'93 E350 Motorhome - really frustrating brake problem

[rgnprof]

I have been chasing this issue - literally - for years. I have a "93 Ford E350 Motorhome with front disc and rear drum brakes (RABS). I have had a very spongy, soft pedal and I'm almost positive I've been stopping this coach with only the front brakes. Recently pulled the rear duallys and changed out everything - new drums, hardware, wheel cylinders, shoes...

And I still have the same issue. Today, I've pulled the rear wheels again trying to adjust the brakes. I have spent several hours trying to get them adjusted but I still have no real brake in the rear wheels to speak of. My wife was in the coach, pressing the brakes and I was still able to turn the drums by hand (no tires installed yet) with the brake pedal depressed.

Also, I changed out the master cylinder last year and I have bled the **** out of these brakes!

Any thoughts? My only thought is I still have a hydraulic problem - although the front disc brakes seem to work, OR I still have not gotten these rear shoes adjusted properly to the drums.

Please help! Thanks!
ryan

[rgnprof]

Great help! Thank you gentlemen!

Something Ron said at the end of his post struck a note: We bought this motorhome from a some parents of friends of ours in 2010. The year before - maybe 2008 - the brakes went out on them in the Rockies. They took it to a brake shop in Estes Park and spent all kinds of money to get everything fixed. The PO discussed all of this with me and also stated that ever since then the brakes had been mushy/spongy. He had taken it to several local places - some thought the shop had put in the wrong bore MC (see my previous threads on this...). But, now I'm thinking they just did it the way Ron described - didn't take the time to do it properly - and everyone since (myself included) has just figured they were adjusted properly...

[navegator]

To adjust the drum brakes first measure the inside of the drum, then measure the shoes on the horizontal diameter and at 45 degrees, adjust the drums until you have a 1\8 clearance, install both drums, adjust both until you hear them begin to scrape.

Now slam on the brake pedal a couple of times and re do the brake adjustment, what you just did was to seat the shoes inside the drum but they are still out of adjustment, the shoes expand in an ark and the adjusment needs to be done several times with the brake pedal being stomped as in a panic stop, this pushes the pistons and shoes against the drum and more or less centers them.

If you over do the nurlled adjuster, you can always back it up, tighten the drums until they are semy hard to turn by hand and back the adjusting wheel 3 teeth.

If you still have a spongy brake then there is air in the line and needs to be properlly bled.

navegator

[j-d]

Ryan, the rear brake hose leads from one end (pretty sure it's driver side) of the axle, from near the differential. On the axle, there'll be a tee fitting. The hose from the chassis, and the two steel lines leading to the wheels. Other end of the hose goes to the chassis.

When we did our old coach, we found one of the steel lines leaked. Probably didn't till we flexed it working on the cylinder. Replaced it with a length of straight brake line from the auto supply. You might need an extra foot or so. We had to roll one end into a loop to get it to get around the spring mountings and connect to the cylinder. Didn't look original, but all you have to do is get the fluid from and to, and not kink the new line or run it where it'll get pinched.

[ron_dittmer]

rgnprof,

I learned something with the rear drum brakes on a dual rear wheel axle (originally a SRW) on our old 1983 Toyota motor home that I believe will be applicable to your problem. Like you, the rear drum brakes were not working. In my case, this was when the original SRW axle was replaced with a true DRW axle. What I did, completely changed the response of the braking system with the 4 rear tires contributing immensely in stopping the motor home. When I was done, I could actually feel the rear of the motor home sinking from the rear axle holding the rig back with great rear drum brake performance. This is what I did which was all about how I adjusted the rear brake shoes.

- lift the rear of the motor home and place the rear axle on blocks
- leave everything assembled, tires and all
- place the transmission in neutral making sure the rear tires spin freely
- focus on one side
- access the adjusters and adjust until a drag (so far it's a text book process)
- have an adult press the brake pedal as hard as they can
- if the wheel spins, adjust again
- do this several times (I counted 18 times on one wheel in my case)
- repeat on the other side
- when done, go back to the first side, then the other side
- when you think you are done, turn on the engine and pump the pedal several times again using the power brake booster
- turn off engine and check for a decent drag on each side
- I had to adjust the brakes tighter multiple times again

The rear brake adjusting process went on and on (and on)....did I say on and on? I thought I would never get the rear brakes to drag significantly to require a little muscle to turn the tires.

I drove the motor home around town and checked for over-heating, but there was no concern. I also checked for rolling resistance which was of no concern. The next drive was a longer test to my job which also was uneventful. So I considered the job done and the brakes performed perfectly for the many years we owned the motor home thereafter.

I think what made the difference was having the rear axle raised up so I could switch between sides as often as needed and checked each brake, and adjust tighter and tighter again. I was very surprised how many times I had to re-adjust tighter after I thought I was done. It took so many tries to get each brake system seated properly into their respective drum, but the results were amazing.

There is no way a mechanic would spend the right amount of time adjusting the brake shoes on that old rig we owned. As torturous as it was to do on my back with the tires on, it was surely worth it all.

[rgnprof]

I have changed out the front hoses last year when I redid the the entire front brakes and the new master cylinder. I didn't even see any thing other than steel hoses to the rear brakes...I'll look again. I did bench bleed and I have always used a Motive power bleeder on this vehicle. When I did the drums earlier this spring, I bled the whole system - again - and really thought I got all of the air out. I have not tried jeffengle's approach yet though...I'm going to wait and take this thing for a drive - now that I feel I've got the rear brakes 'better' adjusted and see how things feel. From what others are telling me, brakes are just a troublesome spot on these chassis...

[Cousin_Eddie93]

jeffengle wrote:
take the lines off at the master cyl.& plug the outlet ports. you should have a full hard pedal. than one by one hook the lines & checking the pedal. when you get a spongy pedal, you know which end is the problem, you can do this for the length of the system. most likely air in the system, a good pressure bleeder should work. jeff

Agreed, I had a 72 ford Galaxie that would never have enough brake pressure unless the lines and cylinder were completely air free.

[jeffengle]

take the lines off at the master cyl.& plug the outlet ports. you should have a full hard pedal. than one by one hook the lines & checking the pedal. when you get a spongy pedal, you know which end is the problem, you can do this for the length of the system. most likely air in the system, a good pressure bleeder should work. jeff

[-Lqdskier]

rgnprof, the brakes on my 94 montara also leave a lot to be desired. Like yours, the pefal is fairly spongy. My rig does have "self adjusting" rear brakes which means you still have to physically adjust them but occasionally going in reverse and hitting the brakes hard supposedly keeps them adjusted.

[j-d]

CharlesinGA wrote:
Flex hoses fail inside. Replace the hoses.
Charles

Agreed. The fronts fail a little worse since they twist with steering as well as move vertically. The vehicles with rear drum have only one flex hose, Chassis to Axle. Then steel lines out to the wheel cylinders. But those with rear disc have three. The one to the axle then one each side, from steel line to caliper, like a front disc brake.

The lines usually fail "shut" but... They can also deteriorate to where they expand under braking pressure. Then, some of the pedal effort gets diverted from the cylinders to the stretching of the hose.

Long shot, but, Ryan, If you haven't changed hoses with all this work, your might as well.

[klutchdust]

Haven't done drum brakes for awhile but as a kid we turned the wheel until the brakes just slightly started scraping the drum and that was it. Great ideas from the other posters.

[CharlesinGA]

Flex hoses fail inside. I've had it happen. They look great on the outside, and the lining collapses on the inside and the fluid won't flow thru. Had it happen to both front hoses on a Mustang.

Replace the hoses.

Charles

[j-d]

Our older (1983) E350 chassis seemed about the same way. When we got it, the thing just barely stopped. Front brakes were rusted together, so replaced shoes, calipers, rotors, hoses. Helped a lot, but rear didn't seem to be doing its share. Removed drums and found new shoes, drums that had been turned and lathe marks still on them, and STUCK wheel cylinders. Replaced all... Shoes, Hardware Kit, Cylinders. Probably should have had Shoes "arched" to match drum diameter but like you did not. Braking was better, still soft pedal. Replaced master cylinder and booster, same... I believe I also swapped the proportioning valve with a used one. Disappointing braking system. It did not have RABS.

[K_Charles]

.

[K_Charles]

Did you bench blead the master cylinder?

[photobug]

I've had 3 ford vans plus my E450 mh every single one of them has had brake issues. seems like ford brakes are consistently bad. couple of times needed the brake bias valve adjusted so it would apply more power to the rear. last time I took the trailer out, fried one of the front brakes, enough to try and pull the whole rig off the road. had to abort the trip and take the ferry home. 45' of rv on a ferry isn't cheep. ended up replacing the whole brake assembly on that side.