Shimmy above 70 MPH

[devilsfan]

Truck has been going from bad to worse lately. With highway driving, if I'm above 70 MPH, I start to get a pretty bad vibration. In the entire truck. That's been since I got the lift...annoying but driveable. Lately it's been doing that around 55-60 MPH after the truck has been running awhile (for the first 20-30 mins on the highway, it runs fine). It's also beginning to pull to the right something fierce if I brake hard. Thoughts on what the deal is here?

Stacy

[MarineHawk]

Originally Posted by devilsfan

Truck has been going from bad to worse lately. With highway driving, if I'm above 70 MPH, I start to get a pretty bad vibration. In the entire truck. That's been since I got the lift...annoying but driveable. Lately it's been doing that around 55-60 MPH after the truck has been running awhile (for the first 20-30 mins on the highway, it runs fine). It's also beginning to pull to the right something fierce if I brake hard. Thoughts on what the deal is here?

Stacy

I'm just a layman, but I assume it's a very bad allignment. Though that doesn't explain the delayed reaction. Hmmm.

[nmu98]

Pulling to the right can be a caster or even camber issue. When you run light on caster it will happen or if your camber is not the same, or within a small degree off...

Your vibration is most likely not from the alignment. It is most likely a tire out of balance or your u joints in your rear driveshaft. How much lift do you have? What size tires?

On edit, the title says shimmy, but the post says vibration.... Please clarify.

[HummBebe]

Check your half shafts.

[MarineHawk]

Originally Posted by nmu98

On edit, the title says shimmy, but the post says vibration.... Please clarify.

Or a vibroshimation?

[devilsfan]

What's the difference between a shimmy and vibration?

Stacy

[mikejr]

to me...a shimmy is when the truck wanders a bit, like the steering components are loose....if you take the wheel and move it quickly left to right slightly...that would simulate a shimmy.....

A vibration on the other hand would be more of the feeling one gets when you hold a drill and you can feel it vibrating...or....like if you run over rumble strips...that would be a vibration.....

just my thoughts on the two....

[fourfourto]

Quick fix....Dont go over 70

The air is thin up here ,makes me light headed

[devilsfan]

Ok, definitely a vibration then and not a shimmy. I can take my hands off the wheel and the truck stays true. It just feels like I have a low tire or something, but the pressures always check out fine and the wheels are on tight. I've had an alignment done recently but not a balance.

Stacy

[drmiles]

Stacy known problem with lifts and front driveshafts. Fab Tech includes a new drive shaft. Wheel balance and tire balance can also cause vibration. You can remove the front shaft and drive it to see if vibration goes away(drive in 4 hi lock). If not front shaft has to be tires. If you have more than 2 ounces on a tire have them rotate the tire 180 degrees on the rim.

Pulling while breaking = breaks on one side grapping harder than the other. Mud in calipers, stuck caliper piston (can't think of the right word) or pads worn or fluid on pad. Have the dealer check the breaks and calipers.

[nmu98]

anything over 35's can be hard to balance, and it is not uncommon in that size to get a tire out of round. I bet yoou have one out of ballance, or out of round. Once you drive for some time, your tires "heat" up, and they can changein ride and roundness....

Speed always has a direct correlation to how bad things shack, and when... Sometimes its goofy, but start there...

[nmu98]

Originally Posted by drmiles

Pulling while breaking = breaks on one side grapping harder than the other. Mud in calipers, stuck caliper piston (can't think of the right word) or pads worn or fluid on pad. Have the dealer check the breaks and calipers.

Dont get worried, it can also be an alignment issue....

[mikejr]

sounds to me like it has to do with the driveshaft or half shafts since the angles on them has changed due to the lift.

I recall after lifting my GMC Jimmy many moons ago I got a very bad vibration, turns out the U-Joint was failing and soon broke ruining the rear drive shaft.

[drmiles]

Half shavt angles don't change that much. the cv joint is able to handle the increase angle. The drive shaft however is not. ON my 03 we had to have a new shaft from Woody shfts made with double ujoints on the tranny side to stop the vibration. The Vibration was always present, just worse at higher speeds. Vibration in the front seats at highway speeds = rear tires. Vibration in the steering wheel at highway speeds = front tires.