The Stovebolt Site Forums The Shop Area General Truck Talk Brakes

Having problems with brakes, Have new dual master cyl, today a new vacuum booster. Running drum brakes on all 4 ( going to change) The Brake pedal works fin on 25% braking, when you slam it to the floor, you get good brakes but not great. Can't lock them up. It just feels like you reach the bottom of the stroke and no more. Talked to a speedway rep this week at the street rod ants and He thought the master cyl might be at fault (I bought it from them) Ideas??

Still has air in the system??? Kinda sounds like it.

Jeff

Have you adjusted the brakes?

I agree with Cletis,
When I first reassembled my truck Mine were like that until I adjusted up my rear drum brakes again, I think my pads centered themselves up when I got on the road for the first time and were not adjusted properly, after a readjustemnt I got a full pedal and can now lock up the tires if I need to.
Tim

Did you bench bleed the master cylinder prior to installing on the truck? I have seen many units have air in them.

Brakes? You don't need no stinkin' brakes.

Bled the brakes and master cyl. before instillation
adjusted brakes twice. Air would cause a spongy pedal. Mine is like a rock.

Just my wishful thinking Lonnie, I pretend my truck is fast.

might be in your wheels : D

install your old ones back and you will be good to go

you might check with Trev, he just finished plumbing his 37
click here

It sounds like you have front brakes only. I would bleed the rear brakes again, then the master cylinder at the rear fitting.

Sometimes there can be air trapped in the master cylinder and it won't work itself all the way into the brake lines.

I only say this because it has happened to me.

Will try again on the master cyl. All 4 brakes are working. can see skid marks on gravel and the drums are all warm equally.

Joker, You might have a issue. The 20 inch wheels are a lot harder to stop than the 16 inch?

The overall height of the tire/wheel assembly will be a factor. If a 15" wheel and a 20" wheel have tires that are about the same height by comparison, the stopping ability will be similar. Most of the 20's I've seen have about an inch and a half of rubber on them. If the 20's are taller overall, there's more leverage on the brakes, and less stopping effect.

Maybe the truck is embarassed to have those ugly wheels on it, and it's trying to run away from them!
Jerry

I agree with Hotrod lincoln the reason it won't stop is because it is looking for a big pothole to hit so it will bend the rims on those 20's LOl. I am just kidding no hard feelings I hope!! I hate to explain this but on my 1937 Plymouth I had the same problem until I re-bled the master cylinder some vehicles are very touchy that way

Ok you guys have been getting coaching from the Joker on the ugly wheels. I hope you know that anybody under 40 thinks they are HOT. Too bad I am over 40 but I paid for them, now I have to stick up for them or die of embarrassment.

Now fix my brakes.

Hey I am under 40 and I don't like them. But that is me. all that matters is if you like them. quick question do you have a proportioning value for the rear brakes? on other cars and trucks that I have done if you don't have that adjusted properly it can cause all sorts of problems. locking up to soon or not locking up at all.

Some of the brake shoes we get now just don't have a lot of friction in them. They have taken out the asbestes. Ive had to throw away perfectly good shoes that came with trucks when I bought them. Ive been useing Carquest brakes & a guy drove my 58 a while back & remarked how good it stopped. He said it felt like it had power brakes.

As Wrenchbender mentioned, Ive spoken with a local guy who has been friends with my family for the past twenty or so years. Hes owned his shop for a lot longer. He commented on how many people bring in their vehicles because theyre squealing or just dont feel right, although theres nothing wrong with them. He started seeing it more and more once they switched from using asbestos in the pads and shoes.

gazim, what wheels do you have that these clowns you a hard time for? Got a picture handy?

Jeff

I'm over 40 and have 20's on three of my trucks. My '47 COE, my '51 4400 and my '52 6400. 7.50-20's...

Wheel and tire choice can affect your brakes. While we've talked about height, width can have an impact too. If the weight of the wheel/tire combination have increased that will reduce your braking effectivness.

Played with it all day, rebled the master, and finally got around to changing the lines into the master, Helped, is there a difference between the forward outlet on the master to the rear.?? I don't believe I need a proportioning when running drum brakes on all 4. (Going to change)

I'm not sure if this will help or not but here goes.I'm about a week ahead of you in your problem.I had very little pedel if any and I guess I bleed about 3 qts of fluid until early one morning it finally hit me,the wheel cylinders are doing there job,its just that the shoes are not reaching the drums simply because I had not adjusted them PROPERLY.So I removed the wheels,then the drums and found out only one half of the shoe was touching(bairly) one the front left and oposite shoe was touching on the other side.The wheel cylinders exert equal pressure on the shoes so BOTH shoes need to be adjusted equally.I have a 46 1.5 ton and I'm glad this portion is done.

Gazim...I was led to believe that the front and rear outlets on your master are different.
Think about it... The front brakes need to actuate first (they do something like 80% of the work)

Is it possible you have/had them mixed up?
Remember if it's the under floor set-up the m/c will be back to front,relative to a conventional firewall m/c.

Have you checked the pushrod free play? I would say adjust the pushrod 'till you get about 1/2" play at the brake pedal.

Maybe worth checking, I hope this helps.
Jock.

Bota brought up a good point. Sometimes guys are afraid to adjust them up. Tighten them till you get a heavy drag & back it off about 4 notches. you still will have some drag but as they seat in it will be OK. These drums are seldom true.