ABS delete

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Schurkey

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If I were to look on Rockauto, what type of master should I look for? Something that includes f44 in the description?

Same for the booster?
I don't order from Rock Auto, so I can't tell you.

When it was me, the master and booster came from the Treasure Yard, from a '94 extended-cab truck that had JB5 brakes.

The master was replaced with whatever Amazon specified for a '94 extended-cab truck. Has larger bores than the JB3 master. Seems to me the quick-take-up part was 40 mm, and the rest was 1 1/8" or the metric equivalent.

Genuine AC-Delco, made in Communist China.
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Is the prop valve different for the jb6/7 brakes. What about the fittings off of the lins that go into the prop valve?
No idea except the tubes screwed right into the larger master on my '88.
 

evilunclegrimace

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Sure?

I was guessing it's the pedal pushrod for various vehicles--GMT400, full-size car, Squarebody, 2-ton truck...whatever that booster design was used on. So I figure, any booster from a GMT400 is likely a good candidate. I wasn't expecting differences with the master cylinder side.

Used to be that Delco masters, and Bendix masters had different recesses in the primary piston. So one took a longer booster-to-master pushrod than the other. But all JB6/7 masters should be the Delco version.

In the end, I'm just guessing.
Yes I am sure GM has a gauge to check the push rod length.
 

Vodka0tter

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The pedal in my '97 RCSB still is pretty poor IMO. Pretty significant travel before the brakes engage, soft after engagement and improves with a pump or two. I put little shop rear disc, disc proportioning valve, NBS master cyl, new booster, all new lines & SS hoses, Little shop front set up, ABS complete removal and still the brakes suck. Picked up a '99 Tahoe and guess what - it sucks too.

I dono what the answer is but its not in the content I listed above.
 

Supercharged111

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The pedal in my '97 RCSB still is pretty poor IMO. Pretty significant travel before the brakes engage, soft after engagement and improves with a pump or two. I put little shop rear disc, disc proportioning valve, NBS master cyl, new booster, all new lines & SS hoses, Little shop front set up, ABS complete removal and still the brakes suck. Picked up a '99 Tahoe and guess what - it sucks too.

I dono what the answer is but its not in the content I listed above.

The answer is a properly adjusted 9.5" rear end and hydroboost.
 

Schurkey

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The pedal in my '97 RCSB still is pretty poor IMO. Pretty significant travel before the brakes engage, soft after engagement and improves with a pump or two. I put little shop rear disc, disc proportioning valve, NBS master cyl, new booster, all new lines & SS hoses, Little shop front set up, ABS complete removal and still the brakes suck.

I dono what the answer is but its not in the content I listed above.
The content you listed is pretty-much everything but the brake pedal. Therefore, the problem IS in the content you listed. Is this a 2WD or 4WD? If 2WD, are the front wheel bearings adjusted properly?

What rear calipers are on there? Are all the bleeder screws at the top of their respective calipers, or are some facing some goofy angle? Is the park brake adjusted? Does it hold the vehicle? Or did you get the calipers that don't provide for a park brake?

Air trapped in the master cylinder that won't bleed out? Frightfully common on vehicles that have the front of the master cylinder tipped "up". Often need to unbolt master from booster without disconnecting the brake tubes, force the front of the master down so that the bubbles rise to the rear, and then "tickle" the primary piston so the air gets pushed out the ports into the reservoir.

DOT 5 brake fluid? Known for trapping air. Nobody but the military uses that crap. Sounds good on paper, less good in real life. I guess DOT 5.1 is a reasonable product, but I've never used it.

Did you burnish the pads? How do the rotors look? Are the pads wearing evenly, especially in the rear?

Grab an infra-red thermometer, go out on the highway. Make a heavy stop from highway speed, and then immediately test the temperature of the rotors--make sure both rears are the same temp, both fronts are the same temp, and both front and rear are HOT.
 

FrankieD61

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I think I'm going to replace my master for now. Since it's leaking. Then, later, I will do my upgrades. Since this is my first summer with the truck I want to actually drive it..

Is it okay to upgrade my master and my booster without upgrading my actual brakes (rotors, pads, drums, shoes, etc.)?
 

Schurkey

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I think I'm going to replace my master for now. Since it's leaking. Then, later, I will do my upgrades. Since this is my first summer with the truck I want to actually drive it..

Is it okay to upgrade my master and my booster without upgrading my actual brakes (rotors, pads, drums, shoes, etc.)?
Probably. Does your vehicle have the JN3 brakes? The larger-bore master cylinder will have less hydraulic advantage on the caliper and wheel-cylinder pistons; but that's somewhat offset with the larger booster. So maybe it comes out "about" even.

If you've got JN/JB5 or 6 brakes, you've already got the "upgraded" parts.
 

FrankieD61

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Probably. Does your vehicle have the JN3 brakes? The larger-bore master cylinder will have less hydraulic advantage on the caliper and wheel-cylinder pistons; but that's somewhat offset with the larger booster. So maybe it comes out "about" even.

If you've got JN/JB5 or 6 brakes, you've already got the "upgraded" parts.

I have JB3 brakes. The master I bought is a JB3 master as well.
 
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