The Stovebolt Site Forums The Parking Lot Big Bolts 57' 6100

Hey guys, Im Travis with my first "big bolt" project. Let me tell you a little bit about her. From what I can tell this truck was originally purchased in California. The body is in great condition with minimal to no rust. From what I was told the truck has a 261 6 cylinder, 4 speed trans, 2 speed rear end, and 2 speed browning box. and It has it has air over hydraulic brakes.

My idea for the time is to get this truck up and running. I was told its been sitting since 1981. with some fresh gas she starts right up but brakes dont work worth a crap.

If anyone has any has any parts dealer they would recommend, or if anyone has an idea on where to get a repair manual for this beast it would really help. ive done some light searching and have yet to find any repair manuals.
1957 6100

Nice find Travis, I bought a 1957 GMC 450 a couple of years ago. I was able to purchase manuals and parts books on ebay. The books aren't too common but every so often one comes along that has a reasonable price.

Cheers, Bill

Welcome to the Bolt!

Nice truck!

1957 Shop Manuals are being reproduced and sold by most of the vendors for about $30.

Have you looked the brakes over enough to tell what type of system you have? Do you have a standard hydraulic master cylinder with a Air Over Hydraulic booster mounted on the frame rail or do you have a air brake treadle pedal that puts air on a air chamber that has the master cylinder attached to it? If you have a treadle pedal, that's not a factory installed system in your truck.

Brake parts can be found at your local BiG truck parts house and places like Rock Auto (online) and NAPA.

Mike B

Ok so here is my first problem. I have no brakes. No foot brake or parking brake.
Does anyone know if the air/hydraulic brakes were a standard option on this old girl or is this something that some one would of bought as an aftermarket kit. When I press the brake I can here the air can move but I get nothing at the brakes. And as for my parking brake. It's on the rear of the transmission, I don't know of there should be any type of pad on there. I've been searching for info and parts for my brakes any help is appreciated. And please forgive me for stupid questions in still learning my way around this site

My brakes have the air cylinder mounted to the master cylinder. Here's a picture of my master cylinder from the bottom. Would it be better to convert it back to the regular hydraulic brakes or just repair this one

a shop manual would be useful .... find the '55 manual here, as well as the '56 supplement, which should have the brake systems also used in '57, although you could obrain a '57 manual from most of the vendors listed in the links pages .... "converting" not advised, the booster does improve braking

Bill

Travo,

I'm not a big fan of your type of "Air Over Hydraulic" brakes. If you loose air there is nothing you can do except pull on the parking brake. My 1956 9200 has this type of system and I'm going to make it Full Air Brake truck so I can pull an air brake trailer.

Your system was not factory installed. The Air Over Hydraulic system that Chevrolet used was a complete hydraulic system with an Air Booster (similar to the Hydrovac vacuum booster). If you loose air in this system you still have brakes, you just have to push harder.

To make the truck safe I would convert to either Hydraulic with a booster (vacuum or air) or Full Air (change the backing plates out to "S-Cam with Maxi Brakes").

Since you have all of the hydraulic parts at the wheels it would be easy to find a brake pedal setup and go all hydraulic...how do you intend on using the truck?

Also, the system you have is not in the Chevrolet Shop Manual, however the wheel cylinders and shoes repair info will be.

Mike B

Thanks for the help so far guys. Just got the dmv paper work started today. Old girl was out of the dmv system.

The truck would be used just to cruise, I think her workin days are just about over. I like the air over hydraulic brakes because I have working glad hands for a trailer. But as mike said I lost all ability to brake. If I keep this current set up I'll have to change the master cylinder and brake can, they look as if they have seen better days. But I have the idea of safety. I really enjoying having the ability to stop.

Here's something interesting from the dmv. They say my truck is a 1959, and that it was first sold in 1957. I told them they had it backwards but no one listens to me

Registration pic

On my '54 2 ton I changed it over to a dual reservoir Master Cylinder from a one ton truck (same diameter cylinder bore) and tried it without a booster;running empty or with a light load the brakes work much better than they did before,better pedal,more predictable,plenty of power. I mounted a universal proportioning valve to the frame so I could back the pressure off a bit on the front brakes. It took a little time to get everything set to where I like 'em,but it works great. If I load a lot of weight on the trick I can turn up the back brakes even more,since they'll have all the weight on 'em. If I need to add a booster It's not too hard-I just need to move my master cylinder/bracket back to where there's plenty of room,mount the booster on the face of the bracket,tap into the vacuum line that feeds my 2 speed and build a longer pushrod.
You can actually keep your air system intact-just take the brake circuit out of the system. (Handy for running an impact wrench or airing up tires etc.) I'd strongly recommend upgrading to a more modern M/C and booster.
Parking brake-they usually have a lining made of something similar to early brake lining;a brake warehouse should be able to re-line your E-brake shoes for not much $. BTW-I'd fill the stock master cylinder and see if I could pump up some brake,then get someone to do that and hold pressure on the pedal while you go under and see if anything leaks. that'll help you see where you are on the brakes. Your set up looks like if the master cylinder leaks it'll try to fill the air pot with brake fluid,which will ruin the air pot diaphragm pretty quickly.
Speed

I filled the master cylinder. No other leaks other than at the at the MC. I'm going to look into upgrading my brake system. Safety and reliability are what I want.

You already have most of what you need to go "Full Air". I'd look for a front and rear axle and swap the parts. Add Maxi chambers if they are not on the donor rear axle and call it a day. You did mention you like the "Glad Hands", that can only mean you'd like to pull a trailer, so go full air and be done...then you can use the truck as intended. Someone built your truck for some serious pulling...2-speed rear with a Brownie, that's like 16 gears. I bet you walk faster than Low, Low, Low gear...lol!

Does your compressor work? If not there is no way to pump and bleed the hydraulic system.

Mike B

Spring brakes are SUPPOSED to stop the truck,when you lose air pressure,(usually 20 p.S.I.,and below). I drove a 1978 IHC S-1900 tandem straight truck,and it didn't have an air drier. During the Summer,when the weather got humid,I'd stop,and drain the tanks every couple of hours. The compressor gets hot,and causes condensation in the air lines. i was working for an ice company,and the busiest day was the 4th of July. I was assigned the S2200,(semi tractor,with an air drier),/reefer trailer,that day,since I loaded twice as much ice,to cover all of my "stops". I instructed the driver,assigned to "my" 1900,to make sure and "bleed" the air tanks. He didn't take the warning seriously. Going down a 3-mile stretch of 5% grade,he had plenty of pedal,(STANDING on it),but, NO BRAKES!! He pulled the emergency,and parking brakes,(they both pop-out),heard the swoosh,like they applied,but kept gaining speed. He didn't know how to shift the 10 speed "Ranger",either,so he was out-of gear,besides! The truck came back on the tail of a wrecker,and it was TOTALED! He rolled it on its side at the bottom of the hill,(T-intersection). Luckily the driver survived with just a few bumps and bruises. But to be SAFE,with a full air system,PLEASE install an air drier!

Compressor works. It builds air up to about 100psi from what the guage is reading. Has some small air leaks but nothing crazy.

Well wetwilly The air system I have isn't like any air brake system I've worked on. I have a single chamber air can attached to a hydraulic master cylinder. So when I have no air I lose all braking power. Not like the ones I'm use to with the double chambers that allow a spring to apply the brakes when you lose air.

Like I said I didn't know I wanted this project until I seen if for sale and knew I needed it. So I don't 100% know what I'm going to do so I'm just gonna wing it as I go. I've also been thinking maybe I'll keep the set up it has and just replace the air cylinder and M/C. But I'm always open to suggestions or advice

I pulled the master cylinder today. It's frozen and full of gunk and rust. The brake chamber looked good once I cleaned it up but the diaphragm is torn so I'm gonna stop by the napa warehouse and see if I can pick up a new master and diaphram

If the MC is full of gunk, I bet the wheel cylinders look the same. Might be time to redo the steel and rubber lines as well, they rust from the inside out.

Mike B

I've been looking into replacing these widow maker wheels with something more reliable. Has anyone used these wheels?22.5 wheels

ive been reading up on the techtips and anything else I can find regarding wheels but I haven't seen many options for 6 lug stud piloted 22.5

The 6-lug stud piloted were evry common on school busses up into the 70's...find a junk yard that uses busses as storage lockers and start looking. They are not that hard to find. Be careful when you find them to make sure they aren't the 8" wide rims, they are to wide for the TF trucks...you want something close to 6" if memory serves me for a 900x22.5 tire (same tire diameter as a 8.25x20 if that's what you are currently running)

Mike B

Got to pulling my wheel cylinders today. Looks like I will be replacing the lines and wheel cylinders to.

When I did my 57 10500 Fire Engine in 2002 I was able to find new wheel cylinders on the shelf at my local big truck parts house...I think Rock Auto may also have them. If I remember correctly they were less than $30 each.

As an option you can send your existing cylinders out and have them sleeved in brass or SS and never have to worry with them again.

Mike B

I have a Napa warehouse near my work that stocks big truck parts. I'm going to stop by on my way home and see if they have any