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MG Midget and Sprite Technical - rear drum adjuster problems

It looks as if the thread on the adjuster has worn out.
At the moment it I'm not sure if it is the adjuster or the captive thread.
How do I actually get the adjuster out and is it possible to repair the captive in the back plate?

I see back plates are no longer available so repair is the only option.
Clive Berry

Normally to get the adjuster wedge out you take the shoes off, the adjuster 'tappests' out and screw the adjuster wedge from the outside to the inside of the backplate/drum.

Whether you might also need PlusGas, small hammer taps, push or pull apparatus is another matter.

There'll be threads and posts in the Archives on repairs - and probably much more informative posts than mine in due course.

Nigel Atkins

OK, I just dismantled the adjuster and wound it back through the backplate - it catches thread and screws, eventually but..... not when the wedges are in and the shoes and drum on.

Is it likely to be the thread on the adjuster screw or the back plate that is more buggered? will a new adjuster screw solve the problem.

Managed to look through the archive so now have a better idea of what I will need to do.
Clive Berry

These might be a redundant questions but I'll ask -

have you got the tappets in with the angled faces towards the angled face of the screw wedge adjuster

did you clean all threads, trial fit and partially screw the adjuster wedge in facing the wrong way to check and further clean the thread

add some sort of grease to cleaned adjuster parts to aid their movement, and removal in future

I don't know what the threads are but you could check your present adjuster threads by running a few new nuts (of the correct thread) from both sides of the nuts fully up and down the adjuster threads - I'd try more than one as I've found some new nuts have threads that catch on good thread on other items


Nigel Atkins

If the mesh between the adjuster cone and the backplate is worn then you may manage just with a new adjuster. Try this first as it is far and away the easiest. If it's the thread in the backplate then this is much more of a problem.

The solution would normally be a new backplate but for a long time these were unavailable and you would need to find an increasingly rare 2nd hand replacement. Fitting it involves removing all the brake mechanism on that side, removing the half shaft, hub and backplate.

You may achieve a temporary fix by crushing the boss to distort the threads for the backplate. I did this on mine and they remained in correct adjustment for well over a year ( 5,000 + miles)But that would be your decision.

My eventual repair involved drilling out the boss from the backplate and welding in a replacement that a friend made up for me on a lathe. This was done in situ so there was very little dismantling needed. You might be able to do the same by using a Helicoil or similar insert, but the boss wall is quite thin so this may not be possible. Plus the thread pitch is fairly unusual.
GuyW

I have a small stock of good s/hand backplates. As Guy said they're getting rarer so I don't put these on ebay but am more than happy to help out fellow BBS-ers. I'm unsure how many different types there are but the 1275 and 1500 ones are different (hole for the slave cyl locating pin).
David Smith

Thank you Nigel, Guy and David. I have a new adjuster on the way and will see if this helps. Failing that I have another axle I could "borrow" a backplate from but I hate robbing Peter to pay Paul.

Methinks there could be a market for a solution!
Clive Berry

The solution which works very well without the need for dismantling half shafts and hubs is the threaded insert bush I described earlier.
GuyW

It's not that much work to machine out the old threaded portion and replace with a new one. If I remember rightly, Guy has the appropriate tap to clean up the threads if they've distorted at all once the newly made piece is brazed or TIG welded in :)

It's the only solution I could come up with - so don't chuck the old backplate out.
Paul MkIMkIV

Paul was of course the friend whom I mentioned earlier who had made up the inserts for me. Thanks Paul!
GuyW

hi there
i remember being told that there is a chap in one of the morris minor clubs who recons backplates, but you must not say they are for a midget. I am still trying to find the contact at the moment but someone else may have heard of this

rgds tony boyle
tony boyle

I have bought new adjusters and due the the cheaper method of manufacture than the old original parts, the thread extends further towards the cone so we have a solution, for now.

I have gone right through the braking system now and been reminded of how deeply horrible those nasty spring clips for the rear cylinders are. Who, why, when a proper cir clip will do the job came up with these things? God knows how I used to do them grovelling on the ground but it's not easy on a two post lift.

Hopefully I'll get the bleeding done now and the car returned to the road.
Clive Berry

So, new rear wheel cylinders, new calipers, new master cylinder, new flexi hoses, some new sections of copper pipe.

Any ideas why I can't get any real pedal pressure?

I was using a new eezi-bleed, lots of fluid gone through, bubbles all gone but..... soft as a sponge pedal.

I'm also not convinced the caliper pistons are moving much either. Given 50 yards of furious pumping and it does stop but something is not right.
Clive Berry

Clive,
did you bench bleed the new m/c?

If yourflexi-hoses are rubber you could clamp them to see if the problem might be front or rear, front left or right or before flexi-hoses. More details in a fairly recentish thread in the Archive.

Something about calipers too, I can't remember the details.

From my own experience check and recheck and check again the new bleed nipples are fully seated after first, second third journeys.

Also in Archive a simple quick method of fixing the E-clips - by holding the cylinder to the backplate with a small machine screw in the thread for the bleed nipple, leaving both hands free to use a screwdriver to prise on the E-clip - or use the E-clip fitting tool.

Nigel Atkins

Clive you can buy the correct circlips and Belleville washers from AH Spares - mentioned in a previous thread a couple of weeks ago
David Smith

Good point David, I'd totally forgot they were available again.

65A XBRK182C CIRCLIP - Double acting piston cylinder
65B XBRK182W SECURING WASHER - belleville Double acting piston cylinder

https://www.ahspares.co.uk/sprite/Brakes-XBRK101-to-XBRK210/default.aspx
Nigel Atkins

Nigel

I had forgotten, too.

It must be an age thing!
Dave O'Neill 2

I've had it for a good few years now, obviously I can't remember how many.

I wonder if Bill's remembered or whether he's already bought some.
Nigel Atkins

I ought to buy some, in case they’re not available next time I need to change a wheel cylinder. The only problem is, I’d probably forget where I’d put them.
Dave O'Neill 2

Nigel, it wasn't that long ago that these became available again. Around March this year, thanks to a bit of background investigation and lobying, followed by some hard work by AHS. These things don't just happen!
GuyW

Sorry Guy I'd forgotten all that too. Well done to all those involved.

Can I present a list of other parts required. :)

I'm afraid I gave up on trying to sort parts with suppliers a long time back, the last one I think was the (later 1275) heater pipe which was wrong and the correct part not available. I sent my old part as an example and sample but after 18 months I accepted back and that the correct part wouldn't be made available probably because of the large bulk of existing stock and lack of sales to price of the correct part being remade. I must say here that I didn't do much work other than highlight the issue and other the sample someone else done all the chasing.
Nigel Atkins

Nigel, I wasn't claiming to be the one who did the background work on these. Just saying it was done.
GuyW

No, my vague memory was that it was someone else, sorry can't remember who, and MASC(?) and I think like myself you're not a member of MASC. Funny the details won't come to my mind but other more distant subjects and details sometimes do.

I didn't do much background research on that heater pipe other than discover it wasn't right when I was fitting it, after of course breaking the fitment on the old pipe as I wasn't careful enough about its removal.

Nigel Atkins

Nigel,
Warning: Memory update.
It was Dr. John Davies who put in the work to get these parts made available via AH Spares. And I am a MASC member, and have been for around 20 years.
GuyW

Thanks Guy.

Are you sure Dr. Davies is John - and am I a MASC member or was that 20 years, am I going up or down the stairs(?).
Nigel Atkins

I thought you didn't have stairs in your house !
GuyW

Shows how bad my memory is I don't it's a very small semi-detached bungalow!

Now what was I going upstairs for?
Nigel Atkins

This thread was discussed between 22/10/2018 and 30/10/2018

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