Rear Wheel bearing problem, again - Part II

[stuartgb100]

Well, it's definitely a shot bearing this time - in less than 150 miles! So I've either installed it incorrectly, or there's some other problem.

To cap it all, the offside outer driveshaft that I inherited from the PO had VERY marginal threads last time ......... now I think that's it. Will get a machine shop to check, but I expect I'm in the market for a new shaft (big ouch).

I'd like help in narrowing down what has caused the failure, please. Here's a few points that may/may not have a bearing ('scuse pun):

Just staying with the inner bearing for a moment: The bearing puller freed the bearing ok, and it slid freely down the shaft until it reached a point approx 6mm before the taper, and then it 'stuck'. I think this would be approx where the outer bearing would fit the shaft. Would that be normal? I reapplied the puller and it slid free.

The following was all carried out at the time the bearings were changed:

Rear suspension bushes + Diff top mounts + diff torque rod bushes all changed to poly. Adjustable rear spring platforms, 2.25 inch springs and Gaz dampers fitted. Solid driveshafts with inner and outer driveshafts fitted.

I bought the car ('71 Sprint) last Summer and put no more than 1k miles on it before laying it up to do the above mods etc over Winter. Just before I laid it up, I discovered the offside rear bearing had gone, so added that repair to the list.

So that's where I'm at. Any thoughts please?

Regards,
Stuart.

[cliveyboy]

Stuart
It is a few years since I changed the rear bearings on my sprint so this is all from memory.
The shaft has two bearing surfaces either end and a slight relief in the middle so the inner bearing will come free and then tighten up again at the end where the outer bearing would sit.
If the bearings you have removed were good quality bearings, I can guarantee the problem is not faulty bearings.
Do your bearings have rubber seals on them?
How did you fit them?
I prefer to heat up a bearing to fit it onto a shaft.
60 degrees C should be enough to expand it so it slides on.
You can heat them upto approx 120 degrees without damaging them.
If you push fit them on where are you applying the force?
If you are pushing a bearing onto the shaft make sure you only push on the inner ring of the bearing. If you push on the outer ring you are putting all the force through the ball bearings which in turn puts the force onto the inner ring. This puts directional forces into them that they are not designed to take. It can also mean when assembled the bearing always has a constant side thrust which will cause premature failure.

When I assembled my bearings the routine was .
Heat up inner bearing and slide onto shaft. (remember large metal washer/cover and circlip)
Warm up housing and press or pull shaft into housing applying force through the outer ring of bearing.
For outer bearing warm up housing but keep heat away from shaft.
lightly press bearing into housing applying force on inner ring.
This is where you will apply abit of side thrust to the bearing but if the housing is warm and expanded the forces will be low and within the bearings capabilities. Most of the force will go into pushing the inner ring onto the shaft.
Hope this helps.

Clive

[rgh0]

Stuart

Its normal to have to push or pull the inner bearing over the outer bearing seating area.

Really only 3 possible reasons for a failure in such a short time assuming the fit tolerances on the shaft and housing are correct.

1. A bad bearing from the manufacturer - possible but pretty rare if from a reputable company and not a cheap brand or a forgery of a reputable brand.

2. Bearing misalignment - possible if the seats in the suspension hub and shaft were damaged or not clean but the misalignment amount needed to damage the bearing normally means the locating circlips cannot be fitted.

3. Damage during installation typically by not supporting the assembly properly or pushing on the wrong part of the bearing when fitting so loads are transmitted though the balls resulting in ball and race damage. When pressing on the outer bearing you have to support the shaft and warm the housing so that the previously fitted inner bearing is not carrying any load.

If everything measures up OK in terms of tolerances and squareness and no obvious signs of rust damage lack of lubrication in the bearing. Then most likely assembly issues

regards
Rohan

[miked]

Stuart,

As I wrote the other week I have been troubled with play to. Have been reading with interest. Reading Clive and Rohan's account I think I have been doing it wrong. Looks like I have put side load on as I fitted the outer bearing to the casing first and then drifted the shaft with the installed inner one into it. What a Plonker! I must have pushed the bearing shaft right to the edge of its side play limit on both bearings.

So guys, if I read it right, the shaft with the inner bearing (fitted) is pushed into the housing first by the outer edge/ring and then the outer bearing is pushed lightly in via the inner ring.
Question: When pushing the inner bearings in how do you push on the outer ring without damaging the dirt shield. Do you have to make something up to just contact three points between the shaft legs?

Mike

[M100]

Its a while since I replaced by bearings but I'm reasonably sure this is the order I did them in.

Chilled the stub axle

Heated the inner bearing.

Fitted the inner bearing to the stub axle pressing on the inner race

Heated the hub carrier and fitted the outer bearing pressing on the outer race

Chilled the stub axle and inner bearing assembly

Heated the hub carrier inner face and pressed the stub axle in using the centre drilled hole in the middle of the spider and supporting the outer bearing inner race.

[rgh0]

Mike

To push the outer ring of the inner bearing into the housing once mounted on the shaft I have made up a section of pipe the diameter of the outer bearing race with 3 cutouts to clear the drive shaft legs as you described that pushes through the dust shield evenly onto the outer bearing race. The dust shields only last a few fittings without needing trimming as the pressing in extrudes the soft aluminum shields outwards. Chilling and heating the various components helps reduce the pressing loads but not critical provided you press on the right bit of the bearing at each stage.

regards
Rohan

[stuartgb100]

Thanks all for the replies.

After reviewing the suggested techniques, and comparing with my memory of how I installed the bearings......... well I have to presume that I 'm'ucked up somehow.

Expensive mistake. Especially as I now note wear just inboard of the taper. Looks as though the outer bearing is now a sloppy fit on the shaft.
I'll take some dims, but it's clearly visible to the eye ( so you can definitely feel it as you run your finger along the shaft).

I want to up the engine output fairly soon, so I think a new shaft is called for. Or do you think some machining and then a heavy chrome would be okay?

Regards,
Stuart.

[miked]

Rohan,

Thanks for the tip, I will make one up.

Stuart,

My mate has just had the very same on his plus two. What about asking Wiggy at Spyder as he should have some good second hand ones from when he does the plus two's to the new spec'.

Mike