Help Support Ram Forum by donating:


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

Discussion in 'General Discussions' started by Jebb, Oct 22, 2018.

Sponsored By: All Mopar Parts
  1. BWL

    BWL Senior Member

    Posts:
    4,169
    Likes Received:
    2,548
    Joined:
    Oct 14, 2017
    Location:
    In the garage
    Ram Year:
    2017
    Engine:
    hemi 5.7
    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.
     
  2. crash68

    crash68 Senior Member

    Posts:
    3,085
    Likes Received:
    2,166
    Joined:
    Mar 20, 2016
    Ram Year:
    2015
    Engine:
    3.0 EcoDiesel
    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.
     
    Last edited: Nov 9, 2019
    Jebb likes this.
  3. bm02tj

    bm02tj Member

    Age:
    67
    Posts:
    81
    Likes Received:
    28
    Joined:
    Aug 7, 2019
    Location:
    B C Canada
    Ram Year:
    2018
    Engine:
    5.7
    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
     
    Jebb likes this.
  4. Dodge 1500 4X4

    Dodge 1500 4X4 Member Supporting Member

    Age:
    65
    Posts:
    81
    Likes Received:
    49
    Joined:
    Sep 25, 2019
    Location:
    Rochester, NY
    Ram Year:
    2019
    Engine:
    Hemi 5.7
    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?
     
    Jebb likes this.
  5. Jebb

    Jebb Member

    Posts:
    81
    Likes Received:
    35
    Joined:
    Aug 22, 2017
    Ram Year:
    2017
    Engine:
    Hemi 5.7
    The truck was empty and idling.

    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".
     
    Last edited: Nov 12, 2019
  6. Jebb

    Jebb Member

    Posts:
    81
    Likes Received:
    35
    Joined:
    Aug 22, 2017
    Ram Year:
    2017
    Engine:
    Hemi 5.7
    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.

    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.
     
  7. crash68

    crash68 Senior Member

    Posts:
    3,085
    Likes Received:
    2,166
    Joined:
    Mar 20, 2016
    Ram Year:
    2015
    Engine:
    3.0 EcoDiesel
    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.
     
  8. Jebb

    Jebb Member

    Posts:
    81
    Likes Received:
    35
    Joined:
    Aug 22, 2017
    Ram Year:
    2017
    Engine:
    Hemi 5.7
    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).
     
    Last edited: Nov 12, 2019
  9. crash68

    crash68 Senior Member

    Posts:
    3,085
    Likes Received:
    2,166
    Joined:
    Mar 20, 2016
    Ram Year:
    2015
    Engine:
    3.0 EcoDiesel
    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.
     
  10. bm02tj

    bm02tj Member

    Age:
    67
    Posts:
    81
    Likes Received:
    28
    Joined:
    Aug 7, 2019
    Location:
    B C Canada
    Ram Year:
    2018
    Engine:
    5.7
    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
     

Share This Page