Disc brake discussion

[slowmover]

Thanks, Gary.

And to others for the contributions on this long overdue thread.

I'll really feel I've gotten somewhere when antilock discs are on my TT.

The Peterbilt I recently got out of has front discs. There is no substitute for their consistent, reliable performance.

[barts]

Originally Posted by dznf0g

A high pressure hydraulic accumulator like autos have (hydraboost, etc.) is the ultimate answer here, but none of the actuators have them. Tuson engineer said it's not needed with theirs....I'm skeptical.

Hydraulic accumulators store their energy in either a compressed spring (rare) or compressed gas, typically nitrogen.

A powerful voice coil coupled to a conventional vacuum boosted master cylinder + a vacuum reservoir and electric vacuum pump would make a pretty nice actuator capable of very fast response, and would a pretty reliable unit.

- Bart

[dznf0g]

Originally Posted by barts

Hydraulic accumulators store their energy in either a compressed spring (rare) or compressed gas, typically nitrogen.

A powerful voice coil coupled to a conventional vacuum boosted master cylinder + a vacuum reservoir and electric vacuum pump would make a pretty nice actuator capable of very fast response, and would a pretty reliable unit.

- Bart

That's pretty much what the original disc systems AS used in the 70s? was, wasn't it.....without any modern electronics? I guess they worked, but look HUGE!

[dznf0g]

Originally Posted by SteveH

Got some work done today. Not 100% yet, or I would have done it all. Installed the new actuator, and built a cable with a start button on one end so I can bleed the brakes by myself. Need a couple more fittings before I can install the residual valve.

While I was under there looking around, I did notice that on my trailer with the actuator where the factory installed it, the output of the actuator is lower than the input to the calipers when the trailer is level. Make of that what you will.

I'm not sure what to make of that, without knowing the internals of the actuator....and scratching my head trying to reconcile what I know about a sealed hydraulic system and potential drainback.

[dznf0g]

Very tricky indeed, Gary. I am unfamiliar with the Maxbrake, but isn't is displaying the TV hydraulic pressure? Or trailer?

[SteveH]

Originally Posted by dznf0g

I'm not sure what to make of that, without knowing the internals of the actuator....and scratching my head trying to reconcile what I know about a sealed hydraulic system and potential drainback.

I have to call Dexter in the morning to get them to send a pick-up order for the actuator that went belly up, and at that time I'm going to ask to talk with an engineer and find out if the thing has a residual valve built in.

I thought I could install it easily and have the flexibility of going back easily if I didn't like it, but such is not the case. Spare tire is in the way. I have to cut and re-flare one end of the tubing, making it necessary to replace it should I want to remove the residual pressure valve.

[GCinSC2]

Rich,

I've seen used MaxBrake's sell over on Turbo Diesel Register in very short order. The Dodge Cummins crowd will snap 'em up.

The display shows actual TV brake circuit pressure. I just came back from my truck. Engine off, I touched the MaxBrake slider waking it up. Then I pushed on the brake pedal, the display shows TV brake circuit pressure.

Folks,

I can't speak for any other system, but can your EOH and brake controller do this:

Rig hooked up, engine running, vehicle stationary. Push the brake pedal slightly and the actuator starts, low output. Push pedal harder and the actuator ramps up you HEAR it is loading up higher and higher pressure. The controller varies the system pressure according to your rigs actual TV pressure via the hydraulic pressure transducer that is tapped into the TV brake circuit. FWIW the transducer is made by Honeywell and all connections are the same type of brake fittings that the brake system is made with, no issues.

Does any other type of controller system do this?

I'd also like to offer a reminder to anyone looking at reworking any of their system. INSPECT YOUR PISTON DUST SEALS FOR DAMAGE.

Damaged dust seals can allow water in. This water may become trapped and guess what, it can or will create rust between the steel caliper pistons and cast iron caliper housings. The slightest amount of rust can prevent the piston from its very small but required return stroke causing the pads to drag and possibly burning up your pads and rotor. It happened to me. I made the necessary repairs and no further issues. Dexter does offer boot and seal kits. Once you get past your 1st caliper seal and boot R&R, really pretty easy. The cleanup is the only tedious bench exercise.

I've sent some pics and details to Rich and in going thru my old files I found a video I shot of my bench test of repaired caliper halves. I actually rigged up a pickup truck pedal assembly and clutch master cylinder. This allowed me to bleed each half and do a crude bench test. I blocked each piston set from extending using a pretty stout angle iron, uh that flexed immediately. Then I added C clamps across the pistons thinking no way will it flex. On the video the system can easily flex bolted angle iron and C clamps at no more than 400 PSI. I referencing 400 PSI as a pretty realistic pressure created by a clutch hydraulic release system.

Not ever gonna claim hydraulic system engineering skills, just a bit above average DIY'er.

YMMV

Gary

Steve,

Bleeding via remote switch. This will go to 100% output, correct, its either on or off. I'd expect it can spit out a lot of fluid quickly, just keep an eye on the reservoir you do not want it to accidentally empty while bleeding. You'll get to start over as soon as it swallows air.

[SteveH]

Originally Posted by GCinSC2

Steve,

Bleeding via remote switch. This will go to 100% output, correct, its either on or off. I'd expect it can spit out a lot of fluid quickly, just keep an eye on the reservoir you do not want it to accidentally empty while bleeding. You'll get to start over as soon as it swallows air.

Yes, Gary, I understand this. The first time the dealer bled the brakes when doing the recall work, they did it with the emergency brake away switch because they did not have the truck. Same thing basically without the convience. However, they did such a crappy job that I had a delay of about six seconds.

I think my remote switch will be much more controllable. My objective is to be able to do it without my wife's help. We frequently have, oh let's say "difficulty" communicating when under stress.

[dznf0g]

Gary, I've never noticed, nor tried, to see how pedal pressure behaves on a stopped vehicle. The DirecLink has a setting for "stopped brake power", which I keep at 0%. So I don't have any actuator operation at stop. Don't need it with a 2500 most of the time. When I was in the rockies 2 years ago, I set it at 30% by don't recall how pedal pressure behaves. Also the Direclink head is connected to the main unit via a telephone cord. To bleed the brakes one just needs about 25' of phone cord and you can use the manual trigger to get how much ever pressure you want (above 1%, whatever that translates to in PSI).

[switz]

With our Titan pump, the sound I can hear from the cab is it is either on or off. There does not seem to be a slow ramp up of pressure or a low pressure setting (despite the installed DirecLink NE) for stopped.

Thus the thought process of acquiring the ABS conversion using the Tuson pump with their ABS system which incidentally reports back continously the brake fluid level to the display in the cab over the power wire to the pump.

[SteveH]

So I called Dexter today and talked with an engineering guy. Surprise, surprise, he had never heard of anyone with delay problems. He did tell me the actuator is not equipped with a residual pressure valve, and he did say it would not hurt anything to use one.

I explained how my delay would be very short right after bleeding, but over time would increase. I explained that my actuator, in the factory mounting position, was slightly lower than the highest point of the calipers. He suggested I move it higher, and I explained it wasn't practical.

He did ask what controller I was using, and he did say they have had some delay problems with the OEM units. But wait, he previously said he had never heard of anyone with delay problems???? Yea, right!

So, with Dexter of no measureable help, I went ahead and installed the residual valve at the location of the first union. By doing it that way, I was able to secure it with a homemade strap to a frame portion, and if I needed to, could go back to stock. I would have rather installed the residual valve at the output of the actuator, but could not do it without replumbing and going past the point of easy return if it did not work.

After installing, I once again bled the brakes. If you have one of these units, you can hear when it loads up under pressure, and it now seems to load up quickly, and after setting for an hour or so, still loads up quickly.

I also test spun a wheel after pressuring up the system, and releasing and there is no appreciable drag. I have not towed it, but this weekend we are going to a rally and should have more input after that.

Signed, Guiney Pig #1

[dznf0g]

Great! please,keep us informed

[dznf0g]

If a delay was due to a controller, wouldn't we be able to notice a lag from pedal apply to actuator STARTUP? I have never noted that and the delay seems to correspond with the sound of motor load...rather predictably. See Gary's video.....

[SteveH]

Originally Posted by dznf0g

If a delay was due to a controller, wouldn't we be able to notice a lag from pedal apply to actuator STARTUP? I have never noted that and the delay seems to correspond with the sound of motor load...rather predictably. See Gary's video.....

Yes, I agree, but my first controller in my truck, the OEM one, did have a delay. However that was with electric brakes, and before I got this trailer with the hydraulic disc brakes. I can't imagine how bad that controller would have been with disc brakes.

[GCinSC2]

Rich,

Just a clarification. In the video we used the slider to trigger the unit. The test criteria that I tried to address involves was the delay due to air in the system and to prove or hopefully disprove any air.

My comments about the MaxBrake with the rig stationary was to illustrate how the system response is TV PSI based, period. No sensors for vehicle decel, or anything other than my pedal pressure on the TV.

Steve,

Good luck with the RPV. Do your have an IR temp gun to check rotor temps with just for grins?

Might be interesting to see if Dexter or Carlisle can provide any time vs. PSI data. Really might not be surprised at Dexter stating no delay experiences, they build components, but not supplying finished trailers where final mfgr. assembly details determine outcome. Any testing would be with compatible components and you can bet they only assess fully bled systems.

I'll give a Kudos to Dexter for their help. Its a long story but my trailer got new axles. Shortly after (dealer) installation I had smoke coming off of one axle set of brakes, about 800 DEG F with my IR gun. I called Barry Hansel (Carlisle at the time) and he had no explanation to blame the actuator, it has no idea which axle is getting fluid, its all the same delivery system.

Called Dexter, conversation continued, engineer at Dexter is called in to consult. Dexter had the invoices for the replacement axles, description of problem hot rotors on one axle ONLY. Dexter finally agreed to ship NC new calipers, rotors and pads for one axle, I accepted the DIY installation labor as I had already bled the system several times with actuator issues.

My .02$ for reason for hot calipers, RUST. Can't prove it but axles were shipped separately and pretty sure one sat outside waiting for 2nd axle arrival and got rained on. Proof, sorry its only best available theory.

Gary

[SteveH]

Gary,

I do have an IR temp gun, use it all the time to measure tire and hub temps when on a trip.

I will check them, but really don't think it will be a problem as I could easily spin all three wheels on the side I jacked up after putting full pressure on the brakes, and then relaxing it.

Of course I won't know until I drive it, but it sounds like it's getting up to pressure faster, and you know the "sound" I'm referring to.

One thing that I used to notice was the more I used the brakes, like stop light to stop light, the less delay there was, and conversely after running down the interstate for a few hours, the delay was longer, so I'm at least optimistic.

[SteveH]

OK, towed the trailer about 60 miles this weekend, and although not a lot, it was enough to notice a difference.

Before the residual pressure valve was installed, the delay would decrease with more brake use such as red light to red light in town, and increase with less use such as 20 miles or so on the highway. Now the delay does not change, so I'm going to say it is definitely an improvement. Not saying it will help everyone's delay, but it did help mine.

My delay is down to about one second, and I intend to re-bleed the brakes and see if I can decrease that time.

[F450Harley]

Originally Posted by GCinSC2

Rich,

I've seen used MaxBrake's sell over on Turbo Diesel Register in very short order. The Dodge Cummins crowd will snap 'em up.

The display shows actual TV brake circuit pressure. I just came back from my truck. Engine off, I touched the MaxBrake slider waking it up. Then I pushed on the brake pedal, the display shows TV brake circuit pressure.

Folks,

I can't speak for any other system, but can your EOH and brake controller do this:

Rig hooked up, engine running, vehicle stationary. Push the brake pedal slightly and the actuator starts, low output. Push pedal harder and the actuator ramps up you HEAR it is loading up higher and higher pressure. The controller varies the system pressure according to your rigs actual TV pressure via the hydraulic pressure transducer that is tapped into the TV brake circuit. FWIW the transducer is made by Honeywell and all connections are the same type of brake fittings that the brake system is made with, no issues.

Does any other type of controller system do this?

I'd also like to offer a reminder to anyone looking at reworking any of their system. INSPECT YOUR PISTON DUST SEALS FOR DAMAGE.

Damaged dust seals can allow water in. This water may become trapped and guess what, it can or will create rust between the steel caliper pistons and cast iron caliper housings. The slightest amount of rust can prevent the piston from its very small but required return stroke causing the pads to drag and possibly burning up your pads and rotor. It happened to me. I made the necessary repairs and no further issues. Dexter does offer boot and seal kits. Once you get past your 1st caliper seal and boot R&R, really pretty easy. The cleanup is the only tedious bench exercise.

I've sent some pics and details to Rich and in going thru my old files I found a video I shot of my bench test of repaired caliper halves. I actually rigged up a pickup truck pedal assembly and clutch master cylinder. This allowed me to bleed each half and do a crude bench test. I blocked each piston set from extending using a pretty stout angle iron, uh that flexed immediately. Then I added C clamps across the pistons thinking no way will it flex. On the video the system can easily flex bolted angle iron and C clamps at no more than 400 PSI. I referencing 400 PSI as a pretty realistic pressure created by a clutch hydraulic release system.

Not ever gonna claim hydraulic system engineering skills, just a bit above average DIY'er.

YMMV

Gary

Steve,

Bleeding via remote switch. This will go to 100% output, correct, its either on or off. I'd expect it can spit out a lot of fluid quickly, just keep an eye on the reservoir you do not want it to accidentally empty while bleeding. You'll get to start over as soon as it swallows air.

Maxbrake X2 ........
I did install my Maxbrake with help from the manufacturer and Sean of Pro Pride. What a big difference on brake response from my GMC Diesel Denali to the disc brakes on my 30 Ft Classic. Have other controllers on my F450 HD and G55 and the difference is noticeable. DirectLink and others are great and I think it all boils down to the TV set up. MaxBrake is linked directly to the TV brake fluid line ( at the reservoir) so no guessing game. As you manually steps on the TV brake so does on the trailer brake hence almost no noticeable lag time to the human brain or feel. The other factor in my opinion has to do with disc vs drum, drum shoes needs occasional adjustment while disc does not. Two identical TVs with Maxbrake or Directlink or any other controller will behave differently when braking on disc vs drum with new pads & worn pads interns of lag time. Diesel brake pressure vs gas engine brake pressure is another interesting factor to explore.

[KJRitchie]

I'm out west right now in Zion. I'm noticing brake dust on the forward wheel rims and not on the two rear rims. Not a lot but is it normal for only the front rims to get the dust?

Is it like a car where the front axle brakes do more work?

Kelvin

[dznf0g]

They should be equal in application effort, although I can't speak for all actuators. I doubt anyone has any kind of proportioning valve. You would have two supply lines from the actuator, or a valve between the calipers on each side. It COULD be a function of how the airflow is over the area.