MX6.com - View Single Post - Autox/Autocrossing a Mazda MX-6

**gavin** · 2-28-08, 16:59

So here is one persons recepie for a 2nd gen G-stock car. If you have talked to Ryan some of this may be duplicate as we have gone back and forth on what a "modernized" G-stock 2nd gen would look like.

First thing(Im sure you have done this but if you havent shame on you) get on the mazdaspeed driver discount programme. OEM parts for cost. Theres no reason to compete a mazda without using this resource.

Going through the rules..the car isnt old enough to inherit the braided steel brakeline rule so get new oem lines if yours look suspect. Its got an airbag so it also doesnt inherit the steering wheel change option.

Get new front control arms, new trailing arms and new lateral arms. 15 yr old bushings suck to run on. If you cant afford all of them get the fronts, the trailing arms and the rear lateral arms.(PS: shop around for the fronts, I was actually able to find cheaper front arms from a parts house than through mazdacomp)

Go through the engine bay for the usual suspects. NGK plugs and wires, new cap/rotors and new ignitor if yours is dodgy(I recall that some of the 2nd gens had issues with the ignitors). Whatever oil you prefer for the engine. The trans oil will be up to you as well, but I like a combo of MT-90 and one quart of synthetic ATF. K+N drop in filter.

Struts: koni yellows (sport) 8610-1305(front), 8610-1306(rear) . These are a european fitment and are about 1" short for the US issued struts, but it fits in the rules which give you 1" to play with for the extended length of the replacement struts. You may need spacers to make up the length, its not hard to do though. http://www.mx6.com/forums/1g-faq-sus...tallation.html (Koni insert installation)

You can keep the struts with the stock valving, but for a top notch build Id have the konis revalved by Koni NA. Itll cost about $650 to have them all done and you have to be specific about what you want. What you want is the Sport Showroom Stock (SPSS3) valving. This is a very aggressive valving that was developed for the showroom stock racers that have to run on stock springs(kinda like stock class autocrossing). The rebound rates will be higher, but with a crapton of low speed compression. It basically tries to mimic the effect of heavy springs on initial turn-in(this is a good thing). Having this valving done will also have the struts degassed a bit which will lower the rude height of the car by about 1/4".

Theres no warrantee after this move though and Itll also rattle your teeth in daily driving even at full soft so consider it carefully.

Want to go even further with struts? Get the 8611 series double adjustable racing strut insert. This is going to involve custom fitting(they need a unique gland nut to hold them in place from the top of the strut body) and theres no warrantee on them, they are much more expensive, but they are a powerful tool as they have both compression and rebound adjustments. Im pretty sure Koni can make a fitment using your gutted struts, if not I know for a fact that Tri-point have the neccessary parts.

Tires: Hoosier A6s. 225/45/15 That is all. Theses tires will be about 2" shorter than the stock tires lowering the car about 1" and lowering the CG by that much as well. The smaller diameter will give a bit of torque multiplication as well but youll have to use more RPMS to get the the same terminal speed as with the stock sized tires. Lucily since the V6 is a revver you can take advantage of its long legs and ability to make power at redline. Tire pressures will be somewhere in the 42psi front and 45ps rear range (+- 3psi)

Cheaper is the 225/50"15 kumho V710s. A little taller than the Hoosiers, they last a bit longer and are a little cheaper. Ive run on both and the Kumho feels a little less sharp on turn in and with less "stick" than the hoosier.... but sometimes the pocketbook dictates other things.

Wheels: You need stock sized wheels that are lightweight and 15x6.5". For decades people have been using the 2nd gen RX7 convertable BBS wheels, and I dont see any reason to change that. They are the correct dimensions are about 10-11lbs apiece and are pretty cheap as well. The only catch is that the hub center hole needs to be punched out a little to fit on the 2nd gen MX6 hub. Generally, not a problem for a machine shop and inexpensive as well. Even doing all of this youll come out with a set of wheels thats way cheaper than volks or SSRs for a "penalty" of 2lbs/wheel or so.

Front swaybar: biggest you can get. I have heard that the ford Probe GTs front swaybar is larger than that of the MX6 LS, Id get that and swap it in. With a strut car, since theres no appreciable camber gain, when the car rolls the outside tire will go to positive camber and have the tire rolling onto its sidewall. Not much traction to be gained doing that. The fix is to reduce that body roll as much as possible with a big front swaybar, keep the tire patches as flat as possible INCREASING the cars ability to corner. Yes, at the limits you can induce understeer, but youve basically overcooked that corner anyway. The only downside to using a large FSB is that youll have a tendency for more wheelspin at corner exit.

Ive run with smaller and larger FSBs and while youll gain traction on corner exit with a smaller swaybar, everything else is worse. The car pushes and ploughs in slaloms and offsets like a pig, long sweepers will have you have less wheelspin, but theres much more push which tends to overheat the outside tire. Personally, I prefer the larger swaybar, the car turns better, slaloms better, is crisper. Youll have to watch your right foot a bit more with sweepers and corner exits, but overall the car was simply faster hands down with the big FSB. If I could, I would have a custom made one that was even larger.

Alignment: A real alignment is key here. Most shop jockeys will just go by what the machine tells them is "ok". Youll need someone who is willing to ignore the machines flashing red lights.

The front upper strut mounts are offset. Rotate the upper strut mouts to the point where there is the most neg camber and most positive castor( should have the struts closest to the firewall and pointing to the engine). f your shop tech is really cool, have them loosen all the bolts on the sturts and subframe and pry everything to its maximum to get all the slop out of it (you can pick up an extra -.5 deg camber sometimes doing this). Then have them bolt everything down tight. For the rear, get the least amount of amber you can. Youll probably get something like -1.5 deg camber front and -.5 rear. It more than likely wont be even side to side but youll have to take what you can get because mazda doesnt authorize crash bolts in the FSM as a fix for camber.

Toe.. front 1/16 to 1"8" toe out. For the rear, the same(1/16-1/8" toe out). Youll need the car to turn in well(front toe out does this) and rotate well(rear toe out). Overall toe alignment will be up to how brave you are and how much you can afford tires. Ive run as high as 1/4" toe out in front and 1" toe out in the rear on a 1st gen and the car was.....er "lively". It was fast and twitchy as hell, but it ate tires like nobodys business. Youll have to strike a balance for yourself.

Cat back exhaust: (well first I guess you actually need to have a catalytic converter

) For a full system people seem to like the borla. Apparently its light and very free flowing. I havent heard it myself but people say that the aural quality is superb as well. According to the rules the most you need is a 4" turndown right after the cat and thats your "cat back exhaust system". his will definetly drop a whole bunch of weight, but Id suggest earplugs.

Think thats about it for a G-stock build.

good luck

EDIT: more strut info

Gavin

2-28-08, 16:59	#69 (permalink)
gavin Join Date: Jan 2001 Location: santa cruz.ca iTrader: (1)	So here is one persons recepie for a 2nd gen G-stock car. If you have talked to Ryan some of this may be duplicate as we have gone back and forth on what a "modernized" G-stock 2nd gen would look like. First thing(Im sure you have done this but if you havent shame on you) get on the mazdaspeed driver discount programme. OEM parts for cost. Theres no reason to compete a mazda without using this resource. Going through the rules..the car isnt old enough to inherit the braided steel brakeline rule so get new oem lines if yours look suspect. Its got an airbag so it also doesnt inherit the steering wheel change option. Get new front control arms, new trailing arms and new lateral arms. 15 yr old bushings suck to run on. If you cant afford all of them get the fronts, the trailing arms and the rear lateral arms.(PS: shop around for the fronts, I was actually able to find cheaper front arms from a parts house than through mazdacomp) Go through the engine bay for the usual suspects. NGK plugs and wires, new cap/rotors and new ignitor if yours is dodgy(I recall that some of the 2nd gens had issues with the ignitors). Whatever oil you prefer for the engine. The trans oil will be up to you as well, but I like a combo of MT-90 and one quart of synthetic ATF. K+N drop in filter. Struts: koni yellows (sport) 8610-1305(front), 8610-1306(rear) . These are a european fitment and are about 1" short for the US issued struts, but it fits in the rules which give you 1" to play with for the extended length of the replacement struts. You may need spacers to make up the length, its not hard to do though. http://www.mx6.com/forums/1g-faq-sus...tallation.html (Koni insert installation) You can keep the struts with the stock valving, but for a top notch build Id have the konis revalved by Koni NA. Itll cost about $650 to have them all done and you have to be specific about what you want. What you want is the Sport Showroom Stock (SPSS3) valving. This is a very aggressive valving that was developed for the showroom stock racers that have to run on stock springs(kinda like stock class autocrossing). The rebound rates will be higher, but with a crapton of low speed compression. It basically tries to mimic the effect of heavy springs on initial turn-in(this is a good thing). Having this valving done will also have the struts degassed a bit which will lower the rude height of the car by about 1/4". Theres no warrantee after this move though and Itll also rattle your teeth in daily driving even at full soft so consider it carefully. Want to go even further with struts? Get the 8611 series double adjustable racing strut insert. This is going to involve custom fitting(they need a unique gland nut to hold them in place from the top of the strut body) and theres no warrantee on them, they are much more expensive, but they are a powerful tool as they have both compression and rebound adjustments. Im pretty sure Koni can make a fitment using your gutted struts, if not I know for a fact that Tri-point have the neccessary parts. Tires: Hoosier A6s. 225/45/15 That is all. Theses tires will be about 2" shorter than the stock tires lowering the car about 1" and lowering the CG by that much as well. The smaller diameter will give a bit of torque multiplication as well but youll have to use more RPMS to get the the same terminal speed as with the stock sized tires. Lucily since the V6 is a revver you can take advantage of its long legs and ability to make power at redline. Tire pressures will be somewhere in the 42psi front and 45ps rear range (+- 3psi) Cheaper is the 225/50"15 kumho V710s. A little taller than the Hoosiers, they last a bit longer and are a little cheaper. Ive run on both and the Kumho feels a little less sharp on turn in and with less "stick" than the hoosier.... but sometimes the pocketbook dictates other things. Wheels: You need stock sized wheels that are lightweight and 15x6.5". For decades people have been using the 2nd gen RX7 convertable BBS wheels, and I dont see any reason to change that. They are the correct dimensions are about 10-11lbs apiece and are pretty cheap as well. The only catch is that the hub center hole needs to be punched out a little to fit on the 2nd gen MX6 hub. Generally, not a problem for a machine shop and inexpensive as well. Even doing all of this youll come out with a set of wheels thats way cheaper than volks or SSRs for a "penalty" of 2lbs/wheel or so. Front swaybar: biggest you can get. I have heard that the ford Probe GTs front swaybar is larger than that of the MX6 LS, Id get that and swap it in. With a strut car, since theres no appreciable camber gain, when the car rolls the outside tire will go to positive camber and have the tire rolling onto its sidewall. Not much traction to be gained doing that. The fix is to reduce that body roll as much as possible with a big front swaybar, keep the tire patches as flat as possible INCREASING the cars ability to corner. Yes, at the limits you can induce understeer, but youve basically overcooked that corner anyway. The only downside to using a large FSB is that youll have a tendency for more wheelspin at corner exit. Ive run with smaller and larger FSBs and while youll gain traction on corner exit with a smaller swaybar, everything else is worse. The car pushes and ploughs in slaloms and offsets like a pig, long sweepers will have you have less wheelspin, but theres much more push which tends to overheat the outside tire. Personally, I prefer the larger swaybar, the car turns better, slaloms better, is crisper. Youll have to watch your right foot a bit more with sweepers and corner exits, but overall the car was simply faster hands down with the big FSB. If I could, I would have a custom made one that was even larger. Alignment: A real alignment is key here. Most shop jockeys will just go by what the machine tells them is "ok". Youll need someone who is willing to ignore the machines flashing red lights. The front upper strut mounts are offset. Rotate the upper strut mouts to the point where there is the most neg camber and most positive castor( should have the struts closest to the firewall and pointing to the engine). f your shop tech is really cool, have them loosen all the bolts on the sturts and subframe and pry everything to its maximum to get all the slop out of it (you can pick up an extra -.5 deg camber sometimes doing this). Then have them bolt everything down tight. For the rear, get the least amount of amber you can. Youll probably get something like -1.5 deg camber front and -.5 rear. It more than likely wont be even side to side but youll have to take what you can get because mazda doesnt authorize crash bolts in the FSM as a fix for camber. Toe.. front 1/16 to 1"8" toe out. For the rear, the same(1/16-1/8" toe out). Youll need the car to turn in well(front toe out does this) and rotate well(rear toe out). Overall toe alignment will be up to how brave you are and how much you can afford tires. Ive run as high as 1/4" toe out in front and 1" toe out in the rear on a 1st gen and the car was.....er "lively". It was fast and twitchy as hell, but it ate tires like nobodys business. Youll have to strike a balance for yourself. Cat back exhaust: (well first I guess you actually need to have a catalytic converter ) For a full system people seem to like the borla. Apparently its light and very free flowing. I havent heard it myself but people say that the aural quality is superb as well. According to the rules the most you need is a 4" turndown right after the cat and thats your "cat back exhaust system". his will definetly drop a whole bunch of weight, but Id suggest earplugs. Think thats about it for a G-stock build. good luck EDIT: more strut info Gavin Last edited by gavin : 3-2-08 at 16:12.