i have a 2006 f150 fx4 crew and the other day when i was stopped heading up (waiting on someone to park) in a parking garage. i was in drive and took my foot off the brake and my truck started to roll backwards like it was in neutral. i mean it was a sorta steep incline but is this normal?

 

Ya, I can see that happening, but pretty steep (like San Fransisco) and only veeeerrrry slowly. I figure the tranny allows this a bit with the torque converter because at idle it's still slipping a bit. Maybe it's one of those things you take for granted.

 

yea it was like a 30 degree incline. i mean at times even on level ground and pavement. i could come to a complete stop and take foot off brake and my truck will barely move or not at all.

 

That's what I've heard, especially on the new trucks is that you hardly if at all move forward, no gas. Thinking back, my dad has had an 06 Harley, 07 Harley and 07 FX4 and even his 08 diesel 350 seems to do it. My 00 actually goes quite well with no gas both drive and reverse.

 

yea my dad has an 2002 f150 crew that i use to drive around alot before i got my truck and it would move pretty good without foot on the gas. could it be my transfercase makeing it slower ?

 

Different tranny too and his is still the throttle cable. I'm thinking the setup in engine (throttle by wire, CMCV's, less vacuum, more electronic control) things like this. To be honest, I like the way my truck does it, but for Joe Consumer, less noise, softer this and that might play into the design. I don't think this is a bad thing as it might be less likely to snap components or shock them lessening fatigue in the long run, who knows.

 

Unless it is in low range (which might be the same ratio) it should still be 1:1, the same as any other 4x4 in either 2hi or 4hi.

 

guys... it is called a torque converter. when at idle the fluid shears because of the low speed allowing the car to be in gear while your stoped. That and a 6,000 lb truck will let it roll backwards on a hill. when the rpm builds, the fluid is more of a solid when the vanes in the torque converter are spinning. This allows the engine to transmit power to the rear wheels. Very simplified.. but basicly how it works.

 

Kinda like I was hinting at with the torque converter action and not bieng locked yet.

 

Three tons of truck on an incline won't hold itself in place at idle.

 

yep... as already mentioned, rolling back while in drive without your foot on the brake is normal.

Some of the higher-end cars are starting to add "Hill-hold" or "Brake-assist" (there are probably other names too) functions that will apply the brake for you to keep you from rolling backwards while in drive. They use the same modulation unit as the traction control / ABS to add the function. I could see this being helpful for people with stick-shift (especially learners) that aren't good with the clutch but other than that... people just need to learn to drive. (just my .02 on it)

 

Subaru has had a hill holder on their manual transmissions for years.

 

Let me add to this .
I have a custom rebuild that includes a Diesel converter that is a lower stall than the stock OEM.
This causes the idle to hold the truck more on a grade, 'HOOK UP' at a earlier rpm off idle, by intent.

Every converter is not exactly the same so your 30 degree hold should never be expected as a normal thing. That much hookup would cause fluid shear heat and your not even moving under load.

I notice a very sleight tendency to run higher heat in stop and go from my tighter converter stall but overall the average heat is lower from less slip (earlier hookup) thru the acceleration and at speed. So you give away in one area to gain in another.