9" drum to KH disc

[TheDeputy]

I've got the chance to buy a complete disc brake set-up from a 71 valiant. I know I have to get everything from the upper control arms to the lower balljoint, plus the mc and prop valve.
But what kind of brakes would be on the rear of the donorcar? the same 9" drums I have now, or 10" drums?
If they are 10", which I presume, do I need the complete set-up including the backing plate? And what about the axle's, are they the same (both cars have sbp and a 7 1/4)

Thanks,

Antoon

 

[TheDeputy]

Bump.

 

[Longgone]

With a 7.25 rear it`s highly likely 9" brakes.

 

[65 Dartman]

With KH on the front it's possible the rear might be an 8 & 3/4 which would definitely have 10 in brakes. Years ago I parted out a 71 Valiant 4 doors with that very same combination.

 

[grumpuscreature]

You don't need the upper control arms for the KH setup but if they are nicer than what you have grab them. The only swap that requires upper arms is the '73 up BBP discs, and the only reason they are necessary is because of a physically larger upper ball joint.
To answer your question, the rear brakes on a KH disc equipped, or V8 car should be the 10"X1.75" and you will need everything including the backing plates. The axles will be fine since the 10" brakes are actually 1/4" narrower than the 9 inchers (9X2). The difference in brake width is made up for in the dish of the backing plates. I know this swap works since I just did it on my '66 Valiant, just make sure the donor rear is a 7 1/4".

 

[RedFish]

If the 71 was a V8 car it shoild have had 10 drums front and rear with optional front discs.

 

[TheDeputy]

I know for a fact the donor car has a 7 1/4 and that the front brakes are the four piston KH type. I took a look at the rear brakes, and the drums had a strange cooling fin which came out underneath the wheel. It's hard to explain but it looked like some sort of dish?
The donor car is an original valiant, but it's been made in switserland in the schinznach factory.
I'll just take everything from the upper a-arm to the lower balljoint, and on the rear everything from the backing plate out, that way I won't miss out on anything.

Thanks for the input

Oh one more question, what's the minimal thickness of the discs?

Antoon

 

[TheDeputy]

And by the way, the donor has a 225 automatic. no sway bar, so probably no HD suspension.

Antoon

 

[Vs29H1B]

Minimum thickness of the rotors is stamped on the back inner/outer edge of the rotor. Check the factory service manual for the exact minimum, but if memory serves the minimum is .75 thickness.