Had my car in for an alignment check yesterday and the tech told me it was riding like 1/4" low in the back. Fuel tank was maybe 3/4 full. There's not a heck of a lot in the trunk; mostly a bottle of oil, some jumper cables, a flashlight, and the stock jack and mobility kit.

Car has 48k and change on the odo. Alignment turned out to be completely in the green at all four corners; the only thing that I might have wanted to tweak was that the rear had a hair more toe-in on one side, and I figured that's not worth worrying about until after pothole season.

What does Mazda say about how to measure ride height -- i.e. how much fuel, etc.? Is there reason to believe the rear springs have already started to sag?

 

This is a common issue. I don't know what exactly is the root cause, but people on this club tend to say it's the shocks. Again, why the shocks get weak so soon is still a mystery. One member said (can't remember the name) that unlike other cars where most of the vehicles weight is on the springs, most of the weight of the rear in an RX-8 is on the shocks, and that's why they fail so soon. The front seems to be set up well though, because they don't fail as soon as the rear shocks.

Frankly, I have the same issue. My car hits the bump stops quite often when having more than 3 people inside going down a bad road.

 

Is this with R3s in particular, or RX-8s in general?

Regarding where "most of the weight" is, I'm not sure what that could mean. The rear is a coil-over arrangement, so the damper and spring should have roughly the same forces acting on them.

All RX-8s have gas dampers though, right? Maybe the car just depends on that gas support more than other cars do. Either way, if stock ride height is with fresh gas dampers, it makes sense that there'd be some sag. As for why the rear wears before the front, maybe it's because of the motion ratios...?

 

about 52k miles on my R3, no noticeable sag in the back, though I haven't taken it in for an alignment or had the ride height checked yet. I did notice a little fluid leak on the right rear shock a few months ago - I wiped it clean so I could see if there is any new fluid coming out, nothing yet (after a thousand miles or so with some pretty hard driving mixed in there).

 

Put two people in the back and go on a rough road. You'll hear the suspension hitting the bump stops.

 

I hadn't noticed any sag either.

I did ask how the tech figured the car was low in the rear. IIRC, he said something about the alignment seemed just a tiny bit off (i.e. on the edge of the green zone) until he pushed up on the rear axle slightly. Wish I knew/remembered more.