worn Warren Bond Toronto (26 posts) Registered: 06/28/2013 09:56AM Main British Car: 1973 MGB 305 Chevy |
Brake Servo
My MGB has a TR7 servo and master cylinder installed by the PO. The MC works fine but I doubt ever rebuilt, and the servo is leaking and brake fluid is getting sucked into the intake manifold. Simple, replace or rebuild but I'm looking at aftermarket master cylinders and 7" servos made for hot rods. They look good, are inexpensive and I can't see any real problem to adapt, but they have 1" bores. Anybody running 1" bore master cylinder with stock brakes? I believe the pedal pressure required will be quite high, am I right in thinking the servo will even things out and give good pedal feel and braking?
Thanks Edited 3 time(s). Last edit at 12/08/2013 10:48PM by worn. |
88v8 Ivor Duarte Gloucestershire UK (1041 posts) Registered: 02/11/2010 04:29AM Main British Car: 1974 Land Rover Lightweight V8 |
Re: Brake Servo
No, it will be a disaaaaaaster...
Depending which master you have, the bore diameter is 0.692" (early) or 0.75" (late model). Effort is proportional to the piston surface area, which is 0.38"sq and 0.44"sq respectively. A 1" master has a piston area of 0.79"sq. So, that's 0.79 compared to 0.38 or 0.44, say around double the pedal effort for the same braking. No, the servo will not sort that out. You could perhaps fit a second remote servo in series, but there you're into unknown territory afaic. Sorry !! OTOH it would do wonders for your leg muscles. Ivor |
mstemp Mike Stemp Calgary, Canada (222 posts) Registered: 11/25/2009 07:18AM Main British Car: 1980 MGB Rover 4.6L |
Re: Brake Servo
Warren,
I am running a hot rod booster and Ford 7/8" mc wo issue. Not sure why the booster would force you to use a mc of 1". They are a standard size where it protruded into the booster I thought. Edited 1 time(s). Last edit at 12/09/2013 11:55AM by mstemp. |
worn Warren Bond Toronto (26 posts) Registered: 06/28/2013 09:56AM Main British Car: 1973 MGB 305 Chevy |
Re: Brake Servo
The reason I was asking about 1" bore master cylinders is because so far all I've come across are 1" dual line master cylinders and the 3/4" have all been single line.
But, if the size where it mounts to the servo and the bolt spacing are the same, gives me a wider range to look at. |
worn Warren Bond Toronto (26 posts) Registered: 06/28/2013 09:56AM Main British Car: 1973 MGB 305 Chevy |
Re: Brake Servo
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88v8 Ivor Duarte Gloucestershire UK (1041 posts) Registered: 02/11/2010 04:29AM Main British Car: 1974 Land Rover Lightweight V8 |
Re: Brake Servo
Changing the pedal leverage has the same effect as changing the hydraulic leverage by fitting a different master. Except in this example the change is in a helpful direction, compared to that m/c change which wasn't.
In my 74 Landrover (V8) I fitted larger wheel cylinders with a stock m/c, and that had the effect of increasing the hydraulic leverage so I had less pedal effort, but, more pedal travel. The factory could have done that but it meant more frequent brake adjustment to keep the pedal off the floor and would have conflicted with their desire for longer service intervals. Just to mention, the same applies with that pedal mod you flagged; more leverage means more pedal travel. One can do the same sort of thing with the handbrake lever to increase the power of the handbrake, but the brakes have to be adjusted more frequently so as not to run out of travel. Ivor |
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