View Full Version : Need autocross suspension suggestions


PUR NRG
02-02-2004, 10:53 AM
I have an RX-8. I also have the MazdaSpeed body kit, which means my otherwise stock vehicle is now in Street Mod. That means my wallet has permission to hemmorage in the pursuit of go-fast goodies. :)

First up is revamping the suspension. All I know for certain is I want double-adjustable shocks front/rear. Coil-overs are nice but performance is primary. Any good options for autocross? Penske 8100's are nice but at $3500 for a set is out of my budget.

I'd like to redo the entire suspension (shocks, springs, sway bars) in one go. Any help would be appreciated.
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GeorgeH
02-03-2004, 02:43 PM
I can't give you any specific advice about the RX-8, but I've been down this path with my Miata so I can give some general suggestions.

First, as for doing everything at once, don't. You won't know what mod was responsible for which behavior. Do things one at a time so you can understand how you and your car respond to the changes.

Sway bars are the first thing most people will tell you to change, because they are easy and cheap, but given that you are going down the SM path I'd say make sways the last thing you change - the finishing touch, if you will.

I'd say fist choose your wheel tire package. This will define how much grip the chassis needs to cope with, and will help you understand just how much more roll stiffness you need.

Next, I'd get a matched set of coil-overs (Tein, etc). I have Illuminas & GC height-adjustable springs on my Miata, and they were without a doubt the single most significant change I made. They allow you to tune the ride height, which allows you to corner weight the car, as well as tune the cornering balance. Also, the stiffer springs reduce pitch & dive as well as roll. I'm a much bigger fan of stiff springs vs. stiff sways, if you are talking about autocross & track use.

With my Miata, I started with sways, then did the shocks, then the GC sleeves. Once I got the stiffer springs on, I went back to the OEM sways, and now I don't run sways at all! I'll reconnect the stock sways for autcross use, but sways are reduced to fine-tuning tools when you have a good set of coil-overs to play with.

Oh and don't forget about alignment. I just had mine done, but I stayed fairly conservative (about .5 degrees negative camber in the front) but I bet the RX-8 will benefit from more agressive alignment settings while autocrossing, just as the Miata does.

My .02.

George

AlexCisneros
02-04-2004, 09:34 AM
Definitely do the Alignment and then wheel tire combo first. Since you are in SM get yourself some nice 17" rims and slap some Azenis tires on them. They will make a world of difference. I disagree about holding off on the sway bars. The car has a tendency to roll in the front. Go with the front at least.

GeorgeH
02-04-2004, 01:58 PM
Front sway as a starting point makes alot of sense if PUR is running BS (obviously) or if he is looking to keep costs down, but he specifically mentioned a full setup in SM, so a good set of coilovers is the right starting point - the stiffer springs will keep body roll in check. In the end, most SP/SM drivers end up with several different sways to help fine tune the car for different venues, so there's no harm in getting the sways up front. I personally find stiff sways unnecessary when stiff springs are already on the car, but then every car/venue/driver combo will differ.

As for tires, in SM I would think a set of Kumhos would be a great starting point.

George

Killerking1964
03-04-2004, 10:09 PM
Unless you have done more mod's than the Mazda Speed body kit, your 8 should be in the SCCA BS class.

tpryor
03-05-2004, 05:58 AM
Originally posted by Killerking1964
Unless you have done more mod's than the Mazda Speed body kit, your 8 should be in the SCCA BS class.

Nope - it moves him to BSP or SM, due to the body kit not being an "authorized", FACTORY installed option.

Even if Mazda sells it, but it's only available as a DEALER installed option, it is not legal for stock.

How do I know for sure? I was disqualified from Nationals a few years ago for having this EXACT problem.............

Trust me on this one.

Ike
03-05-2004, 11:44 PM
Originally posted by tpryor
Nope - it moves him to BSP or SM, due to the body kit not being an "authorized", FACTORY installed option.

Even if Mazda sells it, but it's only available as a DEALER installed option, it is not legal for stock.

How do I know for sure? I was disqualified from Nationals a few years ago for having this EXACT problem.............

Trust me on this one.

Yeah, it's kind of silly considering if anything it makes us slower...

neit_jnf
03-06-2004, 12:19 AM
Why don't you go all out with Mazdaspeed parts? shocks, springs, sways, front and rear strut bars, underbody bars, maybe even the flywheel if it's still legal for your class. That's what I'd like to do when I get my 8... Dreaming is free!

GeorgeH
03-06-2004, 01:43 AM
Yes, and don't forget the turbo kit. I'm not sure about SM, but in SM2 you need a wallop of a motor to be competitive.