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Smoking Brakes Down Grade

1K views 11 replies 4 participants last post by  Mark Kovalsky 
#1 ·
Yesterday was my first experience towing 8k down a 2 mile 6% grade. I have towed this several times with a 5K travel trailer with no problems, we upgraded to an 8k and less than a mile down started smelling brakes. I pulled over and all 4 truck brakes were smoking. Yeah I did ride them a little, but was not going fast. 35 to 40 as the road was curvy. After letting the brakes cool a bit I used the tt brake controller the rest of the way down and stayed off the truck brakes as much as possible. No more problems.
Do i need to upgrade pads (I have autozone oem pads) or change driving technique or both? I have read about the quick braking, slowing 10 to 15 mph then letting it build speed backup then repeating but that is not as easy on a 2 lane curvy road where you cant let the speed build up too much.
 
#2 ·
I always downshift a gear, plus trailer brakes if needed. Brake quickly down to what would be good for the next gear down, then shift. Start by turning OD off.
 
#9 · (Edited)
Greg687, with a 2003, your TCC engagement/disengagement strategy is different than TVengineer's 2000. This past week, I've been testing this programming difference back and forth on the same truck, driving up and down the same somewhat steep hills in two different versions of a 2000 calibration, versus two different versions of a 2001 calibration.

The 2000 calibrations really force one to use the service brakes to slow the vehicle down. I have a TCC LED light that lets me know exactly when the TCC is engaged and disengaged, and even partially engaging, as the LED light flickers with the pulse width modulated activation of the TCC.

On all my test runs, I've employed different shift lever techniques, ie, overdrive off, downshifting into second, leaving overdrive on and downshifting into second. overdrive off and not downshifting into second, overdrive on and not downshifting into second... that sort of thing.

As an example: In the 2000 calibration, the TCC will disengage the moment the accelerator pedal is released when cresting the hill, regardless of road speeds. In the 2001 calibrations on the exact same vehicle, the TCC remains engaged with the foot off the accelerator as the hill is crested (depending on speed). If you're like me, you don't want to enter the downhill under power. I usually let off the accelerator just prior to cresting the hill, so that the vehicle (and trailer, when connected) can slow down without continuing the momentum of the previous push up hill, when entering the down hill.

There are other differences in TCC strategy between pre 2001 and post 2001 calibrations that contribute to slowing the vehicle down on grades that I am observing as well, but that is beyond the scope of helping the OP, who could very well have a problem that is much more serious than the nuances of TCC strategy.

However, I just wanted to emphasize that what may work so well for a 2003, might not work as well in a 2000. This is a complaint I've had for over a decade and a half, but only recently was I given an opportunity to actually feel and drive the calibration difference in the same truck.


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#3 ·
I started down with OD off. It seemed my rpm's dropped when I turned it off. I then shifted to 2'nd and didn't feel like it dropped back. This was around 35- 40ish. When finally getting to the bottom, I shifted back to D and turned OD back on and rpm's jumped up. I think that is a transmission problem to deal with next.
 
#8 ·
I started down with OD off. It seemed my rpm's dropped when I turned it off. I then shifted to 2'nd and didn't feel like it dropped back. This was around 35- 40ish. When finally getting to the bottom, I shifted back to D and turned OD back on and rpm's jumped up. I think that is a transmission problem to deal with next.
Yes pretty much the way it acted. No engine power holding back at all. When back in D and turned the OD off rpm's went up.
I will drive it and test it again to make sure what it's reactions are.
You'll need to decided which of these two are true. You've stated opposites. I can't diagnose this without clarification.
 
#4 ·
Sounds backward. Even in OD my truck has some engine braking on down grades... turn off OD and rpms jump up. same once I downshift to 2nd, or first if needed.
 
#6 ·
When you turned off overdrive, and when you shifted to 2, did the engine speed drop to idle? If so, that means the coast clutch has failed. The trans needs to come out to fix that.
 
#7 ·
Yes pretty much the way it acted. No engine power holding back at all. When back in D and turned the OD off rpm's went up.
I will drive it and test it again to make sure what it's reactions are.
 
#11 ·
Mark, after re-reading what you quoted I said, the second was a typo on my part. The rpm's went UP when turning the OD back on. When OD off, the engine relaxed. I really do not think I felt it downshift to 2'nd when I manually shifted. At the bottom I don't think there was a change after shifting back to D. Only when turning the OD on did the rpm's go up.
 
#12 ·
OK, then I know what's wrong. Your coast clutch has come apart. There is a snap ring that holds the clutch together and it's come out of it's groove. Without the coast clutch there is only engine braking in fourth gear.

Unfortunately the trans has to come out and be at least partially torn down to fix this.
 
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