Steering, Suspension, & Brakes

tips, technology, tools and techniques related to non-driveline mechanical components

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Merv
Merv Hagen
IL
(104 posts)

Registered:
05/21/2008 05:48PM

Main British Car:
1980 MGB Buick 215 T-5 Trans

1980 MGB Brakes
Posted by: Merv
Date: July 28, 2011 10:45PM

Earlier this spring the brakes on my 1980 MGB started getting about 1" more pedal travel then it previously had. Fluid level was fine; brakes were not spongy as it would be with air in the lines, just that extra 1' of travel when applying the brakes.

Installed new rotors, rebuilt calipers, new wheel bearings and bled and flushed all brake lines. All rotor and bearing tolerances checked out well within spec. and when the engine is off the brakes are rock solid and the pedal travel is just where it has always been.

Still have my extra 1" of pedal travel when applying the brakes.

My gut say's that it is something to do with the brake booster but not sure.

Any ideas?

Merv


socorob
Robbie
La
(173 posts)

Registered:
09/17/2009 04:42PM

Main British Car:
1963 Sunbeam Alpine Series 2 Ford 2.8 V6

Re: 1980 MGB Brakes
Posted by: socorob
Date: July 30, 2011 07:40AM

How old are the hoses?


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: 1980 MGB Brakes
Posted by: Bill Young
Date: July 30, 2011 03:48PM

Merv, If you still have the drum brakes on the rear then the problem may lie there. Try adjusting the rear brakes and see how that affects the pedal travel. On my Midget it made a big difference. If that does help you might consider installing an in line residual pressure valve in the line to keep the springs from contracting the shoes all the way. That really helped shorten my pedal travel and compensate for the wear on the rear linings so that I'm not constantly having to adjust them to keep a nice firm pedal.


Merv
Merv Hagen
IL
(104 posts)

Registered:
05/21/2008 05:48PM

Main British Car:
1980 MGB Buick 215 T-5 Trans

Re: 1980 MGB Brakes
Posted by: Merv
Date: July 30, 2011 11:28PM

Brake hoses are 3 years old and are stainless.
Rear end is GM 10 bolt and brakes only have about 25000 miles on new rear end & brakes, but this is something that I haven't checked.

I will give a try with this adjustment.

Extra pedal travel seemed to happen overnight. Not gradually like adjustment changing.

Has anyone had the master cylinder go out on one of the chambers? Not sure if my wording is correct, but I think that either the front or the rear portion of the brake master cylinder can malfunction and you would still have brakes.
Just wondering if one of the portions of the master cylinder going out could cause this extra pedal travel.

Thanks
Merv


Merv
Merv Hagen
IL
(104 posts)

Registered:
05/21/2008 05:48PM

Main British Car:
1980 MGB Buick 215 T-5 Trans

Re: 1980 MGB Brakes
Posted by: Merv
Date: August 01, 2011 03:13PM

Bill, I tried your suggestion about rear brake adjustment. I really thought due to S-10 rear end auto adjust brakes, that this would not be necessary, but sure enough, rear brake on left side required quite a bit (about 20 clicks) of adjustment while right hand side was really quite good.
Adjustment seemed to help reduce pedal travel quite a bit but still not where I remember it being,

Did you use a line residual pressure valve? If so did you use it on front or rear brakes, or both?
Looking on summit web site, looks like they have 2 psi (Disk brakes) and 10 psi for drum brakes and the cost seems very reasonable.
Hopefully there is something so simple that it almost gets done by its self.

Your adjustment suggestion, really helped, but still not perfect.
Thanks
Merv


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: 1980 MGB Brakes
Posted by: Bill Young
Date: August 11, 2011 03:01PM

Merv, sorry about the delay in answering your question. Yes I did install a residual pressure valve in both front and rear lines when I converted to my Wilwood master cylinders. I used a 10psi valve in the rear and a 2psi in the front, although I'm not sure the front one helped any at all with pedal travel or feel. The rear did make a difference.
brakes small.jpg



Edited 1 time(s). Last edit at 08/11/2011 03:02PM by Bill Young.


Merv
Merv Hagen
IL
(104 posts)

Registered:
05/21/2008 05:48PM

Main British Car:
1980 MGB Buick 215 T-5 Trans

Re: 1980 MGB Brakes
Posted by: Merv
Date: August 18, 2011 03:11PM

Bill, I have to give you a !!! BIG GOLD STAR !!! For your suggestion of an in line residual pressure valve.
There was already an in line residual pressure valve installed for my rear brakes and apparently it finally decided to quit working, which would explain why my brakes felt different.
Installed a new 10 LB residual pressure valve and brake system is back as it should be.
Can't thank you enough for your suggestion. No way would I have thought to look for this solution.
Merv



mgb260
Jim Nichols
Sequim,WA
(1968 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: 1980 MGB Brakes
Posted by: mgb260
Date: August 18, 2011 07:15PM

Merv, Thanks for letting us know the problem was resolved,way too many threads aren't complete.


kstevusa
kelly stevenson
Southern Middle Tennessee
(916 posts)

Registered:
10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

authors avatar
Re: 1980 MGB Brakes
Posted by: kstevusa
Date: August 20, 2011 08:19AM

Merv, don't forget to bring Bill a Large cup of coffee and Dount from Tim Horton's! he may not know what he is missing.
See you in Tx. next year


Merv
Merv Hagen
IL
(104 posts)

Registered:
05/21/2008 05:48PM

Main British Car:
1980 MGB Buick 215 T-5 Trans

Re: 1980 MGB Brakes
Posted by: Merv
Date: August 20, 2011 08:33PM

Kelly, I was thinking about getting Bill a couple bottles of "DICKEL WHISKY" (Did I say that correctly?) but as you said a SMALL cup of coffee might just be a better choice.
See you in Texas.


kstevusa
kelly stevenson
Southern Middle Tennessee
(916 posts)

Registered:
10/25/2007 09:37AM

Main British Car:
2003 Jaguar XK8 Coupe 4.2L DOHC/ VVT / 6sp. AT

authors avatar
Re: 1980 MGB Brakes
Posted by: kstevusa
Date: August 21, 2011 09:45AM

The cup of coffee will be OK. He will drizzle a little of the Irish Whiskey in it and have a "Toddy". Bill is ok with Dickel, but prefers the Irish. That is the choice for the "Curb Service" Maybe we could get Mr. Maloney to sponser a new award, "The Arkly" ,
for unusual conversions.
SAFETY FASTER!


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