The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Converting 65 to a dual master with all drums...

Hey guys...

I am in the process of upgrading the single brake line to a dual brake line system on my 1965 C30.. I installed a dual master for all drums from a 1968 C30 truck. I noticed the old master stuck in the firewall looks like an extra inch more than the 1968 master. Sure enough, the brake pedal push rod is not long enough. At the furthest extension, the bottom of the brake pedal travels between 2 and 3 inches before engaging the master.

Does anyone have advice on what to do? Is the pushrod from 1968 longer than the one from 1965? Any help will be greatly appreciated.

Thanks, Russ

OK... I think I fixed the pushrod issue. I took a 7/16 by 20 thread by 1-inch bolt, cut off the end, and used a long nut to attach it to the end of the pushrod. Now I have 1/2 inch of pedal travel as expected.

Now, the next problem. I can bleed the front brakes, but I cannot bleed the rear. I noticed during bench bleeding of the master that only the front reservoir was bleeding. There was no movement in the rear reservoir. I thought I had a defective laster (bought from AutoZone new, not rebuilt), but I realized that if I push the master in further, the rear would bleed. It seems the rear engages a little less than 1/2 the way in.

Now, when I press the brake pedal, I can see fluid pushing up in the front reservoir instantly. About 2/3rds the way down, the brake pedal gets hard, and the front drums engage. Before the hard part in the pedal, the front drums do not engage.

I hope I am doing something wrong or, at worst, the master is defective, but I would hate to find out at this stage that this idea will not work. Again, any help or insight would be greatly appreciated.

Hy Bornco, you could try going to a wrecking yard and seeing if the 1968 rod is longer, most rods have an adjustment feature built into them. You could try extending the one you have, but make sure you make it strong and re-enforce it so it can't bend/break, after all your life and the lives of those on the road around you depend on the integrity of your brake system!

Hi 3B...

I had a friend check a 1968 truck, and he pulled the rod. It seems to be the same size. I know what you mean regarding the brakes. This is why I am upgrading to a dual brake line setup. I lost my brakes on my other truck, and it was not a fun feeling.

It is funny.. so many people from my cruise nights told me it is a simple upgrade.. but now that I am having problems, those who told me it was simple are scratching their heads..

..Russ

OK... I feel silly and almost want to delete this post, but maybe someone else might learn something.

Remember, I come from a single brake line environment... I just assumed the front reservoir was for the front brakes and the rear for the rear brakes...

I switched the brake lines around so the front brakes operate off the rear line from the master, and the rear is now hooked up to the front of the master.

I still have to get more air out of the lines and re-adjust the brakes, but it does seem to be working. I am just mad.. I had the lines nicely bent with all the right bends and even a stress relief circle, and now they are all bent up to fit. Maybe later on I will make new lines with the right bends.. Sorry guys for bending your ears...

I have a 65 that I want to convert to a dual line system. Over the years I have had the brakes fail twice,luckily both times I managed to get it stopped without hitting anything. Was it hard to bend the new lines?

Hey Rac65...

The key to bending the new lines is to find a bending tool, take it slow, and practice first. Honestly, before starting this project, bending the lines was my biggest concern, but after bending the first line, it wasn't anymore.

The tool I used came from Harbor Freight. It was around $7 and made the project a lot easier.
http://www.harborfreight.com/tubing-bender-3755.html

You will also need a flaring tool because most lengths have to be cut from longer straight tubes. Here is the set I used:
http://www.harborfreight.com/double-tube-flaring-tool-kit-66534.html

Two key notes:

1. When flaring the tube, use a wrench to tighten the flare tool as tightly as it will go. If not, the tube will move during flaring and ruin the flare.

2. When you start bending your tube, start with the smaller brass fitting side. When you get to the other side of the tube and you are ready to cut it to size, you will have to flare the end. The longer fitting that seems to come with every tube length I bought, will cover over the mark left from the tube flare tool.

Hope this helps...

Many folks use the flaring tool you have suggested. However, I became totally frustrated with such a tool because it NEVER made a good flare.
Just trying to be helpful here, but I suggest that if such a tool doesn't work well for you, then here is my suggestion.

See my earlier post.
https://www.stovebolt.com/ubbthread...Main=109878&Number=869725#Post869725

Thanks for the info guys. I am going to keep the drum brakes but the single master cylinder has to go. That feeling you get when you step on the brake pedal and it slaps the floor is not pleasant.

Howdy, I haven't seen any mention of the bias valve in this discussion. I would get one from a '67-'70 C10-30. If you can, get the little short lines, too. They are usually in good shape and are a booger to make because of all the bends in such a short distance.

On EVERY '67-'70 truck, the dual brake drum/drum system you want to duplicate, that I have seen the front pot feeds the front wheels and the back pot feeds the rear. Somewhere in your system near the front is a "T" fitting in the brake line that splits the front and back. Carefully remove it and replace it with a connector, being sure that both fronts are together and the rear is separate. Extend the rear line to the back of the bias valve, being careful to clamp the new line in with the old line so there is no chance of vibration. Use line the same diameter as the rear line that is already on the truck. That's it! Bleed system.

It really is an easy system upgrade, but sometimes folks who have done it don't realize how daunting brakes can be to a beginner. Soon you will be teaching others!

best wishes,

Les

I converted my brake system in the same way in which you described. The push rod is the same size for each, and I had no issues in that aspect. The 67-72 used either a proportioning valve or a distribution block (i cant remember which one) in the brake system. I did not include it in my replumb. The biggest problem that I had was getting my rear brakes bled. I gravity bled them for an extended period then had to bled them in the traditional manner multple times to get the remaining air out of the lines. The brakes work great, and I have no fears of losing all stopping ability when a wheel cylinder goes out like it did a few years back.

You need to use a rod connector not a nut for this. The threads in a nut will fatigue and break (and my luck you'll be behind me) because not enough of them are engaged.

If you are a novice to bending brake lines get a brand called Armour Plate (Advanced Auto). They cost a little more but are teflon coated so they won't rust but better yet they bend almost 270 degrees without kinking - without a bending tool!

Hey guys...

Just an update and a few comments to address above...

My brakes are working great. After switching the lines so the front brake lines go to the rear reservoir and the rear brake lines go to the front reservoir, I was able to bleed both front and back brakes.

I also had to adjust all four brakes. Unfortunately, the replacement drums for the front did not have punch-outs to adjust the brakes. I had to drill a 1/2" hole in each backing plate and use a plug to fill the hole. Trust me, you want to do this to keep the brake fluid from dripping in when bleeding. It is hard to bleed the front brakes without dripping.

Regarding using a 'long nut'. This is also called a connecting nut. I did not know the name of it at the time I wrote the original post. In either case, it was a temporary fix until I had the bolt end welded on by a professional.

Regarding needing to adjust the brake push rod. I noticed the original master had a larger section where it went through the firewall, vs. the dual, which had a shorter one. I am not sure, but I think the longer one is for manual brakes and the shorter one is for a power booster.

Regarding the proportioning valve or distribution block... since we are talking about drum brakes in the front and the back, they are not needed, but could be used if desired.

Thanks again guys for all your help.


...Russ