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Brake Question 75B

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Stewart

Stewart

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I rebuilt the rear brakes in my B right before I had to head back to the god forsaken Dakotas but at least I was able to see the sun here after 3 strait weeks of rain in so cal though the temp has been south of 0f the entire time.

I ran into a problem with the brakes the day before I left after rebuilding them. The rear brakes appear to work fine but braking is not that great and it appears the fronts are not doing any of the work. Pedal feels softer than before but firms up when the E brake is pulled.

I've also found that the brakes will soften up after starting the engine like powered brakes. It's never done this before for as long as I’ve had the car prior to the rear brakes being rebuilt. The rear cylinders were in very shape. To put it mildly the side I thought was very bad was dwarfed by the other one. Were the B’s equipped with boosted brakes?

Anyone have any ideas on what the problem may be.
Only the rear was rebuilt the fronts were left alone and had plenty of pad left.

Also since I'm not going to be around back for a few months and brakes are rather important and to keep the b safely on the road I need to find a lbc mechanic near Pasadena. Anyone have any suggestions on who to use.
 
Hi Stewart,
MGB brake systems for North American(NA) cars had a direct-acting servo (booster) fitted approx. from NA roadster car number 368082. This occurred in December 1974, the start of building the 75 model year. Non-NA cars had the servo as an option since approx. 1970.
Regarding your questions, I would first re-check the basics--be sure the shoes were adjusted properly after installing the brake drums. I assume you bled the system but it's worth a recheck to be sure there is no air in the lines whatsoever. I had a similar problem with my 72 car and re-bleeding solved the issue. Good luck!
 
Whenever I hear "but firms up when the E brake is pulled", it sounds like you haven't got the rears adjusted properly. The common phrase in the manual is to "adjust until the wheel locks and then back off slightly". Since the sequence of the adjuster is: it gets tighter then encounters a notch where it gets slightly looser and then gets tighter again, you need to make sure you've turned it far enough to really lock the rear wheel. When you do back off from this locked position, you will feel the notch where the wheel does turn easily. Using this extra tightness will actually recenter the brake components that were moved during the rebuilding process so you can get to the proper adjustment. Since you probably didn't do it this way initially, the components probably have recentered themselves during operation so now you need to do another adjustment. This may not be the last one because your shoes may further "bed" in and require another adjustment.

And don't forget to do the handbrake adjustment after everyhing else is OK.
 
Steward, I hope you bleed the whole system and not just the back portion. Always run the car for a couple 100 miles and then readjust the rear shoes. That should fix you up. Wayne
 
Nothing additional to what has already been said, but to mention that when I did my 78Bs brakes a while back I had a very similar issue with the rear brakes.

Prior to working on my brakes I noted that my hand brake would stick from time to time but other than that I didn’t really have any “noticeable” problems parse. So for no other reason than to improve my cars braking - I up rated the front end to some nice cross-drilled vented rotors, a set of performance pads and toped the upgrade off with a nice set of braded stainless steel teflon hoses. Not wanting to neglect the rear, I went ahead and purchased a new set of OEM/stock style brake shoes. But after I pulled the drums, I discovered that the shoes hardly looked warn at all.

It appeared to my untrained eye that the PO or whomever did the job, never properly adjusted the rear brakes as described above in an earlier post. This would seem to explain why my emergency hand brake wasn't working properly.

Anyway once this was all done, I completely bled & flushed the entire brake system (front & rear) and replaced with fresh fluid.

While she ain’t the fastest – my B can now stop on a dime.

Who needs ABS! /ubbthreads/images/graemlins/thumbsup.gif
 
After having worked on a number of braking systems, the best advice I can give after manipulating the brake system in any way is to bleed bleed bleed, and when finished, bleed one more time, always with fresh fluid, until there is no doubt about bubbles or debris. In addition, on my midget, I never even think about the E brake until I have the hydraulic and main braking system (shoes/pads,fluid etc) properly adjusted. Once they are dialed in, the e brake, on many older systems (mine included), is just a mechanical adjustment of a flange bolt for cable travel and tautness. The first couple times on my Midget, I got out of sequence on the bleeds and they were not effective. Paying attention to the order, feeding a lot of fluid through (gives a good flush), and patience paid off.
 
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