Rear drum brakes have uneven brake force

[Ornamental]

After technical inspection, I was told it the rear brakes have uneven brake force distribution, with one side having 30% more brake force than the other.
Is this something that can be adjusted in the drum brakes?

If not, where can I buy new parts?
Tried browsing Mancini Racing and Summit, Roseville, Josh's, and Jegs without noticing any other parts than the drum itself.

[Bullitt-]

Parts are available through most US parts stores ... Rockauto.com might be a good choice if you need shipped overseas

Star Wheel and properly working automatic adjusters is the key... you can manually adjust with a brake spoon

Worked on this issue the other day,   leave the cable off the cable guide until you hook the overload spring in the  adjuster lever, then pull the cable over the guide..... after all back together grab the adjuster lever with pliers & pull straight down & it will "cock" & when released should pull in and against the star wheel.    You can work the adjuster by pulling against the cable to see that the star wheel is being engaged.

[Ornamental]

Thank you very much Bullitt! 

[dfrazz]

You may only need to adjust the brakes with out new parts, however I would double check the springs to make sure they are still good and in place.  The adjuster screw can be accessed through a slot in the back bottom of the drum.  There is a official spoon tool, but I've done with a small flat screw driver.  You will hear it click as it turns.  To loosen move the adjustment lever up and spin the screw the opposite way.

['Cuda Hunter]

Could this have something to do with the proportioning valve?
Or would that only change the front to back distribution.

[dfrazz]

Could this have something to do with the proportioning valve?
Or would that only change the front to back distribution.

That is front to back with the line to that back teeing off at the axel.  He could have a blockage in the line to the weak side I guess. 

[YellowThumper]

That is front to back with the line to that back teeing off at the axle.  He could have a blockage in the line to the weak side I guess.

Also if your brake line is not properly bled on one side compated to the other it will not be as effective.
Make sure:
Properly bled
Brake pistons moving freely with no leaks
Star adjuster also clean and free moving. Along with proper adjustment.

If pads are new make sure their full surface is in contact. Most times initially they will not start out the proper matching diameter. This is norm because they will wear in to fit. But before then there could be a difference in contact surface.

Make sure the contact points on the backing plates are not warn leaving a ridge the pads edge could get hung up on. It's not much movement but must slide evenly.

All things work in concert with each other.

Mike

[Chryco Psycho]

Make sure the shoes with the longer lining are on the rear on both sides , the reduced grip could have a shorter lining on the rear  this is a common mistake

[Ornamental]

Thank you all for much good advice here!!