JR RX8

I recently noticed (2 months?) after replacing my winter wheels back to summer
wheels , that my 2005 RX8 seems to sway a little in the rear mainly, whenever I
hit a bump or some other thing like a construction plate or missing
asphalt/uneven road surface. What will happen is that when I hit the bump/s, or
whatever, it seems to "break loose" and get a bit swishy/squirrely in the rear.
It is a bit unnerving.

After changing the wheels I had the dealer check out the alignment and balance
and of course re tightened all the lugs properly. So I know its not loose lugs
or unbalanced wheels. I also keep the tored inflated to recommended 32 PSI
(Cold).

I drive in NYC where the roads are atrocious and not many smooth ones to begin
with and I know the car is set up pretty tight to begin with, but it never
seemed to break the way it does now. I'm riding on Dunlop Sport 8000s with 22K
on them. The shocks still seem pretty tight, no soft ride here I also keep
the DSC (DTSS) on all the time. When I push up and down on the car or side to
side while parked, she's pretty solid as well.

I read somewhere that this swaying could be caused by the DTSS bushings going
bad, which I could see easily happening given NYC roads and since I keep it on
all the time ( it DOES work great) She rides perfectly well on smooth surfaces
but on anything approaching bumps, its really annoying. She doesn't roll when I
go into a tight turn at speed nor do the tires break either, this only usually
occurs when the road surface is rough or isn't flat and smooth.

Any ideas before I bring it into the dealer so I don't get whacked at the
register?? And should I take it to a non Mazda dealer / wheel alignment shop
instead? Also if it IS the DTSS bushings any idea what I might be looking at
cost wise?? Thanks in advance.

BTW it's 5 years now, people still compliment me on the car and its good looks,
think its brand new and I love driving it. Wouldn't give it up for anything
else.

kartweb

Could be bushings but I'm suspicious its in the rear dampers - (or shocks as you would say).

Dampers have two methods of flow regulation;

Low speed which pushes fluid through an orifice. Simple enough, that works mainly when suspension moves relatively slow like braking, turning, acceleration.

High speed is different; nail a bump and the wheel needs to move faster then what the orifice will allow. It builds lots of pressure on the compressed side in turn opening a bypass valve.

Those actions happen both in a compression and rebound mode. One direction is generally higher in forces because the area of the piston doesn't have to subtract the area of the piston rod. If you're still with me so far.......

Dampers don't just absorb the bump energy, they tune the amount of time a tire is exposed to forces and loads. If the left & right dampers are out of synch with the high speed bypass valve they will cause the car to do what you've described.

No you can't simply jounce the car to find it. You need a damper dyno. But its probably easier just to change out the dampers.

If you want a good animated example take a look at http://www.racecartuner.com/03/403.html

SayNoToPistons

iTrader: (8)

The DTSS bushing problems apply to FC3S generation of RX7s, not RX8s. Your dampers might need replacement (as kartweb stated), I am pointing towards that direction more than bushings because I am familiar with how bad NYC roads can be on shocks. One of my shocks in the rear needs to be replaced because I see oil on the shocks from leaks. I am also experiencing nervousness in the cars handling when it comes to uneven surfaces around corners. How many miles is on your RX8?

JR RX8

Shocks makes sense to me given the state of NYC roads. I'm bringing it in to the dealer sat to have a look at it. I don't see any oil leakage, but then again, you never know.
Car only has 22K on it. But like I said, NYC roads are ROUGH and your shocks really do take a beating. Even the expressways are full of pitting and rough patches so I can see where the dampers/shocks could really get overworked and blown before their time.

Will keep you posted and what they say this weekend.

Thanks again
JR