Treangen

Looking for some help. I have an 06 mega cab with the 5.9L with 22K on it. 6sp that is stock except for H2 wheels and a glacier diesel secondary fuel filter. It feels somewhat like a rocking boat. It seems to surge forward and back ever so slightly at highway speeds on the flats. Seems if I am on a hill upward or down or under acceleration or have a load it does not do it. Seems to be most noticeable on a cross wind day. I am thinking shocks possibly......any other input??

btolenti

Is the tranny hunting for the proper gear???? Torque converter locking and unlocking? Did you have your speedo corrected for the larger tires?

Treangen

6 speed here and no the speedo was not corrected.

Ironstone

Sounds like a bad tire to me.

Treangen

Nothing noticeable on any of the tires such as bulges or loss in pressure....just a recent discovery after about 10K on tires.

1-2-3

My vote goes to the tires. I bet you also changed tires when you got the new rims. This is usually caused by tires not rated for the job. The sidewalls are too thin. What tires did you put on? How many sidewall plies? How much air do they take?

It can also be caused by the too wide of a rim for the tire? How wide are the rims?

Treangen

These are H2 take offs. They were never even removed fromt eh factory H2 rims. BFG 315/70/17's

wreedCTD

the BFGs from GM are load range D you need load range E for 2500/3500 trucks

TonyB

Rotate the tires & see what happens. May not help, but it couldn't hurt!

Tony

Treangen

Tires rotated and no change. It is just an ever so slight motion. You can not pinpoint it to a corner or anything.

TonyB

Oh, well, had to try!

Let us know what the solution is!

Tony

madhat

Could be a front shock/coil spring problem, too. I'd go with the tire problem, tho...

darkvader

Is This With The Cruise On?
Clark

Ironstone

Put the old tires back on it and see if it still does it.

Hopper

I had this problem on my last Dodge truck. It started at 20k miles and went through 100k before I solved the problem along with fore and aft U-joint on the drive shaft, and front and rear seal on the tranny. Turned out to be the throttle position sensor (TPS), a $21 part. 6 Dodge dealerships couldn't figure it out. I couldn't either until I learned the truck was "drive-by-wire."

Not to say this is your problem, but things to look for would be:

1.) While in neutral and idling, you see the RPM guage slowly pulse at set intervals. My last one pulsed every 10 seconds. The pulsing starts out very small and continues to get larger with time. At the begining it was more of an audible sound but near the end when I figured it out, I was seeing pulses of 500 to 1000RPM. (Again Dodge said they couldn't find anything wrong despite the obvious jumps in the RPM) This was the reason for blowing out the U-Joints. It can really suck when your pulsing gets up to 200RPM and it happens just as you're letting off the clutch. Give a nice lurch and jerk to your drivetrain.

2.) While on the cruise control you'll see the rpm try to jump and the vehicle seems to speed up for a second then drifts back to normal. On an automatic, it may try to downshift because the vehicle is sensing an immediate need for throttle and will downshift to get the vehicle into a stronger power-band.

3.) On automatics, the pulsing is also destructive during transmission shifts. It can cause a double shift depending on speed and trottle position input from the gas pedal. During downshifts, it can cause an immediate upshift which can weird-out the tranny.

Leaving this go too long is a good excuse to do a forced upgrade on your drivetrain parts.

Just my $.02.