Need some advice

[RadioMan]

I have a 79 Concord Wagon with the 258 2v auto, front disk and rear drums.
Here is my story. I took a look at the rear shoes and noticed I ought to
replace the shoes before the rivits dug into the drums. I bought rebuilt
shoes from Advance Auto Parts. The next weekend I replaced the shoes. I
did one side at a time so I could look at the side I had not touched yet for
locations of springs just in case I forgot. I've done this for years replacing
rear shoes. I did NOT have the drums turned because there was no damage
to them from what I could see. By the way, there is 75k miles on the 79 so
this was the first time shoes were replaced. Everything went back together
like clock work. I adjusted the new shoes to where they touched the drums
then backed them off a bit.

Here is the problem. I took the car for a test drive. I was going around 50
mph and applied the brakes kinda hard. The rear of the car vibrates bad
untill I let off the brakes or get to around 25 mph.

I then thought maybe the drums do need turned so I removed them and took
them to have them turned. I had them check both drums first to make sure
they still could be turned plus are they out of round. Both drums have never
been turned and both were not out of round. They did turn both drums as I
waited and watched.

I re-installed both drums and took the car for another test drive. Same thing.
Vibrates when brakes applied untill around 25 mph.

What I ended up doing (for now) was I backed the rear shoes off even more
to where they hardly do any braking at all. No more vibrating and the brakes
are doing their job. I can lock up the rear wheels if I want to (tested it).

So guys, what the heck did I do wrong with this simple brake job?
I grew up replacing shoes both front and rear and never ran into this
problem before. It's hard to believe I might have had the shoes adjusted
too tight, or did I? The old (still serviceable) shoes on the car worked just
fine and no vibration or problems at all. I just wanted to replace them before
the rivits hit the drums.

You can leave a reply here or E-Mail at. n8fis@juno.com

Thanks for any and all replys. Bill in Ohio

[Big Bad AMX]

It's just a suggestion but you may want to back-off the emergency brake cable equalizer. If someone adjusted the emergency brake in the past it may be too tight for brand new shoes. Also, check to see that the emergency brake cable moves freely. It may be sticking and need to be lubed.
Good luck and let us know if you find the problem

[donsjave]

I kind of wonder if the self adjustor is doing its job to well. You might want to also take a look at the star wheel (same place as where you did your original setting). They say you should back up the car and moderately press your brakes. They should adjust themselves automatically. If the starwheel is stiff or not working properly, then your brakes will not adjust correctly. Also take a look at the linkage to the starwheel and adjusting unit and make sure that they are routed correctly.
I have fought drum brakes on my Javelin for years, ended up going to Disc Brakes last year for the front, but I am similiar problems of the brakes vibrating badly especially the right front.
Also you might want to look at the proportion valve. Do not know much about those, just a thought

[RGBJavelin]

You probably fixed this by now, I wonder if maybe the hardware might be the culprit, a weak return spring? Or maybe contamination? I have ended up with defective relined shoes, are the linings attached straight, maybe one is cock eyed. Lastly, Do you have the primary and secondary shoes in the right locations? just a thought.