MGA MGA rear brake adjustment

[Dan_Willert]

After replacing bearings/spline hubs on all four, rear brake shoes started to seriously drag and heat up. Adjuster is all the way down and still had a tough time removing the drum after cooling down; still hard to get back on over shoes and wheel will not turn. One note; I did hear and feel a weird noise on the parking brake when I pulled it before I set out on the test run. But the cable appears to be loose now. Hydraulic lines seem to be OK. Never touched the master cylinder. My next step (since I'm out of ideas) is to perhaps bleed the system?

 

[DrEntropy]

Is your rear flex line new?


Welcome, BTW.

 

[Dan_Willert]

Thanks. Not really new. But haven't noticed any obvious defects on the lines. But I can double check.

 

[Stewart]

Outside of the line may look fantastic but the inside can be trashed. If you have any doubts replace all of them.

 

[Dan_Willert]

Would it help narrow the solution a bit if I had my trusty assistant (wife)pump the brakes while looking for action at the individual wheel cylinders? You can tell that drum brake adjustment is not my thing.

 

[DrEntropy]

Nope. The flex lines can be damaged from the inside and act as a one-way valve, allowing fluid to be forced to the cylinders but NOT allowing the fluid to be released back with the relatively weak pressure of the shoe's return springs and cylinders of larger diameter.

If you unscrew the bleed screw on a rear cylinder it'll relieve the pressure and the shoes would return to their "neutral" position.

 

[Dan_Willert]

Understood re the blockage, and fluid release. Perhaps, I'm not understanding what is meant by "flex lines". My hydraulic lines are solid tubing (copper or steel?) running on top of the differential and axle to the individual cylinders.
BTW...the cylinders aren't looking so hot; lots of gunk and grunge build up, which could also restrict the action and cause this issue.

 

[DrEntropy]

Been years since I laid hands on an A but somewhere under there you have a rubber flex line to a union supplying the hard lines on the diff.

 

[David_DuBois]

Been years since I laid hands on an A but somewhere under there you have a rubber flex line to a union supplying the hard lines on the diff.

Should be just to one side or the other of the differential.
Cheers,

 

[Dan_Willert]

Sure enough.....solid tubing from the firewall all the way back to a mounting block near right hand side battery...transitions at a fitting to a rubberized (woven) flex tubing about 10" long to a junction block mounted on the axle, where it splits into two solid tubing directed to each rear wheel. Solid tubing seems OK (no pinches etc)and no obvious damage to the flex (very slight age cracking in rubber). I'm assuming the next step is just to replace the flex; thinking about the advisability of replacing most of the tubing with new armored tubing, along with new wheel cylinders?
appreciate your patience.

 

[DrEntropy]

The flex line oughta be replaced just on General Principle if it shows cracks. The wheel cylinders are not expensive so go for it!! While you're doin' the "system" ya ~might as well~ replace the front flex lines if they appear to be "vintage" too. If the solid lines appear to be in good nick, no need to replace 'em.

 

[Dan_Willert]

Dr: If you're still out there..........pls check my last post on brakes. Still rubbing after replacing the flex, both wheel cylinders, and bleed. Adjuster all the way down, difficult to get the drum back on........and then it just does not want to turn easily, and rubs. ????????????