I've got a 2001 4dr 4wd Blazer. 62,000 miles. When driving around town and slow highway speeds the truck drives great. On the highway I can cruise at 60-62mph as normal. As soon as I approach 64-65+ I get a shimmy in the vehicle that is quite annoying (so I slow back down to 60 or so). It doesn't seem to be in the steering wheel, but more throughout the entire vehicle. I know its been this way for about 8k miles or so, but not sure if it was exsistant before that or not.

Here's what's been changed since the issue has been noticeable:
-Front ball joints
-idle arm
-passenger side wheel bearing
-sway bar links
-tires balanced (and rebalanced within the last 1k miles)
-universal joints on drive shaft
-brand new rear calipers and resurfaced rotors within the last 1k miles

There might be something I missed, I'll have to check my receipts.
I also had a mechanic shop put it on a lift and feel the tierod ends and they seemed to have very little play.
I'm pretty well stumped on what this could be and the shop that did the most recent work (universals, rotors, calipers, balanced tires, and checked tierod ends) are stumped as well. Any ideas? As I said, it cruises smooth at 60-62mph, but hit 64-65+ and the shimmy comes on.
EDIT: I haven't used the search feature yet, as I'm running into work and wanted to make a quick post rather than filter through issues that have caused shimmy's that have already been addressed on my vehicle. Maybe this is a common problem? I'll spend sometime searching after work. Thanks.

 

well being that you already got the wheels balanced that should not be the problem, my thoughts are do u have fix-a-flat in 1 or both of your front tires maybe not by you but from the old owner i dont know how long u have had your truck but fix a flat will cause that and also cause a problem when its being balenced

 

Negative on the fix a flat. I have installed these tires while owning the truck. About 30k on the tires.

 

You did get an alignment after getting the ball joints replaced right? That exact 65+ mph shimmy happened to me a while back, and when I got an alignment (lifetime alignment at firestone $120) my shimmy problem stopped. Maybe one of your wheels are slightly bent? A slightly bent wheel can be balanced, but still cause a shimmy.

 

You know I did question the alignment thing. I did not get an alignment done when the ball joints were replaced, persay, but the shop that did the ball joints should have done that if it was required, correct? Or is that 'supposed' to be my duty to ask for it done? The other shop I recently spoke with thought that an alignment would only need to be done if the vehicle was straying one way or another. Or, the shimmy would be noticeable at lower speeds as well. And like I said, 62mph and under its great, 64/65+ its shimmying.
How can you test for a bent wheel?
The shop also mentioned possible seperated tire..

 

As far as I know, after anytime you repalce the ball joints you need to get an alignment. I would bet that's your problem. Typically, a shop will do anything for extra money, so unless you told them to only replace the ball joints they should have known to do an alignment......
As for a possibly bent wheel, I believe you would have to go to a wheel repair shop, where they have the proper equipment to check the rim.

 

Two other items come to mind after reading what you have already done. A bad hub/ wheel bearing or a bad cv axle. Typically a whining noise appears as when a hib starts to go bad, which you are not describing, so I would speculate a CV axle may be the issues.

 

I did have the passenger side wheel bearing go out twice on me, so as long as they typically act the same, I should recognize that. I've got a 1200 mile trip coming up, so would like it good to go by then. Ill look into getting an alignment, any way to check on the bad cv axle? Are you guys ruling out seperated tire?

 

To check for separation, I think you have to look for a knot/bump in the tread. How old are the tires? That will typically happen on old tires or after hitting something very hard. Broke CV axles make a clicking sound when turning.

 

The shop that did my recent work had mentioned seperated tire, and checked for one but could not find any indication of seperation. This would be on the tread area as you've mentioned, correct? Im gonna say I had the tires installed around 2007. As far as the cv axles go, I have not noticed a clicking or binding issue when turning (we just had one go on our work truck and I picked up on that instantly), everything seems great.