Steering, Suspension, & Brakes

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

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geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
MGB rear disc brakes
Posted by: geezer
Date: November 20, 2017 01:50PM

I have designed rear disc brakes for my 74 MGB. I'm not new to this so I know the benefits and pitfalls of rear disc brakes. My question here is about the master cylinder. Does the check valve for the rear circuit need to be removed on from the stock MGB master cylinder? I have everything mocked up to my satisfaction, just need to address the M/C before I install everything on the car..

On some of my conversions on other cars I did have to remove the internal check valve and then replace it with a 2psi external valve, on other MG's I could leave it in. I did do a research on rear disc conversions and have not found any mention about the M/C internal check valves in a MGB M/C.
small IMG_1867.jpg
small IMG_1874.jpg



Edited 1 time(s). Last edit at 11/20/2017 07:27PM by geezer.


mgb260
Jim Nichols
Sequim,WA
(1811 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: MGB rear disc brakes
Posted by: mgb260
Date: November 20, 2017 10:21PM

I don't think the MGB master has a residual check valve. People have had trouble with the brass H where the lines meet. I would do away with that and separate front and rear. I do like the aftermarket 2lb residual valves for disk brakes.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5354 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: MGB rear disc brakes
Posted by: BlownMGB-V8
Date: November 20, 2017 10:27PM

Seems to me the '74 had the MC with the big round cap. Later MCs had the rectangular reservoir and there was a built-in brake balance switch. Not sure about any check valves though.

Jim


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: November 21, 2017 08:26AM

Yep, My M/C has the round cap. The parts breakdown for the M/C does show check valves in the ports. I just can't find the values for those valves. I'm going to try it without mods and if I need to remove them, add 2lb inline valves. The valve in question is item 21. Since both are the same part number in the Moss catalog I doubt they are more than 2lb.
MGB master cylinder.jpg


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5354 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: MGB rear disc brakes
Posted by: BlownMGB-V8
Date: November 21, 2017 12:31PM

Sounds to me like a good approach.

Jim


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: November 29, 2017 01:00PM

Started the install over the weekend and then it stalled out. Thought I had wheel seals and the discovered I only had one. Only got the right side done. Oh well something to do next weekend.
assembled.jpg
IMG_1919.JPG


WernerVC
Werner Van Clapdurp
Lynchburg, Va
(76 posts)

Registered:
09/06/2009 12:56PM

Main British Car:
MGB 1977 Rover 3.5

Re: MGB rear disc brakes
Posted by: WernerVC
Date: December 01, 2017 07:09PM

Looking good Charles. Nice work.



geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: December 01, 2017 09:47PM

Thanks, hope to get back on it tomorrow afternoon or Sunday afternoon.


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: December 02, 2017 10:19PM

Took the GT for a spirited test spin today. The brakes have a good firm pedal. Temps are 190 front 130 rear. I really dislike the Wagner PD900 pads. The box says ceramic but the pads feel and look like metallic. They squeal even when just driving down the road. I'm going to try something else next weekend. The rear brakes do not lock up first.

I need to make some adjustments with the park brake cables. That will be simple enough to rectify.
assembled.jpg



Edited 1 time(s). Last edit at 12/04/2017 09:51PM by geezer.


Scott68B
Scott Costanzo
Columbus, Ohio
(499 posts)

Registered:
10/25/2007 11:30AM

Main British Car:
1968 MGB GM 5.3 LS4 V8

authors avatar
Re: MGB rear disc brakes
Posted by: Scott68B
Date: December 02, 2017 11:08PM

Excellent work Charlie!


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: December 09, 2017 04:49PM

Found the noise. The anti-rattle shims that come with the PD900 pads were the cause of all of the ills. I rounded up another set that are a different shape and now the irritating racket is gone. The new shims hold the pads more securely. Rotor temps today were 90 rear and 160 front. The stops are straight and no surpries during vigorous brake application while turning.

When I get a chance I may experiment with some 38MM 240SX calipers that I have. That will be for another time.

I'm happy now.

1st 2 pics are the troublesome shims
last 2 are the good shims

troublesome shims.jpg
troublesome 1.jpg
good shim.jpg
good 1.jpg



Edited 2 time(s). Last edit at 12/09/2017 05:09PM by geezer.


rficalora
Rob Ficalora
Cypress, TX
(2389 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: MGB rear disc brakes
Posted by: rficalora
Date: December 10, 2017 09:35AM

Cool! But, where in the world were you able to get just the anti-rattle shims? I've never seen them sold separate from the calipers or pads.


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: December 10, 2017 09:37PM

The hardware can be had at Rockauto and I'm sure at NAPA

[www.rockauto.com]

In my case one set came with the calipers and the other with the pads


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: December 10, 2017 09:56PM

The next challenge is one of the reman calipers has inop park brake. Discovered the problem when I raised the car to check things over. With the park brake set the right was applied solidly, the left not. I want to see if I can discover the problem with the left side before I move on.

While fiddling today I made a proof of concept mounting for a 38MM 1998 Nissan 240SX rear caliper. The 240sx caliper requires a different offset for the axle bracket. I was able to make a simple 4 hole bracket attached to the bracket for the Sentra caliper. The alignment is good and it uses the same rotor. Basically it's 4 10mm holes spaced 115MM x 29mm with a cut out to clear the 240sx caliper cylinder.

The 38mm will give more bias to the rear at the expense of a little more pedal travel.


geezer
Charles Durning
Magee, MS
(14 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: December 12, 2017 05:07PM

I decided to draw up the adapter. I'll make a template out of steel this weekend and give it a test fit on the car.

The adapter provides the required additional offset and move the the 240sx mount holes out for alignment with the existing rotor. I did add an additional hole that attaches to a nearby bolt for strength.


IMG_1956a.jpg



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