Hydraulic/Disc brake problem

[dznf0g]

Originally Posted by perryg114

It is possible for these rubber hoses to fail internally even when they look fine on the outside. If they are bent at sharp angles they could be even more suspect. What can happen is the fluid gets trapped when the interior of the hose collapses and it lets fluid into the caliper but not out. Calipers are simple devices. There are pistons and they should more freely in the bore. It should be possible to push on them when them with the bleeder open and fluid should come out the bleeder. On cars, I use a big C-clamp and it pushes the pistons back in so the pads can be replaced. If the caliper is not sliding left to right it may cause slight dragging but usually the pad opposite the piston will wear more if this is the case. Pistons usually don't sieze in the bore unless they are very old and get stuck from lack of use. The biggest enemy of a hydraulic brake system is sitting. Fluid should be changed yearly or replaced with DOT 5 in which case it will last forever. I agree with the other guy that said that if you have one wheel dragging it is not the brake controller or actuator. It has to be a caliper or hose. Standard brake fluid is evil stuff. It sucks up water and will rust caliper bores. If you use it every day you keep the rust from forming. If it sits for long periods water can corrosion can build but I think you are having hose problems.

Perry

Yes, it is most common for the internal layer to fail before any apparent outside problem. This is true with any vehicle. That is why they say NEVER to let your calipers hang by the hose while doing a brake job.

When the inner layer tears and creates a "flap", one or both of these occur:
Brakes on that wheel is slower to apply than the other three. This usually causes a pull to left or right upon brake apply.

Slow to release (or not completely releasing). Causes accellerated pad wear on that wheel, heat buildup, rotor blueing and wear.

[perryg114]

Stainless hoses are good but they have their limits as well. They still have rubber liners inside them but they are much better than the rubber hoses. Most folks use them because the provide a more solid pedal feel which is not a big deal here. You can get slighly more braking force at the caliper because the hoses don't expand as much.

Perry

[nickmeloy]

Originally Posted by Don.44

Has anyone ever put an brass elbow fitting at the end of the brake hose to reduce the bend in the hose ?
Don

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We installed banjo fittings on our 2006 Classic to solve the kinked brake hose problem. These fittings are equivalent to a 90 degree fitting.

Nick

[barts]

Originally Posted by perryg114

Stainless hoses are good but they have their limits as well. They still have rubber liners inside them but they are much better than the rubber hoses. Most folks use them because the provide a more solid pedal feel which is not a big deal here. You can get slighly more braking force at the caliper because the hoses don't expand as much.

Perry

Since the hydro-electric systems are essentially pressure amps (the brake line pressure is a linear function of input current), the effect of brake hose compliance on our trailers is to create more brake delay on application, and slightly reduce the speed with which the brakes are released.

- Bart

[perryg114]

So you are saying stainless BAD!!!!!!!!!!!!!!!!!

Perry

[barts]

Originally Posted by perryg114

So you are saying stainless BAD!!!!!!!!!!!!!!!!!

Perry

Nope - just not needed here. They're wonderful on motorcycles, sports cars and the link, and if your brake lines are attacked w/ knives, they make a difference. I just don't think you're going to notice much in this application. As I said, if you replace the rubber hoses w/ stainless, the brakes will come on slightly faster, and and come off slightly faster as well - but not so much as you'd notice.

The steel lines, of course, are much stiffer than any hose. I fixed some unusual resonance problems once in a piece of experimental farm machinery by replacing the long hoses with short hoses connecting steel lines.

- Bart

[Don.44]

After looking at the picture of the brake hose on such an angle I removed my wheels to inspect my hoses and none of mine were mounted on an angle like this one shown in the picture . (2005 classic) . No chance for a kink Do you think you could have a brake line routing problem ? Could you have the wrong caliper ? Also could someone tell me if hydraulic/disc brakes were an option in 2005 because another 2005 classic I inquired about has electric with drum brakes . Regular hydraulic brake hoses have worked fine for years I see no need for steel renforced hoses for this application .
Don

[GCinSC2]

Originally Posted by barts

Since the hydro-electric systems are essentially pressure amps (the brake line pressure is a linear function of input current), the effect of brake hose compliance on our trailers is to create more brake delay on application, and slightly reduce the speed with which the brakes are released.

- Bart

Bart,

I have worked on my trailer disc brake "system" more than I really ever wanted or expected to. And unfortunatelly I'll be going over a similar repair but not as bad as the OP described possibly Thanksgiving week. We should also include the thread by HAP3 with his destroyed brakes & hoses. I had a HOT rotor and a VERY HOT rotor on a single axle on my dual axle 30'. Both of these axles were not even 1 year old, an undiscussed long story. I actually drove home with just the front axle brakes working, I had to plug off the lines to the rear axle. Wasn't that hard to do, did it at my campsite. A couple of comments on your comments.

Trailer uses steel brake lines, cars and trucks same. Trailer uses brake hoses, cars and trucks same. Brake pads, rotors and calipers same again. IMHO mechanically these are essentially the same components just in different packaging. Where we do have a significant component difference is how the hydraulic pressure is created, single stroke master cylinders for TV brakes vs. electric motors and a pump in our trailer actuator to create pressure. We also have the controller to sense the request for braking and create the signal to the actuator to start creating pressure. This is the big difference and then we want to coordinate the two independant braking systems.

Using the same "plumbing" on our TV's we should expect the same:

"the effect of brake hose compliance on our trailers is to create more brake delay on application, and slightly reduce the speed with which the brakes are released."

I do not see this as my TV's braking habits or expectations. My 2005 Dodge has about 120,000 miles on the original brakes, performing as I expect them to.

The areas that I would advise an owner with disc brakes to review:
Controller to actuator compatibility, must be checked. My dealer sold me an incompatible (non listed) controller, why, I think they were just not used to working with disc systems. Now I have Maxbrake.
Wiring, wiring and wiring. These connections must be 1st class.
Hoses, several discussions here about short hoses and their problems.
And for the possibly most challanging, are your brakes COMPLETELY bled? While my profession is not braking, my profession DOES involve another DOT 3 based single stroke hydraulic systems (automotive clutches) and I cannot over emphasize how important and detremental air bubbles are in these systems. In our TV brakes, we use a single (master cylinder) stroke to create braking pressure in the lines but in our trailer the controller tells the actuator to run and the trailer could be 1/2 air in the lines and the pump just keeps pumping and pumping compressing the air in the lines and eventually (read delay) creating braking pressure. Also a possible source of brake delay in a correctly functioning hydraulic system would be rotor runout. If excessive runout existed the caliper pistons would be slightly in a retracted position as the wobbling rotor pushes the pads away from the runout. This extra air gap requires more time to press the pads against the rotor compared to a true running rotor that had a minimum gap.

I wish I had an ultrasound gizmo that I could put on the system and from the outside detect or prove that air exists in these systems, ain't got it. Air = delay, period.

I will comfortably state that IMHO the mere flow of DOT 3 out of a bleed screw is not a guarntee that all air has been expelled.

Going back to the OP's original complaint of intermittant brake locking up or drag IMHO a single wheel incident must point to components confined to the indivudual wheels brake components and supply hose.

If I was to buy a X-Mas gift for a fellow RV'er it would be TPMS that monitors internal wheel temp and a point and shoot temp gun.

[GCinSC2]

Originally Posted by nickmeloy

++++++++++++++++++++++++++++++++++++++++++++++
We installed banjo fittings on our 2006 Classic to solve the kinked brake hose problem. These fittings are equivalent to a 90 degree fitting.

Nick

Nick,

Any chance to post a picture, I'd like to see this, sounds interesting.

Gary

[barts]

Originally Posted by GCinSC2

Using the same "plumbing" on our TV's we should expect the same:

"the effect of brake hose compliance on our trailers is to create more brake delay on application, and slightly reduce the speed with which the brakes are released."

I do not see this as my TV's braking habits or expectations. My 2005 Dodge has about 120,000 miles on the original brakes, performing as I expect them to.

The areas that I would advise an owner with disc brakes to review:
Controller to actuator compatibility, must be checked. My dealer sold me an incompatible (non listed) controller, why, I think they were just not used to working with disc systems. Now I have Maxbrake.
Wiring, wiring and wiring. These connections must be 1st class.
Hoses, several discussions here about short hoses and their problems.
And for the possibly most challanging, are your brakes COMPLETELY bled? While my profession is not braking, my profession DOES involve another DOT 3 based single stroke hydraulic systems (automotive clutches) and I cannot over emphasize how important and detremental air bubbles are in these systems. In our TV brakes, we use a single (master cylinder) stroke to create braking pressure in the lines but in our trailer the controller tells the actuator to run and the trailer could be 1/2 air in the lines and the pump just keeps pumping and pumping compressing the air in the lines and eventually (read delay) creating braking pressure. Also a possible source of brake delay in a correctly functioning hydraulic system would be rotor runout. If excessive runout existed the caliper pistons would be slightly in a retracted position as the wobbling rotor pushes the pads away from the runout. This extra air gap requires more time to press the pads against the rotor compared to a true running rotor that had a minimum gap.

I wish I had an ultrasound gizmo that I could put on the system and from the outside detect or prove that air exists in these systems, ain't got it. Air = delay, period.

I will comfortably state that IMHO the mere flow of DOT 3 out of a bleed screw is not a guarntee that all air has been expelled.

Going back to the OP's original complaint of intermittant brake locking up or drag IMHO a single wheel incident must point to components confined to the indivudual wheels brake components and supply hose.

You're right: air == delay. Air introduces compliance into the system and this is what causes delay as the pump has to work to pump up the pressure. Hoses also cause delay because they're springy. [Stainless steel hoses are less springy, but not so you'd notice in this application; one can definitely feel the difference on a motorcycle, for example] There's of course some delay inherent in the movement of the pucks against the rotors.

I bleed the brakes using a remote switch hooked to the break-away line on the controller. What would really make the job easier is a large bottle of brake fluid arranged to keep the master cylinder full as I purge the individual lines; that way I'm not crawling out from underneath the trailer to refill the master cylinder all the time. I installed the discs when we replaced the axles on the Tin Pickle; it took several round the trailer trips to get the air out of the lines, and I'm sure there's still some in there somewhere.

I'm also considering going to the MAX Brake controller; my Prodigy has been fooled into surging in stop and traffic on downhills, which is annoying but not dangerous.

- Bart

[Don.44]

It is important to be sure you have good clean fluid in the brakes. Contaminated fluid will reduce the effectiveness of the braking system. Fluid also absorbs moisture . I would recomend flushing and bleeding the brakes every other year for best results . If the master cylinder has no check valve in it you can use a vacuum pump at the caliper bleeder . If it does you will need a pressure bleeder at the master cylinder .
Don

[nickmeloy]

Originally Posted by GCinSC2

Nick,

Any chance to post a picture, I'd like to see this, sounds interesting.

Gary

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I do not have picture capability. However, the following link to an automotive video may prove instructive.

Video: How to Remove the Banjo Bolt | eHow.com

Nick

[ROBERTSUNRUS]

Hi, I think Airstream still sells a drum brake conversion kit.

[GCinSC2]

Nick,

I know what the banjo bolt fitting is and looks like, I just was curious how your line routing looked using the banjo bolt approach.

Thanks,

Gary

[ROBERT CROSS]

UMMM....wonder why?

Bob

Model: 2012 - 31'W CLASSIC LIMITED DINETTE TRAILER

CHASSIS
10,000# GVWR • 10,000# Axle System • 7174# UBW • 2826# NCC • 805# Hitch Weight • Aluminum Wheels • 15" Radial Black Wall Tires, LRD • 12" Electric Drum Brakes w/ Nev-R-Adjust Brakes & Nev-R-Lube Hubs • Electric Hitch Jack • Manual Stabilizer Jack w/Pads • Aluminum Step w/Extension • Stainless Steel A-Frame Protectors • Spare Tire & Bracket.

[Don.44]

I didn't think the surface on the caliper was machined for a banjo bolt fitting but if it works you can't argue with that . I have 90 degree fittings screwed into my calipers and they work fine .
Don

[nickmeloy]

Originally Posted by GCinSC2

Nick,

I know what the banjo bolt fitting is and looks like, I just was curious how your line routing looked using the banjo bolt approach.

Thanks,

Gary

+++++++++++++++++++++++++++++++++++++++++++++++
The brake hose comes straight from the banjo fitting fitting to the existing steel brake line. The tricky part is getting the length of the brake hose correct. Too short and something will break when the tire goes through its' maxium verticle travel. Too long and one is back into the danger of the brake hose rubbing on something. From memory, my brake hose length is 12 inches, but measuring is critical, and each trailer is probably slightly different.

I also purchased some of that split wire protection stuff from Radio Shack and put a piece around each brake hose, held in place with nylon tie straps.

Nick

[GCinSC2]

Nick,

When I reconfirured my hose, I just didn't think of a banjo fitting config. I can see the idea in my head, a pic would be nice. I used a hose and a short piece of pre-flared steel line going from M10 to 3/8", picture already posted.

One feature that your banjo connection and my steel line attaching to the caliper allows is inboard caliper bleeding in addition to the bleed screw.

But if I started over on this, I would look at approaching this from the front of the axle, somehow routing it down the trailing arm and then attaching. For a comparison look at a motorcycles rear brake. The hose does not come in from behind to the caliper, it comes down the swingarm.

I have a set of new Dexter calipers in the garage, I'll take a picture of the connection, M10 bubble then others can see the face of the caliper casting at the connection.

[nickmeloy]

Originally Posted by Don.44

I didn't think the surface on the caliper was machined for a banjo bolt fitting but if it works you can't argue with that . I have 90 degree fittings screwed into my calipers and they work fine .
Don

++++++++++++++++++++++++++++++++++++++++++++++
You are correct in that the casting is not machined to a very smooth surface. Another member of the forum had sent me a PM on his success with using banjo fittings in this application. I decided to try it, and have had no problems with fluid leaks.

I went to banjo fittings because I was unable to locate any 90 degree fittings with the correct threads. If memory serves me correctly, the threads are metric on one end and SAE on the other end. Where did you find the 90 degree fittings?

Nick