Budget GP Build - Give me a plan, keep me on track

[Steve Hoelscher]

Hang on guys...

The proper spring rates depend a lot on the application. One setup doesn't apply to everybody equally.

For a prepared class car, GP in this case, on slicks will have more grip and need to stay flatter than an SP class car on DOT tires. So the rates need to be different.

Many years ago when I first started with the all spring setup, I ran 500/400 front/rear. As I developed the car, the rates went up. The last version of the setup on my Championship winning DSP car was either 700/550 F/R (as my "stiff/concrete" setup) or 650/500 (as my sealed asphalt/rain setup). The stiff setup was intended to keep the car well under 1.5 degrees of total roll at max lateral g on Hoosier A series radials.

These two setups are probably too stiff for all but national caliber cars/drivers and are wholely unsuitable for street use. I typically recommend rates in the 500/550 front and 400/450 rear for most other drivers.

I should point out that the setup on my current DP car (which is 250 lbs lighter than my DSP X1/9) uses 700 lbs front springs. The offset on the LSD equipped MR2 is noticably different than the open diff DSP X1/9.

 

[spiggs]

Not sure where you got the 600-550 numbers.

Those are the spring rates the struts came with. Recommended by Jim Susko for my application.

The proper spring rates depend a lot on the application. One setup doesn't apply to everybody equally.

I understand and was hoping that as delivered the struts would be ready to go. I'll buy some 450lb springs for the rear and go from there.

 

[Dr.Auto]

Those are the spring rates the struts came with. Recommended by Jim Susko for my application.




I understand and was hoping that as delivered the struts would be ready to go. I'll buy some 450lb springs for the rear and go from there.

Actually.....if I were you I would get 500rear springs. I too have purchased a complete G-force engineering suspension setup. And although Jim is very knowledgable Steve is the magician for the practical setup and handling department. Jim's alignment figures are pretty reflective to steves in most points. But listen to steve for alignment and spring rates.
I set my car up for 600front and 500 rear. setup ride hight as per Steve and Jim. Then formulated my own alignment angles that were a cross between what Jim said and Steve said But leaning more towards what Steve says. The end result is just amazing. I was last running on the Advan A048 tires in 13" miata spec. And although I never had a g-meter hooked up to it I had never driven a car the handled this good. The car is more capable than I am. For the longest time I didn't even know where the traction limit was for a corner. I finally spun it out on a solo track and it was a hurendous spin out without damage and a standing ovation from the croud.
Wen you set up te rear alignment as per Steve the car gets a very pleasant tail happy feel but it actually sticks and is very predictable in a turn.
Steve once said some thing about his DSP car that I can relate to now. It was somethng along the lines of being able to fence with the X-1/9 but then still trying to fence with the Mr2 but it's more of a gladiators axe. I cannot say enough how driving my X-1/9 at the limit is truly a dream in handling charictoristics. I've been able to do things in my car I never thought possible. And now.... if the tail pops out i can actually control it! it's like if i try to out run the tail of the car..... i do. I have to say that the way my car is setup right now I doubt that there is another type of production can on the planet that can compare other then porpose built race cars never intended for street use.

 

[spiggs]

Steve once said some thing about his DSP car that I can relate to now. It was something along the lines of being able to fence with the X-1/9 but then still trying to fence with the Mr2 but it's more of a gladiators axe.

I remember that statement and being a fencer myself I know what a precise weapon the foil can be. It is also a bit depressing reflecting on the number of times I have had my butt kicked on the fencing strip and comparing that to choosing a like weapon for my autox efforts :shock:

 

[Steve Hoelscher]

My Quote?

If I remember correctly, I said something to the effect that the X1/9 was a fencing foil where my MR2 was a battle axe.

A fencing foil is quite the weapon in the hands of a skilled fencer. Used with grace and precision, it relies on being light and nimble enabling the fencer to gain the advantage by the out manuvering his opponent by the effective use of its agile nature.

The battle axe is also a formidable weapon in the hands of a skilled warrior. It relies not on agility and grace but on effitively applied brute force. So used, its size, mass and well honed edge can crash through any opponents defenses. It simply overwhelms the opponent with sheer force and strength.

With my DSP X1/9, I was always able to deftly carve a precisely chosen line to maximum advantage. The car's excellent chassis, massive grip and responsive engine made this technique possible. The MR2, while lighter, has never been as precise or manuverable. However, its massive grip and power requires the technique of the battle axe. The driver simply overwhelms the course with its grip and power.

 

[Xmember]

I love threads like this!! I just read every post with excitement. GL on the build, and listen and do exactly as Steve recomends, I mean its not like hes a national champ in x1/9s or anything :wink2:

 

[Dr.Auto]

If I remember correctly, I said something to the effect that the X1/9 was a fencing foil where my MR2 was a battle axe.

Ya.... That was what I was trying to remember. :nod: Right from the horses mouth... there you are.

Hopefully by june I''ll be able to post up my X-1/9 in a Blue Dallara kit. Engine bay and trunk all getting painted right now. That darn Dallara kit is a fitment nighmare though.

 

[spiggs]

...
Offset is where you start. And I really don't think that 600s are stiff enough for the front anyway. The setup starts with the total roll rate, then divide it to get the desired roll ratio.

Having re-read the advice given and rolling it over in my head for a few days I see two things I should pay attention to. One is everyone says follow Steve's advice(including Steve :wink2, two Steve says a 600lb spring is not stiff enough for the front. New plan, I will get some 700lb springs for the front and retain the 550lb springs on the rear. As budget allows I'll also get some 500, and 650lb spring sets so I'll have a range from 500-700lb in 50lb increments to tune with. Does this like I am in the ballpark?

 

[etownsley]

Battery Relocation Questions

Is there any benefit to relocating the battery to the spare tire well?

I am considering this mod to move the weight lower in the car and more toward the center of the car. This would also allow a battery cutoff switch to be installed in the shifter tunnel or on the rear fire wall.

I don't have any experiance with corner weighing an X-1/9. Does anyone know if this would hurt or help the balance of the car?

 

[AngeloX19]

I'd keep the battery in it's oe location. Grab a 300 cca utility battery if you haven't yet, their usually in the 14-16 lbs range are more than enough to run the electrics in the car. My 310 cca turns over my 11.2:1 1.8L with ease. Moving the battery to the spare helps your cross weights (left/rear and right/front are always heavier to start), but hurts your front/rear bias.

 

[Dr.Auto]

Sounds good to me..... 700 in the front will be getting pretty stiff. As Steve already mentioned though. It depends on what kind of track/surface you're running on. Keep that in mind.

I chose the 600/500 to start with because It was right around in that area where Steve and Jim told me.... And the stuff I run on can be kind of rough sometimes and it's always black top.... and all the black top we run on has been chip sealed at some point.

These were with my 600/500 springs. You can see that these courses are kind of rough.

 

[Rooster]

LOL, maybe I'm old and "soft", but...

I like my 500/400 setup. Of course that'll most likely change when I swap it all over to the Race X...

 

[racerx]

and

from what I was told by Steve .H 550 front 450 rear is the about the highest spring rate you'll want to go if the car is still street driven .
also you have to remember that Steve's DSP car ran Konis with a vary special shock fluid I'm not sure that regular Konis can take much higher spring rate then 550-600 only Steve.H or Lee from Koni would have the answer to that.

 

[Dr.Auto]

The Koni "race" shocks cn handle up to 800in\lb if I remember correctly and it is a chock that came out just within the last 4 years or so. There is no warranty on them even though they are basically a revalved Koni yellow to handle the spring rate you're using on them.
I did my suspension right before these shocks were introduced to the public in any other form then just custom valving yellows.

I ended up using the ADshocks which seam to work fine for me right now... although Steve doesn't agree with the progressive dampening curve the have which I can under stand. If I had it to do over I would have went with the Koni's but I was already waiting a year for them to be in stock and got impatient. Oh well.

Side note.... I drive my car to race events. It's really not that bad. Just take it easy.

 

[spiggs]

The Koni "race" shocks cn handle up to 800in\lb if I remember correctly ...

Side note.... I drive my car to race events. It's really not that bad. Just take it easy.

Yeah I would be a little disappointed if my new double adjustable race struts could not handle a 17% increase from the as delivered spring rates. I am assuming they have the stock Koni valving. Thanks for the above pics. The surface I'll be running on 80% of the time is similar to what you show, maybe a bit better. Just to be clear I am looking for a dedicated setup for a GP car running slicks.

 

[Dr.Auto]

Yeah I would be a little disappointed if my new double adjustable race struts could not handle a 17% increase from the as delivered spring rates. I am assuming they have the stock Koni valving. Thanks for the above pics. The surface I'll be running on 80% of the time is similar to what you show, maybe a bit better. Just to be clear I am looking for a dedicated setup for a GP car running slicks.

Double adjustable? Did you get the Advance design shocks?

 

[spiggs]

Double adjustable? Did you get the Advance design shocks?

No they are the Koni DA strut inserts.

 

[Dr.Auto]

Ahh.... thats right. I was getting the adjustment with those mixed up with the Koni yellows I've been dealing with on the civic. I had to visit the G-force website to gt a mantal refresher. :whistle:

All in all I like the ADshocks though. You"ll have to let me know if you have the same problem as I do on the front struts. Not sure if the strut stroke length will be the same on the Koni vs AD. But at proper ride height the front springs have about an inch of droop off the purches. Was becomeing a problem for fast transitional manuvours like as in sloloms. The spring on the inside turn would actually become unloaded. You could feel it in handling too. Jim helped tune it out with some rebound adjustments. But it had happened so much that some of the threads were worn on the purch from the spring. And it's tough on the purch centering lip.
My fix is to install some helper spring from Ground Control to keep things centered up and loaded. Already have the spring alignment cups. Just ordered the spring today. We'll see how it all pans out this season after I have everything set up again.

 

[spiggs]

Radiator exit in hood

As seen in another thread. Are these radiator exits legal in GP? I thought they where not.

 

[JimD]

Pretty sure the vents were closed on this day

On the day I took these pictures, I am pretty sure the vents were blocked off inside the frunk. Apparently, the vents can be there. It is a matter of whether they are functional or not.

I am sure one of our autocrossers will correct me if I am wrong.