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MG MGA - MGA 1500m Disc Brake Conversion Questions

I am considering converting my 1500 over to front disc brakes. What is the simplest and best way of doing this? Do you buy a "kit", or do you use other MGA disc brake parts, or do you use an MGB set up, or what??? Do you need any other parts other than the rotor / caliper set up?

Also, is this a very big job, or is it as basic as a normal brake rebuild?

Lastly, is it worth the trouble and cost, or would I be just as good rebuilding my current drum brake set up??

Danny T

Danny, I'm aware to three methods to use for this conversion.
1. Convert to the complete upright assembly from a disc brake MGA. (Requires the correct parts, but is basically a bolt in)
2. Use 1600 hubs and rotors with MGB calipers which require an adaptor mount for the drum brake spindles.(Requires the adaptors, MGB calipers, and the 1600 hubs and rotors.)
3. Use MGB upright assemblies. (Requires the MGB parts along with spacers for the upper trunion, new brake hoses, modifications to the tie rod ends.)
For a wire wheel car, wheels will work fine. For a disc wheel car, early drum brake wheels will not clear calipers, later 1600 wheels needed.
More detailed information in the archives. I used the complete MGB assemblies, but my car didn't have any front suspension at all when I bought it and they were more available.
Bill Young

Lots of info in the archives on this. Your last question will probably elicit a variety of responses on this board.

My two cents worth: On my 56 1500 I installed front discs using the MGB calipers and the Greene caliper adaptors (plus the other bits and stuff needed). I think it is a great system. I believe it has better stopping power and certainly it takes less leg muscle to get the car stopped. It makes the car more like the modern iron that is stopping right in front of you.

I always thought it would be interesting to take two MGAs, one with drum brakes all around, one with front discs, both in good repair, and have them compete on time and distance to stop from 60, 50, 40 and 30 MPH. My money would be on the car with front discs.
Frank Nocera

An additional thought is that the MGA "screw" type spindles have been known to break under extreme braking forces with disc brakes and modern tires. The MGB king pins are much stronger and not as prone to wear.

Another benefit of this swap is using the "fancy" MGB taper roller bearings rather than the ball bearings of MGA. They handle side loads better.

Once you have all of the parts cleaned up, the swap is not difficult. There are a couple of different schools of thought on how to modify the shocks. The B shocks have the bolt pattern reversed so you have to either modify the bolt pattern on the B shock, take the levers off of the B shock and put them on the A shock, or reverse the levers on the B shock and mount it "backwards".

The discs definately make difference if you drive your car hard, otherwise I'd stick with the drums.

John
John B



See Steve Gyles' website:

http://freespace.virgin.net/stephen.gyles/mga_1500_disc_brake_conversion.htm
for onwe of many available descriptions.

Shane
shanerj

Shane

You took the words out of my mouth! Nice to see my website being viewed and used. It gives me encouragement to keep it up to date with new information. My conversion still giving me no problems. Works very well. Mind you, the prices I quoted will probably have gone up a bit with inflation.

Regards

Steve
Steve Gyles

With my conversion to B units, I slotted the B shock mounting holes 1/16" and everything bolted on with no spacers. The early 1500 steel wheels will fit over the B calipers too. I went with Carroll Shelby Saab wheels which matched the spacing perfectly. 3/4" in and 3/4" out, everything fit well.
Scott

When I did my 58 I found a complete B donor crossmember and stripped what I needed from it. I used the B shocks swapped around so they fit on the studs. Ground a new flat on the shafts to locate the B arms on the "wrong" way. Shortened the tierods as needed. All I bought new were rotors, pads, caliper kits, hoses, and wheel seals. Easy swap and cheapest way to get disc brakes on an A. Using the B uprights is stronger. The A and B calipers use the same size pistons so they brake the same. B stuff is much easier to find also. If you save the old stuff all you need to return to stock is inner tie rods. Another advantage of the B swap is the ability to use 14" B wheels and tires. 1600 caliper won't clear B wheels.
Randy
R J Brown

This thread was discussed on 09/11/2005

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This thread is from the archive. The Live MG MGA BBS is active now.