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MG MGA - MGA Front Disc Brake Conversion

Here is the delima. Time for new front brakes. Adjusters are worn and won't hold, shoes are done, drums are out of spec, but all the hydraulics are tip top.

I acquired many years ago (free) partialL/R 1600 suspensions from the swivel pins out. They include the trunnions that are fine, but will need bushings, the caliper mounts, almost new wire wheel hubs, but no calipers. Bearings are fine as well. I also got a set of Moss caliper adapters and a set of MGB calipers with good pistons, but they need a rebuild. These were free, too.

To fit the 1600 setup I will need to replace all the trunion bushings, distance tubes (which I have), rubber bits, hub seals (also have these), disc rotors, and of course source some good 1600 calipers.

I could also fit the caliper adapters to my 1500 suspension, rebuild the calipers, change the hoses and be on my way. This would also require new discs and i think i can use the hubs from the free 1600 suspension..

Finally, I could just get all the 1500 parts and rebuild the stock brakes.

Now the final bit. Since I live in Japan, shipping is very expensive. Add to that import taxes, etc. if I go the stock 1500 route, the shipping for the drums alone could be more than the cost of the parts. The calipers may not be that much different to ship. But to be honest, I don't really want to use the Moss adapters but it may be the most economical.

Any suggestions? I will end by saying that I have nothing against the drum brakes and don't feel the need to use disc brakes, either.
Tommy Baker

You may find it hard to find callipers. I have had a new pair on back order at Moss for two years!

I too have a 1500 with a disc front end, and the brakes are great and have never caused a problem. I only have a new set of callipers on order because the ones installed are now 25 years old, and I regard brakes as an item that don't have an indefinite lifetime. They still work great, but I want to replace them before they get to the point of not working as they should.
dominic clancy

Tom, I ordered a single caliper from Moss in 2012 and they were out of stock. They said it would be six months away depending on the number of pre-orders in the meantime. I assumed at that time they hadn't placed an order on the supplier However, in the end it came quicker than expected (September 2012) and the cost was 80. I was pleased with the standard of workmanship and would recommend them. There were just two features differing from original 1. there was no embossing (Lockheed, etc.) on the exterior and 2. all three of the bleed nipples had metric hexagons instead of UNF. As I didn't fancy finding two different spanners when wanting to bleed I swapped the nipples on my old damaged caliper. I've had no problems with the caliper on the car.

When obtaining new suspension seals on no account use the ones from Moss. I tried two sets and they both rotted and disintegrated after six months. The ones from Scarborough Faire are made from a more sensible nitrile rubber and are much more substantial in construction. Moss may have changed them since but I certainly wouldn't risk it.

However, if your car were mine I would stick with the drum brakes and give them a complete overhaul. I remember doing this for the drum brakes on an early 50s car I used to own . I had the drums reground, new cylinders, new shoes etc. and the result was truly amazing. Don't let anyone convince you that drum brakes are poor. ........................Mike
m.j. moore

I've recently seen brand new complete conversion sets for sale on Ebay Australia.
Gary Lock

The item number is 141365342133
Gary Lock

The Moss bracket to hold the calliper is aluminium. The calliper and the suspension it bolts on to are steel. Careful insulation is needed especially in a maritime climate.
Roger Walker

Jeff Zorn has the MGA calipers; my brother bought a pair from him recently.

D Rawlins

Thanks all. Yes, the MGA callipers are as rare as hen's teeth so it appears. Reviewing Steve Gyles' information, and a little discussion offline, I am leaning towards using the calliper adapters and the MGB callipers.

Drums plus shipping will run about $240. Add to that adjusters and other various sundries and it hurts the pocketbook. I can get all the 1600 parts I need shipped for less.

Still thinking.....
Tommy Baker

Tom emailed me off line about my 1500 conversion back in 2003 after I had previously converted to wire wheels. I went this route after installing an 1800 with 5-speed in 2000. The kit was supplied to me by Bob West, including 2 x MGB callipers for 105 plus VAT. The conversion can be seen here: .

11 years on the assembly is still going great with no corrosion to the aluminium plate. I did hear that some owners had issues with the plate, suffering slight movement in use and causing vibration, but thankfully that has not been an issue with me. I believe I had an early 'prototype' plate so may be the tolerances were tighter then? One issue is whether the original 1500 flexible brake hoses can still be used. My colleague was unable to get full lock without stretching the hoses when he did the modification a couple of years later. He had to relocate the anchor plate by about an inch I believe. Mine screwed straight in to the MGB calliper and gave full lock with no problem. May be my after market hose was a little longer when I bought it from Bob during my rebuild back in 1997.

I know a lot of guys say the drum brakes are fine for stopping, so why change? Fair comment. My philosophy was to have a similar stopping rate to modern disc braked cars around me all travelling at 70 mph. To date all has gone well. I don't have to worry about that extra 'drum brake' distance (including possible fade) between me and the car in front. I remember on my first test run with the discs that the power of the brakes was quite noticeable, throwing the passenger seat back sharply forward; not something I had experienced before in my car with drums.


Steve Gyles


I went the 1600 route. The biggest problem was finding a brake lines. To make the conversion work the brake lines need to come into the chassis anchor tabs from the top. So the stock 1600 lines will be too short since the 1600 anchor tab is in a different location than the 1500 tab. I ended up making up my own lines. Plenty of pictures on Barney's site.

For those of us that happen to have steel wheels we pay dearly for the disk brake hubs. There are a couple on eBay right now for something like $170 USD each.

All in all very happy with the conversion. Definitely a more responsive pedal and eliminated my battles with the drum brakes tending to pull to one side or the other.

John Backman


Just a couple of points.

When I was thinking of going the Moss plate route a few years ago one of Bob West's staff was wary as he said getting alignment correct was difficult, I think it was to do with some holes having been drilled metric rather than imperial. In a subsequent conversation with Bob he said don't go for the plate as at that time you could get the 1600 calipers so you may as well stay pure MGA but I guess availability has changed again.

As I have said here previously several experts have said to me 'stay drum' as 'it not worth the effort' as 'fade is a non issue in any normal driving', 'there is almost no difference in actual stopping power', ' properly setup drums shouldn't pull', and 'with correct setup drums have the edge on feel'.

I have steel wheels hence life is more complex but if at any time I decide to 'go wire' I might still be tempted to go disk but I would only consider the standard 1600 route.


PS Steve, my passenger seat always flies forward when I test my drum brakes before MOT!
Paul Dean


You are probably correct about the metric size holes being the issue. I mentioned that my plates were a very early, possibly prototype, so may be mine were the correct imperial size. I mentioned the seat on my car before and after the mod as a way of comparison. I guess it depends how worn the hinge rivets are as to how much braking power tips it forward. It certainly never did with my drums.

Steve Gyles

Moss is now showing the 'MGA callipers as in stock

dominic clancy

Great info from all, thanks. The set of adapters I have are indeed imperial so they must be an early set. The easily bolt right up to my MGB calliper cores.

Now the issue of brake lines. Moss UK sells the complete conversion kits, no mention of modifying the brackets to account for the lines. I inquired if I could just get the lines and have not heard back yet. Sadly, even though I can weld and have a welder, I can't do the work here and shops typically won't do something that small.

In any case, I would need a solution (i.e. longer lines) to make this work without modifying the brackets. I am also a bit limited on finding anything not metric off the shelf around here. Are the MGB lines long enough?
Tommy Baker

NAPA has brake lines in various lengths with either SAE or metric flare nuts.
Barney Gaylord

I always forget about NAPA, and they ship to Japan. I need some new oil filters, too so this may work just fine. How much longer than stock would I need if anyone had to guess?
Tommy Baker

the Moss UK site has a components cataloge that lists the lenths of the various brake flex hoses, so you can determine the standard lentgth of what you have, and get a part number for what you need.. On the midget I restored last year, I had hoses made up by HEP with the correct length, but make sure you order the matching banjo bolts with any hoses as they are by no means stanidard with the special hose manufacturers.
dominic clancy

Just bought 2 new MGA calipers from LB Car Co.

This thread was discussed between 11/01/2015 and 26/01/2015

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