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MG Midget and Sprite Technical - Dual Circuit Brakes on 1275

Is is possible to replace the single brake circuit on the earlier cars with dual circuit?

There would seem to be a safety advantage. Would the dual master cylinder just swap with the single circuit? If so, is the spec for the master cylinder a match for the 1275 brake components?
G Williams (Graeme)

Graeme, I posted an answer to this on the “brain, advice, MoT - all fails” thread on the midget General section. At the time, I didn't know you had posted it here. Here is what I said in the other thread:

A few posts back, you asked if converting from single line to twin line brakes was done. I did it to my 65 Sprite. I installed the pedal assembly from a newer model Spridget. I did have to enlarge and brace the hole that the assembly bolts to, but I was already in the middle of a lot of cutting and welding when I did it.

Charley
C R Huff

Thanks Charley, just seen the other thread too!
G Williams (Graeme)

I did the same as Charley on my 59 Frog. Since you now have two lines going from the MC to the brakes instead of the one, where it splits off at the four-way coupling, I put in the T from the rear axle for the front brakes and ran the rear brakes through an extra piece of tube and a female to female coupler. I'd already put discs on the front and since I had a complete rear axle assembly from a 76 Midget, I threw those rear brakes on as well though you don't really need to do that. The hardest part was cutting the oversize hole for the pedal box.
Martin Washington

The pedal box aperture on your car isn't a problem, as it is a Mk4.
Dave O'Neill2

So is this a mod which is regualrly carried out? I get the impression it isn't.
G Williams (Graeme)

Hiya,


It'll involve a fair bit of replumbing the brake lines as well to incorporate the PDWA.


Sounds a lot of work to me.


Regards Steve.
SR Smith 1

Steve - what's PDWA stand for?
G Williams (Graeme)

Ok - got it! Is that purely a mechanical balancing valve?
THere are sensor/switches - do they do more than bring on warning lights?
G Williams (Graeme)

Hi.

It's stands for Pressure Differential Warning Assembly I think.


Guess it's not essential, but basically it's a link between the two circuits with a shuttle valve thing in it.


As long as the pressure is the same in both circuits the valve stays central. If one side loses pressure, the valve shifts across, trips a switch and on the OE installation the Brake Warning lamp illuminates.


On the 1500 it's fitted at the rear of the engine bay on the nearside, brass thingy with a white plastic switch screwed in it. Serves as a junction point for the brake pipes as well
SR Smith 1

This thread was discussed between 09/04/2013 and 10/04/2013

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.