Tag axle brake fluid

[ebprod]

Does my 1994 KA tag axle have it's own brakes? How would I check the brake fluid if I needed too? It is a F53 chassis.

-Joe

["007"]

Here is some information found in the Ford Chassis forum about tag brakes.

[ebprod]

This is picture from near the tag axle. Does this run the brakes? Nothing looks like a master cylinder to me.

The brakes seem to work fine- I just wanted to check the fluid, if I needed to.

-Joe

[Dave78Chief]

Some possibilities:
On gas based rigs, tag axles were typically either hydraulic or electric brake. Look on the backside of the drum backing plate of the tag wheel and see if their are hydraulic or wires going to it.
If hydraulic lines are going to it, then the system most likely looks simular to this thread Hydraulic Tag Axle Brake Information. Your F53 would most likely have a Hydromax system rather than a Hydroboost system.

If there are just wires, then it would be a basically a trailer brake system and there would be a brake controller in the cockpit.

Your pictures look like a accumulator for a a air system. It may only be for an air bag system but it is always possible to be for brakes. You need to find out what type of lines are gong to the tag drums and go from there.

Dave

[Nick-B]

Agreed. The F53 does not have air brakes.

JOE, crawl up between the drive axle and tag axle. Look for a vacuum diaphram (like a power brake booster) with a master cylinder bolted to it. That is where you check the fluid level - provided you have hydraulic and not electric tag brakes.

[Max Hubrich]

Joe-

My old '86 HR, 33' with a tag axle, had a seperate master cylinder aft of the mid-entrance door. Mine was on a Chevy P-30 Chassis, but the tag axle brakes were Ford drum brakes- I think F-350, if I remember correctly. I do remember the master cylinder was mounted real high , almost butting the floor and I had to use a turkey baster with a piece of plastic tubing to add fluid. The brakes never worked good- until I added a brake buddy to my little Saturn. Then I could stop the rig with some confidence about not rolling through rapidly changing traffic lights.

When I got my current Workhorse W-22 rig, I thought I had died and gone to heaven when I first used the brakes. What a great difference. I can now actually stop this much larger rig easily.

Good luck,

[ebprod]

At least I know a little more of what to look for. I won't get a chance to crawl under there until Saturday. I'll let everyone know what I find.

-Joe

[ebprod]

I found this in the engine compartment. The top of the black cap says to use "DOT 3 brake fluid only". Can I assume I found the master cylinder?

I tried to get the black cap off, but it won't budge. It appears to made of plastic. Any suggestions?

-Joe

[Dave78Chief]

I would say you found the tag axle booster, master cylinder and sychronizer valve (lower left corner of first picture). That would be a screw on MC cap. The MC istself reminds me of a trailer brake MC. Should be able to unscrew it with a open end or cresent wrench. Slip joint pliers may damage the plastic cap. The brake line from the front of the MC should go to a Tee on the tag axel itself. The other 2 legs of the Tee should go to each tag wheel.

Dave

[ebprod]

I got the cap off, and the reservoir is bone dry. What next? Just fill it with brake fluid and hope it works?

-Joe

[Nick-B]

You can try filling with fluid and hoping for the best but if you want tag brakes that you can trust it is time to go thru the system.

Mine was the same way. Master cylinder is probably rusted inside and won't hold fluid or at least won't make much pressure. You got some work ahead of you.


At the very least:

1. new Master Cyl.
2. New wheel cyls
3. rebuild synchro valve

I had to replace the entire brake assembly on each side since the later Dexter wheel cylinders were cast one piece with the backing plate. My shoes, springs and hardware were all shot so I needed everything for each side anyway. Only thing I re-used were the drums.

Both Dave and I have been there - done that, so ask away.

You'll want to pull the drums and assess the condition of the shoes and hardware and whether the wheel cylinders are bolted on (good thing) or part of the backing plates.

Don't despair, that's why we're here - to help!

[ebprod]

I am going to fill the reservoir tomorrow and see if I get any braking power to the tag. Otherwise, this is a job that is beyond me. I have a friend that I am going to ask to help, or else I will need to find a shop that can fix it.

I've already driven over a thousand miles without the tag brakes. The stopping power isn't great, but still adequate. Is there any danger driving the way it is now? I have a short trip planned for next weekend.

-Joe

Quote:

Originally Posted by Nick-B You can try filling with fluid and hoping for the best but if you want tag brakes that you can trust it is time to go thru the system. Mine was the same way. Master cylinder is probably rusted inside and won't hold fluid or at least won't make much pressure. You got some work ahead of you. At the very least: new Master Cyl. New wheel cyls rebuild synchro valve I had to replace the entire brake assembly on each side since the later Dexter wheel cylinders were cast one piece with the backing plate. My shoes, springs and hardware were all shot so I needed everything for each side anyway. Only thing I re-used were the drums. Both Dave and I have been there - done that, so ask away. You'll want to pull the drums and assess the condition of the shoes and hardware and whether the wheel cylinders are bolted on (good thing) or part of the backing plates. Don't despair, that's why we're here - to help!

[KenSherwin]

Quote:

Originally Posted by ebprod The stopping power isn't great, but still adequate. Is there any danger driving the way it is now?

The statement answers the question. No tag brakes poses two problems:

1. Because you have less brake, it takes more pressure on the remaining brakes to achieve a given stop, which you have already noticed.

2. The more subtle and dangerous condition is that when you really, I mean REALLY need brakes, this is what will happen. The tag is carrying weight, unloading the rear axle. Under hard braking or during slippery conditions, that axle can lock up and want to slide the back of the coach sideways. It is a somewhat interesting feeling when your coach starts oversteering on you, especially when you don't know it's going to happen. I've slid coaches both accidentally and on purpose and, trust me, doing it on purpose is a lot of fun but having it happen when you don't expect it and you are very busy with the emergency at hand, it is no fun at all. Makes the ole heart go pitter-pat!

You want all the brakes pulling the right amount of load so that your coach understeers at the handling limit because understeer is much more predictable.

You are almost certain to get away with driving it this way but "almost" is a long way from "completely". Is what you are carrying worth doing it right?

If all this was spoken like an engineer, perhaps one of you can translate it into English for me.

[ebprod]

I seem to sorta have brakes. The motorhome is on the jacks at the moment, with one of the tag wheels off the ground. I filled the reservoir, started the engine and pressed the pedal. I had to add a little more fluid, but not much, after the first trial. It seems to be holding fluid now.

The braking power is inconsistent. Sometimes the wheel is locked in good, other times the wheel spins freely. When I tried it last time, the brakes seemed good.

I won't be able to get it on the road until next weekend. Any ideas on whether the brakes are going to work?

-Joe