Converting from a single brake line to dual


Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:26 pm

Converting from a single brake line to dual

1. single line brake system.jpg
single line brake system
Over time, I have read a lot from this website, and learned a lot as well. I have several projects going right now, but have what I think I'll need for one later on. I took pictures of the parts I have so far, and wanted to post them for responses before I spent a lot of money on something that wouldn't work. First picture is of a '66 IH 1500A brake system. The truck is too heavy to stop without power brakes.

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:29 pm

Re: Converting from a single brake line to dual

Second picture is of a frame mounted brake booster underneath the cab.
Attachments
2. frame mounted brake booster.jpg
frame mounted brake booster

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:32 pm

Re: Converting from a single brake line to dual

Third picture is of the brake switch, and where it is mounted on the output of the brake booster. All this is under the cab.
Attachments
3. single system brake switch.jpg
power booster output with brake switch

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:42 pm

Re: Converting from a single brake line to dual

Fourth picture is how IH converted trucks to dual brake line systems back in late '67 and into '68. But this doesn't have a power brake booster, nor can I use the frame mounted booster for more than one side of the master cylinder. I suppose I could use a fender mounted booster for the other side of the system, say, one to feed the front brakes, and the other booster to feed the back brakes. The boosters can not have a firewall booster feeding them as it will blow seals, if you're lucky. To keep the system simple, I thought about doing away with the frame booster, so I don't have too much fluid going to the one side, and get a fresh dual circuit MC that would have just enough fluid to engage both axles. This would not have enough power to safely stop the truck, though.
Attachments
4. firewall mounted dual brake syswtem.jpg

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:49 pm

Re: Converting from a single brake line to dual

To get power brakes, I decided to take the brackets from a different truck I'm using for parts. I bought a '71 IH 1210 for parts and plan to use the booster mounting bracket and push rod from the bracket pedal to have power brakes, and still have a stock looking effect. I will need a new vacuum booster and the right MC, but I plan on getting that later.
Attachments
5. firewall brake booster.jpg
firewall mounted booster

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:54 pm

Re: Converting from a single brake line to dual

One detail is the brake light switch. The old system has the brake light come on with the brake lines being pressurized. In the newer system, that might get awkward. Since the newer systems had the switch mounted under the dash, on a bracket mounted next to the brake pedal, I figured I might as well do the same.
Attachments
6. brake light switch with mounting bracket.jpg
newer brake light switch and mounting

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Mon Aug 24, 2015 11:57 pm

Re: Converting from a single brake line to dual

This is a view of the adapter plate that IH used to convert the brakes to dual line systems. I put a tape measure next to it for a reference to it's size. If any one sees something I missed, or got wrong, please let me know. Thanks, Bill
Attachments
8. 1st view of brake adapter plate.jpg

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Tue Aug 25, 2015 12:00 am

Re: Converting from a single brake line to dual

If it helps, this is a view of the same bracket with the tape measure on the other side. Bill
Attachments
9. brake adapter plate 2nd view.jpg
bracket with tape measure next to it.

Golden Jubilee
Golden Jubilee

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Joined: Thu Dec 27, 2012 12:45 pm

Location: Canada's left Coast

Post Tue Aug 25, 2015 8:48 pm

Re: Converting from a single brake line to dual

I have very strong feelings about brakes being done well and safely. The description given suggests a cobbled together combination of stuff and no guarantee that is will ever work. My experience with things automotive would suggest that doing it right and with new stuff is less costly and if this vehicle is going to share the road with other vehicles, it had better be done right or the builder will lose his a$$ in civil action if and when the failure involves others. Death and injury will keep a person in the poor house for life.
http://www.mpbrakes.com/ is a good place to start and there are others.
If the brakes in your truck will not offer adequate braking as is, it is likely that the brakes will stop anything any better with boost assistance. Brakes use friction to turn kinetic energy, from forward motion, into heat. If the stock brakes are not able to dissipate the heat without a boost, it is very likely the brakes will not perform any better with assistance.
So the options are, slow down, lighten up, better brakes or ........................... or axle transplants.
I would rather have tools I do not need than to need tools I do not have
Thinking risks being controversial and possibly being offensive

Rusty Driver
Rusty Driver

Posts: 125

Joined: Fri Nov 30, 2012 2:04 am

Post Wed Aug 26, 2015 1:17 am

Re: Converting from a single brake line to dual

Nik, a couple of things I didn't mention. One detail, is that I had a leaking MC. I bought what I was told was the correct replacement from NAPA. It turned out to be for a half ton truck, not 3/4 ton or bigger. When I went to find the old MC to see about getting it rebuilt, one of my kids had thrown it away, thinking it wasn't any good. The parts pictured are all stock. Different years of truck, but all stock. The point of this whole dialogue was to see if I had overlooked anything. The dual brake system without power brakes is in a '68 IHC 1210 4X4. Those brakes work quite well, but that is a smaller truck than the '66 IHC 1500A model. The other choice I could use that might be stock would be to use both a frame mounted booster and a fender mounted booster with a dual MC, but using both boosters might be to much for the wheel cylinders. I want to stick with stock parts, if it is safe to do so. I've worked on enough semi's when I was younger to have a very good idea what sloppy brakes might cause. I've been taught many things on this site, and intend to keep learning. Your thoughts are appreciated, but not as necessary as your reply seems to say. I have driven the truck before, and the brakes worked fine at one time. The MC has become quite rare. That's why I what to upgrade to a newer system, such as a '71 IHC model 1500 has. After you think about it, I welcome you to comment again. Bill
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