engine vibration
 

hi all,
i know it's been posted before and i did my search too, but this is quite unique. i was driving around today and got up to 50 mph and all in a sudden my car started to vibrate, i punch the gas a little and it would go away, but each time i would go between 50-54 mph my car would vibrate badly. i had the ac on at the moment , then i turned it off ( cause i've read that sometimes that could be a problem) but it was still doing it. i did a search and some people mention that it could be the motor mounts. but if it's so, then why does it only vibrate between 50-54 mph? once it did also at 48 mph, any lower or higher its normal. any help would be appreciated.

are you an auto or manual?

6 spd AT

i notice a little vibration a couple of days ago, but pretty today.

any one has an idea of what can be wrong with my ride?

Any lose of power or anything ?

no lost power, just the weird vibration.

This is just a shot in the dark but maybe ur tires are wearing unevenly?? I've experienced first hand that when tires are going bad the car vibrates pretty bad..

Or it could be your Wheels

I had 2 bent wheels (thanks to Great New York City's Road), the car drives fine during low speed (less than 30mph), but when it gets faster, its shaking really bad. at first I thought my wheel balancer was knocked off, but its not, so I took it to pace tire for a check up, then I found out 2 of them actually bent, its so bad that you can actually see it in person.

i don't know, it's unlikely since my 8 has just about 600 miles on it, the thing is new, so why should it have problems with the wheels, i'll check anyways, but it the vibration occured only at certain speed, when i revved up it seemed to go away but once i got back to 50 mph the vibration came back. i drove to work today and tested it at that speed and nothing......could it be that rx-8's just don't like long trips....my 05 rx-8 that i traded for this one used to have weord nioses after long trips...steering wheel, wheels, you name it.

Have some tire shops to check the wheels, I mean professional ones. Not BS like Pepboys, and NOT dealership.

if you can simulate it pretty easily, then the dealer should be able to help. Tires are a possibility.

Will do guys, thanks for your replies, you've been a good help.

Here's and update on the engine vibration: i took my 8 to the dealership for inspection and they told methat my engine is fine...the problem are my tires. They said my tires are cupped. me not knowing much about this did some searching and found out that this condition happen due to uneven wear on tires. I was told since my car was in the show room without being driven at all the tires develope "flat spots" and was also told that the issue should resolve itself by just driving around.
Me being inquisitive, took my car to a tire center. the resident expert there told me that my tires are most likely ruin and should get new one, since once new tires are cupped it is very hard for them to wear normal. makes sense to me. so i'll since my car is brand new and under warranty i will summit a claim to the tire manufacturer to get replacements, since the dealership says they don't deal with the tires. i read the warranty on the tires and i can actually summit a claim to and authorized goodyear/dunlop dealer. so now i'm hoping these people can help me out. the vibration in my car is just getting worst, almost feel like im driving on gravel all day!.
Thanks for all those who showed concerns and try to advise me.

Hi all,
i'll continue where i left off last week. so...last friday i took my car to the goodyear/dunlop tire experts, this time they inspected my tires and also the balancing. They could not find anything wrong with them. the only thing was that the wheels had too many of those little stick on weights on them. So they removed a couple and my car felt somewhat different but i still had the same problem from before....as soon as i hit 50 mph in 6th gear my car vibrates...so with that said, i'll take the car back to the dealeship once i get a chance most likely next week and see what happens. this is getting fustrating...a brand new car shouldnt have issues like this.

Have you tired driving 50 in 4th & 5th?? It is strange that the dealer would say your tires are cupped and the tire shop says they aren't. I am more inclined to NOT believe the dealership. Another things to try putting it in neutral and rev it to about 3,000 and see if it virbrates. You car could have also been damaged before you bought it. Things do happen during the trip from the dock to the lot. Try to find out the history of your car before you got it.

i've driven it in 4th and 5th and had no vibration. So far as i know the car has a clean history, it was sitting in the show room, when i got it it had just 48 miles on it and felt really smooth for the first couple of weeks. i now have about 940 miles on it.

Have you thought about the transmission?
I know the TSB symptoms are different than yours but you've tried lots of other stuff without success...
http://www.finishlineperformance.com...10-06-1712.pdf

Hey, thank you so much Darkbrew, i will take this paperwork with me next time i go to the dealership and show it to them. hopefully that solve my issues. And yes, my first tought was transmission issues, since my old 05 rx8 had transmission problems and they actually had to replace my transmission back then.

i also had vibration on my engine before.. it turned out i had a bad tires..

It should be easy to troubleshoot- the dealer should just substitute a set of wheels and tires from another car onto yours, and if it is still there it ain't the tires.

It could also be a dry U-joint in the driveshaft vibrating. Make them fix it.