N/A z31 for road racing

Hmmm...."Bend the rules"
8)
I vote this as there are a few small things that'll make an improvement that can go un-noticed with-out a thorough tear down.
#1…a set of my TSS "Morgan Style" adjustable cam gears to get that motor to work in the rpm range you'll be needing it to for SCCA.
**I'll let others chime in for a few of the "other" changes that'll fall under my heading of "Bend the Rules".

slotted shock towers to give you more camber in front, if you are careful and use larger washers you can hide the elongation of the holes and get almost a degree out of it

from memory I think they allowed a larger front swaybar too… no way I'm reading that pdf right now

oh yes and I forgot, you will be able to see the strut doesn't line up with the hole in the middle perfectly, but if you use the adjustable turbo cover plates you can hide that too

alternately look for chrysler k-cars and get some of their foam shock tower covers, easy to modify, and will hide everything

I'm not sure if we are steering you in the right direction or not, but ECU changes are also virtually undetectable. Another simple solution for a few hp on an NA car is to advance the timing via the distributor. I believe as far as suspension you are not allowed to change ANY mounting points, so camber adjustment both front (which would be very helpful) and rear is out of the question. I know somebody posted on this same subject a couple years ago on z31.com, but I never saw an end result.

yea one of the kiddies posted how they won some auto-x but a miata guy snitched on his camber and they found he slotted, but he slotted them several degrees so the holes were obvious

like I say be careful about it and it can be hidden

Holy CRAP, I just breezed over this part.



You can make an EASY 20WHP gain between retuning fuel, timing and whatnot on a NA car with full exhaust (ask me how I know). With the cam gears you could make another 10-15. You can run an adjustable FPR, which means you probably won't even need to upgrade fuel injectors. The limitation only holds you to using a Z31 ECU. You would think this should be some exciting news that will make the Z31 a little more competitive in IT.

thanks to every one for the tips.
I will send some pics when the car is finished.

I cant believe I forgot to mention 87-89 front control arms. They are almost indistinguishable from 84-86 control arms and will give you a half degree negative when used with 84-86 struts.

ST rear springs will give a bit of rear camber as well and they are stiff enough that it should help your handeling quite a bit. They dont change any mounting points and require no modification of stock components so I dont see how they would not be allowed unless there is a specific statement about higher rate springs.

Jason beat me too it, i was going to suggest 87-89 front control arms paired with 84-86 strut housings. This is what i have and am now changing to 87-89 strut housings. Its great for negative camber up front! I have like -2 degrees up front at least is my guess, but kills my tires for daily driving, but so does 450RWHP spinning the rears, i shouldnt complain.....

I can't see why you wouldn't be able to get away with using some decent sway bars as well…maybe some SS sway bars would be a good choice.

rules usually only allow the addition of a rear swaybar if none existed on the car and increase size if it did, but generally they want the front stock

well couldn't an SS sway bar be argued to be stock…I mean it came on a stock Z31…so maybe it could pass

Shows how many of you people actually read the rules before giving suggestions. Some of those "cheating suggestions" are allowed by the rules.

In IT any drop in spring is legal. However, all drop in springs are crap for what you are trying to do. Also, you need to keep the 5" of ride height, which pretty much rules out any aftermarket spring with the exception of SS reproductions (which are crap for what you're trying to do.

With that said, as I thought, IT allows adjustable perches so long as they mount in the original spot. Last I heard Ground Control stopped offering rear "coilovers" for our cars, but give them a call now and tell them right away, "I'm building an ITS 300zx and I need adjustable perches."


If they give you some BS about not having those, tell them you want a front 300zx kit and some 2 steel adjustable perches that are 3.5" long and have a 2.25"ish inside diameter (You need to measure this to make sure it's correct. Follow use the method that Butter and I (Pylon_Boy) used and modify the lower mount on the control arm. Do whatever you wish to keep the control arm from opening up too much.

If you still can't do Adjustable perches, send me a PM or an e-mail along with the weight of your car at each of the rear wheels and I will help you select a spring rate and length that will be beneficial for what you are trying to do.


Recommended spring rates for the rear will be probably over 700 in/lbs. Fronts probably less. I'm used to solo type setups, and I didn't spend enough time tinkering with springs when I raced my Z.


You will need a limited slip differential, any ratio is legal.

You will probably need a front bar 100 times more than a rear bar. Who ever told you that they don't really recommend front bars is trying to beat you in a dishonest way.


and my last point. Who ever cheats in ameture motorsports has some serious issues.