Changed EVERYTHING, brake pedal still goes to the floor.

[Schurkey]

Drum brakes WILL self-adjust. but only after they get fairly loose, and the self-adjuster mechanism is set up so that it only adjusts when going in reverse.

You're thinking of Duo-Servo rear brakes. Most of the 1/2 ton trucks use Twin Leading Shoe brakes, which need the park brake to adjust.

Prejudice? Maybe. I really hate Twin Leading Shoe brakes.

its different than what you think, mine doesnt have a slot in the backing plate to get the adjuster and its not reverse on mine, it works off the parking brake

Yep.

 

[SonnysSweetTea]

You're thinking of Duo-Servo rear brakes. Most of the 1/2 ton trucks use Twin Leading Shoe brakes, which need the park brake to adjust.

Prejudice? Maybe. I really hate Twin Leading Shoe brakes.


Yep.

Also just to verify when I'm bench bleeding a master cylinder, the OEM style 1-1/8 one, every time I bleed this style the primary port spits fluid straight up out of the reservoir like a solid stream. Every single one I've bled. Is that normal? All my reman cylinders did the same thing but it was a volcano of bubbles, the brand new one still shoots a stream straight up but no bubbles. I've never seen any other master cylinder type do this

 

[Schurkey]

No bubbles = no air. To me, that tells you you've done a good job of bench bleeding.

IF (big IF) this is a QTU master cylinder, there'd be a greater volume of fluid squirting due to the huge rear piston.

 

[SonnysSweetTea]

No bubbles = no air. To me, that tells you you've done a good job of bench bleeding.

IF (big IF) this is a QTU master cylinder, there'd be a greater volume of fluid squirting due to the huge rear piston.

Yeah I went back to the OE style one I had but brand new, its listed as a 1.125" bore which is 1-1/8. It stops perfect now. It's soft but it's always been soft on these abs trucks. Everything is brand new now and I have a lot more knowledge of hydraulics than when I started this crap a month ago. Like you said don't change it or you'll be in deep **** lol

 

[Chevy-SS]

You're thinking of Duo-Servo rear brakes. Most of the 1/2 ton trucks use Twin Leading Shoe brakes, which need the park brake to adjust......

Yeah man, u b right.

As I mentioned in previous post, I've been doing brake jobs for almost 50 years (literally thousands of brake jobs), and the ass-kicker is; I MIGHT have done one vehicle with Twin Leading Shoe brakes, everything has been duo servo. And I've done plenty of trucks. Weird. Maybe it's a rarely used style?

For those that don't know, here's a pic of the Twin Leading Shoe brakes versus Duo Servo style:

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[454cid]

Why is this picture hosted on a "FREE discount Drug Card" website?

 

[Schurkey]

WHOOPS!

I FUKKED UP!

Not "Twin Leading Shoe" brakes, they're "Leading/Trailing Shoe".

The adjuster is ABOVE the axle/bearings, just below the wheel cylinder.

The design is screwy in part because the front shoe on each side wears twice as fast as the rear shoe on each side.

This is not exactly right, but closer.

You must be registered for see images attach

 

[James077]

Yeah I went back to the OE style one I had but brand new, its listed as a 1.125" bore which is 1-1/8. It stops perfect now. It's soft but it's always been soft on these abs trucks. Everything is brand new now and I have a lot more knowledge of hydraulics than when I started this crap a month ago. Like you said don't change it or you'll be in deep **** lol

I could buy you a few beers! I have done this exactly like you but stock calipers and still goes to floor. After reading this story, I found that the master cylinders I have installed were all bad. Finally after 5, I gave up and built our own with a kit and now have good brakes. Thanks for the great write up here.