Rear backplate

[MacD]

How difficult is it to remove rear backplate.? I seam to have damaged it and can’t get the new brake cylinder to fit.
I think there is a wee twist on the plate!

[geoberni]

Well I've never done it, so can't tell you, but I'm pretty certain it will depend on which Rear Axle you have, the early one looks to be quite easy, not so the latter one.


Having just replaced my wheel cylinders a few weeks back, I'm wondering how you've damaged it.
I had to release the Half Shaft to fit my rear cylinders.
Can you not get a G Clamp and use that to correct any bend in the back plate?

[simmitc]

With the cylinder already off, you must have removed the drum and shoes, so now it's a simple matter of removing the half shaft and hub; and then undoing the four bolts that hold the plate to the axle. Ensure that you clean everything before taking it apart to avoid getting dirt inside. You may need to soak the nuts with Plus Gas or similar to get them free.

Are you using a genuine or pattern cylinder? My experience is that the pattern ones are much more difficult to fit than "original". It is very difficult to bend the backplate, so are you sure that is the problem?

[MacD]

Thanks for the replies..I’ve managed to get the cylinder in.Phew!

[JOWETTJAVELIN]

I’m just about to do this job myself as I swap axles. The one going in has a damaged backplate where someone has levered the drum off. So I am swapping it for the good one on the ‘old’ axle.

[JOWETTJAVELIN]

Just done this job. The hardest part was removing the hub with bearing, for which I had to use a puller. I am going to look at making a special cylindrical tool with a bevelled edge that can sit just inside the axle tube, to intersperse the puller. Otherwise the hub nut threads are vulnerable and using an old socket has obvious problems.

[philthehill]

To remove the rear hub from a Minor 1000 rear axle I just use a Sykes-Pickavant impact hammer connected to a Sykes-Pickavant classic Mini hub removal tool. The hub removal tool is fastened to the hub by two wheel nuts. The Minor rear axle hub hub just comes off with very little effort and no damage to the axle tube or threads.

Hub puller.JPG (1.49 MiB) Viewed 1849 times

[JOWETTJAVELIN]

I thought a trip to my brother’s works to ask him to make a special service tool was in order, because I didn’t want to risk damaging the ‘new’ axle for certain.





Now if you can visualise how this works I got him to make up a 30mm diameter mandrill with a chamfered edge which fits in the axle tube, and drilled the other end so the puller screw has something to go into securely. This service tool of mine is interspersed between the puller and the axle and will ensure a good even pull without damaging any axle components. To be tested when I replace the backplate.

[JOWETTJAVELIN]

Just to round this topic off from me, I changed the damaged backplate today for the good one. My special service tool was deployed in conjunction with the puller, and it worked exactly as I’d expected. Couldn’t have gone any better.







And so I changed the backplate which had been carefully prepared - the vast majority of time and effort is in careful preparation - and cleaned the dismantled parts before putting it all back together. I’ve just got to transfer all the remaining brake parts over and fill the axle with GL-4 EP90 and then it will be good to go.




If anyone is interested I would supply one of these special tools for a nominal fee. Whilst I was replacing the hub I realised something else - that all of you who, in recent discussion, claimed the different thicknesses of paper gaskets should be used to adjust bearing end float - are wrong. The bearing is pressed into the hub and that alone determines end float. The thickness of paper gasket is irrelevant really, and actually the thicker ones are better for oil sealing.

[philthehill]

The thickness of the gasket paper is what determines the nip or clamping load of the bearing in the hub. It is nothing to do with bearing end float.
There should be no end float of the bearing or hub.
To get that correct nip or clamping load BMC wrote in wksp manual AKD530 section HH.2 specific instructions for the amount of protrusion of the bearing from the face of the hub and paper gasket.
The only way you can get the correct protrusion is to use the correct thickness of gasket. Therefore the thickness of the gasket paper is not irrelevant.

[JOWETTJAVELIN]

The hub nut, with the locking tab, secures the bearing. Are you honestly saying that a thin piece of paper, which doesn't even contact the bearing, is what is meant to clamp it and account for its protrusion? It is there to prevent oil leaks only. I don't know where this idea came from but it is complete hokum.

Please explain if you would measure the bearing protrusion when pressing a new bearing into the hub, and if it was out of spec, would you press it in further or go about fitting paper gaskets, which the workshop manual says nothing about?

[jagnut66]

If anyone is interested I would supply one of these special tools for a nominal fee.

PM sent.
Best wishes,
Mike.

[philthehill]

As I have already stated elsewhere - read and understand the manual.

[ManyMinors]

Copy taken from the BMC factory manual for the Minor 1000: Might or might not help.

[philthehill]

ManyMinors
Thank you for the information above.
I am not sure what edition workshop manual it was taken from but it has muddied the waters somewhat with the word 'Not'.
Your edition says that the bearing should 'not' protrude.
My AKD530 edition and the 14th (latest edition) state that the bearing should protrude beyond the face of the the hub and the paper washer from 0.001" to 0.004" when the bearing is pressed into position. This ensures that the bearing is gripped between the abutment shoulder in the hub and the driving flange of the axle shaft.

Phil

[jaekl]

Both manuals have a .004 range. Could the move of the nominal be due to the implementation of the O-ring?