"White knuckle" moment - steep driveway, hard brakes, not stopping!

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BWL

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Hard to know for sure without trying it myself, but if he boiled the brakes that would cause the air and bad fluid and trying to brake against the engine staying engaged to the drivetrain would cause that. Especially on hills that already tax the system. The fact that it stops in neutral seems to point in that direction.
 

crash68

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If it was the torque converter staying locked up then I would think the engine would stumble/struggle when the truck comes to a stop.
I'm thinking an issue with pads and or rotor surface being glazed over. I'd take the truck out to a deserted road or parking lot and slam on the brakes from about 40-50 mph. See if the anti-lock brakes will kick in and the truck still wants to push.
Anyone that has "burped" the turbo on a diesel truck knows the brakes will hold back a considerable amount of engine torque before you push through them, a lot more than a 5.7 makes at idle. That's provided the pads and rotors are in good condition.
 
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bm02tj

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If he has 392 gears with an 8 speed with a locked converter I could see it as hard to stop
my jeep with all the good stuff will not stop if I have all in low with a 4 speed atlas 10.34 reduction
and 4.10 gears
I have friends with automatics that had to go with high stall converters so they could stop with out going into neutral
 

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Hi all try backing out of that descending driveway and see what happens, do you have electric ebrakes just pull lever up in steps to stop truck if you have foot lever do the same thing, I've read this whole thread and I think its a Master cylinder problem, can you pump the pedal up to stop?
 
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Jebb

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The braking systems are a bit light to haul a heavy assed 35"+ tire down from speed,especially if the truck is loaded and heavy.
The truck was empty and idling.

If you guys insist on running bigger then stock tires and then whining about the lack of brakes...
I've been running oversize tires on 4x4's for the past 30 years. I'm well aware of the physics of oversize tires but I've NEVER had a truck behave like this.

Factory tire option on this truck is 33". Going to 35" tire is only a 6% torque increase at the brakes (equivalent to a ~330 bed load w/33's). If this truck can't handle THAT how does anyone tow a boat with these trucks?

Not buying "the tires are the problem".
 
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Jebb

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If he has 392 gears with an 8 speed with a locked converter I could see it as hard to stop
my jeep with all the good stuff will not stop if I have all in low with a 4 speed atlas 10.34 reduction
and 4.10 gears
I have friends with automatics that had to go with high stall converters so they could stop with out going into neutral
That's exactly what it feels like - HOWEVER if the TC was locked the engine should stall or at least buck. It doesn't but the TC does feel very tight as shifting to neutral helps significantly. If I had 3.92 gears, or was in 4-Low I don't think I COULD stop it on this hill.

Hi all try backing out of that descending driveway and see what happens
Good put and haven't tried that yet. Could be the "hill assist" feature. It's supposed to hold brake pressure to resist rolling backwards on a steep UPHILL grade - maybe it's releasing pressure on a steep DOWNHILL grade? In other words, maybe there's a flaw in the Hill Assist software that controls the brakes/ABS? I haven't tried turning it off but that is something I will check.
 

crash68

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Could be the "hill assist" feature. It's supposed to hold brake pressure to resist rolling backwards on a steep UPHILL grade - maybe it's releasing pressure on a steep DOWNHILL grade? In other words, maybe there's a flaw in the Hill Assist software that controls the brakes/ABS? I haven't tried turning it off but that is something I will check.
Hill Start Assist disengages after about a second when you release the brakes or you step on the throttle. It also only works when the vehicle can roll the opposite of which gear(Drive or Reverse) the vehicle is in.
 
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Jebb

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Hill Start Assist disengages after about a second when you release the brakes or you step on the throttle. It also only works when the vehicle can roll the opposite of which gear(Drive or Reverse) the vehicle is in.
Right - that is what it is SUPPOSED to do. However, since the computer has control over brake pressure it seems it COULD be involved if the software and/or sensors are not working right.

BTW - HSA doesn't seem to work. The instant I take my foot off the brake pedal on any slope the truck starts rolling (with HSA turned on).
 
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crash68

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Right - that is what it is SUPPOSED to do. However, since the computer has control over brake pressure it seems it COULD be involved if the software and/or sensors are not working right.

BTW - HSA doesn't seem to work. The instant I take my foot off the brake pedal on any slope the truck starts rolling (with HSA turned on).
The HSA doesn't "apply" the brakes, it holds the braking pressure you apply. I can't remember what the angle percentage is but I think it has to be better than 5%-7%. Mine works good on the boat launch, I also intentionally heavy foot the brake when stop on the ramp.
With you mentioning it "doesn't work" that sort of rules out the torque converter, if that was the problem you wouldn't roll backwards.
If the ABS was controlling the pressure of the brakes, you'll feel the pump motor in the pedal.
 

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Practice shifting the transmission into neutral so you can do it quickly when it feels bad if still bad it is brake pressure related
If it stops well try to set a camera up on display so it show RPM , speed with fuel economy
so you have some thing to show dealer
 

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I've been reading this one over time. Folks that are indicating a locked torque converter would push the truck forward with brakes applied - shouldn't the brakes be able to overcome the power of the engine regardless? I recall demonstrations of this (different vehicle) where even if your throttle was stuck wide open and transmission locked in gear your brakes would be able to stop the vehicle as they are capable of 2 - 3x more force than the engine.
 
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Jebb

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I've been reading this one over time. Folks that are indicating a locked torque converter would push the truck forward with brakes applied - shouldn't the brakes be able to overcome the power of the engine regardless? I recall demonstrations of this (different vehicle) where even if your throttle was stuck wide open and transmission locked in gear your brakes would be able to stop the vehicle as they are capable of 2 - 3x more force than the engine.
I had an '04 Hemi QC with 33" tires, 4.56 gears and Eaton True-Trak LS. I could hold my foot on the brake while flooring the gas ("burnout") and the truck didn't move.

I drove that truck down this same driveway - for years - and it NEVER felt like it was getting away like this one does. There is something wrong with THIS truck!
 
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Jebb

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Practice shifting the transmission into neutral so you can do it quickly when it feels bad...
That's what I typically do. Question is WHY do I need to do that?

My concern is what about on the freeway or mountain road in normal driving or out 4-wheeling - am I going to need a tree to stop me or rear-end someone if I have to stop hard? I don't know what I have here. I don't trust it.

try to set a camera up on display so it show RPM , speed with fuel economy
so you have some thing to show dealer
Good suggestion. Will do.
 
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Jebb

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The HSA doesn't "apply" the brakes, it holds the braking pressure you apply. I can't remember what the angle percentage is but I think it has to be better than 5%-7%.
Understand but in my truck it doesn't work. It does not hold applied brake pressure for any amount of time at any angle. As soon as I take my foot off the brake the truck starts rolling. I drive with two feet when on any kind of slope.


A final thought (FWIW). I bought this truck new custom built by Huntington Beach Jeep/Ram Off Road shop. This truck was "upgraded" by the dealership with ceramic brake pads. According to RockAuto the OEM brake pads for this truck are semi-metallic. I know that ceramic pads typically do not "bite" well until hot. Is it possible THIS is the problem?


Anyone here drive in San Francisco, Colorado mountains, West Virginia, etc., experienced problems stopping their 1500 QC on steep roads?
 
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pacofortacos

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It could be a number of things and maybe several together.

I didn't see if you mentioned what gears you have but 3.92's with 1st gear on the 8 speed is a significantly steeper ratio than your old truck had with the 4.56's. Big difference.
Add on to that the 35" tires and you are really making it worse yet - the laws of leverage will not be denied - there is a reason people use a pipe or breaker bar on the end of a ratchet! Which is what 35" tires are to the brakes.
Throw in cold ceramic pads and they could all add up to your issue - especially if your engine rpms are higher than 500-700 rpms - IMPORTANT.
But
You could also have an issue with the brake system.

I would try stock pads with new or machined and properly bedded rotors and if you can possibly do it, borrow a set of stock 20" wheels and 33" tires and see what happens. (Basically a stock truck)

IF it still does it after that then you would have to almost conclude that it is a braking issue - master cylinder, proportioning valve, air in lines, stuck caliper, etc.
 

pacofortacos

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I live in PA and have only ever experienced what you describe once - my truck sits for weeks on end and on one occasion while cold and damp, the brakes didn't want to stop very quickly on the first stop which was down a steep hill ( same as you describe - firm pedal but slow to stop). I now stop several times as quickly as I can to dry the pads and warm them up and have never experienced again.

I also go to Colorado every winter and have never experienced what you are describing.
But my truck is a Crew Cab with stock brakes and stock size ( 33") tires.
 
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Jebb

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It could be a number of things and maybe several together.

I didn't see if you mentioned what gears you have but 3.92's with 1st gear on the 8 speed is a significantly steeper ratio than your old truck had with the 4.56's. Big difference.
Add on to that the 35" tires and you are really making it worse yet - the laws of leverage will not be denied - there is a reason people use a pipe or breaker bar on the end of a ratchet! Which is what 35" tires are to the brakes.
Throw in cold ceramic pads and they could all add up to your issue - especially if your engine rpms are higher than 500-700 rpms - IMPORTANT.
But
You could also have an issue with the brake system.

I would try stock pads with new or machined and properly bedded rotors and if you can possibly do it, borrow a set of stock 20" wheels and 33" tires and see what happens. (Basically a stock truck)

IF it still does it after that then you would have to almost conclude that it is a braking issue - master cylinder, proportioning valve, air in lines, stuck caliper, etc.
I have 3.21 gears (which are too low for 35's, BTW).

The past several times I have made sure the engine was warmed up (idled down) to 500 rpm or so and pumped the brakes a few times before heading down. The problem I posted here is AFTER doing that. If I just started up and headed down I would likely roll right out into the cross traffic.

I found another Dodge/Ram dealer not too far from me where there are some hills. Will take it over there and see what they can do.


Question in the meantime - can you guys push your brake pedal to the floor (down to hard stop) with engine running? I can and that's where it is when I come down this hill. No more brake pressure/pedal available.
 
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bm02tj

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if the pedal is goes to the floor you have master trouble or air or bad flex hoses
 

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if the pedal is goes to the floor you have master trouble or air or bad flex hoses


I agree with this......if pedal is going to the floor , you have master or air trouble

And just from my own experience....even w/ 3.92 gear & 35" tires with the brake held firm & rpm's up you should either slide frount tires or spin back tires
 
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