Vibration/shake between 68-73mph????

[redgtxdi]

1998 i-4 LE. 147,000 miles and maintained meticulously. Put on new struts about 10K ago and enjoyed smooth ride since day 1. Everything looks great, but since neither wife nor myself rarely get over 60mph (mostly side streets every day) neither of us noticed a recent shaking at high speeds.

Tires about 50% (or better) and evenly worn. Had 'em balanced 6 months ago and again about two weeks ago as I figured that was the problem. (2 different Costcos ta' boot). But, it's definitely there. I can feel it in my seat when the car reaches about 68mph and stays until about 73mph where it smoothes out again 'til you get over 80mph then you can feel it a little again, but I don't get much over 80 ever so can't say after that.


Any ideas?? Since I feel it in my seat and not the steering wheel, I was thinking rear, but what the heck's back there?? Bad wheel bearings??

TIA

[bigbird]

wheel bearings will usually make some noise when goin. its possible that a weight was thrown from one of the wheels. how severe is the shaking?

[redgtxdi]

Ya, that's what I was thinking earlier, that's why I had the wheels rebalanced and I explained that to the guy at the 2nd Costco. (I figured new people, new balancers, weights, etc. should eliminate anything that went wrong at the first Costco). But the same vibration is still there.

It's not bad. I can just feel it in the seat. My wife can't feel it but I could probably help her understand it better if we drove and isolated the problem for her to feel, but I just know that it's definitely there.

Just totally confuses me. I hate elusive crap like this.

[EEngineer]

i had the same problem before i changed to coilovers

i didnt want to deal with it heh.

i do believe though, it has something to do with tires, u should run your hands around the tires and feel the treadwear urself instead just looking at it.


also, are u driving with alloy rims or steels?

u might need hub rings

[feijai85]

wheel balance?
wheel alignment?
control arms?
motor mounts?

[a94autoCamry]

does this happen only when you step on the gas around those speeds?? what happens if you let off the gas around those speeds??

i have this problem only when stepping on the gas, and it turns out that my driver side axle was bad, replaced that, and now i'm vibration free..

but be sure to have those other things checked before ruling out the axle, as the price + labor for that job is expensive..

[fakehawk]

just curious what is the tire pressure in all 4?

[redgtxdi]

stock steel rims and seems to be there regardless of on gas or coasting, though that sounds like what's up with my 95 Prizm and exactly what the mechanic suggested for that one.

I don't know what tire pressure is but I assume costco set em at 35. I had another thought since which is to rotate the tires to see if I can move the problem to the front. If so, then I'd at least know its isolated to the wheels/tires!

[Dave's]

Almost always a tire balance issue. However, bad struts can cause the rear tires to 'cup' which you may be able to feel by running your hand over the tread. If they get swapped to the front you will definitely notice it but probably all the time. Also have had the inner belts separate which can't be balanced out completely. This could be your problem. I had mine balanced several times before they admitted they were having problems with that band of tire and replaced them. Good luck.

[cykaaro]

I re-read this and what I thought doesn't work. An inbalanced wheel will give you a strange vibe around 70km/h or so. If it's a bad alignment, at about 60km/h you will start to get death wobble, depending how bad will depend on how bad your alignment is. [driving with a bent tie-rod when you hit 60km/h feels like the whole thing will literally shake apart!!]

Now you're talking 70mph which is more like 120-125km/h. This is along the lines of what I get. When I get to about 130km/h I start to get vibes. Nothing major, but just enough to feel they're there. I've been thinking suspension of some sort, maybe worn bushings causing the problem. Not entirely sure, but would make sense given the age of the vehicle and all seems to be well otherwise. The vibes are not pin-pointable to one particular area. Just a general vibrating. I did change out the dog bone and the vibrating in the steering wheel is now gone though, but that's an always thing and has nothing to do with speed or driving.

[redgtxdi]

hmmmm ya kinda what I was thinking. I'll have the mechanic check it out and if he can't find anything I'll probably just live with it..... Or just never drive over 65!

[cykaaro]

Just have all the bushings checked for wear. Doesn't hurt in general to check them anyways.