auto-x alignment 2015 FRS
 

so i have a decent amount of track experience (not in the FRS. in old AE86's, 1st gen MR2s, 3rd gen supras, and an '08 civic Si). but this weekend was my first auto-x, and wow! i didnt expect it to be so different. it feels so much more frantic and violent. everything happens way faster than on a full on race track. weight transfer and transitions are so much faster. and you don't really get time to learn the track... 4 runs in the morning, then 4 in the afternoon, only the afternoon is running the course backwards, so might as well be a new course. this has exposed several flaws in my driving, and possibly some in my car. namely way more understeer than i thought the car had, and a weird hop-ish feeling thing on the front end.

my question is about alignment and suspension for auto-x. on quick left to right transitions, im feeling my front wheels hop a little. almost feels like understeer, but instead of sliding on the ground while pushing to the outside, the tires are taking little hops as they push. i've never felt this on a car before. what causes this? and how do i correct it? my car is basically a stock 2015 FRS. my only mod is whiteline camber bolts in the top hole. everything else is stock.

these are my current alignment specs:

FRONT:
caster: left 5.54 right 5.65
camber: left -1.46 right -1.42
toe: 0.00

REAR:
camber: left - -1.50 right -1.34
toe: 0.00

thoughts? suggestions? im pretty sure this is mostly driver error.. but even with that in mind.. if i make an error, should it really hop like that? or is there something i can do to prevent that? im fine with under/over steer when i mess up.. but this feels way more violent and i can only assume it's very hard on my car.. same as rear wheel hop is really hard on a car.

Driver error, you're entering the turn too quickly. More camber will help give you some free front grip, but look ahead at the ruleset if you aim to be competitive, you may not be allowed it in the class you choose.

Some discussion on it in this thread w/ a video that seems way more violent than you're describing:
http://www.ft86club.com/forums/showt...t=74882&page=4

Starts at post #56 and continues for a page or so.

thanks. that answers my question perfectly.

slow down dummy! lol.

slow is smooth, smooth is fast. and all that :)

that said though.. is more camber my best bet for reducing that shudder? seat time is the ultimate fix.. but if i wanted a band-aid to lessen the abuse on my car while i figure out my driver issues.. would camber be the way to go? would sway bars help at all?

If anything adding camber would mean you'd be going faster when you step over the line making the shudder worse.

But faster. What I meant was that if you had more camber and did exactly the same thing, I believe the car wouldn't shudder. The reality is you'd go faster until you went too fast.

so essentially it doesnt matter what i do, its all about over driving the car

any mods would just make the limit higher, but as soon as i go over that limit, i'll get this shudder

Do you have any video of this happening where we can also see your steering inputs?

I just did my first autocross with the FRS prepped for CS and found that my first guess at sways and alignment produced considerably more understeer than stock. I was able to play on a traction circle and drive another twin for comparison and the car itself (my car) understeers.

That being said, I did not experience any shudder, so I'm wondering about your steering angle when this is happening to you. I suspect wrenching on the wheel while the car is understeering (as apposed to just lifting to tighten your line) might cause hop, but I'm unsure.

BTW, for any setup gurus, this understeers now:

TRD springs and sways

Koni shocks

Front:-1.3, 1/16" toe out

Rear: -1.8, 1/16" toe in

I am considering either going back to stock bars front and rear, or maybe even just back to stock bar front. (leave TRD sway in the back)

That's not a lot of front camber which doesn't help but the sways have a large effect regardless. Are the sways adjustable?

- Andrew

The front camber is all I could get with Toyota crash bolts. I gained more camber in the back of the car, from lowering on the TRD springs, than I anticipated. (and I don't think I have a way to adjust rear camber in CS)

The bars are not adjustable.:(

If the bushings in the front lower control arms and/or strut mounts are worn out, the shudder could be caused by bushing deflection. I don't think bushings in good shape would do that though.

Tire pressures might also be a factor. You might want to reduce your tire pressure by a few psi and see how it feels.

Or, it could be caused by dead front struts.

Basically, if it's a mechanical problem, there's undamped movement that'll need to be fixed. Of course it could be driver error, but I haven't seen anyone reporting this front end shuttering, so I'd start my trouble shooting with mechanical items.

The only time I experienced hopping on the front end in autocross was when I pumped up the compression and rebound too much on my coilovers, resulting in the car basically skipping across even the slightest uneven surface.

In the case of your stock car, that obviously isn't it. It sounds like you're simply understeering. Keep in mind that the parking lots, and other venues where autocrosses happen are NOT race tracks. They generally aren't very smooth surfaces. You're also making much sharper turns at much lower speeds. Understeering through a sharp, uneven road surface can cause the front to skip around a bit.

As everyone else has said, the biggest issue people have is being smooth with their inputs at autocross. It's much harder to be smooth than on a track, with big, open, sweeping turns (relatively speaking) that naturally lend themselves to slower, smoother steering inputs. In autocross it's LEFT, RIGHT, LEFT!!! and people just kind of saw the wheel back and forth, which unsettles the car. They also just tend to plow too quickly into turns (something I'm still working on two years later).

Stock front bar and TRD rear is a bad idea with a Torsen diff. If you sufficiently unload one of the rear wheels it becomes an open diff.

One option is to go to a slightly smaller front bar than the TRD bar.

I personally would increase front rebound (on the Konis I ran 1.25 turns from full soft) and/or play games with tires pressures. Sean Grogan ran his Konis really stiff (0.5 turns from full hard front and rear, or thereabouts) and I felt it was too stiff and prompted too much rotation at times, but you might like it. (I disagree with insane rebound forces on principle, but in Street you don't have many knobs to turn).

Dave Ogburn mentioned that by varying wheel spacer sizes he was able to get the right amount of rotation from the car (bigger spacer front than rear).

Totally bone stock car, including tires? Don't expect much from those tires. And yes, sounds like driver error - you put the tire into such an unhappy place that it had an aggressive argument with the road. It sounds to me like you were going too fast and used too much steering wheel lock.

Just because cones and corners are coming at you like machine gun bullets - i.e. the rate at which you need to make different inputs - does not mean you should increase the speed with which you perform the inputs themselves. You still need to be smooth with the car just like on the road course.

For sure on a lot of autocross courses you will need more steering wheel lock than on a road course but you still need to ease into it.

wouldnt stiffer sway bars help prevent the torsen diff becoming "open"? by preventing body roll, you would keep the weight more evenly distributed between the tires and help prevent one from lifting, no?

If you put a softer bar on the front it'll be more likely to lift the inside rear tire.

To a point, then when your suspension becomes too stiff you are more likely to lift a wheel as posted above, kind of like lifting the corner of a sheet of paper vs. lifting the corner of a sheet of cardboard.

Think of it as an inverse, when you lift a corner of a sheet of paper it's like pushing down on the suspension, paper soft, the other 3 wheels stay where they should, cardboard stiff, the other wheels begin to 'lift' as well, in reality the corner you lifted is being super compressed the car is hunching down on that corner and the opposite corner (still on the table) is actually 'lifting' up in the air. In autoX the outside front tire takes a ton of load as you hunker down on it to turn, the inside rear wheel lifts.

But you have available to you what you have available to you, I say try going back to OE front bar, they're not that difficult to swap. iirc most are running stiffer rear bar in CS w/ OE front.

FWD cars usually end up running soft fronts and stiff rears, this is the result:
http://www.galaxieman.com/wp-content...ocross-445.jpg


AND as another example, in oval racing the cars get setup the opposite way with relatively soft rears the car hunkers down on the right rear and the left front lifts. You can also see it in certain road course series too.

http://thumb7.shutterstock.com/displ...ar-3331114.jpg

What? Who is?

I'm bigger in the front, with a Hotchkis bar and TRD in the back, and love it. The OP should check out the CS thread if he hasn't already. http://www.ft86club.com/forums/showthread.php?t=35855

With a similar background in cars, my initial impression of the FRS was that it was friendly and maybe even dull. I never spent a moment on the stock tires though...

I was experiencing this 'shudder' at canadian nats (and not the only one) I've never experienced it elsewhere. I attribute it to the surface and my overdriving the car. I had the whiteline front bar on full stiff which certainly didn't help (rest is stock in CS).

All the CS guys I know have close to -2F/R and the same toe and are legal. They also have koni shocks with the insert, as well as the TRD springs and sways. that setup on re71r's is very good.

as for your alignment. the rear will have more grip in the corners. so when the front grip runs out, rear grip is still there= understeer. I play in SM with mine.

I would like to know how people are getting -2 degrees front camber in CS. I know there is a little variance from car to car, but that's a big gap.

My best guess at the TRD sways is that the front is ~70% stiffer than stock where the rear is only ~40% stiffer than stock. (Understeer)

I installed an ST front bar this week and used the softer setting (~40%) I'm hoping that the sway bar balance is stock-ish now. (-Feels better on the street, but I won't know if it's enough until I run it at 10/10 on the track)

Contact Infinite Motion in San Marcos CA. GAVIN does all the alignments. He must have figured something out.