Braking issues

I do not know what brake pads you have installed but the pad/lining composition can have a very big impact on brake performance. Inexpensive pads/linings are just that. Inexpensive. I have played with brake compounds for years and have talked with a number of pad material engineers during those years and there are tons of variables in getting the performance you need. In drag racing you need a pad that simulates a "soft" pad, good cold performance, on the starting line to hold the car and yet a pad that needs to be able to reach maximum stopping force when applied cold at the top end but still have consistent brake modulation as the temp spikes from a 180mph application. This is a lot to ask of any brake pad/lining. There were "performance" pads on the market in the 80's that everyone used, but me, that would not stop a car and had the feeling of air in the lines. You could actually feel the first stage of the M/C hit the retaining pin for the second stage in the M/C. I recently replaced the front GreenStuff pads in my Santa Fe with an mid range priced ceramic pad and it does not stop near as well as before but it only goes 5 miles to the boat ramp so this is not an issue. Your problem can be fixed rather simply but first it needs to be diagnosed by a professional before someone gets hurt.
Randy

Does the ABS system work? If so you may need to activate the pump to get all the air. If not, depending on where the pump comes to rest it may be next to impossible to completely bleed the brakes. I had this issue on a van awhile back.

The problem is with your TV's brake system. Most likely fluid has
been compromised with H2O, air in the system, leak, bad
fitting/connection, bad MC...NOT with the trailer brake
controller...or the trailer brakes

The Triflex is very similar to the P2, both inertia sensed and switch
by the TV Brake Pedal Light Switch

The controllers only association with the TV is with the brake pedal
switch, where it is mounted, where it gets it power and other signal
sources from

eap wrote:
This is my first post to this forum and I am hoping that someone can point me in the right direction.

To start with I have 2000 4WD GMC 1500 and I am pulling a 30' x 8.5' v-nose trailer with 3500 pound axles. I am using a Triflex brake controller for the braking system on my trailer. I just purchased the trailer new last spring and have only put maybe 100 miles on it.

The issue I am having is that after having stopped at a few lights my brake pedal starts to go to the floor with almost no resistance. Pumping the brakes does not appear to the resolve the issue. I have replaced all the brake pads and turned all of the routers. I thought that this helped for when I towed the trailer empty the other day the truck felt like it had a lot more stopping power. Unfortunately when I got to my destination about 15 miles away from my house the brake pedal started going to the floor. When I got out of the truck I immediately could smell the brakes. I am thinking that the smell was caused by the brakes being new. I have driven the truck since I changed the brakes but this was the first time I towed my trailer since changing them.

If I drive the truck unloaded I do not have any issues at all stopping. It is only when I am pulling the trailer that I experience the braking issue.

Thanks,
-Eric

4X4Dodger wrote:
If your brake pedal is going to the floor under hard braking then you have a problem with your TRUCK brakes.

I agree with those above that say you may need a new master cylinder and all new fluid with a complete and professional brake bleed job.

Your trailer brakes may not be working as some have said but This is easily tested.

Put your brake controller to it's maximum setting then sitting still, not moving apply the trailer brakes fully at the controller only. Then try to pull ahead with your truck. it should not move or be very hard to move.

As a second test let your truck idle forward then apply the trailer brakes at the controller only, do not use the pedal, you should come to a halt very quickly.

This will tell you that the trailer brakes are indeed working and eliminate that issue.

The problem is in your truck.

I am definitely leaning toward the truck having the issue after reading everyone's reply.

If your brake pedal is going to the floor under hard braking then you have a problem with your TRUCK brakes.

I agree with those above that say you may need a new master cylinder and all new fluid with a complete and professional brake bleed job.

Your trailer brakes may not be working as some have said but This is easily tested.

Put your brake controller to it's maximum setting then sitting still, not moving apply the trailer brakes fully at the controller only. Then try to pull ahead with your truck. it should not move or be very hard to move.

As a second test let your truck idle forward then apply the trailer brakes at the controller only, do not use the pedal, you should come to a halt very quickly.

This will tell you that the trailer brakes are indeed working and eliminate that issue.

The problem is in your truck.

beemerphile1 wrote:
It sounds like this has nothing to do with the trailer brakes or the brake controller.

You should ALWAYS flush out all old brake fluid every time you work on the brakes. Read you manual, it probably recommends every two years or so. Brake fluid is hygroscopic and absorbs water from the air right through the rubber lines.

The master cylinder certainly could be bad.

Keep in mind this is a 16 year old vehicle. The rubber lines are likely shot if never replaced. A rubber line can collapse causing pressure to remain in the caliper and cause the brakes to drag. If your brakes are dragging they will heat up and stink. Even if the rubber lines look good on the outside, replace them.

Good point. I did not think about the lines connected to the calipers.

It sounds like this has nothing to do with the trailer brakes or the brake controller.

You should ALWAYS flush out all old brake fluid every time you work on the brakes. Read you manual, it probably recommends every two years or so. Brake fluid is hygroscopic and absorbs water from the air right through the rubber lines.

The master cylinder certainly could be bad.

Keep in mind this is a 16 year old vehicle. The rubber lines are likely shot if never replaced. A rubber line can collapse causing pressure to remain in the caliper and cause the brakes to drag. If your brakes are dragging they will heat up and stink. Even if the rubber lines look good on the outside, replace them.

Yea GM has had lots of issues with poor braking. I think part of their problem is small master cylinder. I remember the brakes on my 2004 Silverado would barely stop at times. Switched trucks and no more brake issues pulling the same trailer. Replacing master cylinder, flushing the system all may help, but dont hold your breath.

eap wrote:
When I changed the brakes I had to open one of the bleeder values but bled them after putting the new pads on. I'm going to contact Auto Zone later today to see if they have a vacuum kit that I can rent this weekend so that I can change the brake fluid.

Pick up a new master cylinder while you are at Auto Zone.

I recommend a pressure bleeder or classic two person bleed over all other options.

eap wrote:

rjxj wrote:
Another old issue

More

I do seem to remember people complaining back then about the pedal going very low at times.

Since you initially posted your comments on braking issue for my 2000 GMC I began searching around and I did see several people complaining of the same issue. Since the master cylinders are not that expensive I will look into replacing mine.

Thanks for all of the information.

Well... Again I would be very careful about opening the system. Tread lightly or it may end up at the dealer. Read all that stuff and be sure the trailer is right. My guess is you do want that trailer to be as aggressive as possible and you may still have an issue.