The Stovebolt Site Forums The Shop Area Driveline Drum Brake Linkage Issue

I've come to a crossroad in an attempt to getting the rear drum brakes to function properly. Again late model Camaro 10 bolt. What I'm encountering is the orientation of the star wheel adjuster to that piece that opposes it and allows you to advance the wheel one click at a time.
Notice the link indicated with blue arrow....and note the gap at what should be a contact point between the star wheel and the plate, blue arrow. The only thing that keeps upward pressure in order for this to ride on the wheel is the link. Of course this is a pre-bent stout piece and should work the first time every time...wrong. So, unless I'm totally missing something that link will need to be tweaked (bent) a little to shorten its overall length. Easier said than done. So what am I missing here fellows?????

bump!

Quit bumping your posts. 19 minutes and your bumping. Be patient.

10-4

Hy Apache1, I don't know if this will change anything with the adjuster, but if that cable that appears in the right lower area of your picture is the emergency/parking brake cable, then your brake shoes are on backwards. Your primary shoe is on the rear and should be on the front.

The shoes straight out of the box are identical side to side...front to back...not sure I follow. E-brake hardware was not disturbed during rebuild and btw they are not connected under the truck.

I read where this linkage in question had to be tweaked before on older GM vehicles, in order for the adjuster to work?

I believe the green spring is incorrect and it may be putting too much pressure on the link and not allowing it to drop in the correct position. If I remember correctly the spring is smaller in diameter and has a smaller coil wire size.
Fred

I agree the kit provided had the (green) spring as a replacement. For the sake of argument I cut and removed about a coil and a little to see if that would relax the arm more...it did but not enough. When you pry up on the arm where the link is attached it drops the arm right into position. So it seems once again the link is a shade to long.

3B : After you made me aware to the primary/secondary shoe configuration, I went back and looked carefully at the drivers side. They are mounted in correct position...I will disassemble and correct passenger side. Good eye...there is such a subtle difference but there is a difference.

In the 1st pic left to right notice the beehive spring under the adjuster level. That appears to be correct. Didn't have one of those in the aftermarket spring kit. Also, the horizontal spring in the same pic at 6 O'clock just behind the star wheel is supposedly installed correctly. Easy to switch mine around. Don't think that's given me any interference problems.

The fixed link in the other two pics is from another tech article having the same issue showing before and after its tweaked then re-installed. That's the only other potential for adjustment I have. Hard to believe I must attempt to modify (bend) a stout brake component that has a fixed length designed by mechanical engineer and by trial and error to make it work. Crazy......

Comments/feedback...thanks

Who is our resident brake expert?

You are looking for a Camaro brake expert.

I'm not an expert and it's a long time since I installed my brakes, but it seems to me that you have to adjust the shoes so that they are close to the drum diameter before you install the drum. When you do this, the adjuster moves closer to where it should be. So try turning the star wheel while watching the adjuster and see what happens.

In the future, it is always wise since we all get distracted at times, to take pictures before we disassemble anything, also if one is working on two or more identical items, it is always wise to leave one assembled while the other one is worked on. Saves a lot of headaches like this one.

Ed

For the record...I did take pictures...before and after. The before pics show...non-working brakes...leaking cylinders....saturated shoes...etc.

This problem may not be in peoples wheelhouse on this site. Note: the relationship between the star wheel and the contact point doesn't change when expanding nor retracting shoes.

Don't bend the linkage rod- - - -it's much more likely that the sheet metal piece that contacts the star wheel has gotten twisted than the actuating rod getting bent. That is usually caused by a rusted adjuster screw that refuses to turn. Give that part a slight twist so it puts a little pressure on the star wheel teeth. Also look for wear at the point where the pawl meets the star wheel- - - -a rounded-off edge will not engage the wheel properly. You can file the edge sharp again- - - -the metal isn't hardened. A quick way to see if the adjuster is working is to use a big screwdriver to pry the rear shoe away from the anchor pin at the top above the wheel cylinder and see if the adjuster advances a notch on the wheel. Anytime the lining wears enough to allow a certain amount of brake shoe movement, the adjuster will advance one notch. Since the self adjuster only works in reverse, a quick way to make a final brake adjustment is to make 10-20 accelerate/full stop maneuvers in an empty parking lot, etc. with the vehicle backing up.
Jerry

OK... then I will not bend the linkage rod and concentrate my efforts on the sheet metal arm. Worth noting it must have been a bad design because everything else I see on the web is showing this as one piece...also with an additional spring that more than likely aids in keeping things in full time contact. Not sure of the GM vintage set-up I have.

Also, for good measure while I'm figuring this all out with everyone's help...I will replace the worn down star wheels as well. Can't hurt.

Alright I'll check back with the prognosis.

Thanks as always

Actually, that design is a big improvement over the first-generation automatic adjusters that used a cable to move the adjusting pawl. Up in the snow/salt country, those cables had a lifespan measured in months, not years! At least the system used on your brakes doesn't corrode away like the earlier types!
Jerry

Just one more thing....the fact that my e-brake cables are not functional but still in place thru the backing plate...etc., has no bearing on the functionality of the adjusters...CORRECT?

Are the parking brake cables free? If they are frozen they are likely holding the actuating lever forward.
Many applications had an oval spring on the tie bar that I don't see in your pictures, but I think they were for anti rattle, not really functional to the system.
It's been years since I've done a set of those so don't crucify me.

When you mean free....are you referring to the movement of the cable inside the outer sheath? I have no idea...but will check. In fact I'm not sure if or how the e-brake interfaces with the adjuster if at all.

The e-brake system is an entirely different mechanism. It consists of a cable operated long lever arm and a strut bar that bridges the gap between the brake shoes above the axle shaft. Pulling on the cable expands the shoes by mechanical leverage, no hydraulics or self-adjustment is involved. Severely loose brake adjustment can minimize the effectiveness of the parking brake also, however, since the shoes can't expand far enough to get a firm grip on the drum. Just be sure the cables aren't frozen and keeping the lever arm from retracting all the way.
Jerry

I will be sure to inspect the cables as I attempt to get the adjusters working. Thanks for pointing this out.