Highway shudder over bumps

KBT · #1 (**permalink**) 03-05-2007, 08:56 AM

2004 DC w 39k miles. Bought used at 33K about six months ago. When traveling on the highway and hitting expansion joints or other road "bumps" the truck seems to shudder...Not necesssarily vibrate. It seems like the front wheels shudder left to right for second and the rest of the truck seems to follow. Not having a truck before, I've been thinking that this is attributed to being a truck and not a car.
I rotated the tires at 38K and noticed the front tires are starting to cup.
I have not received the ball-joint recall, but my VIN is listed.
I want to go to the dealer and am trying to educate myself about possible reasons for the cupping and shuddering. The truck is in the Certified program, but the 3 months warranty is up, as is the 3 year/36K. The powertrain warranty is still in affect.

Question: Any ideas on what to look for/discuss with the Stealer?

DJ · #2 (**permalink**) 03-05-2007, 09:33 AM

Likely it needs a wheel alignment. The cupping wear is a dead give-away, but there is more than meets the eye.

When front wheel alignment is off, especially in "total toe", the wheels of the front axle don't necessarily try to roll the same direction. For example, if the left front wheel is pointed a bit to the right, and the right front wheel is pointed a bit to the left, then the two wheels fight each other. They actually scrub sideways a bit as the vehicle rolls straight ahead.

Now suppose the right front wheel hits a slight bump, which knocks it upwards a bit, thereby reducing its friction with the road. The left front wheel then exerts more force to the right than the right front wheel exerts to the left, and so the vehicle lurches to the right a bit. This can happen repeatedly as the bumped wheel bounces, and so the vehicle shudders.

If it were my truck, I would check wheel alignment first.

KBT · #3 (**permalink**) 03-05-2007, 01:00 PM

Thanks for the quick response! I made an appointment with the dealer and have asked for them to use the alignment specs posted. The dealer said they would...as long as they are within Toyota specs.

DJ · #4 (**permalink**) 03-05-2007, 05:26 PM

Quote:

Originally Posted by KBT

Thanks for the quick response! I made an appointment with the dealer and have asked for them to use the alignment specs posted. The dealer said they would...as long as they are within Toyota specs.

That's the idea.

Begin with Toyota's specs for your vehicle. Set camber and caster dead on Toyota's recommended settings and set caster right at the upper end of the range Toyota's specs for your vehicle allows. These are within Toyota's limits for your vehicle and will provide the maximum steering stability those specs can provide.