[John Ct]

On my 66 stock bonneville with power drum brakes. I think I have a serious brake fade!! It doesn't take much to get the brakes hot. I can head down a short hill by the time I get to the bottom I have get ready cuz I don't know how the brakes will act it's not enjoyable to drive. What I've done so far with the stock brakes are.
1-a complete brake job with napa rear linings
2-all new wheel cylinders
3-new double reservoir master cylinder
4-new power booster
5-had new cast front drums drilled for heat venting and used recommended brake linings from the company who drilled drums
6-rear drums turned they were in spect Is their something I can do to improve stopping?
To convert to disk brakes is out of the question $$$$ I have a lot $$$ into what I have now.

[rohrt]

Did you change out the flex lines?

Do you have a temp gun? Maybe take it down the road with no stops and check you drum temps, see if you have any collapsed lines.

[John Ct]

Originally Posted by rohrt

Did you change out the flex lines?

Do you have a temp gun? Maybe take it down the road with no stops and check you drum temps, see if you have any collapsed lines.

Yep I didn't mention I replaced the 2 flex lines , but a tem. gun is a good idea. I forgot about that (another senior moment)

Thanks

[mkoser]

Your new dual master isn't a disc/drum master, is it?

If it is, the disc masters are designed to hold pressure. If it is holding pressure, it could be causing the shoes to rub, heating everything up, and boiling your brake fluid.

MK

[Sirrotica]

There are so many variables with drum brakes to get them stopping well with reasonable fade.

Contaminated, or cheap brake fluid will boil at a much lower temp than pure good quality fluid with no moisture in it.

NAPA sells cheap brake lining as well as quality lining, so just saying it was bought at a NAPA store means little. On the edge of the lining there is an two letter imprint that grades the brake lining. The further down the alphabet the higher quality the brake lining is. FF would be the lowest lining I would use on a drum braked B body Pontiac. FE is not a good lining in this instance. Riveted lining would also be my choice over bonded lining.

The rear lining is not going to be really pertinent for good braking since the front wheels do about 75% of the stopping.

Drums need a smooth finish as grooves limit the sweep area of the lining to drum area.

On hobby cars it's seen quite often that one or more wheel cylinder pistons will seize in the wheel cylinder during storage. Any moisture in the system settles at the lowest point corroding the pistons as it sits. You need to verify that all of the pistons are moving in their bores as having one frozen piston diminishes braking 25% on one axle.

Cheap brake fluid has a lower boiling point than top quality brake fluid.

All 4 wheels need to be adjusted correctly and verification of the self adjusters working correctly to have top notch braking.

In 1966 the emphisis was on going fast, not stopping. The braking systems were adequate for daily driver duty, they were borderline for spirited riving or towing a trailer. Even descending long grades it was a good idea to use engine braking to keep the cars brakes from being used up.

Yeah, I have driven a good many miles in B bodied Pontiacs with drum brakes and worked on them for many years as my profession. Disc brakes would be a night and day difference on your car.

[Deadhead]

I would check to see what kind of linings were used. If they are metallic or semi-metallic, that could be your Prob. These are terrible on these cars.

If you did not use a metering block or used a proportioning valve with the new dual master, this could also be your issue. Also as mentioned, it should be the drum/drum master and not a disc/drum. Both were available.

Do you have consistently hard pedal? If not, you may still have air in the lines. As Sirrotica says, cheap fluid could also be an issue or a contributing factor. Not sure I have heard of anyone else drilling drums on these cars, so that is a new one for me.

Changing all those items at one whack makes it more difficult to diagnose. I am guessing that you have multiple issues causing the Prob. Starting with the metering block/proportioning valve for the dual master is what I would suggest. If that is correct, check & see what kind of shoes were used. Then, if no joy, bleed or have system bled again.

With the correct shoes, and the system working as it should, I have plenty of experience braking these big beasts, and they do stop pretty well. 8 lugs better than conventional but still. Should be fine with the correct shoes.

[John Ct]

I wanted to thank everyone for making all of the great suggestions on what the problems are with my brakes. I wouldn't be surprised if I have the wrong master cinder. I wasn't aware that there is 2 different types. I purchased it at a swap meet I still have the part number and I can find the person that sold it to me. If it's the wrong one where can I purchase a good quality master? Or part # and brand.

[stevep]

I always use NOS Delco shoes.

[Goatracer1]

You should be able to use a master cylinder from the same model but a 1967 vintage. Should be available from almost any place.

[Bill Hanlon]

Some (all?) 67 Pontiacs had front disk brakes. Make sure that the master cylinder you get is for drum front brakes. RockAuto shows 16 different combinations of Manufacturers and models for 1967 Bonneville master cylinders. Six specifically say they are for front disk brakes, the other 10 do not say. Some talk about Moraine brakes, some specify "except" Moraine brakes. Here
http://www.rockauto.com/en/catalog/p...le.com+URL+%2F
is the link. Prices vary from under $26 to over $93.

[Deadhead]

Right. I have used a '68 Bonneville Drum/Drum model with success as well.

[Goatracer1]

I bought a 1967 Drum brake master from Ames for my 1964 GP. Worked fine.