DIY brake hose swap

[ii_amnt]

I would like to replace the brake hoses at the wheels on my bus. My right front brake drags for the first few minutes of a drive. I was told this could be due to a deteriorating brake hose collapsing.

How difficult is the brake bleed on a full size bus with hydro brakes? I was going to pay a shop to do the replacement and bleed, but I am considering tackling it myself.

[jazty]

Replacing lines is easy enough if you have line wrenches and a propane torch (to heat up the fittings if they won't budge). An International dealer will be able to supply you with the appropriate rubber hose pieces.

I can't see how a dragging brake could be due to a hose collapsing, though. I don't thing there's ever any vacuum in the brake lines.

Does your bus have disc brakes? I have more frequently seen brake drag due to a sticking brake piston or caliper that isn't sliding properly. If it's a drum brake it could possibly be due to a broken spring or things just generally seizing up.

[cadillackid]

having one of the pistons stick is quite common on disc brakes as mentioned... I'd look into the caliper before the hose.


-Christopher

[slaughridge85]

I've had this exact thing happen on a ford pickup. The inner lining of the hose gets a bulge in it and traps fluid in the caliper until the brake line heats up enough for the bulge to smooth out and start passing fluid. The hose that is deteriorating and causing this issue will eventually seal itself off and cause the brake to seize... Brake lines are cheap go ahead and replace them, change brake fluid, bleed brakes and see if your problem goes away. If not then it might be time to rebuild the caliper. Bleeding brakes on a bus is the same as on a car, just bigger. Start with the wheel furthest from the master cylinder and work your way around...

[roach711]

In my Ford the brake hoses are known to clog over time so a hose problem isn't totally unheard of.

Put a wrench on the bleeder screws and see if they'll turn. If those are frozen or snap off the calipers will need to be replaced anyway.

[jazty]

Originally Posted by roach711

In my Ford the brake hoses are known to clog over time so a hose problem isn't totally unheard of.

Put a wrench on the bleeder screws and see if they'll turn. If those are frozen or snap off the calipers will need to be replaced anyway.

Oh yeah.. Ancient bleeder screws can be a full on pain. If they don't budge with moderate force I always put some heat on them. Careful not to burn any rubber lines! Ah, what the heck.. You're replacing them anyway, right?

[Carytowncat]

Great topic because i JUST replaced ALL my brake lines,

And YES a clogged hose can cause a caliper to stick.

Also i used a $20 Harbor freight bleeder hand vacuume, and it was worth it's weight in gold. Crack the bleed valve on the caliper, smudge a little grease around the valve so it doesnt just suck air from around it (which mine did) and pump a vacuume. It allowed me to totally vacuume out all my old grimey brake fluid and suck new synthetic brake fluid through the entire system. Ahhh to be meticulous here felt soooo nice, spoiling myself with new fluid and all brand new brake lines

A local hydraulic hose shop took my old lines and made beautiful new ones for like $40 each, a whisker less than ordering new ones online even!

Also i felt that flushing the old fluid out and new synthetic fluid really refreshed the calipers. Calipers operate with a piston and super tight clearance tolerance, so gunky fluid is going to make em funky...like a monkey.

Also this; the bus had sooo much room i was able to sit underneath it and work on the brakes Never had to pull a wheel. Not a bad job at all.

I was patient and tapped at stubborn bleeder screws.

Good luck!

[jazty]

This is good information! If I am ever stuck guessing at the cause of a sticking caliper I'll also take a look at the rubber hoses.

[ii_amnt]

Cary, thanks for the info there. That's exactly what my bus needs. Somehow I've gotten away with never really doing brake work before. I've overhauled suspension and done bearings, but never even changed a brake pad. So, I'm a little hesitant for my first job to be on a bus. I should be able to tackle it, though. Plenty of good write ups out there.

[Stu & Filo. T]

Originally Posted by Carytowncat

Great topic because i JUST replaced ALL my brake lines,

And YES a clogged hose can cause a caliper to stick.

Also i used a $20 Harbor freight bleeder hand vacuume, and it was worth it's weight in gold. Crack the bleed valve on the caliper, smudge a little grease around the valve so it doesnt just suck air from around it (which mine did) and pump a vacuume. It allowed me to totally vacuume out all my old grimey brake fluid and suck new synthetic brake fluid through the entire system. Ahhh to be meticulous here felt soooo nice, spoiling myself with new fluid and all brand new brake lines

A local hydraulic hose shop took my old lines and made beautiful new ones for like $40 each, a whisker less than ordering new ones online even!



Also i felt that flushing the old fluid out and new synthetic fluid really refreshed the calipers. Calipers operate with a piston and super tight clearance tolerance, so gunky fluid is going to make em funky...like a monkey.

Also this; the bus had sooo much room i was able to sit underneath it and work on the brakes Never had to pull a wheel. Not a bad job at all.

I was patient and tapped at stubborn bleeder screws.

Good luck!

The best bleeder I ever used actually connected to the bleed screw & pumped fluid back to the master cylinder, you do need someone to watch so you don't overflow but its what I've had the best luck with.

[ii_amnt]

Can someone tell if these brakes are redundant/independent? My old Mercedes is designed so that if there front brakes fail, the back are still functional and vice versa. I've got to imagine a school bus would be the same way.

[Tango]

All American vehicle hydraulic brake systems since about 1967 are front/rear split at the master to prevent total loss. Unfortunately...I once owned a 1966 Ford pickup. Ouch.

[Rameses]

Originally Posted by Tango

All American vehicle hydraulic brake systems since about 1967 are front/rear split at the master to prevent total loss. Unfortunately...I once owned a 1966 Ford pickup. Ouch.

That might be the case with passenger vehicles, but I can tell you with 100% confidence that the 1979 Ford F700 did not have a split master cylinder.

To check the vehicle in question, look at the master cylinder and see whether the front and rear brake lines are threaded into separate ports, or if there is one port with a Y fitting threaded into it (or a single line with a T somewhere downstream.)

If there are two separate ports, it is a split system and the front and rear brakes are isolated from each other.