David53]

All seems OK now. Just completed a 75 km run at 50 mph and wheels are cold to touch. I think it is the braking in heavy traffic that was causing them to heat up.