Question on Tie-Down Vented Disc brakes...

[gsmith3286]

After inspecting my brakes at the end of the year, I suprised to see that both pads were shaved down to metal. I thought maybe my emergency brake engaged or something without me knowing it. Anyway, I just replace the rotor/pads and bled the system according to the instructions....a couple things...

1. When priming the dampener, the instructions say to push in the coupler a few times...well i did it by had but it didn't move much and i'm wondering if i should have hooked it up to my truck or something.

2. I bled all 4 vents. I never bled brakes before...I used the manual process to pump fluid into a glass container filled with brake fluid. I pumped to till all was clear but after pumping there were pockets of air in the tubing...is that normal? or should the tube be totally full of fluid?

3. After bleeding, I noticed that the pads were very tight on the rotors...is this normal? I checked the emergency brake system and it was disengaged. The instructions also say these brakes are self-adjusting...but they just seemed really tight....i had to use quite a bit of force to get them to move.

Any help appreciated..thanks guys.

 

[Bondo]

Re: Question on Tie-Down Vented Disc brakes...

or should the tube be totally full of fluid?

Ayuh,.. If you've got Bubbles, you ain't done yet...

I noticed that the pads were very tight on the rotors...is this normal?

Nope, not normal,...
Are the calipers free on thier anchor pins,..??

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

Thanks Bond-0

The fluid was running clear but there were air pockets in the tube...I was using kind of a long tube, but it doesnt sound like it should matter. You're saying that the tube should be full of fluid with no air pockets right?

The caliper is one of those floating things that sits on pre-installed pins and they supposedly self-adjust. However, they don't move at all cuz the pads seem to be locked down on the rotor.

 

[dingbat]

Re: Question on Tie-Down Vented Disc brakes...

In order for a hydraulic system to work correctly there must be absolutely no air in the system. Hydraulics work by transmitting power via a non-compressible media i.e. hydraulic oil. If you get air in the system the power compresses the air instead of transferring the power ?thru? the media to the remote. Air is compressible n a hydraulics system will cause the system to air lock.

The actuator on your trailer is used to apply a push - pull devicepressure and generate a ?vacuum?. The pressure (push) is used to transmit the ?force? generated at the coupler to the pads. The vacuum (pull) is used to "pull" the pads back off the rotor. If you have air in the brake lines the pads, the system will not function properly causing the accelerated pad wear you reporting.

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

Thanks ding....I must still have air in the lines then. Or maybe I just need to pull the coupler all the way out.

Any idea how much brake fluid is required to get all the air out? I pumped through almost a whole 32 oz. bottle on all 4 vents.

GS

 

[Bondo]

Re: Question on Tie-Down Vented Disc brakes...

The caliper is one of those floating things that sits on pre-installed pins and they supposedly self-adjust. However, they don't move at all cuz the pads seem to be locked down on the rotor.
Any idea how much brake fluid is required to get all the air out? I pumped through almost a whole 32 oz. bottle on all 4 vents.

Ayuh,... Is the Coupler,+ the disc brakes a matched set,..?? drum couplers usually aren't compatible with discs...
Drum brakes use springs to force the fluid back to the coupler, discs don't...
As for the Air,...
Is the Res. kept Full at all times,..??
Are all the lines in servicable condition,..??

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

Thanks Bond-O..

Yeah, I'm basically replacing the original parts that came with the trailer...it's the Tie-Down actuator (model 70lp) with the Tie-Down vented disc braks

Lines are ok, reservoir kept full...I think you guys probably hit earlier when you indicated that there might still be air in the lines.

When you bleed the brakes, how much fluid do you usually need to do that? I used about 32 oz. for the whole thing.

 

[sdsaw]

Re: Question on Tie-Down Vented Disc brakes...

Did you pop the pistons out of the caliper to examine them before pushing them back into the caliper for the new pads?

I made a post about this awhile back addressing a problem that I had after replacing my disc brake pads.

Granted, it took 4 years for this to happen to my pistons

http://forums.iboats.com/showthread.php?t=263248

Scott

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

I replaced the entire assembly (rotor+caliper w/pads)....I just fitted the whole assembly over the spindle and onto the pre-installed posts for the floating caliper.

I'm just wondering how fluid do I need to bleed properly...is it gallons?? or just a few 8oz bottles??

how much volume does the brake system hold?

 

[bruceb58]

Re: Question on Tie-Down Vented Disc brakes...

Question...are you using a drum brake actuator or a disc brake actuator. If you are using one made for drum brakes, that would explain why your pads wore out so quickly. It's very easy to convert the master cylinder for use with disc brakes. You just have to puncture the residual valve. If you don't punch this valve, there will always be a residual pressure applied in the system without any force on the master cylinder. This will cause the wear that you got.

 

[dingbat]

Re: Question on Tie-Down Vented Disc brakes...

I replaced the entire assembly (rotor+caliper w/pads)....I just fitted the whole assembly over the spindle and onto the pre-installed posts for the floating caliper.

I'm just wondering how fluid do I need to bleed properly...is it gallons?? or just a few 8oz bottles??

how much volume does the brake system hold?

I can complete drain and refill my system with a little over the pint.

Did you prime the actuator per the instruction manual?
Did you bleed the brakes starting at the farthest from the coupler and work your way forward?

 

[Bondo]

Re: Question on Tie-Down Vented Disc brakes...

I'm just wondering how fluid do I need to bleed properly...is it gallons?? or just a few 8oz bottles??

Ayuh,... Your Qt. should have been Plenty...

Bruce hit upon the point I was headed for, when I asked if it was a Matched set...

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

Hmmmm, well, I have Tie-Down 70LP...there is one model for Disc and another for Drum. I'm not sure how to tell the difference without trying to find the part number. Is there something easily identifiable between the two types?

I'm pretty sure I didn't bleed the brakes enough, but this is yet another thing to confirm. The actuator came factory with disks, but that doesn't mean it was done right....thanks for the head up on that.

GS

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

I definately need to confirm that I have a "matched set".

I talked to the guy at Tie-Down and he said that there should be absolutely no air in the tube at all....I finished the bleeding process with some air pockets in the tube and I should have kept going I guess. He said when replacing calipers, the system fills up with a lot of air.

I did "prime" the actuator and I did bleed in accordance with the instructions but apparently not enough bleeding.

I appreciate you guys' input on this, you've been really helpful...I'll let you know how it turns out after I get back to work on it later this week.

 

[bruceb58]

Re: Question on Tie-Down Vented Disc brakes...

If you can find the part number on the side of the actuator:

47202 is for drum
47204 is for disc

This where I got this info in case you have a non-standard actuator

http://www.tiedown.com/pdf/c720.pdf

 

[gsmith3286]

Re: Question on Tie-Down Vented Disc brakes...

Thanks again... actually I have a model 70LP....in case anyone is interested.

http://www.tiedown.com/pdf/c462.pdf

Model 70LP (Low Profile)
Actuator* for
Trailer Brakes
7000 lbs Capacity
Part #47225/47226 - Drum Brake Ready
Part #47228/47227- Disc Brake Ready

 

[NYBo]

Re: Question on Tie-Down Vented Disc brakes...

This is probably a dumb question, but did you keep the end of the tube submerged in the fluid in the glass container at all times while bleeding?

 

[bruceb58]

Re: Question on Tie-Down Vented Disc brakes...

Thanks again... actually I have a model 70LP....in case anyone is interested.

http://www.tiedown.com/pdf/c462.pdf

Model 70LP (Low Profile)
Actuator* for
Trailer Brakes
7000 lbs Capacity
Part #47225/47226 - Drum Brake Ready
Part #47228/47227- Disc Brake Ready

My mistake.

So what is the part number of yours?

Is it listed on the side of your actuator?

 

[Lou C]

Re: Question on Tie-Down Vented Disc brakes...

This is probably a dumb question, but did you keep the end of the tube submerged in the fluid in the glass container at all times while bleeding?

As far as the bleeding problem...for sure if the tube did not stay under the level of the brake fluid in the container it could draw air in defeating the point of the bleeding procedure. We used to take a coke bottle and tape a plastic tube to the neck and fill it about 1/3 full with fluid and then start the brake bleeding procedure with the brake the furthest from the master cylinder....this was a 2 person procedure because one had to pump the master and one had to keep an eye on the coke bottle for bubbles and overflow! Lisle makes a plastic one man brake bleeder that accomplishes the same thing...I have used it with my drum system and it works well. The rapid wear of the pads sounds like it could be a drum brake actuator....or sticking capliers or caliper pistons....

 

[dingbat]

Re: Question on Tie-Down Vented Disc brakes...

As far as the bleeding problem...for sure if the tube did not stay under the level of the brake fluid in the container it could draw air in defeating the point of the bleeding procedure. We used to take a coke bottle and tape a plastic tube to the neck and fill it about 1/3 full with fluid and then start the brake bleeding procedure with the brake the furthest from the master cylinder....this was a 2 person procedure because one had to pump the master and one had to keep an eye on the coke bottle for bubbles and overflow!

It's easier to just loop the tubing up higher than the caliper before going into a collection vessel. That way the air lock is in the tubing and the bottle serves no other purpose than to collect the excess fluid. Route the tube out over the fender and into the bottle so you can see the line from the coupler. Becomes a one man operation at that point.