Was in tow/haul,leaving campground, stopped at main highway on a pretty steep grade, with 8200 lb 5er hitched up! When I took my foot off brake to feed gas, I started to roll down hill and qickly clamped on brake. It cought me totally off guard as Im just on my 3rd weekend trip with the rig ! I only rolled down a few feet but wonder if the tranny would have locked up and stopped the downhill decent! Is this normal ? Is it because of the heavy load ? Do I have a tranny problem ? Im lucky nobody was tight behind me ! This is a 01 Gmc 1 Ton. What are your thoughts and experience in this situation ! Thanks so much ! Dan

Gravity hard at work. Yes it can roll backwards even though its in drive. I doubt anything is wrong. You say it was a pretty steep grade and you were towing a 8200lbs trailer so to me its sounds normal. In a similar situation I would have one foot on the brake and the other on the throttle and rev it up a bit and let off the brake slowly. Come to think of it I've had to do it several times while towing my 5er. It's pretty much second nature once you have some experience towing.

I frequently tow at about that weight, and in hilly mountainous areas (4WD events). Max is right, it's a 2 foot affair regardless of what you're driving...

Sounds normal to me. The torque converter at idle is not a lockup device. There is a designed in happy medium between idle speed and torque converter slippage. Loads will overcome this balance.

"Max is right, it's a 2 foot affair regardless of what you're driving...
" unless u got a ZF then u get to play w/ all three feet.


Be glad u got an Allison http://www.dieselplace.com/forum/smileys/Big Smile.gif

http://www.dieselplace.com/forum/smileys/Shocked.gif Now just a minute, with the torque of the d-max at idle I've never found a situation that required my foot on the throttle to get rolling in 1st gear (which is 5.79:1 "granny gear") with the ZF.


Just keep the right foot on the brake and ease the clutch out until it loads the engine, then let off brake and clutch together. http://www.dieselplace.com/forum/smileys/Clap.gif


It's times like that that I'm glad I'm not driving gasser, but I've never regretted having the ZF.


I drove Allison equipped school busses for years, any of them would roll back at idle. In some of them (forward control types) the steering shaft prevented the 2 foot routine, so you just had to move quickly, or if it was a big enough problem set the (air) parking brake.