Will a 3/4 ton Brake Booster work on a 1/2 ton?

[Gene]

Im gonna have to buy a new booster and was wondering if a 3/4 ton will bolt right up to 1/2 ton brackets with no modifications, and will it improve braking?

[Gene]

ttt

[Gene]

Anyone??

[JimKshortstep4x4]

I believe the brackets are the same but I will get some measurements in the morning if no one confirms this. The 3/4 ton boosters work nicely on the 1/2 ton trucks. You will need the 3/4 ton MC and lines as the MC reservoirs are opposite the 1/2 ton reservoirs, (the front reservoir feeds tthe rear bracks on the 3/4 ton while the rear reservoir feeds the front). Here is a pic of the 3/4 ton setup installed in a half ton.

[The Youngen]

Like stated, you will need the mc for the 3/4 ton as well and maybe the bracket to attach the booster. Do you already have power brakes? If not you will definitely need a booster bracket. As far as i've read though, the 3/4 ton setup will stop better due to it being designed for heavier trucks.

[Livrat]

A 3/4 ton disc brake setup will work.. but you will need the following from a 3/4 ton, booster, booster mounting brackets, master cylinder and the lines from the master cylinder to prop valve.
Yes it will improve braking as the 3/4 ton booster is a dual diaphram.
An easier way to go is use a 3/4 ton drum brake booster and brackets, then you can use your current master cylinder.

[Gene]

Originally Posted by Livrat

An easier way to go is use a 3/4 ton drum brake booster and brackets, then you can use your current master cylinder.

Thanks, I believe this is the way I will go, can I use my 1/2 ton prop. valve too?

[Livrat]

Yes, you can use your prop valve, just get a booster, brackets and rod off of a 67-70 3/4 ton..

teeitup has one for sale..
http://67-72chevytrucks.com/vboard/s...=brake+booster
post #1 picture #5

[Tangerine]

I'm facing a similar problem, I am using a 3/4 ton cab on a 1/2 ton chassis. I mistakenly ordered a 1/2 ton booster and master cylinder. The rod on the 1/2 ton booster is about 5" long whereas the rod on the 3/4 ton is only about 3". I suspect the mounting brackets for the 1/2 ton are longer to compensate? I am going to have to pay some shipping charges to exchange unless there are some other options.

[Livrat]

From what you are describing, It sounds like all you need is the booster mounting brackets from any 67-72 1/2 ton.
Like this setup.
http://67-72chevytrucks.com/vboard/s...d.php?t=517694

[THE BOSS]

are the proportioning valve different from 2WD to 4WD?

or is it just the lines that are different, do they simply cross (flip/swap) over to the front and rear fluid supply ports and using the same valve?

it sure looks like in the pic above.

[Livrat]

the valves are the same 2WD or 4X4. they swap/cross lines between the
disc brake 1/2 tons and 3/4 tons.

[DeadheadNM]

I'm gathering parts to do this swap in my 72 Blazer and have a clarifying question:

Can the 1/2t master cylinder currently in my K5 front disc truck be used with the 3/4t booster set up I have from a disc equipped K20? In other words, do I have to buy a 3/4t MC and new lines to the prop valve or can I make use of the existing 1/2t disc brake MC/lines?

I'm not sure if the rod for the MC on disc equipped trucks is as long as that on the 1/2t drum trucks. I also read that a 1/2t MC from a 1977 truck is a direct bolt up to a 3/4 booster and allows for use of existing 1/2t lines from the MC to the prop valve. Can anyone confirm this?

Thanks, Pete

[Livrat]

Pete, Sorry to say that booster will not work, the 3/4 ton booster has a shorter rod than the 1/2 ton.
I do not know the answer on the 1977 m/c interchange.

[THE BOSS]

No, the 3/4 ton master cylinder and booster are matched, rod lenth are different and matched. Also the 3/4 ton master cylinder front and rear brake lines are reversed.

[67chevy1series]

So with a 3/4 ton booster and mc on a 1/2 ton will you get sooner and a more firm pedal then with a 1/2 ton booster and mc?

[michael bustamante]

And heres another ? to throw in the mix. Is there a diffference between a big block booster and a regular 3/4 ton booster? Disc

[DeadheadNM]

Originally Posted by Livrat

Pete, Sorry to say that booster will not work, the 3/4 ton booster has a shorter rod than the 1/2 ton.
I do not know the answer on the 1977 m/c interchange.

Thanks! That clears it up for me.

Originally Posted by THE BOSS

No, the 3/4 ton master cylinder and booster are matched, rod lenth are different and matched. Also the 3/4 ton master cylinder front and rear brake lines are reversed.

Supposedly, the 1977 1/2t MC is a direct bolt on for these and use the same 1/2t plumbing to the prop valve. The sure bet would be to use a 3/4t MC and it's lines.

Originally Posted by 67chevy1series

So with a 3/4 ton booster and mc on a 1/2 ton will you get sooner and a more firm pedal then with a 1/2 ton booster and mc?

From what I've read it offers a big improvement in braking especially with 4wd's. I've got 33" tires - trying to stop the K5 from 70mph is tough, I stand on the pedal. For me it's a no-brainer safety improvement.

Originally Posted by michael bustamante

And heres another ? to throw in the mix. Is there a diffference between a big block booster and a regular 3/4 ton booster? Disc

Don't believe so, just disc vs. drum. See Livrat's excellent guide here: http://67-72chevytrucks.com/vboard/s...d.php?t=214559

[THE BOSS]

I put a lot of $ in my trucks brakes the winter of 12-13
it is a half ton cab on a 3/4 ton 4WD frame, so to make It look right I put on the 3/4 ton booster all new correct preformed lines, wheel cylinders, calipers bla bla bla

IMO it don't stop any better than before, you have to push the pedal harder than newer car/truck, but it stops alright for me.

[DeadheadNM]

Originally Posted by THE BOSS

I put a lot of $ in my trucks brakes the winter of 12-13
it is a half ton cab on a 3/4 ton 4WD frame, so to make It look right I put on the 3/4 ton booster all new correct preformed lines, wheel cylinders, calipers bla bla bla

IMO it don't stop any better than before, you have to push the pedal harder than newer car/truck, but it stops alright for me.

You swapped out an existing single diaphragm 1/2t booster in a driving vehicle for a 3/4t booster and saw no benefit? If so, your experience runs counter to that of many other members who have done this swap.

[RSVP1968]

So just to be clear, i just bought a 1976 K5 4x4, it has a 6" lift with 35" tires i want to convert the booster and MC to a 3/4 T setup for better braking. I have drums on the back and front disc. what exactly will i need? I dont mind buying the parts just would like to hear from someone that has already been down this road. Thanks

[Bigdav160]

i want to convert the booster and MC to a 3/4 T setup for better braking.

I have a 3/4 ton and I am going hydroboost. just saying

[RSVP1968]

Anyone have any thoughts????

[Steeveedee]

Originally Posted by RSVP1968

Anyone have any thoughts????

I haven't swapped a 3/4T master and booster for a 1/2T setup, but I think you'd be better served by putting bigger rotors on the front. Maybe the 3/4T stuff reduces pedal effort, but you're still stopping the same spinning weight.

[allen71]

I have a 1971 K10 Suburban with stock 1/2 ton booster & master cylinder. Brakes are weak, an understatement. I bought a 3/4 booster/master unit. Does anyone know if the brake rod from the pedal to booster, brackets and bell crank will work with the 3/4 booster/master? I know about switching the lines from the master.
Allen