Disc brake problems

[bmcecosse]

Taper roller bearings must be done up TIGHT! The design requires the inner races to be bedded tightly together against a central spacer. If the bearing is then 'loose' then the central spacer must be thinned down very slightly. Equally - if the bearing is 'tight' then shims must be added to the central spacer until the bearing is just right. If a wheel bearing becomes loose in use - then something has worn. Either the bearings or the housings - but something has worn and with hardened surfaces this is not right!

[Stig]

Taper roller bearings must be done up TIGHT!

But how tight depends on which bearings & hubs you've got, the torque setting for Marina front bearings is scarily low! If you compare Marina and Minor manuals the tightening procedure is different. Of course this isn't much help to the original poster with a Ford-based conversion but perhaps someone's got an Escort(?) manual somewhere and could help out.

[Cam]

When the mechanic was tightening and slackening repeatedly he was jsut trying to get them to locate properly. It's good to hear that he did that.

Minor BALL bearings need to be TIGHT, but it's only the inner bearing housing that you are tightening laterally. You are putting no pressure on the actual bearings themselves which is why the wheel still turns freely even though they are tightened at a high torque. Of course the disadvantage of these is that when they wear they cannot be 'nipped up' and so have to be replaced if they have play in them.

The disc kits (with non-original bespoke hubs) are supplied with taper roller bearings. These are a completely different animal and only need light tightening. If you really tighten them hard then the wheel will not move! and you are putting MAJOR stress on the bearings themselves. There are many horror stories about Minor owners with disc brake kits having MoTs and failing on bearings only to have the garage tighten them up and then later on them failing completely as they have collapsed due to excessive heat and wear. This is the fault of the garage as they assume that they are ball bearing types and not roller so treat them incorrectly!! With the taper bearings it's perfectly fine to run with very SLIGHT play in them. As mad as it may seem but after they are seated properly, finger tight adjustment is all that is needed in the majority of cases.

[bmcecosse]

Not so Cam - the taper rollers will not be under any stress when the centre spacer is correctly sized. All that is being tightened is the inner races of the two bearings against the spacer. When done correctly the rollers will have just the right amount of freedom to revolve but without the hub having any significant play. The Mini front hub for example (which has big robust taper rollers) is tightened to 150 ft lbf, and then ON to the next split pin hole ! Ball bearings need to be tight too of course - but this thread seemed to be about taper rollers.

[Cam]

BMC, you are perfectly correct when talking about the mini hubs etc, but I was talking about the bespoke hubs that come with the Minor disc brake kits. These are a different animal to both the mini type and the original Minor type. This is quite often a cause for confusion. Especially if you have never seen them before.

[Peetee]

Surely the only way to properly adjust these bearings would be to adjust them with the wheel horizontal. Only then can the static load of the wheel be presented evenly across the bearing and ajustment be accurate and true. This is a pretty impractical way to do things as the wheel is almost certainly going to be in its normal vertical position it could account for the instruction to 'tighten' the bearings as the bearing face will not be true due to it 'hanging' on the hub.
There's another way to look at it too. I've worked on some pretty high spec push bikes in my time. When I was taught to assemble Campagnolo crank axles you had to over tighten the adjustable bearing cup so that when the lockring was fitted it's tightening backed off the adjustable cup a bit and the bearing fit should be spot on. There was a real art or feel to this and it was almost impossible to get it right first time. There was either a bit f binding or a slight clunk in the axle - especially on a new assembly. Similarly with the nut and split pin on some car front hubs, when you fit the split pin the nut is not tight against it - it can still back up slightly - enough to take the tightness out of the bearings and give propper adjustment.

[Packedup]

Replaced a front bearing on my old Dolomite, and recently nipped up the slack on the fronts of my 2000. Trust me, tight (as in spanner tight is too tight for these) would result in a totally locked wheel! In fact, to get the bearing to bind to the point where I couldn't move the wheel by hand only took moderate pressure on a normal ratchet, to give you some idea of the scarily low forces needed. These are both rwd cars of course, on fwd it's probably a very different matter.

To quote the manual on refitting the tapered rollers on the 2000 front hubs:

"To obtain the correct adjustment, assemble the hub bearings dry [various instructions about putting bearings in right way round...] Simultaneously, rotate the hub by handand tighten the nut only enough to remove any slackness. Slacken the nut back to the nearest split pin hole and mark the position by scribing a line on the washer and nut."

It then goes on to say remove the lot, pack with grease, refit and tighten to the point marked.

I think it's the rears on the old mk3 (and probably later) Escorts that were the most worrying. The manual said to literally do the nut up finger tight!

[ianselva]

Taper roller bearings must be done up TIGHT! The design requires the inner races to be bedded tightly together against a central spacer. If the bearing is then 'loose' then the central spacer must be thinned down very slightly. Equally - if the bearing is 'tight' then shims must be added to the central spacer until the bearing is just right. If a wheel bearing becomes loose in use - then something has worn. Either the bearings or the housings - but something has worn and with hardened surfaces this is not !

They say a little knowledge is a dangerous thing !
Taper roller bearings MUST NEVER be done up tight ! they will overheat, weld themselves together and tear the end of the axle off at high speed . The taper is so you can tighten them up till there is vitually no play but still a little play at the wheel rim. This is usually one flat of the nut. On other types of non taper wheel bearing such as a MINI both inner races tighten together and there is no adjustment. Please be sure which type you are dealing with bedfore attempting to asdjust them.

[Onne]

Maybe someone on this board is more used to drum brakes....
and that is what the thread is on about!

Sadly I don't know anything about bearings, so I won't butt in.

[bigginger]

  Disc brake problems

Is it?

[Onne]

Yes mate not drums. So you noticed too?

[bigginger]

Aha - so THAT isn't what the threads on about

[Onne]

Its not about carbs either

[Cam]

They say a little knowledge is a dangerous thing !
Taper roller bearings MUST NEVER be done up tight ! they will overheat, weld themselves together and tear the end of the axle off at high speed . The taper is so you can tighten them up till there is vitually no play but still a little play at the wheel rim. This is usually one flat of the nut. On other types of non taper wheel bearing such as a MINI both inner races tighten together and there is no adjustment. Please be sure which type you are dealing with bedfore attempting to asdjust them.

Precisely! This is what I was getting at in my earlier posts. Don't mix the types up or you'll be heading for the ditch!

[jonathon]

I'd have thought that the alloy hub based disc kit is the same as ours in regard to tightening up the bearings. Normally I suggest that the hub nut is tightened hand tight, then gradually tightened with a ratchet and socket to remove any play in the hub.I do not suggest a torque setting as its best to go on the feel of the bearing, as the mechanic correctly did in the post mentioned earlier. Once the road wheel has been fitted then re check the play, adjust as required then fit the split pin. As a safety margine I suggest that the bearing play is re checked after about a week once the assembly has bedded in.

[bmcecosse]

It's about bearings - leave your taper rollers slack if you will - but at your own peril !!!!! I wish my Minor drum brakes had taper rollers - but so far the standard bearings have been fine. And I do know about discs too - having pioneered the Fiesta brake conversion for the Mini. But I agree - i have not got direct experience of the disc conversions for Minors - but if you have to fiddle about and not do the securing nut up too tight - then it's definitely not for me! When a taper roller bearing set is pulled up tight with the correct clearance set on the central spacer - the actual rollers are not being nipped in any way - they will not overheat! If pulling the nut up tight binds the bearing - then the central spacer is too thin and a shim is needed. To leave the nut slack is folly.

[Packedup]

Surely it depends on the design? On the Triumph (as used on many trailers I think, going by part numbers) the thrust washer acts on the inner race of the outer bearing, which carries the rollers. Tightening it presses the rollers harder into the outer race. As this happens, the hub is also pressed back slightly, pressing the rollers on the inner bearing into the outer race. Hence do it too tight and you'll have a cooked bearing in next to no time, do it very tight and I'd be surprised if you could drive away without the car pulling to one side just a little and leaving a dirty great strip of rubber on the road!

None of my Minis had tapered rollers on the front, and I don't think I've ever had much need to play bearings on other cars I've had, but certainly the barely tight on the non-driven wheels roller bearings works, and I think is quite common.

[bigginger]

Think I'll stick with the maker's instructions, certainly...

[Stig]

When a taper roller bearing set is pulled up tight with the correct clearance set on the central spacer

Ah, there's the difference. Midget bearings, for example, have a central spacer but Marina bearings don't. Hence the different procedures.

[Cam]

... and the need to make sure you know what you are doing before you proceed!