Anyone else here race a 240 on a paved oval track? Or a dirt track? I run a '89 on a 3/8 mile paved ovel and would be interested in discussing suspension setp.
-Martin.
Paved Oval racing setup?
Re: Paved Oval racing setup?
martin wrote:Anyone else here race a 240 on a paved oval track? Or a dirt track? I run a '89 on a 3/8 mile paved ovel and would be interested in discussing suspension setp.
-Martin.
OK, no takers so far on this.. how about road racers? Anyone out there that has to run stock type struts (ie. not coil overs)? How did you get stiff and low without bottoming the suspensuion out?
Anyone have to run on street tires? I have to use minimum 200 treadwear, 205-60-15.
-Martin.
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MainEvent212
- Posts: 4182
- Joined: Tue Mar 04, 2003 1:21 pm
- Car: 95 Nissan 240SX SE w/ SR20DET+goodies
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Nismo_Freak
- Posts: 10314
- Joined: Wed Jul 24, 2002 10:42 pm
- Car: 89 Nissan 240SX
Yeah, I'd use a Miata or RX7 for that sort of racing. They both come standard with good suspension, low roll centers, and have a more common LSD standard. Being limited to a certain tire compound and width your gonna want a car that comes factory lightweight and with excellent distribution. Honestly a FC3S Turbo II RX7 comes to mind as an excellent contender, however a Miata would do excellent as well.
If your looking for hard spring rates, don't be afraid to call up some of the spring makers and ask for a custom make. Tein offered to produce a "1 of" set of coilovers for the 240SS, fully setup to our spec for drag launches.
If your looking for hard spring rates, don't be afraid to call up some of the spring makers and ask for a custom make. Tein offered to produce a "1 of" set of coilovers for the 240SS, fully setup to our spec for drag launches.
mainevent212 wrote:i heard RS*R makes some bad *** springs if you can get a shock that will take the beating...
i dont think 240sx's are a hot item on the paved donut tho
Yeah I read about the RS*R springs in the FAQ...
I have to disagree about the 240 not being hot on the oval though. This is my third season with the 240, and I'm trying to take it to the next level. Really I'm being forced to.. becaue I won too much they implemented a new rule, every time you win a feature you add 50lbs of weight to the passanger side seat area. I'm currently the only car running around with an extra 100lbs :-)
-Martin.
Nismo_Freak wrote:Yeah, I'd use a Miata or RX7 for that sort of racing. They both come standard with good suspension, low roll centers, and have a more common LSD standard. Being limited to a certain tire compound and width your gonna want a car that comes factory lightweight and with excellent distribution. Honestly a FC3S Turbo II RX7 comes to mind as an excellent contender, however a Miata would do excellent as well.
If your looking for hard spring rates, don't be afraid to call up some of the spring makers and ask for a custom make. Tein offered to produce a "1 of" set of coilovers for the 240SS, fully setup to our spec for drag launches.
Not allowed twin cams, or turbos. They banned my '83 Rx7 after the '98 season when I cleaned up winning 10 out of 13 features. I ahdn't thought of getting Tein or ? to make custom springs. What kind of money were they talking?
Yeah, finding a non-adjustable stock (looking) strut will be a challenge. I was considering building some custome ones, taking the stock tubes, welding on a threaded collar and finding inserts that are designed for much more weight, ie. T-bird (just a guess). I need to need a shock spec book from the parts store and see what I can find.
Anyone tried anything like this?
-Martin.
What are you allowed?
If adjustable struts are allowed, try something with a short stroke design. I have the KYB buzz specs which is a JDM only, short stroke circuit sturt. I have those coupled with a ground control coilover setup... If you can use adjustable perches, then Ground Control may be the way to go for you b/c you can get basically any s/r you want from them.
I don't know where you can get those struts though, but you can find the Gab Super Strokes (same exact strut as the buzz spec) at http://www.cyberauto.com They aren't cheap though...
If adjustable struts are allowed, try something with a short stroke design. I have the KYB buzz specs which is a JDM only, short stroke circuit sturt. I have those coupled with a ground control coilover setup... If you can use adjustable perches, then Ground Control may be the way to go for you b/c you can get basically any s/r you want from them.
I don't know where you can get those struts though, but you can find the Gab Super Strokes (same exact strut as the buzz spec) at http://www.cyberauto.com They aren't cheap though...
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Nismo_Freak
- Posts: 10314
- Joined: Wed Jul 24, 2002 10:42 pm
- Car: 89 Nissan 240SX
OK here's what I can and can't use.
- no coil overs.- no adjustable shocks- must have stock spring perches- must use OEM type springs (ie. must sit on stock perches)
What I'm using now is Tokico Blues with stock springs cut down to ~ 3 coils, with 2.5" formula car springs inside of these (like a dual valve spring setup). The approx spring rate currently is 450lb RF. Big problem is Tech inspector is starting to "yap" about my formula car springs, saying they don't fall into the "OEM type" category. It's only a matter of time before he insists that I remove them so I need a contingency plan.
Slightly off topic... Does anyone know of an OEM style brake Bias valve that can be adjusted with shims, or some other way? I had a real bias adjuster, but they made me remove that :-( Now I have way too mucg front brake with the 300Zx front setup. So I'm locking up the fronts which makes it very difficult to get turned in.
Thanks for any help...Martin.
- no coil overs.- no adjustable shocks- must have stock spring perches- must use OEM type springs (ie. must sit on stock perches)
What I'm using now is Tokico Blues with stock springs cut down to ~ 3 coils, with 2.5" formula car springs inside of these (like a dual valve spring setup). The approx spring rate currently is 450lb RF. Big problem is Tech inspector is starting to "yap" about my formula car springs, saying they don't fall into the "OEM type" category. It's only a matter of time before he insists that I remove them so I need a contingency plan.
Slightly off topic... Does anyone know of an OEM style brake Bias valve that can be adjusted with shims, or some other way? I had a real bias adjuster, but they made me remove that :-( Now I have way too mucg front brake with the 300Zx front setup. So I'm locking up the fronts which makes it very difficult to get turned in.
Thanks for any help...Martin.
I assume you've read some books on gettnig your car setup. You'll want to work on things like tire stagger, camber and getting rid of oversteer(which is bad bad on an oval).
I'd definitely call around to a few manufacturers and tell them what you're doing, offer to run a sticker on your car just for helping you out with custom rates made in a stock spring size. As far as brake bias, can you not upgrade your rears? What about using a slightly more aggressive pad out back as a crude way of changing the bias? Have you looked into any other stock proportioning valves that would fit from other Nissans?
I'd definitely call around to a few manufacturers and tell them what you're doing, offer to run a sticker on your car just for helping you out with custom rates made in a stock spring size. As far as brake bias, can you not upgrade your rears? What about using a slightly more aggressive pad out back as a crude way of changing the bias? Have you looked into any other stock proportioning valves that would fit from other Nissans?
Def wrote:I assume you've read some books on gettnig your car setup. You'll want to work on things like tire stagger, camber and getting rid of oversteer(which is bad bad on an oval).
I'd definitely call around to a few manufacturers and tell them what you're doing, offer to run a sticker on your car just for helping you out with custom rates made in a stock spring size. As far as brake bias, can you not upgrade your rears? What about using a slightly more aggressive pad out back as a crude way of changing the bias? Have you looked into any other stock proportioning valves that would fit from other Nissans?
Thanks for your response "Def"... It's sometimes difficult to know where to start when bringing up a new subject on the Forums. Too much detail and it doesn'rt get read...
I've been racing for a while. I have two championships under my belt, and one I missed by 3 points. I run ~ 2" rear stagger, 1/2" front. 7.5 degrees -ve RF, 2.5 -ve RR, 3 +ve LF, 2.5 +ve LR. The car is regularly scaled, 52% front, 55% left, cross weight can be anywhere from 49 - 53% depending on how I shim.
Oversteer is nowhere near as bad as understeer, at least not in my opinion. Understeer is my big problem right now, caused by the front brakes locking up (because they made me remove my bias valve).
I'm looking for any OEM bias valve that I can use to reduce the front brake pressure. Adjustable would be perfect, non adjustable would be worth a try. It just can't be adjustable while I'm driving, or a racing one (which is what they made me take out). I'd love to be able rto put teh racing one back in under teh hood, but that won't fly!
The springs and shocks/struts... I'm anticipating a problem here in the near future. I know this is the next thing the tech inspectors are going to pick on me about so I was trying to come up with a solution in advance. Calling the manufacturers is a good idea. Once I figure out what spring rates I need I'll do that. So far my spring rates have been basically guesswork. This is something that isn't covered very well in any book that I've read. The mini-stock books only cover the mustang/pinto which have twin A arms front and solid rear axel. The road race books say something along the lines of "springs are a personal choice, I recommend enough spring to keep the car from dragging on the track and to keep the suspension from bottoming out" which doesn't really give me much to go on :-)
To stock struts are the limiting factor here, trying to find a non-adjustable stock shock that can deal with high spring rates is tough which is why I was thinking of building some using inserts from a much haevier car. Currently I'm using Tokico Blues which I've tried with spring rates from stock up to 800lbs.. with 800lbs the car was low and handled like a go-kart, but bounced like a son-of-a-***** on the bumps around 400-450 seesm to be tha max these car take without bouncing too bad.
Hopefully that is enough background, and detail to give you guys something to work with . That's way more secrets that I'll usually dissclose in a public forum ;-) My competition might be lurking...
Thanks for any help... Martin.
Sounds good. Yea, you definitely seemed like you knew what you were talking about - that's why I even mentioned things like stagger etc. 
I'll admit I don't have any experience with oval racing outside of what I read. So take my suggestions with a grain of salt.
Your stagger looks good and I'm guessing your camber is setup correctly for the track surface, tire stiffness and camber curves.
So now we're onto springs and dampers! With the dampers, you can usually send the "better" models out to the manufacturer to have them revalved for higher springrates. I know with Koni Yellows many distributors can revalve them, and even shorten the shock body so you can go that much lower while still having suspension travel(which seems to be a huge problem in these cars up front). No adjustable shocks rules out Koni Yellows, but why not look into Koni Reds? They're the non-adjustable ones, but I *think* you can still have them revalved and shortened like the yellows. I'd give Koni NA a call and talk to them, or maybe Ground Control suspensions - although GC's customer service has slipped as of late IMO. Get a solution for your struts and you'll have the flexibility to choose any springrate you need.
Now about spring rates, that depends on how you want the car to feel. It seems you're complaining about understeer, which isn't fast - but is much safer than getting oversteer on an oval! Try to countersteer to correct for the *** coming around and into the wall you're going. To really get to where you need to be, it looks like you need to get your brakes squared away. Why don't you just be ghetto about it and get some small small plumbing barbs and put some inline with your brake lines up front to restrict those a hair. Thus gaining more rear bias and still being legal. Or you could take a shot in the dark and try out a proportioning valve from different model 240SX's and 300ZX's or something like that.
After you get the brakes setup, then you can start thinking about what springrates you would like. For a car that sees only steady state cornering like an oval car, I would maybe go just a "hair" stiffer on the rear wheel rate(assuming you have the same width tires front and rear - and you also have the roll centers about the same front and rear). Do find the wheel rate out, you need to find the motion ratios for your car. The motion ratio is simply the length of the suspension arm to the strut mounting point divided by the total length of the suspension arm all the way to the hub. It is merely a ratio which describes the leverage the suspension's geometry affords the wheel acting on the spring. To find the wheel rate, just multiple the motion ratio by your desired spring rate and you'll get a number that represents the springforce the tire "sees" when it gets compressed.
So... take that info for what it's worth since I'm making way too many assumptions to be providing specifics here. Hopefully this will give you some ideas that you can take and run with - and maybe it'll ensure you keep getting the Championship for many years to come.
I'll admit I don't have any experience with oval racing outside of what I read. So take my suggestions with a grain of salt.
Your stagger looks good and I'm guessing your camber is setup correctly for the track surface, tire stiffness and camber curves.
So now we're onto springs and dampers! With the dampers, you can usually send the "better" models out to the manufacturer to have them revalved for higher springrates. I know with Koni Yellows many distributors can revalve them, and even shorten the shock body so you can go that much lower while still having suspension travel(which seems to be a huge problem in these cars up front). No adjustable shocks rules out Koni Yellows, but why not look into Koni Reds? They're the non-adjustable ones, but I *think* you can still have them revalved and shortened like the yellows. I'd give Koni NA a call and talk to them, or maybe Ground Control suspensions - although GC's customer service has slipped as of late IMO. Get a solution for your struts and you'll have the flexibility to choose any springrate you need.
Now about spring rates, that depends on how you want the car to feel. It seems you're complaining about understeer, which isn't fast - but is much safer than getting oversteer on an oval! Try to countersteer to correct for the *** coming around and into the wall you're going. To really get to where you need to be, it looks like you need to get your brakes squared away. Why don't you just be ghetto about it and get some small small plumbing barbs and put some inline with your brake lines up front to restrict those a hair. Thus gaining more rear bias and still being legal. Or you could take a shot in the dark and try out a proportioning valve from different model 240SX's and 300ZX's or something like that.
After you get the brakes setup, then you can start thinking about what springrates you would like. For a car that sees only steady state cornering like an oval car, I would maybe go just a "hair" stiffer on the rear wheel rate(assuming you have the same width tires front and rear - and you also have the roll centers about the same front and rear). Do find the wheel rate out, you need to find the motion ratios for your car. The motion ratio is simply the length of the suspension arm to the strut mounting point divided by the total length of the suspension arm all the way to the hub. It is merely a ratio which describes the leverage the suspension's geometry affords the wheel acting on the spring. To find the wheel rate, just multiple the motion ratio by your desired spring rate and you'll get a number that represents the springforce the tire "sees" when it gets compressed.
So... take that info for what it's worth since I'm making way too many assumptions to be providing specifics here. Hopefully this will give you some ideas that you can take and run with - and maybe it'll ensure you keep getting the Championship for many years to come.
Dori Dori wrote:Like I said before, call around and see if you can get the Yellow's made unadjustable. There are ton's of Koni rebuilders out there...
Yeah, I might give that a try, but it sounds kind of expensive... before you say it I know you have to pay to play :-)
I'm going to do some research on replacement strut inserts, I'm sure I can find an application that will work for significantly less than the koni's.
Thanks...Martin.
All information I have read points to the much cheaper Koni Red's using the same valving as Koni Yellows, but just doesn't have an adjustment mechanism in the strut shaft. I don't see why Koni or a distributor couldn't revalve the Reds for whatever springrates you want to run(I'm thinking 800+ lb/in for oval racing on a good surface). You're probably looking at slightly over the cost of a Koni Yellow to get a Red and revalve it. Just make sure you pick the right springrates you want them to valve the shocks for!
Also - what are you doing about aerodynamics? This is a HUGE part of high speed racing, and I'm sure the rules are rather restrictive. But racing isn't racing unless you're bending the rules a bit!
Also - what are you doing about aerodynamics? This is a HUGE part of high speed racing, and I'm sure the rules are rather restrictive. But racing isn't racing unless you're bending the rules a bit!
Aerodynamics.. what are they :-) We're not racing at high speeds, it's just a 3/8 mile track, I think we reach 70mph.Def wrote:All information I have read points to the much cheaper Koni Red's using the same valving as Koni Yellows, but just doesn't have an adjustment mechanism in the strut shaft. I don't see why Koni or a distributor couldn't revalve the Reds for whatever springrates you want to run(I'm thinking 800+ lb/in for oval racing on a good surface). You're probably looking at slightly over the cost of a Koni Yellow to get a Red and revalve it. Just make sure you pick the right springrates you want them to valve the shocks for!
Also - what are you doing about aerodynamics? This is a HUGE part of high speed racing, and I'm sure the rules are rather restrictive. But racing isn't racing unless you're bending the rules a bit!
BTW.. I think we sorted out the brake BIAS problem last night for $0... I love a bargin solution! The first heat was horrible, locking brakes, understeering etc. My crew chief suggested swapping the front and rear lines on the master. We weren't sure if it would get better or worse, but figured worse couldn't be much worse. It got better, in fact it's alomst right back to were it was with the adjustable bias valve... except of course it's not adjustable. At least the car is driveable again and I can concentrate on a better spring/shock solution.
-Martin.
Sounds good! Although aerodynamics could still be an issue with speeds around 60-70mph. You'd just have to get more aggressive with them to really see a benefit.
How is your car powerwise compared to other cars? If you can keep up/pull them on the straights, then I suggest getting a splitter/underbody panel for the front - possibly canards on your front bumper, a rear spoiler of some type(probably want it low and extending off the trunk to smooth the airflow out) and might want to think about making a custom diffuser out back.
Nothing too radical, but if you concentrate on "clean and efficient" ways to make downforce you shouldn't lose much if any speed on the straights, but could probably pick up a few mph in the corners.
I'd give the guys at http://www.ground-control.com a call and discuss your shock/spring situation with them.
How is your car powerwise compared to other cars? If you can keep up/pull them on the straights, then I suggest getting a splitter/underbody panel for the front - possibly canards on your front bumper, a rear spoiler of some type(probably want it low and extending off the trunk to smooth the airflow out) and might want to think about making a custom diffuser out back.
Nothing too radical, but if you concentrate on "clean and efficient" ways to make downforce you shouldn't lose much if any speed on the straights, but could probably pick up a few mph in the corners.
I'd give the guys at http://www.ground-control.com a call and discuss your shock/spring situation with them.
Shoot me an email at [email protected] if you want to discuss aero or anything like that in more detail. I don't have a great deal of formal training in this area, but I've worked with a few windtunnels for a short while and gotten to visualize flows over a variety of surfaces. Intuition will often get you 90% of the result of doing detailed calculations and measurements. So let me know if you want any help on aero stuff(it really can make a difference).