New member w/ 1 ton brake questions!

[Devon]

Hi All,

First off, wow! What an amazing site! I just joined the site but have been browsing for a long time now. It's great to see so many people with a common interest capitalizing on each others know how and knowledge.

Since I can remember I've always wanted a 67-72 Generation Chev/GMC and finally picked one up last week. Here she is (Hope the Pics show up):



-C3500
-1ton cab and chassis
-350 SB
-Originally used as a water truck for a small town fire department
-Front wheel disk brakes

She runs alright but I think I am loosing vacuum through the brake boosters. When I went to investigate, I found that the boosters where in rough shape and likely will need replacing. I have a few questions regarding the braking system for all you 1 ton owners/enthusiasts:

1. Did all 1 tons come with two brake boosters (one for the front and one for the back brakes) mounted under the cab? Mine has a Master Cylinder in the engine bay with no booster and then two boosters running off of a Vacuum which are mounted under the cab. When I go to the parts stores in town and search for a booster for the 1 ton, the computer brings up a booster/MC assembly to be mounted in the engine bay (the booster listed is a 10 3/4" dia. double diaphragm).

2. Has anyone replaced this two booster set up with a typical Booster/MC assembly in the engine bay? I am considering purchasing the one that the parts store computer recommends and am wondering if this is what some 1 tons were equipped with originally.

3. I want to put a dump bed on this baby, restore it, and use her as a weekend warrior work truck so I want to put a reliable brake setup which is easy to find parts for. Can anyone recommend a solution? Here is what I believe my options are. If anyone can suggest some more or make a recommendation based on your experiences, it would be much appreciated.

A. After-market booster/MC assembly in the engine bay. Remove existing boosters and run new lines.

B. Install the booster/MC assembly that the parts store computers come up with (10 3/4" double diaphragm booster). Remove existing boosters and run new lines.

c. Swap in some parts from newer 1 ton models to get better part availability. Has anyone done this?

I am basically looking for suggestions on a brake upgrade that will be reliable, simple, and be relatively easy to find parts for in the future.

Thanks in advance!

P.S. is there a place to make donations to the site?

[jorgensensc]

First off welcome!! You will be addicted before you know it! That is a great looking truck. As for the boosters, I personally haven't seen any two booster setups, are you sure they go to the brakes? The one ton I recently worked on had the dual diaphragm booster at the firewall with the master cylinder attached. It is a great setup and stops the truck easily, even with no back brakes and no pads on the front rotors (long story, better you not know). I will say this, I drove the truck from Arizona to texas like that (unknowingly of course, i would never do that on purpose) and it drove and braked just fine. As for newer technology, like hydraboost brakes. Yo can definitely do that, but your wallet will have to give a little more and your time fabricating will be more. If it were me i would just go to the Regular power brake and booster setup. However you may have to find the right rod to go from your brake pedal to the booster and you may also need to find the brackets, which don't come with the setup from the parts store. PM me if you need the brackets, I have an extra set I will sell you as well as the pedal rod if I'm not mistaken. Again welcome to the sight and it is a great looking truck!! To subscribe click the link at the top of the page that says subscribe. I would highly recommend it as you will get info here to help you that is 10x the cost of the subscription. Good luck and let me know if I can help you out.
Shawn

[special-K]

I have never seem your set-up.I`ll say what you have is a fairly rare HD 1t truck.I can tell by the bigger hubs,5-lug front and 10-lug rear.I`m guessing that is how those systems came.I`m sure you couls replumb the cowl mounted master cyl/booster combo that the regular 1t trucks call for.You probably won`t need the heavier system anyway,or would at least be fine with it.I imagine those original boosters would be a tough find.Maybe some place could overhaul what you have.The post-72 1t trucks use the hydro-boost system utilizing power steering pressure rather than vacuum.With all the parts from a donor it`s a bolt-on upgrade.That may be your best option.That`s what I`d consider.All 6.2 diesels had the hydro-boost,too.But,you`d need the pump bracket from a gas small block 1t.

BTW...WELCOME TO THE SITE!!!

[babyJay]

Whoa, a fire truck! Can't help on the brake question, but welcome to the boards.

[Shyguy]

It depends on where these boosters are. Could it have air brakes on the rear, if it does there would be a compressor mounted on the engine some where.

Just a guess though.

Danny

[67_C-30]

Welcome to the board! Very cool truck!

I've seen another 1 ton like that, and it used the boosters like off of a medium duty truck. That stuff was probably made by either Delco Morraine or Midland, and is obsolete and if you find any of it. It is also usually expensive. I had to put a Midland master cylinder on my '67 C-50 and it cost me nearly $500 after I finally found one. You'll never load that truck to need anymore that a conventional booster, so I'd swap it over. The hydroboost set-up would be another good choice, but you'd have to change out the bracketry on your engine to accept the hydroboost pump. I'm going with hydroboost on my '67 C-30, but the Diesel I'm using already has the brackets and pump.

BTW, what dia wheels does it have, 19.5's?

[Rod]

That would be a 1 ton with the 11000 lb rear diff. A couple around here ...havent crawled under one in a few years but I remember the glove box sticker had a steep rear diff in the 6.17 range. Should be a 14000 lbs. GVW truck with a 157 inch wheel base by the looks of it in picture. These have a bigger diff that the HO72. The salad bowl cover has a bulge in it for ther bigger gears so it would not accept the H072 gears. Rear Brake drum and parts are hard to come by for those if you need drums to pass inspection if required.Still a Good truck in all accounts.

[special-K]

Could that rear accept a 2spd?Isn`t it the same as the medium duty rear?I don`t know much about those trucks.

[Devon]

Thanks for all the info Fellas,

By the sounds of it, I think my best option is to go with the booster/MC combo that came standard with the 1 tons. I also like the power booster idea but for simplicity, I think I'll just do away with the undercab boosters and go with the firewall mounted booster/MC/vacuum configuration. If I do go with this setup, does anyone have an upclose picture of the booster/bracket mounted to the firewall of a 1 ton. It looks like I may have to drill a few holes in the firewall to install the booster/MC assembly (see picture below for comment). Mine has two studs that bolt up to the MC and two studs directly above those with nothing bolted to them.

Rod, I think you are right on with the axle being 11000lbs and the GVW being 14000lbs based on the VIN Plate in the cab (see pictures below).

What were the standard rear ends that the 1 ton trucks came with? Which was the most common? Are parts still relatively easy to get (drums ets.) for the most common rear end? If not, has anyone done a swap to a newer axle or an aftermarket unit? If the drums do go, I would likely swap out the rear end for one that I can easily get parts for if possible.


Tires say the wheels are 18" front and back.

Thank again for all the help!

[babyJay]

Throw a GM 14 Bolt in there if ya have to swap. Bulletproof and parts galore.

[pumpkin]

That looks like the same diff I have in my blazer. An ho72. Mine came out of a 3 ton. Don't swap in a wimpy 14 bolt.

[ChevLoRay]

Welcome to the board. I'm a fire apparatus fan. Congrats on your find/purchase. It looks like it's gonna be a keeper.

I'm not blessed with any knowledge of the One-Tons, so the comments are nice to add to a wrinkle in my feeble, damaged brain.

I'm of the opinion that pulling the rear end and replacing it with a more-common variety will make maintenance easier, but what about your desire to put a dump bed on it...will it be sufficient to "haul the mail", so to speak?

The agglomeration of variety on your truck speaks to the ability of someone reading the Truck Data Book for '72 and seeing what they could specify on the order. I have "played" with my book for the 1/2-tons from '69, but never thought about playing with the bigger ones.

I rememeber (fairly recently) a C-50 from '68 in my area that had metallic turquoise paint and was a Custom Cab. It had all the chrome that a Custom Cab should have and was a sharp truck. The owner had also installed ALCOA aluminum wheels on it and for a single-axle dump truck, it was sharp.

[Devon]

Thanks again for the comments guys!

I think they started making a 14 Bolt GM 1 ton axle in 73' (correct me if I'm wrong). The 1 ton version had larger spring perch widths and larger drums from what I have read. Apparently this was a very strong axle.

Has anyone ever swapped or heard of swapping a 73 (or newer) 1 ton 14 bolt into their 67-72 1 ton? Any welding required ?

Also I think I forgot to mention above that my truck is a 72.

Thanks in advance!

-Devon

[68GMC454]

nice truck.. would make a good logging truck...the probelm with swapping the rear axle you gonna need 2 spares, unles they are already 2 different patterns.. cool truck though

[67_C-30]

Originally Posted by Devon

Thanks again for the comments guys!

I think they started making a 14 Bolt GM 1 ton axle in 73' (correct me if I'm wrong). The 1 ton version had larger spring perch widths and larger drums from what I have read. Apparently this was a very strong axle.

Has anyone ever swapped or heard of swapping a 73 (or newer) 1 ton 14 bolt into their 67-72 1 ton? Any welding required ?

Also I think I forgot to mention above that my truck is a 72.

Thanks in advance!

-Devon

I put a 14 bolt in my '67 C-30, but it was a wide dually rearend out a '97 C3500, and I had to move thje perches. *I think* a 73 - 87 cab and chassis 1 ton 14 bolt used the same width, but please confirm that before you buy one.

[factorystock]

That is not a 1 ton it is a 1 1/4 ton. The 5 lug front and 10 back are the give away. This truck is similar to the Chevy C-40.

[Devon]

Sorry about the confusion. I meant to say rear end, not axle in my above post!

-Devon

[MrBeast]

you also might want to look at installing a hydroboost, it runs off of your power steering pump instead of being a vacuum booster, that is what I am doing to my truck, and they are readily available for newer model Chevy 1 tons.

[Devon]

Hi All,

Its been a long time since I've posted because I've been so busy. I've made some progress on the truck and wanted to post a couple quick picks.

Whats been done so far:
-Disassembled the truck
-Picked up front end components from a 85 1 ton (from the ball joints out)
-sandblasted everything
-POR-15 on the frame

Plan forward:
-Front chassis components to be painted next week and installed
-Still lookin for a 14 bolt Dual Rear Wheel near Saskatoon, Saskatchewan, Canada if anyone know of one! LOL

[427 70c-30]

well had you come to me I could tell you EVERYTHING ABOUT YOUR TRUCK!!! 1 your truck is the 14k model(carries 14,000lbs).2 your truck has the same wheels as a 3500hd(94-99)truck.3 the booster on the bottom is a step up booster that was for the fire dept.4you CAN AND WILL FIT a 3500 hd rear,but use the first generation rear which is drum brakes.If you want to use disc in the front al u need is the rotors from a 3500 hd truck.pretty sure they fit right on.5if you want to use rims that are one piece use the rims from a 3500hd.6to replumb the brakes.use a master from a 70 or newer truck with front discs and run the lines straight to the wheel;the front of the master or what is marked front ,run them down the chassis ,"t" them to the right and left ,then into the wheel cyclinders.in the rear ,run the line down the rail,plumb into a brake propartitioning valve(wilwood or speedway has these)than straight ,than "T" to right and left and whamoo........it stops.If any one wants to see this truck or brakes in action go to youtube.com,go to piston knockers drill team and watch the vids that say brig or brig truck.we stop these trucks with 790hp and 5 guys on the back weighing about 7000lbs.any questions call me at 516.250.5292 or email at hemicuda33@hotmail.com

[Devon]

Hi all,

Thanks for all the insight and comments regarding the brakes and rear end. 427 70-c30, thanks for the info on the truck!

I thought it was time to start a build thread so please check out:

http://67-72chevytrucks.com/vboard/s...=1#post4385300