Car Shakes at 60+ mph

`That makes sense :) I had an old Valiant Hemi 6 [yes such an engine existed in 215,245 and 265 cubes.It was not a slant-6] The Ozzy 265 E-49 Charger had OEM 3 twin-barrel Webers, OEM headers and 280 hp. Ran 13.8 sec 1/4 mile ETs. It was at the time, the fastest 6 cylinder locally produced car.

Any way the Val was always experiencing a vibration which came and went. Turned out one rear axle was slightly bent. Because the axles were always turning in an ever-changing was to each other due the action of the diff, this gave the variable nature of the vibe.

JJ
 
So I def had my steering wheel shaking like crazy... and I ended up rotating my tires, and it fixed the problem not sure if your fix will be as easy, but I was surprised!
 
Update- I'm going to take the car back to the Chevy dealer Monday and have them make sure the wheels are balanced and get them to measure the wheel runout (they didn't measure it when they originally road force balanced them). If everything checks out I guess I'll have to get General Tire to replace the tires since I'm 99% sure the issue isn't in the car.
 
Yeah tks for that:) It hilights the fact that a wheel can be oval [slightly even] still balance OK,..but when on the road, the ovality causes the wheel to vibrate as the high and low spots run against the road-surface.

I learnt something,.thks :)

JJ
 
Cheap wheels > oval than better wheels. Same for tires. Generally you get what you pay for.
 
Well, after 10,000 miles of shaking I finally got pissed off enough to order new tires. I ordered 4 BF Goodrich g-force Sport COMP-2 tires. I'm going to get them road force balanced and make sure the rims aren't bent. If that doesn't work I'm going to borrow my stock rims off of my buddy's ZX2 and see if that fixes it. I hated to order new tires when my old ones were only half worn out but I'm tired of having a brand new car that can only go 60 with feeling like I'm riding a jackhammer. Plus, if the tires aren't the problem I'll have 2 good sets that I will eventually use.
 
Well. The rims are perfect, new tires were road force balanced to within 6 pounds. (25 is still acceptable, so 6 is excellent) New CS struts, centering rings, matching lugnuts, wheels properly torqued, new alignment, everything is tight and in good condition. AND IT STILL SHAKES!!! I'm fed up. I think I may go try out a Focus ST or a MS3 whenever I get a day off work/school and get rid of this money pit.
 
Well. The rims are perfect, new tires were road force balanced to within 6 pounds. (25 is still acceptable, so 6 is excellent) New CS struts, centering rings, matching lugnuts, wheels properly torqued, new alignment, everything is tight and in good condition. AND IT STILL SHAKES!!! I'm fed up. I think I may go try out a Focus ST or a MS3 whenever I get a day off work/school and get rid of this money pit.

Does it still shake only when you're above 60? Is it a certain MPH or RPM or straight, turning, braking?

Shakes can be frustrating. How do your wheel bearings look? If there was a previous problem you lived with for 10k miles it could have beat them up pretty bad.

Good luck!
 
I'll check the bearings, haven't heard them make any noise though. With the General tires the vibration would occur consistently at speeds over 65 mph. The car would vibrate for about 5 seconds, and then be smooth for about 5 seconds, same all the way through the 10k miles no matter how the tires were rotated. With the BF-Goodrich tires the handling is 500% better and the vibrations are less, but still there. Now it starts around 62 mph, stops around 70, and resumes around 75+. I couldn't get a very good feel though because I haven't been on the interstate yet. I'll be driving around 250 miles on it sunday so I should get a better idea then. Would an alignment help? I had one about 10K miles ago but I've hit a bunch of potholes and taken my suspension apart a few times since then.
 
Lemon Law?

Regardless of where you go from here, It'd drive me nuts until I could figure out what the problem is, if only for curiosity.
 
I doubt I could get anything done with mazda. My buddy told me to let them look at it but there's no use. Aftermarket wheels, springs, shocks, torsion bar, and the wrong size tires. I guess I could borrow my stock wheels and revert everything to stock and see if it shakes...I'm just tired of messing with it though. If this wasn't a new car I wouldn't be at all concerned about it, but I'm putting so much $ into payments, insurance, and mods that I'm determined to fix it.
 
The car would vibrate for about 5 seconds, and then be smooth for about 5 seconds, same all the way through the 10k miles no matter how the tires were rotated.

The on/off/on bothers me. Is it the same regardless of load/gear? does it happen coasting down a hill?

Toe *might* be an issue, but I wouldn't go there yet. Build/buy some basic toe plates and never pay somebody to do it again.
 
Yep. Happens when coasting too. Absolutely no difference no matter the rpm, gear, or anything else.
 
Yep. Happens when coasting too. Absolutely no difference no matter the rpm, gear, or anything else.

That is good.

The bad news is that it's time to put stock wheels/tires on your car (from a car that doesn't shake) after you check wheel bearings. I bet the issue goes away.
 
Well, I took all of my wheels off and torqued the lugnuts properly. Some of the lugs were so tight that in order to break them loose i had to jump up and down on top of a 2 ft bar. (175 lbs, so ~350 ft lb) Others were so loose I could loosen them with the factory wrench and the flick of my wrist. It seems the guy at the tire shop just slapped the wheel on and impacted them on one at a time. I made sure the wheel was perfectly centered and tigntened the lugs slowly and evenly. It seems to have helped, I took the car from 60-80 over the course of a mile and it seemed much better. I'll be driving about 300-400 miles of interstate tomorrow so I'll report back then.
 
Well, I took all of my wheels off and torqued the lugnuts properly. Some of the lugs were so tight that in order to break them loose i had to jump up and down on top of a 2 ft bar. (175 lbs, so ~350 ft lb) Others were so loose I could loosen them with the factory wrench and the flick of my wrist. It seems the guy at the tire shop just slapped the wheel on and impacted them on one at a time. I made sure the wheel was perfectly centered and tigntened the lugs slowly and evenly. It seems to have helped, I took the car from 60-80 over the course of a mile and it seemed much better. I'll be driving about 300-400 miles of interstate tomorrow so I'll report back then.

I assumed this was done correctly since you were pretty specific in previous posts. The issue is non hubcentric wheels with a spacer that isn't perfect.
 
That's my thought too... Double check that your hubcentric insert/spacer(s) are in proper shape... Hopefully that's all it is!
 
No spacers and hub centric rings were on all along and fit perfectly. Drive at 70-80 mph for 90 miles. The new tires fixed 70% of the shaking and putting them on correctly and softening the struts all of the way took care of about half of the shaking that still existed, so that leaves ~15% or so of the original shake. So therefore-
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