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MG Midget and Sprite Technical - Brakes - rear backplate replacement tips?

Hi

I am putting later rear brake backplates and wheel cylinders on my MkII 948 Sprite as part of a front disc brake upgrade (from drums) with the correct master cylinder.

Any tips for replacing the rear brake backplate?

I have experience of Mini drum brakes, but not midget rear axles. I am looking forward to removing the hub nut, and plan to replace the paper gasket, other two seals and maybe the hub bearing.

Recent threads on hub nuts and clutch bleeding will be handy, as well as remembering an experience of working on rear brakes on a Minor with oil leaking onto the brake shoes and how easily the half shaft came out and oil too! (hence the paper gasket replacement as well as having the car level on axle stands).

Cheers
Mike
M Wood

They are oriented differently, but will still work with minor mods the the parking brake rods.

They may also foul the drums and the drums will need to be slightly ground/turned shorter.
Trevor Jessie

I kept my original sliding cylinder backplates but replaced them with later Morris Minor 3/4" cylinders rather than the original 7/8". It all stops well with good balance and saved all the faff with the hubs etc.
Bob Beaumont

Good point Bob, but I prefer the late style adjusters. The little cam teeth on the early style seem problematic.
Trevor Jessie

OH, and IIRC the later rear brake wheel cylinders also come in two different sizes. If you have backing plates from a 1500 rubber bumper car you may need to redrill the hole for the locating pin to fit the size cylinders you need.
Trevor Jessie

I did this on my Frog and like Trevor Said, they parking brake rods align differently so you should use the later ones if you can and redrilling the locating hole isn't a problem. Just take your time and make sure everything moves like it's supposed to.
Martin Washington

Having the car level, you are likely to lose more oil.

If you're not draining the axle, jack up one side at a time, so the oil flows away from the end you are working on.
Dave O'Neill 2

The Wolseley 1500 drums use teethed cam adjusters and they are a dream to work with and never seize.

Bob - are the late Morris Minor 3/4 cylinders teethed cam adjusters?

Daniel Stapleton

Daniel

yes you can re-use the original item. I have to say I quite like the teethed cam adjusters. As you say they don't seize like the later spridget ones. The little teeth can wear over time but replacements are available.
Bob Beaumont

Hi all

Thanks for the very helpful info relating to switching from 7/8 to 3/4 inch rear brake wheel cylinders on a MKII Sprite.

Bob - I had not realised that there is a Morris Minor 3/4 inch single piston wheel cylinder that will fit the existing MKI/III Sprite backplates (front drum braked cars). I had wrongly thought that the only way to get 3/4 inch rear wheel cylinders was to use later backplates with the twin piston wheel cylinder. Am I correct that part numbers for the 3/4 inch Morris Minor wheel cylinder is the FBK106/GWC1116 from the 1098cc MM?

Cheers
Mike
M Wood

To my earlier post today, is the Morris Minor 3/4 inch wheel cylinder an RBK106 (Unipart GWC1116)?

Thanks
Mike
M Wood

Moss list GWC1111 for the 803 & 948 Minor, and GWC1116 for the 1098.

They don't specify the diameter, but that should be easy to track down.
Dave O'Neill 2

Yes the rear 3/4" rear cylinders are GWC1116 or Lockheed/Delphi LW11287.
Bob Beaumont

I should also have mentioned that a more recent number for the 3/4" cylinder is BBW 1554
Bob Beaumont

Thanks for the additional part numbers and advice. Superb!

I tracked down a set of Morris 1000 (1098cc) sliding rear brake 3/4 inch wheel cylinders as Alan and Bob suggested. Great tip, thanks. NOS - let's hope they work!

On my travels round brake part number land for rear brake and master cylinder repair/upgrade, I found the following useful, the first link is for the original manufacturers, Lockheed, now Caparo (was AP Caparo). Note more numbers abound for aftermarket parts not in the links below, e.g. the Quinton Hazel (QH, now 'Brake Engineering') numbers or Bob's suggestion for Borg & Beck (BBW1554)

http://www.caparovehicletechnologies.com/uploads/file/Complete%20Classic%20Catalogue%202013-Issue%2008.pdf

http://www.saintgeorgeltd.com/Part-Listings/Brakes/BRAKE%20MASTER%20CYLINDER%20KITS.html

Interesting to see what Caparo still make.

Also there seem to be specialist suppliers out there for brake and clutch parts, e.g. Past Parts Ltd, Coastings Ltd and Powertrack Ltd - anyone tried them?

When looking out for OE spec brake drums and MkI Sprite OE spec rear brake shoes, Peter May Engineering sell Lockheed//Delphi, but otherwise tricky to find. I have concerns about the quality of non-Lockheed drums that seem widely available - any experience?

Cheers
Mike
M Wood

I have purchased from Powertrack, slightly more expensive but they do have a good range of original parts. Coastings attend all the big autojumbles and I picked up a pair of NOS lockheed calipers from them in their original packaging for 70.

Its also worth trailing round a few motor factors, I recently picked up a pair of NOS Lockheed rear cylinders for 5 each.
Bob Beaumont

This thread was discussed between 07/08/2015 and 18/08/2015

MG Midget and Sprite Technical index

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