There have been many posts about replacing the rear brake cylinders with larger GM or Napa cylinders, but not much has been said about adjusting or maintaining them or how they work afterwards. I thought it would be best to start a new thread.

It is my opionion that when you replace these clyinders you should replace the brake shoes and turn the drums also. If the old ones are soaked in brake fluid or gear oil like mine where then the larger cylinders won't do much good.

My experiance has been that they work great, and are easy to install. More stopping power, less pedal pressure. There was a "vibration" at first however, like the wheel is out of round. This seemed to happen only when they were hot and only at first or after I adjusted them. After they cooled down they were fine until they heated up. This lasted for about 300 miles or so, then everything was fine. I'm assuming it takes time for the shoes to "seat". Anyone else have this happen?

I would like someone else to chime in with adjustment proceedures as we all know the self adjusters don't work well.

 

There's supposed to be a screw you can turn to adjust them. Not sure though as I have discs on the rear.

 

I changed to the larger cylinders a while ago and I still follow the "adjust rear brakes at oil change time" It works for me. Seems as though the adjuster has a few more clicks though......
Tom

 

Actually the adjustment should be the same regardless of the cylinders. Only that it will be more frequent since the shoes will wear. (Not so with the stock setup )
When changing the shoes I usually file a 45deg angle on all the edges. This reduces the vibrations IMHO

AlpineRAM

 

I had to adjust mine after the install a couple of times but I did replace the shoes and the drums were turned but this is normal on any rear drum brake job. As for the vibrating you may have had them set to tight.

 

I've installed the 30mm cylinders on over ten rigs and have never had to do anything special as far as adjustment, but none were oil soaked and no other parts were replaced. I've had the 30mm cylinders on my own rigs for three years, same drums and shoes, no problem. In fact I waited to be sure there were no problems before recommending them here.
It will definitely make your shoes wear faster but that's the whole idea right?

The vibration Geico describes sounds like typical oil soaked shoes. When they get hot the entrapped oil will come to the surface causing the friction surface to rapidly skip, thus causing vibration. Only solution is to replace the shoes.

 

I replaced the shoes and turned the drumns when I put the larger cylinders on. I might have them too tight. What is the proceedure for adjusting them correctly? I guess I' never have know what it is for a Dodge truck. Any thoughts?

 

My self I tighten the brakes up till they don't turn the back them off about 3-5 clicks,but you are going to have to push the adjuster arm out of the way to do this.

 

3-4 clicks is all? I back them off 1/2 turn. Too much?

 

If the drum is true thats all I back them off.

 

The way I do it it click the star wheel while spining the tire till the brakes just start to rub, that's it you're done. No need to back off, the first time you use the brakes the shoes will center themselves and the rubbing will stop.

 

That works to have set them that way many times

 

Thanks for the advise all! Now were did I put that screw driver?

 

Count me in as another happy GM cylinder user... and who agrees with Infidel's procedure for adjustment.

Weird thing.. I am fully comfortable pulling engines, fabbing roll cages, re-designing suspensions, etc... But I gave up on changing the brake shoes... Those springs are too darn stiff/... I HATE drums!!

But these work pretty darn good now...

 

Eskimo, I agree man. Brake springs can be tough. Get yourself some of the tools the pros use and it makes the job alot easier. When I was a kid I would just grab a pair of pliers and have at it. Springs go flying everywhere. Now with the proper tools its a snap. Also, I use a huge paid of 90 degree needle nose pliers. Piece of cake now.