# 1966 GTO rear brakes diagram \original equipment.



## Pinexcorp (Jul 12, 2020)

I wonder if someone out there knows or can confirm for me if a 1966 GTO rear brakes came equipped with a brakes adjusting mechanism. I recently purchased a 66 and it seems like someone had installed springs that were not appropriate for the system and I started wondering if the whole thing was out of whack. My brakes do not have an automaic brake adjusting bar. I have tried to look for diagrams but without any luck. I would like to confirm if indeed original brakes had the automaic adjustment bar. A diagram will definitely help to determine correct spring location. Thank you


----------



## PontiacJim (Dec 29, 2012)

Pinexcorp said:


> I wonder if someone out there knows or can confirm for me if a 1966 GTO rear brakes came equipped with a brakes adjusting mechanism. I recently purchased a 66 and it seems like someone had installed springs that were not appropriate for the system and I started wondering if the whole thing was out of whack. My brakes do not have an automaic brake adjusting bar. I have tried to look for diagrams but without any luck. I would like to confirm if indeed original brakes had the automaic adjustment bar. A diagram will definitely help to determine correct spring location. Thank you


Yes, automatic adjusters. Some will pull them off and not replace and then you will have to manually adjust them.

Purchase a Service Manual for your car which will have what you need. Found Here- 








FAQ - General: GTO and Pontiac Reference Sources


Surprised this has not been brought up - a suggested reading list for us Pontiac enthusiasts. Let's list any books, journals, factory literature, CD's, or other printed materials tht may be of value. And, it does not have to necessarily be Pontiac specific if it can be applied to out hobby...




www.gtoforum.com


----------



## Pinexcorp (Jul 12, 2020)

PontiacJim said:


> Yes, automatic adjusters. Some will pull them off and not replace and then you will have to manually adjust them.
> 
> Purchase a Service Manual for your car which will have what you need. Found Here-
> 
> ...


Thanks Jim I really appreciate your response. Do you by any chance have a picture from this manual switch that I can determine the correct position of the springs. In the kit that I purchased from O'Reillys has a shorter spring in a longer break return spring. Not sure which one goes in which side. When I bought the car the brakes were totally locked up and I'm sure had to deal with the incorrect springs being put on there. I will purchase the repair manual as you suggested but I sure would like to put this baby back together today. Thanks


----------



## PontiacJim (Dec 29, 2012)

I do not have a '66 Manual. Most GM A-body brakes are the same. The rear will have the parking brake cable lever on the shoes. So most any diagram online will show this. Here are a couple.









Drum brake assembly by R Slaughter






www.pbase.com









Mastering GTO Restorations: Brake Guide







www.pontiacdiy.com









Drum Brake Assembly, Rear, 1964-72 A-Body, Complete @ OPGI.com


Brake assembly rear Drum brake assembly rear




www.opgi.com





Larger lining shoe is called the "primary" and does most of the braking - goes on the rear of the drum looking at it. The shorter "secondary" shoe goes on the front.

Here is a video from Youtube. Don't waste your time to watch as it really doesn't give you much in instructions as it is more like a follow along for someone who already knows what they are doing. Instead, move up to the 4:49 - 4:59 time frames. You can pause at any time. This shows you some great detail of the rear brake assembly and you can easily follow this as a guide and see the items that may be missing/needed.


----------



## Pinexcorp (Jul 12, 2020)

Thanks James that really helped at least to put my mind at ease. I will put it together without the automatic adjuster bar and will probably buy one and all the parts and install it later. I'll start working on it today. Thanks for your help. Be safe


----------



## Pinexcorp (Jul 12, 2020)

Pinexcorp said:


> Thanks James that really helped at least to put my mind at ease. I will put it together without the automatic adjuster bar and will probably buy one and all the parts and install it later. I'll start working on it today. Thanks for your help. Be safe


I had actually seen that video before but because it has the automatic adjustment bar I was not sure if I was looking at it right year/configuration.


----------



## Pinexcorp (Jul 12, 2020)

Pinexcorp said:


> Thanks James that really helped at least to put my mind at ease. I will put it together without the automatic adjuster bar and will probably buy one and all the parts and install it later. I'll start working on it today. Thanks for your help. Be safe


Hey Jim just a comment. After looking at that video and pictures and per your info it's finally dawn on me that the reason why what I had and what I'm supposed to have in so far as the oem configuration on my brakes, is that when they took out the self adjusting mechanism they also took out the connecting rod that goes from the post to the self adjusting bar and that holds the shorter spring. They had both springs connected to the post. Whoever put the brakes together was a real doofus. To my surprise Orileys actually has the self adjusting kit which includes all the parts.


----------



## O52 (Jan 27, 2019)

This should help. BTW with the exception of the Olds Vista Cruiser and Buick Sport Wagon, all 64-72 BOPC (Buick, Olds, Pontiac Chevrolet) A body brakes are the same. Some minor differences in the drums from year to year.


----------



## O52 (Jan 27, 2019)

Heres a great picture


----------



## Pinexcorp (Jul 12, 2020)

O52 said:


> This should help. BTW with the exception of the Olds Vista Cruiser and Buick Sport Wagon, all 64-72 BOPC (Buick, Olds, Pontiac Chevrolet) A body brakes are the same. Some minor differences in the drums from year to year.
> 
> View attachment 136258
> View attachment 136259
> ...


Thanks. I sort of assume they would be the same but when I opened the drum and saw what I had, I had no idea why someone would put the brakes together they way they did and it made me question it all. I found all parts to put together just like the pics. Thanks again.


----------



## GTOJUNIOR (Aug 7, 2011)

So please help me understand how your brakes could work/function without the Adjuster? 
I must be missing something??


----------



## PontiacJim (Dec 29, 2012)

GTOJUNIOR said:


> So please help me understand how your brakes could work/function without the Adjuster?
> I must be missing something??


I took it to be the adjustment bar that rotates the star wheel, ie self adjuster arm and not the lower brake shoe adjuster. These can be a problem in some instances. Up in the icy north, I recall my dad had an issue with one of the rear brakes on the '65 Impala freezing up. His mechanic told him to remove the self adjuster and he would have to manually adjust the star wheel as needed. He did it and the problem was gone.


----------

