Right there with you, Stephen! I put a bunch of new suspension on my S550 this off season. It feels ok, dealing with a little understeer too. Was hoping it'd be faster, not quite there yet. Big changes come with lots of tuning, tweaking, and relearning the car. We'll get there!
I hadn't thought about the camber gain and jacking effect of increased caster. I can definitely see those being helpful in pretty much any application. But the flip side is that the primary purpose of caster is high-speed stability-- which actually implies resistance to steering. I would have expected too much caster to be a problem with autocross since you want quick steering. So I'm genuinely curious where the happy medium is between "enough jacking" and "too much stability". Something else to consider, if you haven't already, is that the rolling radius of the tire plays a role. Caster angle is really just a convenient way to measure "trail", which is what's actually at play. It isn't a commonly used term (that I've seen), but it's simply the longitudinal distance between the point where the steering axis meets the ground and the center of the contact patch. So, the tangent of the caster angle times the rolling radius of the tire. If Griggs is recommending 8 degrees based on a 28" tire and you're running a 26" tire you would end up with about 7.5% less trail than they had. Significant? I have no idea. I'm mostly just typing because I like the sound of my keyboard. Seems tire width and wheel offset have to play a role in the jacking effect as well. Suspension geometry is basically voodoo. I wanted to add that yours is the first SN95 I've ever seen that I would gladly drive. I've never liked the body style, but the spoiler, hood vents, hood pins, and fender flares really change the look.
I agree on the looks of the car. I wasn't a fan at first either (foxbody guy), but it's grown on me now. That's a good point about how tire size can affect some items and I'm not sure what Griggs was designed to or recommends. Suspension design is all about compromises. And there are so many little adjustments. But I can say the caster increase definitely helped.
Man that car just looks so good. At the speeds of autocross, do you think the splitter and spoiler are beneficial? They both look incredible regardless
@RinerAutomotive I agree for sure. My background is drag racing so I can relate. I'd say in the higher speed sweepers and slalom it has to help. Regardless they look so good it's a no Brainer haha
9* caster, -3 camber. It's easy to get an autox car too stiff. These 200tw tire like roll to get them into the track. My opinion is your front bar is too big and it shouldn't need a rear bar at all. Just my opinion, but that setup is proven (LS Fest Grand Champion Vintage, SCCA Chasing the Dragon Hillclimb record holder, etc.) But it's a learning game. Try things until it works for you. Nice work on the car.
Right there with you, Stephen! I put a bunch of new suspension on my S550 this off season. It feels ok, dealing with a little understeer too. Was hoping it'd be faster, not quite there yet. Big changes come with lots of tuning, tweaking, and relearning the car. We'll get there!
That's for sure. No magic go fast button
I hadn't thought about the camber gain and jacking effect of increased caster. I can definitely see those being helpful in pretty much any application. But the flip side is that the primary purpose of caster is high-speed stability-- which actually implies resistance to steering. I would have expected too much caster to be a problem with autocross since you want quick steering. So I'm genuinely curious where the happy medium is between "enough jacking" and "too much stability".
Something else to consider, if you haven't already, is that the rolling radius of the tire plays a role. Caster angle is really just a convenient way to measure "trail", which is what's actually at play. It isn't a commonly used term (that I've seen), but it's simply the longitudinal distance between the point where the steering axis meets the ground and the center of the contact patch. So, the tangent of the caster angle times the rolling radius of the tire. If Griggs is recommending 8 degrees based on a 28" tire and you're running a 26" tire you would end up with about 7.5% less trail than they had. Significant? I have no idea. I'm mostly just typing because I like the sound of my keyboard.
Seems tire width and wheel offset have to play a role in the jacking effect as well. Suspension geometry is basically voodoo.
I wanted to add that yours is the first SN95 I've ever seen that I would gladly drive. I've never liked the body style, but the spoiler, hood vents, hood pins, and fender flares really change the look.
I agree on the looks of the car. I wasn't a fan at first either (foxbody guy), but it's grown on me now.
That's a good point about how tire size can affect some items and I'm not sure what Griggs was designed to or recommends.
Suspension design is all about compromises. And there are so many little adjustments. But I can say the caster increase definitely helped.
Man that car just looks so good. At the speeds of autocross, do you think the splitter and spoiler are beneficial? They both look incredible regardless
It's hard to really tell. They aren't hurting that's for sure. When sometimes battling for tenths need every advantage can get.
@RinerAutomotive I agree for sure. My background is drag racing so I can relate. I'd say in the higher speed sweepers and slalom it has to help. Regardless they look so good it's a no Brainer haha
I agree on the looks
What rollcage do you have?
It's a 4 point but I can't remember the company.
Sub frame connecters
Maximum motorsports
9* caster, -3 camber. It's easy to get an autox car too stiff. These 200tw tire like roll to get them into the track. My opinion is your front bar is too big and it shouldn't need a rear bar at all. Just my opinion, but that setup is proven (LS Fest Grand Champion Vintage, SCCA Chasing the Dragon Hillclimb record holder, etc.) But it's a learning game. Try things until it works for you. Nice work on the car.
Thanks for sharing setup. I'm open to trying those suggestions. Part of suspension tuning is figuring out what works for you
What front and rear wheel rate do you run?
@@RinerAutomotive Front is 425lb springs, .875 motion ratio, 31* shock angle, so about 200lb wheel rate I believe. Rear springs are 375lb.
Interesting. I'm much stiffer. Wheel rate of ~315 lb front and 275 rear