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MG MGB Technical - Brakes Conversion

For the group--
During the restoration of a '67GT I'll be rebuilding the brakes, and I'm wondering if anyone's ever replaced the single line master with a later non-servo, tandem system, like the one in my 72 roadster. I'd replumb the car the using the 72 as a guide. I'd like to believe that a "functional improvement" will somewhat offset the cries of the "originality" fans. I can still remember the day that the 63 VW lost its brakes.
Anyone have experience or an opinion?
Thanks in advance
Rich
RichB

Rich,
Go for it. A little redundancy never hurts. I would go ahead and buy a new piping kit for a 72 GT, those steel lines are getting pretty old. Moss listed a nice Nickel/Copper set; although opinion varies on this board as to using Nickel/Copper. I would also replace the flex hoses with stainless steel jacketed Teflon hoses.
Leland Bradley

Rich, for some classes of SCCA racing you would HAVE to replace the single line setup. I also say go for it. I would leave out the bias switch, though, unless you happen to have a good one laying around. They are $$$$$$$$ and a potential leak in and of themselves.
Ken Lessig

Rich,

I've already done this conversion on my '67 GT, I think it was about nine months ago, and it's still working fine. I couldn't bear to leave the hardly used(and expensive) master cylinder in my '70 GT after somebody kindly totaled it for me. Anyway, it's a fairly easy swap, the master cylinder fits into the same housing as the single circuit one, although it would be beneficial to get a later cover as it already has a threaded insert for the mechanical brake light switch. As long as these pieces are out you might as well have the bracket, cover, brake, and clutch pedals powder coated black. I suggest powder coating as any spilt brake fluid will not damage it as easily as paint.

Getting back to the subject, you will need the brake lines for the front half of a dual circuit car, as well as the distribution block that mounts to the fender. I removed the plastic warning light switch that from the block, I plugged it with a short bolt and copper washer. You will also need a sutible length of new brake line as well as a F to F connector to plumb the rear line in, just make sure you get the right type of flares as most american cars have a different style.

To get started you will need to remove the front lines from your single circuit system, as well as the old distribution block. Install the bracket containing the master cylinders into the car as well as the short lines leading to the distribution block and then the block itself, mount this like the later cars. Now you can run that new line from the new block to where the end of the rear line is poking up on the other side of the engine, I just ran it in front of the heater as it's the easiest place and it looks right.

For the front brakes I did not run the lines in their original place as it would have been too dificult with the motor in the car, I ran the right line right alongside the rear line instead of across the backside of the suspension crossmember for simpicity. I was able to run the left line in a similar location as the later cars. It doesn't look bad, but if you know where the later lines are plumbed in,it doesn't look quite right either.

Anyway, I hope all this came out clear enough as I'm new at dispensing technical information on this board, if you have any spesific questions I can actually go look at my car and see what I did rather than try to remember it from my chair. One more thing, don't forget to extend the wires for the new brake light switch as the old one was a pressure switch on the old distribution block that you are no longer using.

Hope this was helpful.

-Jared
Jared Snider

Rich-
What you're contemplating falls into the catagory of "Definitely A Good Idea". Safety Fast, you know.

I don't know about Wisconsin DMV regulations, but many states have outlawed the nickle/copper alloy pipes due to their tendency to crack. I'd go with stainless steel brake pipes, even though the metal is a little harder to work with. Any decent auto parts supplier should have it. Not only will they not crack, but they're impervious to road salt.

Like Leland, I also use the teflon-lined braided stainless steel brake hoses. They don't expand under pressure and result in a nice firm pedal. Modulating the force of the brakes becomes a much more precise affair. Small increases in pedal pressure result in equally small increases in braking force. I've also helped two of my sons put them on their MGBs. They cost more, but they're worth every penny!
Steve S.

Steve I am starting to read your article (thak you for it again) about handling and I know you are in favor of double circuit for the braking sistem (for obvious reasons). I want to keep my 69B as original as possible so I realy dont want to change to the double plumbing but for that uprating the one I have is my idea.
When restoring the car two years ago all rubbers hoses and cylinders where renewed but I kept the original metal pipes. Are they suposed to be changed to ? Do they sufer from metal fatigue to?
Thanks again
Miguel
Miguel

Miguel-
Yes, they can suffer from metal fatigue and fracture. Your metal brake pipes are now at least 32 years old, so replacement falls into the category of "A Good Idea". Replace them with stainless steel.
Steve S.

Has anyone out there eliminated the pressure failure switch, which has a slight leak on my '72B (fluid in the connection) I see no purpose to it, if a line breaks I will certainly know it without a light going off. Is there a replacement that eliminates the H shaped block without repiping the entire system? The cost of the entire switch and body is excessive, @ over $300 in Moss, and just as high or unavailable at other suppliers.
Joe

If you replaced the switch with a correct sized pipe plug it would do exactly what a broken switch would do- the brakes would continue as usual, but the warning light wouldn't light/go out, so also simply disconnect the electrics at the switch.
Ken R
Ken Rich

This thread was discussed between 10/12/2001 and 14/12/2001

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