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MG Midget and Sprite Technical - Metro turbo calipers

Ive just got myself a pair of these to go on the Sprite. The "adjustment to the mounting lugs I know, but what have others done to make them work with a single circuit brake system ? The metro caliper has two seperate circuits. Neil
neil munn

You can get off the shelf pipes to fit these calipers to single circuit Minis. Basically a single line that splits in 2 at the caliper. They might be usable on Spridgets too?
G Hawkins

Minispares C-AJJ4024 is the mini version.

http://www.minispares.com/
Dean Smith ('73 RWA)

A picture says a thousand words. Can't remember where I got my hoses from!


Tarquin

a note: the sealing faces on the caliper will need to be emery papered smooth, as the original fitting didn't use banjo's.
Tarquin

Tarquin, I'm still kind of waiting for the Mascot article...

alexmatla at tele2 dot nl
Alex G Matla

Alex - you could always join and get this article and many others ;-)
Toby Anscombe

alex i e-maild it to your eon mail (it was the only one i had on my home email?!)
Onno Könemann

Toby, I am a member...
Alex G Matla

Thanx Onno, received it. Interesting read and a nice new project.
Alex G Matla

Alex - you should have said...

You can always log on and download all the Mascots that you want ;-)

Glad to hear that you are sorted!
Toby Anscombe

What, can you log on? How do I get username and password? Or did I miss something?
Alex G Matla

It's in the front of mascot each month. Mail me offline for a link and user/password!
Toby Anscombe

Ofcourse I do know the website, its a sticky on my google front page
Alex G Matla

on't want to start world war 3 again but most of us on here will give our infornmation feely to whom ever requires it. Its called friendship!
Robert (Bob) Midget Turbo

Cool - I look forward to being able to read the back issues of Safety Fast ;-)
Toby Anscombe

You can come and collect mine if you like... It'll stop my wife moaning at me to get rid of them...
James Bilsland

Any technical article you want Toby just ask, or if you want anything from me as you are well aware simply ask. I and many others on this MG Enthusiasts Club website will help all we can without strings attached.

Has anyone here demanded something from you for their help?

Robert (Bob) Midget Turbo

Quick question for the author if you don't mind Tarqs, I assume the disks are metro vented disks? do they bolt straight up to the Spridget hub?
Robert (Bob) Midget Turbo

If I get time after my holiday I will try and do the conversion and write it up for the good people of this Enthusiasts club. :)
Robert (Bob) Midget Turbo

I looked at doing this conversion many years ago, what i didn't realise at the time was there are two different types of Metro calipers, the AP ones i had were very expensive for standard pads. The caliper hole spacing didn't quite line up & would have needed offsetting which i didn't fancy on cast calipers, so i stopped the project & went for a 9" setup with mgb calipers.
Brad (Sprite IV 1380)

Tarquin,
I too have this conversion, exactly like yours, I am very pleased with it, has been fitted for 3 years.
I am curious about one thing in your photo; the calipers appear to have extra bleed nipples on the outside edges piston pockets ?? Does this work well and did you do it yourself ? I have never felt that my calipers are bled of air 100% and perhaps this mod was to alleviate this problem, with patience they are 99% good but not perfect. I would wonder how the nipples seal, as they should seal on the lower taper of the nipple and there doesnt appear to be enough depth of metal in that area.
Neil
I was able to re use my already fitted braided hoses and just purchased the short bridging hoses plus 2 longer banjo bolts, hoses were purchased from a local hose/hydraulics company, made in Aeroquip, Minisport do a kit which is also suitable.
Ian
Ian Webb '73 GAN5

Bob

Unlikely to be Metro Discs as the metro/mini hubs are a different design I would guess...

I know that Ford 2.8i Capri Discs work with a spacer (thats what i have on my racer)- these could be Ford Escort Turbo discs - I started working on a conversion using those because the measurements appeared similar to a Spridget disc but stopped when I was gifted a set of Capri discs and spacers already set up...
James Bilsland

an I do not understand your question about the bleed nipples. The calipers shown in Tarq's picture are normal and Metro calipers do have 2 bleed nipples as standard. They can also be supplied for fitting to a solid disk or vented depending on the spacer that is fitted between the 2 halves of the caliper as can be seen on the photograph.

Brad I too am not in favour of opening out of the fixing holes but it is not my car. When we did this conversion on Minis many years ago one of the original mounting holes was "plugged" with an interference fit bung and then redrilled to make a proper engineering job. This is not difficult and I personally think is worth the extra effort.

James
In my garage I must have a couple of midget hubs and should be able to find a couple of Mini Metro Disks so could confirm but I thought a quick question to Tarq (Matt) would solve the question, certainly looks good. I must admit that they do remind me of a metro vented disk but hey you could say that about probably 75% of disks. Not keen on a spacer idea. :(
Robert (Bob) Midget Turbo

Yes they are standard Metro vented disks. The disks have to be modified - bell opened up to accept the midget hub, and new holes drilled & tapped. I will try and email the article out tomorrow, if I remember.

The hub has to have the outside edge machined down to clear the caliper.

Ian, the nipples came as standard on the calipers. Don;t yours have them?
Tarquin

Thanks Matt.
I would therefore assume that if the calipers had the central spacers removed to allow fittment to a solid disk then we should be able to use the existing Spridget disks and not have to machine the hub to avoid hitting the caliper?
On the other hand the vented disk conversion looks the biz.
rjwelchmidget"at"aol.com
Robert (Bob) Midget Turbo

I would think so Bob, but I bet the solid disk calipers won't magically align central with the midget disk.
Tarquin

Gents ...I must be cracking up in my old age checked my metro calipers today and my nipples are exactly as in Tarquins picture !!
Ian Webb '73 GAN5

Without actually bolting it up, my calipers (no spacer- solid disc) seem to sit exactly where the originals did, so they seem to align centrally OK. Also, without wishing to boast, my calipers have 3 bleed nipples each !
neil munn

I thought they would Neil and I see on ebay that there is a company selling reconditioned plated calipers with bunged and redrilled fixings ready to fit for 160 quid a pair, not bad me thinks for a bolt on conversion, does state Mini but Midget is the same.
Robert (Bob) Midget Turbo

As far as I've discovered, mini is same as metro and therefore both are different from midget. This is from having some mini calipers lying about - the mounting holes are not the same as my midget ones

Rob
Rob Armstrong

Not sure how to sort that then Rob? the Mini ones I have are the same as the Midget and different from a Metro, or maybe I have some Midget calipers that I have assumed were Mini?
Robert (Bob) Midget Turbo

Rob just copied this from the Mini Mania site

""The only car that has any degree bolt-on brake compatibility with the Mini is the Metro. Brakes from the Austin 1100/1300, MG Midget and other BMC cars will not fit - many are of the same conceptual design but the sizes, shapes and angles of the hubs, calipers and discs are wrong.""

I am seriously believing that the calipers that I have in my garage that I thought were Mini are in fact Midget!!
I am sure a couple of years back I exchanged 2 mini calipers for 2 recon Midgets, bet they were not happy when they started reconning!! :)

Robert (Bob) Midget Turbo

I'm confused now!!! If I buy a set of STANDARD metro discs and calipers (all metro's were fitted with four pots as standard), can I take it that they will NOT just bolt on to my Midget?

If they do, a great and cheap, easy upgrade to the brakes, if not...then I'll stick with the standard ones!
Robin Cohen

No they will not Robin. have just measured the difference in the fixings for the calipers. The hole centres in the midget caliper are a 1/4 inch different to the Metro. I believe some people have elongated the hole in the caliper to account for this 1/4 inch and then fitted the caliper. I think if you got the metro caliper for solid disks then you could use it with the Midget disk with just the hole centre modification.
If you wanted to make a pukka job of fitting the metro caliper then it should have one mounting plugged by and interference fit bung and then redrilled to suit the different mounting bracket. This would be inexpensive at a everyday machineshop and is the way I would do it, but the choice is yours as they say. :)
Robert (Bob) Midget Turbo

Bob,

The later 12" wheeled Mini had the same caliper mounting centres as the Metro, but used 2-pot calipers. The earlier Mini ones were different, could they be the same as a Midget?

The Metro solid calipers work very well with the standard Midget disc; no clearance problems with the hub. Changing to Metro discs, vented or solid, means machining the disc and tapping 4 new holes to mount it to the Midget hub. On the Minor, any caliper is fitted using a 'J' bracket on the original drum backplate holes, so for Metro calipers, had to get new brackets made.

With a vented disc caliper, which can either be a 'spaced out' version of the solid, or a 'proper' vented version with no spacer (I use these (AP) and I think they are more common?), the Midget hub does need machining, and here I would suggest great care is taken.

If you simply reduce the outside diameter to clear the caliper, much of the bearing area for the wheel is lost. It is probably OK for alloys, which have a flat back to them, but the steel wheels need a much bigger area around the stud to sit on.

On the first hub I machined, I did it by reducing the o/d, with a limited taper on the back, but was not very happy with the wheel mounting area, so have tapered the back of the Midget hub much more and moved the Metro caliper inwards to provide more clearance. Of course I had machined the 'bell' on my nice new vented discs to suit the original design first, so had to start all over again with 2 new ones!

Richard
Richard Wale

This thread was discussed between 20/03/2010 and 03/04/2010

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.