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Repairing the Mazak horn ring on the A90

Part 4 shows how George went about fixing up the damaged horn ring that was fitted to his Austin A90.

Read about how repairs to this Mazak casting were effected.

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"The horn ring on my A90 was broken off and missing. In getting some A90 spares last week I was given an A70 Hereford hub with horn ring and was told its not the same as the A90 so couldnt be used. As it 'looked' like what I wanted I thought I would check out further.

In taking the A70 Hereford hub to bits (not easy!) it did look like the ring was the same as the A90. All 3 ring spokes on the A70 ring had broken of there mount plates.

I decided to have a go at 'Technowelding' them. This is very difficult as Mazak or any pot metal is very difficult to gauge and tends to melt away without warning. Anyhow, its a long story but using my medium nozzle in the gas brazing set I managed to Technoweld the original A70 mounts onto the spoke ends thinking it might be OK for someone for a Hereford I then thought I would check the A90 hub on my car.

So, I took out the centre hub from the steering wheel and took that to pieces (nearly as bad as the A70 hub) and removed the ring hub mounts (the original A90 ring was not with the car). I could see that the A70 ring was in fact an A90 ring that had been re-worked to a new arrangement. The original spoke 'bumps' han been ground off and the spoke mounts drilled and riveted onto a steel ring plate. One of the A70 spoke mounts was broken in half and part missing.

Austin
As welding of the mounts to the spokes proved very difficult indeed (they deformed their shape) I decided the cut down my A90 spoke mounts and cut off the A70 ring mounts to mate the two. This was more difficult than it sounds, Mazak is amazingly hard and the steel disc cutter found it slow going.

In all it seems possible to modify a good unbroken A70 ring to fit an A90 but you would need to drill out the rivets and remove the steel ring plate and either rivet or drill and tap for screws the A70 version to take the A90 retaining 'ears' which were originally mazak rivets and put back the ground off end 'bumps', that's all asuming you can find a good A70 ring in the first place!

Mazak is surprisingly hard to cut and file and is a pig to weld. The A70 ring does have a slight buckle in it but I can live with that, its a relief that it seems to have worked at all. For a while last night I didnt think I was going to be able to do it but determination won through in the end.

A90 hornring (mazak casting)

A70 hornring (mazak casting)

A90 hornring (mazak casting)

A90 hornring (mazak casting)




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