Hey everyone I am a new owner of an 06 RX-8 manual. Its got 21,000 miles on it and new Pirelli Pzero Nero M+S 225/45/18 91W. The problem I am having is that anytime I jump on the highway the car is shaking up and down its almost at any speed I went down to 40mph and you could still feel it. Yet on any surface that has blacktop you don't feel a thing. I just got it back from the dealership they did a roadforce balance and said that they could not duplicate the problem yet the second I jump back on the highway it was there.

Anyone have any suggestions that I can give to the dealership. I'm going to take it back after the holidays and insist they go out with me driving. I had a friend drive the car and I drove his and you could see from the outside that the front end would hop up. But it was hard to tell where it was coming from.

I've looked over tons of posts and read about the engine mounts but that doesn't seem like that would be the problem. They checked the suspension apparently and said it was ok.

Anyway thanks for any help!

 

balance eh?

sounds like you have a bad tire. Check them out physically. There may be a bulge, indentation or bubble on the tire.

Even if you can't find it you can still have a bad tire.

 

If it were a bad tire wouldn't you think that I would feel something on normal pavement? Thats what confuses me the most it only happens when I am on concrete.

 

by shaking up and down...

is it kinda like the hole front end seems like it is just moving up and down? I think what you are describing happens to my car too. It is only on certain lengths of concrete, but it is obnoxious. Dealer wasn't able to find anything wrong with mine either.

 

Yeah it seems like its the whole front end. At night you can see the headlights beam bouncing on the bumper of the cars in front of me. It's incredibly annoying in mine and is bad enough it starts to hurt your neck after awhile.

 

well when concrete warms up in the summer and cools in the winter, parts of it rise and fall. the first 10 minutes of my drive to work in the morning are like a see-saw, but i dont care, i still love my 8

 

The problem isn't making me not like the car. But I do a lot of highway driving during the summer and I could see this being a real pain. I may just have to test drive one of the new ones and see if it does the same thing.

I just want to make sure there is no problem with mine right now. Since I just bought it they are willing to cover things like tire replacements and balancing for free but in a week or 2 if something is found and things like this aren't covered under warranty its going to come out of my own pocket.

 

its just a stiff(relatively) suspension coupled with the fact that concrete roads suck. nothing is wrong with your car.

 

man up, stop being a wuss. the stiffness just means you have great suspension

 

maybe a blown shocks?

 

blown shocks would make the ride bouncy, not stiff

 

Yeah this is defiantly not a problem with the suspension being too stiff.I've been in vehicles with stuff suspensions and they didnt bounce up and down. If a suspension was stiff the ride would be harsh on concrete but it would not bounce and I'm getting a gradual bounce where it not the wheels are still making a solid contact with the pavement put the car itself has a movement up and down.

 

a gradual bounce?

 

Yes its very hard to explain.


From the outside of the car all wheels never move off the pavement. I had a 2006 Cobalt SS Supercharged and that was very stiff and the car was rough on the highway but this isnt a vibration or a rough feel. We just had the highway redone so its not even like im hitting a rough spot

 

I thought it was a blown shock because thats what it feels like. But I can find no evidence of this. Also if it was a blown shock I would think it would be a constant problem.

 

Stiff suspension shouldn't mean the tires are leaving the road (unless it's track stiff.) I would think a blown shock would make the car rock from side to side a bit because the damping is uneven. Are the shocks and springs stock? Sounds almost like stiff springs and weak shocks (horribly unmatched.)

 

Sections of the 880 highway in oakland are made from concrete. I guess temperature or earthquakes have created a washboard type pattern in the road. You drive down it and the entire car rocks forward and backwards as you travel over the bumps. Every car does it, especially the old beaters with bad shocks. they bounce up and down like bobble head dolls. The road also makes a very distinctive "ba-dump ba-dump ba-dump" sound as you drive over it.

This could be what you are describing, and you just never noticed it on your old car with a softer suspension.

Does the speed of the rocking change with the speed of the car?

 

i suggested that to him, cause thats what happens to me (even though i care less. handling > comfort for me) but he says its a gradual build up.

indy, if you can, try and post a video of it so we can actually see what your talking about

 

I do appreciate all of your feedback. You may be right,I have never driven another RX-8. But I have ridden and driven in high performance vehicles and some exotic vehicles on the same stretch of highway and never felt anything like this.

But I'll just take it back in next Monday and have a tech ride with me and test drive another one and see if it does the same thing. If it does no big deal. I'm not complaining. I just don't want to have to cover the cost of replacing something that might not be covered under warranty if there is really something wrong.

 

Any resolution to this problem?

I have the same issue on concrete and can't figure it out. It not something that can be ignored or put an other way, can't believe anyone would say "I don't care because I love the handling or handling > comfort is moronic.

 

i've noticed the same...it's just the wheel length of our cars combined with the stiff suspension produces this rock.....i get the same also on a short creek bridge at only the entrance and exit....

 

Have you checked your tyre (tire) pressures? When I first got mine I thought the ride was just awful - then I found out I had 48psi in the tyres not the recommended 32psi. Professional mechanics - what can you do eh!

 

The members from Indianapolis have mostly moved to their own forum/website and only intermittently check here. Logon to the indyrx8club.com to get your answer. I believe the OP is the president of their club.