Pictures and suspenstion tuning

Hey All,

If some of you suspension gurus can take just a minute, take a look at this. It's me at Solo Nationals.

https://picasaweb.google.com/116511746312170569817/2012SoloNationalsFSP?authkey=Gv1sRgCP6TufmikKnRZA#5786228007934596770

https://picasaweb.google.com/116511746312170569817/2012SoloNationalsFSP?authkey=Gv1sRgCP6TufmikKnRZA#5786228020036134258

(Sorry, couldn't figure out how to hotlink them)

So, I think there are some things I can learn about the car here, but wanted to run them by you guys before I start changing things.

First, really need to up the air pressure. That front looks like it's about to come off the wheel. I looked at a bunch of other pics and didn't see any other cars rolling over that much. Ouch. But easy to fix. Those pics were at 25 lbs. front, 22 rear. This weekned I'll try 30/27 to start.

Second, the car is roling a lot. Again, just looking at other cars, looks like that's more than I want.

Third, as hard as that front is working, the rear looks like it's not doing as much, which I think is realted to the roll observation.

So, looking at those, would you say I need more front spring? Right now it's got 550 lb. front and 6.5k (363 lb.) rear. I have the only aftermarket sway bar I could find, and Addco that isn't adjustable, or I'd say maybe more front bar. There's no bar on the rear right now.

I know this is pretty basic stuff, but this is all still pretty mysterious to me. Just starting to figure things out a little.

Your car looks kind of depressed, it's just staring at the ground.

I am FAR from a suspension expert and I have only run one Solo2 event on R comps so take anything I say with a shaker full of salt.

What kind of alignment are you running? Are those Hoosiers?

It looks to me like it could use a bit more camber in the front or some caster if that's an option.

Can you lower the rear roll center a bit? It looks quite a bit higher than the front just from looking at the attitude of the car.

Adding a rear bar (if that's an option) might ease the burden on the front tires and it wouldn't roll under as much, but still I would put a bit more pressure in the tires. Maybe even a bit more rear spring if a rear sway is not an option. The inside front looks like it's completely unloaded and nearly off the ground.

Yes, the tires are Hoosier A6s. I have camber plates in the front and all the negative camber I can run. I did add caster after these pics were taken and have it maxed now. That should help some.

Lowering rear roll center is on the list, just need to order parts. I suspect that will help some too.

Wouldn't rear bar transfer more weight to the front? I could easily be wrong (which is why I'm asking for help in the first place) but that's how I thought it worked. I thought it looked like the rear needed to be softer - or the front stiffer. And with all the body roll, I kinda thought more front spring was the way to do that.

But please let me know if I'm off base. I'd love to not waste more money than I need to.

A rear bar would take some of the cornering load off of the front and reduce fore-aft weight transfer.

90% of what I know about suspensions came from this:

Can I ask a few quick questions?,what diff is in the car?,what rear bushings?,static camber and what camber plates?. Whiteline makes a decent 3 way front bar(best used with heim endlinks btw) so that should be better than the addco bar,for these cars with nearly stock weight a med sized front bar is a good starting point.I'm not a fan of using bars if I can get away with a light enough car to just use springs.My autox only AE86 was best with no bars but was much lighter and more importantly had a much lower CG with lowered engine and composite body including roof. These cars work best with a fair bit of static camber,-3 should be the starting point.If the rear is tail happy and seems to be lifting/nearly lifting the inside rear its usually a result of the rear bushings binding and the only way to deal with it is to either change them for softer bushings or go heims or keep stiffening the rear springs untill the car rolls so little the binding is reduced.Not the best way imo,deal with the bushings 1st otherwise it won't put power down well.

I'm not familiar with that tire, in that size, on your car - but 35-40lbs is closer to average for most tires at autocross.

Second, how is the balance? Any problems with understeer/oversteer? And if so, when does it happen? That's the first thing you should try to affect by suspension tuning - get the car balanced, work to see if you can increase ultimate grip w/o any bad side effects, then fine-tune the car to work with the driver(after you've gained enough seat-time in the car to be consistent).

EDIT: To answer the question re: increasing rear swaybar rate - by increasing the rate of the bar, weight is transferred off the inner-rear wheel, to the outer-front wheel...up to the point the rear wheel loses contact with the ground, then you have reached 100% weight transfer.

kevlarcorolla wrote: Can I ask a few quick questions?,what diff is in the car?,what rear bushings?,static camber and what camber plates?.

It has a Kaaz 2 way diff, Energy Suspension throughout, T3 Camber plates and Ground Control coil-overs. The camber is max negative. I'm not sure I'm using my camber gauge right, but I think it's about -2.5. Seems like I should be able to get more than that, but the top of the strut is touching the center hole in the chassis and the rules won't let me make the hole bigger.

kevlarcorolla wrote: Whiteline makes a decent 3 way front bar(best used with heim endlinks btw) so that should be better than the addco bar,for these cars with nearly stock weight a med sized front bar is a good starting point.I'm not a fan of using bars if I can get away with a light enough car to just use springs.My autox only AE86 was best with no bars but was much lighter and more importantly had a much lower CG with lowered engine and composite body including roof. These cars work best with a fair bit of static camber,-3 should be the starting point.If the rear is tail happy and seems to be lifting/nearly lifting the inside rear its usually a result of the rear bushings binding and the only way to deal with it is to either change them for softer bushings or go heims or keep stiffening the rear springs untill the car rolls so little the binding is reduced.Not the best way imo,deal with the bushings 1st otherwise it won't put power down well.

Thanks, that's good stuff. The Whiteline bar for the Celica is no longer available, but I've heard the Supra bar will fit just fine. I may have to go that route. It's possible there's a binding issue, but I think right now I'm just not getting enough weight transfered to the rear.

The car feels different on different surfaces. With little grip, it's real tail happy. But on the concrete in Lincoln there was no hint of that. But I think that may just be grip covering up problems.

petegossett wrote: EDIT: To answer the question re: increasing rear swaybar rate - by increasing the rate of the bar, weight is transferred off the inner-rear wheel, to the outer-front wheel...up to the point the rear wheel loses contact with the ground, then you have reached 100% weight transfer.

I don't think I want to transfer any weight to the outer front. It looks like it's got all it can handle already.

I didn't even look at the pics but I can tell you one thing for sure-if you are rolling over your front sidewalls that badly you can't base any suspension planning on the cars current behavior. Get the pressure somewhat right and go from there.

What I am not seeing in Your first post is tire temps. Evenness of temps across the tread is what you should be using to determine camber and tire pressures, not what it looks like in still photos.

In reply to MrJoshua:

Yeah, that's probably a good point. It was clearly way off. Don't know where I got the idea that pressure that low was a good idea. The Hoosiers are kinda new to me. On Kumhos, on the MR2 I always ran mid 30s.

fast_eddie_72 wrote: The car feels different on different surfaces. With little grip, it's real tail happy. But on the concrete in Lincoln there was no hint of that. But I think that may just be grip covering up problems.

But is it tail-happy on corner-entry? If so, are you trail-braking into the corner? Does it happen under throttle, and is it easy to catch when it does? What about slaloms? Or does it let loose in an unpredictable manner? That can be a sign of some other problem.

If you want more weight transferred to the rear, go with a larger front swaybar. I've seen CP cars picking up the inside-front wheel mid-corner - granted, they have a bunch more HP in them, but the only way to know for certain is to try it.

IIRC I ran 29 psi in that tire on the civic, and I suspect the civic had lower corner weights. I also agree on stiffening up the front. More front bar will help you put power down better as a bonus, but if that's not an option, more spring at a minimum. Those tires generate a LOT of grip, and thus a lot of spring is needed to deal with it.

petegossett wrote:

fast_eddie_72 wrote: The car feels different on different surfaces. With little grip, it's real tail happy. But on the concrete in Lincoln there was no hint of that. But I think that may just be grip covering up problems.

But is it tail-happy on corner-entry? If so, are you trail-braking into the corner? Does it happen under throttle, and is it easy to catch when it does? What about slaloms? Or does it let loose in an unpredictable manner? That can be a sign of some other problem. If you want more weight transferred to the rear, go with a larger front swaybar. I've seen CP cars picking up the inside-front wheel mid-corner - granted, they have a bunch more HP in them, but the only way to know for certain is to try it.

Well- I got my go-pro set up to help me start answering questions like that. What I think I do and what I actually do isn't always the same.

On low grip surfaces, I'll have issues spinning in long sweepers. Now, I think I keep my foot in the throttle, but I've had good drivers ride along to help me out who swear that I lifted. They're probably right.

I haven't had a problem with slaloms. Could be if I was going faster I would. I've seen FSP cars lift the inside front too (RWD). I mostly just want to go fast, but I'd love it if I can hang that wheel off the ground just 'cause it looks cool.

DILYSI Dave wrote: IIRC I ran 29 psi in that tire on the civic, and I suspect the civic had lower corner weights. I also agree on stiffening up the front. More front bar will help you put power down better as a bonus, but if that's not an option, more spring at a minimum. Those tires generate a LOT of grip, and thus a lot of spring is needed to deal with it.

Awesome- that's what I was thinking. I'll look into the Supra Whiteline bar. In the mean time, I might be able to borrow heavier springs as a test.

Ok,the 2way kazz was the right choice so good job.

If you can't get more camber legally than the only real choice you have is to bump the front springs to reduce the roll that requires the added - camber in the 1st place.I'd go up in spring rate before going to a stiffer front bar with the 2 way,if it was a stock lsd or open I'd say leave the springs and go to a big honkin' front bar. Look at it this way if you add front bar over increasing front spring rate you transfer weight off the inside front and onto the allready overloaded outside front which hurts trail braking(also cause you need lotsa camber) and mid corner out. For the record when you get the car to work well on grippy tires/surface it WILL be loose on anything less than that-just the nature of a solid rear end.I'd consider exchanging those poly rear bushings for even oem's,it really is important to let that housing be able to rotate independantly of the chassis. I went to an equal lenght 3 bar heim jointed set-up with adjustable height panhard mounts for mine,worked pretty damn well.

Btw I thought most AE86 bits bolted to this chassis?.

As an aside - Looking at Perry's photos of my car was one of the best tuning aids I ever discovered. The dude is a badass with a lens, and has a knack for shooting at the right moment. If his stuff is helpful, throw a few bucks his way to help the cause. He's a one-man operation who takes a week off of work to shlep out to Nebraska, so every bit helps.

+1 for bigger front bar and/or more spring. I'd probably go for more bar first.

What does that thing weigh? What is the front motion ratio? (struts or DWB?)

ProDarwin wrote: +1 for bigger front bar and/or more spring. I'd probably go for more bar first. What does that thing weigh? What is the front motion ratio? (struts or DWB?)

Haha,if you don't even know what the suspension is you probably shouldn't be recommending a set-up.

kevlarcorolla wrote:

ProDarwin wrote: +1 for bigger front bar and/or more spring. I'd probably go for more bar first. What does that thing weigh? What is the front motion ratio? (struts or DWB?)

Haha,if you don't even know what the suspension is you probably shouldn't be recommending a set-up.

Its RWD, its got too much front roll. It needs more front roll stiffness. That much is true, regardless of the geometry.

In reply to kevlarcorolla:

I read through that whole long ass thread on Club 4AG that Van started when he was building his 86, so I knew a lot of the parts that should work well. Most 86 bits do work, but not all. My Kaaz is the part number for an 86. Front sway bar, unfortunately, is one that doesn't work. That weird thread through the brackets deal up front is further apart on the A6 chassis, so the 86 bar bends in too soon. The Supra bar is supposed to fit fine, just with a big dip in the middle to clear the engine that isn't needed on the RA64.

I need to review the rules before I build anything, but I'm pretty sure I can change out the top links with rod ends, but not the bottom. I need to do something anyway to try to get the pinion angle back to where it should be. So that should help.

DILYSI Dave wrote: As an aside - Looking at Perry's photos of my car was one of the best tuning aids I ever discovered. The dude is a badass with a lens, and has a knack for shooting at the right moment. If his stuff is helpful, throw a few bucks his way to help the cause. He's a one-man operation who takes a week off of work to shlep out to Nebraska, so every bit helps.

Man, I agree- and having all the other cars in your class at the same point is great too. Makes it easy to see what I did that's different from guys who are a lot faster than me. You bet - I'll pop over to the site and help him keep it going. By far the coolest pics I have of the car so far. Aside from learning stuff, I'm really glad to have the great looking shots.

In reply to ProDarwin:

Its struts up front, solid axle rear with a four link and panhard bar. I took measurements tonight to order parts to build a new panhard bar so I can lower the rear roll center.

I'm just getting started, really, trying to tune the suspension. I haven't done any kind of really accurate measurements, but the struts literally bolt directly on top of the ball joints, so the wheel rate in the front is very nearly 1:1. As it sits, it weighs 2300 lbs. I can probably get another 50 out of it. Maybe a tic more.

As strange as it sounds, coming in 13th of 16 in FSP at Nationals, I kinda feel like this car can work, especially looking at the pictures and seeing just how far off my set up is. Nobody else's car looked that jacked up. I never realized how far it was rolling. Those two pics show it really well. You can see my left hand - it doesn't move between the two pics, but that's a lot of distance to cover while the chassis is still trying to take a set. Imagine how much time it spends just rocking back in forth in a slalom.

By the way, there was an awesome Saturn in FSP. Really, really nicely put together too. He had trouble getting the power down - all the grip in Lincoln had his inside front too light. Otherwise I think he'd have done really well. He beat me, but then, that's not saying much. lol

No advice, but I can hotlink.

I think it might be worth figuring out if the tire size is suitable for the rim width. Since the picture only shows the outside of the rim, and the inside is in the shadow. The air pressures aren't THAT low, that is why I suspect maybe the rim is a little wide for the tire.

ProDarwin wrote:

kevlarcorolla wrote:

ProDarwin wrote: +1 for bigger front bar and/or more spring. I'd probably go for more bar first. What does that thing weigh? What is the front motion ratio? (struts or DWB?)

Haha,if you don't even know what the suspension is you probably shouldn't be recommending a set-up.

Its RWD, its got too much front roll. It needs more front roll stiffness. That much is true, regardless of the geometry.

One needs to be very careful in generalizing that too much front roll is bad. Some cars, that's the intention. In this case, I do agree, you can see the tire starting to angle to the outside.

What caster are you running? If you can run a lot more caster, then you can get some dynamic camber- as in turn the wheel, and caster generates camber as the wheel changes direction. That gives you more camber in corners, and less while braking- a good thing, mostly (if you can handle the extra steering effort).

This is one of those cars where adding front stiffness will reduce understeer. My car does the same thing- not enough will get the angles wrong, and going stiffer is a good thing. Do you have an option of a much stiffer sway bar in front? That may be an option instead of just stiffer springs...

Looks like a fun project! Too bad my GTV is in DSP, or you could see Spiders and GTV's out there along with you....