TR2/3/3A The ABCs of Brake Calipers

[TomMull]

My TR3A is #58023 and according to the literature it should have the type "B" brake caliper since the change was made at #56384. It has A type calipers. If this is correct, then it seems likely that the calipers are not original. That would indicate that the A and B calipers are interchangeable. Can anyone confirm that? I would prefer the B calipers particularly if my car actually came with them.
I do know that the C calipers, which would be even better, will not fit without lots of modification.
Tom

 

[Hamish Racing]

Yes a and b will fit and are interchangeable and have the slightly larger disc (rotor) and the the pads are held in with spring plates top and bottom.
The later calipers TR4a through the tr6 the pads are held in with through pins ( but of different size dia.)
Some P16 imperial or P16m metric for the pipe input.
The disc is slightly smaller too.
These later calipers need a different hub mount ring. But they do fit the hubs.
So not a massive change.

 

[TomMull]

Thanks for the detailed reply. My biggest reason for the change is that I have a pair of "B" calipers. The later "C" ones would have the added benefit of being less than 1/2 the price of either of the earlier ones but I don't have any of those.
Best regards,
Tom

 

[airetex]

My TR3A has an A Type caliper on the left side and the right side caliper is missing. I'm currently searching for a replacement A Type caliper for the right side. It sounds like a B Type caliper can be used on the car. The B Type calipers are more available so would it be safe to have an A Type on the left and a B Type on the right until I can find another A Type for the right.

 

[TomMull]

I can't say that it would be safe and it would probably fail most State safety inspections but otherwise I see no reason it wouldn't work. A better choice might be to put on 2 B types.
Tom

 

[bobhustead]

While I do not have any academic knowledge of hydraulics or fluid mechanics, it would seem that the total area of the pistons in each caliper would need to be the same to avoid uneven braking, perhaps a dramatic pull.
Bob

 

[airetex]

It looks like the A, B, and C type calipers all use the same rebuild kit. So the piston area should be the same. I don't know if there is some difference in stroke or some other dimension though. Seems unlikely but I'll just wait to find a mate to the existing A Type caliper that I already have instead of risking a problem due to the calipers not matching.

Thanks for the replies!

 

[mrv8q]

My TR3A is #58023 and according to the literature it should have the type "B" brake caliper since the change was made at #56384. It has A type calipers. If this is correct, then it seems likely that the calipers are not original. That would indicate that the A and B calipers are interchangeable. Can anyone confirm that? I would prefer the B calipers particularly if my car actually came with them.
I do know that the C calipers, which would be even better, will not fit without lots of modification.
Tom

Tom, I have #58370. These are my rebuilt calipers. Don’t know if they are ’A’ or ‘B’ type.

 

[TomMull]

Yup, Those are the "A Type". Appears as though there are some inconsistencies in the numbers. Not unheard of with Standard Triumph. Could be me too. I don't remember where I got that data so the credibility might be suspect.
Tom

 

[jfarris]

Tom, are you sticking with originality?
I have the Toyota 4 pot conversion on my TR3 and they work great. They fit with the original disc, may need a bracket change and the brake line on the caliper end needs a different thread. All parts and pieces available from you local parts store, RockAuto, TSI, etc.
Search Toyota brake caliper conversion on BCF.
You won't be disappointed.

 

[TomMull]

Actually airetex raised the question above. There are several reasons to upgrade including the price and scarcity of the A calipers. The B ones are a bit more plentiful but still pricey. The C ones are even cheaper but require a little modification to make them fit. They will all perform nicely, in my experience. All things being equal, I personally like to keep the originals. But all things are not equal so you make the best choice for your situation.
I have no doubt that your 4-pots are better but the way I drive I've never needed improvement over the original setup.
Tom