1st tow - slight concern

[JordanB]

I don't tow very often - only a couple of times... ever. However, in the last week I've towed quite a bit a weight in the bed. One load had 45 bags of 80 lb. concrete bags and today I had two 873 Bobcat-sized scoops of dirt. The motor and the truck in general are freakin' amazing! My one concern is with the "herky-jerky" motion when the transmission shifts (mainly at lower speeds). Could someone please clarify what this is and if it's normal. My first inclination is that it's the u-joints but I could be wrong. Unloaded the truck acts perfectly fine. This may be normal when you tow this kind of weight but I'm not sure. Any help would be appreciated. And yes I know, the truck is only supposed to have 2,000 lbs. or so in the bed, but hey, I aired up my tires! :-laf Oh yeah, it's an '06 Quad cab SWB 4x4.

 

[rbattelle]

Which transmission?



Ryan

 

[JordanB]

I'm an idiot - it's an automatic.

 

[TRAMPLINEMAN]

Next time you're loaded up, try manually shifting it when you think it should shift. It might smooth the shifts out a little.

 

[JordanB]

I did have it in tow/haul mode but manual shifting of autos with levers on the steering column never work properly for me, meaning I end up shifting past 2nd to drive or past drive into neutral. They never work as well as my slap stick automatic did in my old '73 Cuda. I just need to know if the jerking motion is normal when shifting.

 

[BHolm]

Sounds to me like that is normal. What you probably feel is the springs winding and un-winding due to the torque you were feeding the rear axle. With as much power as these trucks have, and that kind of wieght, the axle will twist and when it shifts the brief lack of power being sent back causes the jerking. You could use the same solution that one would use on a '73 Cuda..... a pinion snubber :-laf That would help limit axle movement.

 

[rbattelle]

Given the payloads you're talking about I'm not surprised the shifts are a bit on the harsh side. In my opinion, the harsher the shifts in an automatic the better, because it means you're not wasting band and clutch friction material making nice smooth shifts.



All that kinetic energy you build up moving all that weight is going to interact with the transmission during the brief lapse in power between gears. In a manual, you'd delay shifting so that the RPM on the next gear is well above the peak torque RPM. But automatics are pretty dumb, and in my experience they tend to have poor timing and poor choice of gear (can you tell I prefer manuals? ).



I wouldn't be concerned with the transmission as you describe it.



Ryan

 

[JordanB]

Thanks for all the help guys! I'm not too concerned any more. I never felt that the shifts were too firm... I also like firm shifts but I was concerned with the back and forth jerking motion during/after a shift.

 

[rbattelle]

I was concerned with the back and forth jerking motion during/after a shift.

Regarding that, I agree with BHolm's assessment of axle wrap.



Ryan