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MG MGB Technical - Removing front Brake Disc

Been restoring a 1972 B for 4 years and figured i need to get the front discs ground before i add new pads. But I'm worried about all the gubins i might find behind them when I take them off, bearings, seals etc. Any advice? I don't think they have paraffin out here to clean the bearing race with. Oh, and what type of grease would I repack the bearing with?
Thanks
Gerry

Paraffin = kerosene You can also just use any type of cleaning solvent to clean the hubs and bearings. Repack with wheel bearing grease rated for disk brakes (about the only kind you can get anymore). Cheers - Dave
David DuBois

Thanks Dave
Sounds stupid, but i take everything out from the back of the hub then then send the disc off to be machined ?
Gerry

gerry
is it me or are mg parts expensive over the water as discs are no more than $20 each over here new (12.95 english pounds) from moss
over here you cant skim discs below a certain thickness before they need replacing
is it the same over there
ste
Ste Brown

Actually Victoria British has them for $29.95 each. Didn't check Moss. Might save a little having them resurfaced.
tom

My local parts store will re surface them for about $10 each, and it looks like there is a lot of metal left. I'd love a slotted pair but out here they'd cost to much.
Gerry

You can get Brembo discs from Britek --the best to my mind. I would not put slotted discs on a road car only on a race car , just looking for water accumulation and problems. My 2 cents.....
Gil Price

Unless they have very shallow groves they will be too thin to use after having them resurfaced. Minimum thickness should be .300" New are around .340" so you can only remove .020" off each side.

FWIW, Clifton
Clifton Gordon

Gil - "I would not put slotted discs on a road car only on a race car , just looking for water accumulation and problems."

I have found just the opposite. Here in the Puget Sound area of Washington State, one is driving in the rain most of the time in the winter months and I always had a problem of wet disks when I had to use the brakes on the highway - step on the brakes and it would take forever for them to take hold (I'm sure it was milliseconds, but when one needs the brakes at 65 or 70 it seemed like an eternity). I finally got a set of slotted disks from the MGOC and have not had any problems since. Cheers - Dave
David DuBois

You probably will have to take the hubs off, then take the discs off the hubs to send them away. That in itself can be tricky, I recall problems with low-profile heads and/or a requirement for thin-wall sockets to undo the disc nuts and bolts.

There is no reason why you could not put the hub bearings etc. back exactly as they are. But if you choose to wash and repack them use multi-purpose lithium-based. To do that you may have to drive out the oil seal as the roller carrier may not fit through it without damaging it, can't remember. If you do *that* you will need a new oil seal.

Pack only from one side, working it in until it starts to bulge out the other side. Don't be tempted to put some in one side and some in the other.

Clean out any grease from inside the hub cavity, and only pack the groove of the oil seal, nothing else. Also smear the lip and the surface of the spindle it runs on.

If you are reusing the bearings (but new are cheap) the outer races of each will remain pressed into the hub, if not they will have to be driven out, and new ones driven in using the old race between hammer and new race to prevent damage. Both races are fitted with their wider inner dimension facing outwards, otherwise the roller carriers and inner races can't be fitted subsequently.

The order of parts on the axle spindle from inside to outside is oil seal, inner bearing inner race, inner roller carrier all inside the back of the hub. The hub is then fitted to the spindle, carefully locating the oil seal. Then the spacer, shims, outer bearing roller carrier, outer bearing inner race, bearing retaining washer and nut are fitted.

If you keep the bearings, the shims were correctly set beforehand, and you haven't got them mixed up between sides, all you should have to do is tighten the nut. But certainly with new bearings, any probably in any case to be sure, you will need to check the shims. First fit the washer and nut *without* the shims and tighten until the hub just starts to bind to seat everything. Then it is a process of fitting different combinations of shims (they come in .003, .005 and .010) until you find two sets .001 apart where the thicker set gives just perceptible end-float or sideways play of the hub on the spindle, and the thinner set does not. Use the thinner set and add a .003. This will give you the correct .002 to .004 end-float. Ignore those who say to leave the spacer and shims out, that weakens the assembly.

Finally the nut should be tightend to a minimum of 40 ft.lb., then tighten further till the next split-pin hole (there are two remember) lines up with the nut castelations. This should happen well before 70 ft. lb. which should not be exceeded.

Paul Hunt 2

Good advice from all so far but given the effort needed to replace the discs and the low cost of new ones I'd really think about a new set rather than skimming the old. Personally I would also clean, inspect and regrease the bearings whilst it's all apart. I found it difficult to keep things clean enough not to contaminate the old grease with dirt and grit from the garage floor (but that may just be my messy garage!!) so had to do this anyway. I also found one bearing had broken up and was held together by the grease even though there was no wear evident before disassembly!

Cheers,
Tim
T Jenner

T.J, Paul, thanks thats what i was looking for. Didn't want to take everything off and find shims, bearings, seals, falling all over the floor. I'll look up Moss and Victoria for the price of new disks.
Thanks everybody, again this site has the best help
Gerry

This thread was discussed between 18/02/2008 and 19/02/2008

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