Swapping rear rotors and bearings on a BX

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alan s
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Swapping rear rotors and bearings on a BX

Post by alan s » 06 Feb 2005, 03:12

Had to do a rush job on a BX that came from the UK.
A rear wheel bearing had collapsed following the seal backing having rusted out due to salt contamination. This of course caused the seal to totally collapse and leave the bearing open to a variety of foreign substances such as moisture and grit.
The result was that the inner cone had become almost corrugated and was both loose and noisy. We had another known good rotor and bearing on another car, so we decided to simply exchange them.
<b>First problem:</b>
<i>How to remove the rotor and bearing from the rear stub axle.</i>
Measure between the centres of two wheel stud holes, diagonally. Take a piece of reasonably stout steel, say about 3mm upwards and drill two holes large enough to take the wheel studs. If a drill large enough to drill holes that size isn't available, two smaller ones with spacers, washers and nuts will surfice.
Screw the two bolts into position (in the case of using nuts etc, these can be placed in from behind as the stud holes go right through) then sit a large socket, I used a 22mm one on the stub axle end after firstly loosly sitting the 41mm nut on the stub. Begin to tighten the two bolts in sequence whilst temporarily holding the socket into position until some pressure is applied. If it seems as though it is jammed; hit the steel plate directly behind the socket to jar it loose. As soon as it loosens, remove the 41mm nut and if it still resists movement by hand, refit all the items bar the 41mm nut and repeat the procedure until it falls off.
<b>Second problem:</b>
<i>Part of the inner bearing race is stuck hard on the shaft</i>.
You will find the inner race comes in two identical parts, split down the centre of the circumference. The first half has come out with the rotor and the rest of the bearing and the other half firmly jammed on the stub. Worst bit is, this is the part that is possibly causing all the noise so you won't get away with leaving it there and it's both too thin to fit a puller to and too close to the rear shoulder to fit one to anyway.
<i>Solution:-</i> Run a small blow torch over the part of the inner race and when fairly warm, leave it for a couple of minutes and then prise off with a screwdriver.
<i>Next problem:</i> We now have a bearing out of the car, the old one has the inner race as rough as a dogs breakfast and can't be re-used without damaging the one you've just bought, the scrap yard you bought the replacement off didn't go to the trouble of taking the piece of the inner cone off the stub you got it from and you're a bit sceptical about heating and prising an inner race off anyway in case it also gets damaged, particularly as in the scappers yard you had no tools.
<b>No worries!</b> The inner and outer sections of the inner races of the bearing are identical, so if you check the outside part of the inner race for condition and find it to be in good condition (as they usually are) you simply use the outer sections from both the old and the new bearings; they're interchangeable. <i>But,</i> <b>remember:</b> They are a shrink fit, so they must be heated (heated, but not made to glow) to be refitted. Once warmed up by playing a blowtorch over them whilst holding with a pair of pointy nosed pliers, they simply slide straight onto the stub and with the mass of steel in the stub, they cool down almost immediately.
The entire job including drilling the steel for the puller should take less than an hour and your BX is back on the road minus the 'orrible back end howl.
Naturally, use a good heavy axle grease in the bearing before refitting and replace the seal at the rear of the hub bearing.
Alan S