FC road racing and autocross alignment settings?
 

Does anyone have any road course and autocross settings for toe/camber/caster on an FC?

thanks
Ben

Settings
 

Ben you have probably not received much response because of the question. The setting are different for the two type of races. I will try to help.

Autox

Max negative camber both front and rear
Toe 1/16th total toe out front
1/4 total toe in rear.

This should get you started. Variables are your tires, shocks, springs and bars.

Road Racing

Camber -1 if you can get it both front and rear.
0 to 1/16th total toe in front.
0 to 1/16th total toe in rear.

This is a start. I used to autox a TII now I autox a 3rd gen.

Good luck.

Spank

Also as much positive castor as possible(~7*). Camber also depends alot on what tires you are using, castor, etc. DOT R compounds will work well between 1.5-3 degrees, I'd run quite a bit more camber in the front than what Spank listed, but every car/tire/driver is different. Maybe less in the rear depending on power output, and spring rates. Lowering the car will get you the camber in the rear(sometimes too much), and camber plates with a castor adjustment will take care of the front. Again, follow the tire manufacturers recomendations, they vary quite a bit. Carl

Thanks guys. I realize that autox and road racing require different setups, I was just asking for suggestions on each.

I have full adjustability all around (AWR individual camber/toe in back, camber/caster in front) and I just needed a good place to start.

Thanks
Ben

Hey Ben, do you have any pics of you camber adjusters installed? I was looking at mine, and I do not see how you can adjust them without cutting a portion of that slotted steel that sits just under the adjuster. Also my Toe adjesters have 5/8" bolts, so i guess I'll need to drill those holes out as well. Anyway, pics would be great, as AWR does not show any, nor do they seem to have any install directions, hints etc. i know these are pretty straight forward, but I have an older set, I think they downsized the bolts in later versions. Thanks, Carl
My Email is c.byck@comcast.net if you get a chance.

I don't have any pics handy but I had to do a bit of cutting and machining to get these items to fit.

camber adjusters- I cut the metal, there just isn't another way to mount them. The metal that the camber adjusters mount into don't need to be joined since they are braced when they are bolted to the camber adjuster.

toe adjusters- you need to drill out the stock tapered holes to 5/8". This is kind of tricky since you need to somehow brace the rear subframe on a drill press/mill. My friend works at a machine shop with a Bridgeport and we did it there. It took some creativity, but it came out really well.

If only I could install a rear wheel bearing without a wobbly hub afterwards...

Ben

So, you cannot do the toe adjusters on the car?

No, not accurately. I guess you could put a 5/8" bit into a big hand drill, but the chances of success are really low. You'll probably end up hogging out the holes. The whole setup relies on having pretty accurate 5/8" for the rod end/bushing setup.

Ben

Arghhh!

I guess I will use a digital level to true my sub frame to the garage floor. I will then make an upside down drill press. Thanks for the heads up. As an aside did you find that the stock adjuster does not have enough range once the car is lowered, and the camber corrected? Carl

It isn't that bad to drop the rear subframe and it'll allow you to install delrin bushings in the subframe, trailing arms, and diff mounts if you don't have them already there. It'll be a lot easier to do if you have the subframe off the car and it'll lessen the chance of something going wrong.

My car has yet to roll since I put it on jacks in June so I have no idea what the limits of the stock setup are.

Ben

I have already done all the subframe bushings, I am trying to wrap things up by april 1. I may skip the toe adjusters for now. My car hasn't seen the track since march. There are so many changes to my car, I cannot think of anything that is the same. It will either have so much Downforce I cannot accelerate, or it will fly, literally :D

:bigthumb:

Speaking of wings- Carl did you ever use the smaller APR GTC wing? The big one is out of my budget range right now (wheels, cage, headers, tires, tuning adds up really quickly).

Anyone else have suggestions for a functional FC wing?

Thanks
Ben

My specs

Front
-3* camber
+5* caster
1/16 Toe out

Rear
-1 (trying to get to -2) camber
1/16 Toe in

Thanks very much. Have you tried any different setups? How does this feel in relation to anything else that you've tried?

Thanks
Ben

The best thing you can do is invest in a tire pyrometer(not the infrared type) and jump on those tires and poke them as quick as you after a run. Let the tires tell you what your car likes. Too much camber will hurt your braking. Don't be fooled by a quick pointing car that actually may not have good steady state cornering. If you can't afford one find some like minded friends and split the cost. Probably the best set-up tool you can invest in.

Paul, why can't you get ~-3 in the rear? An otherwise stock suspensioned FC will get -3 just by lowering ~2" from stock. Usually the camber adjusters are used to dial out camber. You might want to see if you can get 7 degrees pos. castor. Otherwise your settings look good for DOT R tires. Slicks want far less camber(and spring rates ~20% higher than for DOTs), ~1.5 all around I believe as a starting point( for the slicks). Horse power makes a big difference, the more you have, the more camber gain(neg.) you'll get on acceleration. My tire temps with 235-40-17 RA1s are +/- 10 degrees across each tread. I start with ~5lbs less cold on the left side at infineon. Carl

I still have the small wing, I will be sending it to APR in exchange for the large. This is based on what I saw at JGTC. The GT300 cars ran wings far larger than anything commercially available, and I have a power to weight ratio at least as good as those cars. I think the small GT wing is the way to go, they are ~450.00 on the Subaru tuner sites. I will have to reinforce the rear sheet metal to carry the load, the cast aluminum mounts from APR broke at less than 100mph (they were modified, so no reflection on APR)preventing any testing. Carl

jgrewe- thanks for reminding me about the pyrometer, I'll definitely pick one up.

Any idea how much the camber settings would be different for street tires (like Goodyear Supercars)? I'm restricted to run street tires in the One Lap race- can anyone guess if high spring rates (like 600/450lb) not work so well with them? Maybe something like 500/375 instead?

Carl- on the wing- how high did you mount it? My friend works at a machine shop and I may just have him cut a couple pedestals.

Thanks
Ben

Do you have to slot the holes to get this much? I have the K2RD setup, which includes some camber plates that set the strut mount back a bit, but I don't think it's 7 deg.

To get 7 degrees you would essentially rotate your camber plates so that as you gained negative camber, you simultaneously gained positive castor. Instead of the slot being perpindicular to the car, you would mount it so the slot is in the ~1-2 o'clock position with 12 o'clock being its present orientation. Tricky ehh;) Carl

Carl,

Did you notice a lot of gains from running so much castor. Running lots of castor isn't always the best thing. I wonder how much castor my ground control plates can give.

On the spring rates, If I remember correctly the "street" tires can have a spring rate around 1600 lb. So I don't think the rates effect the tire. The big difference street to slick would be the amount of camber gain each tire can put up with from the supension. The softer springs will allow more travel and the street tires may be able to cope with the geometry change better. If we raced on pool table smooth courses this stuff would be easy. A little compliance helps through the bumpy turns as I'm sure many know.

John

Read what you wrote... Not only untrue, but flies in the face of common sense. Regards. Rather than argue it here, tell us why there is more than one spring rate for cars in general LOL...

Silkworm are you racing in SFR SCCA?

We are talking about 2nd gen rx7 here right? there is no camber gain for macpherson suspension. Camber gain is NEGETIVE for this type of suspension. Are you saying the tire wall has an equivalance of 1600 lb/in spring rate? or are you saying you can run 1600 lb/in springs with street tires?

The 1600 lb number would be the side wall rate. That was a number I heard an engineer use as a rule of thumb in computer modeling of suspension. And the negative camber gain depends on the angle that your lower control arm starts out at. If you've lowered the car so much that it is pointing way down toward the middle of the car then you are correct. The other problem is the car probably leans more degrees than the suspension can gain with the right geometry and struts. As for what spring rate, what ride rate can you handle? If you are driving on the street most of the time don't go to high it will wear you out. I stand by my "a little compliance can be good" statement though. Ever race at Nelsons Ledges? It's a washboard surface in a lot of places and a softer car is faster.

I'm still dusting off the racing brain cells, I may have to go soke them in Rum again! LOL
John

I ran -2* up front an -1* out back. Daily driver that was road raced on the weekends at a real track by switching to RA-1's. Worked well for me.

I ran K2RD.com coilovers (400#/275#) with KYB AGX shocks/struts, camber plates, Energy Suspension poly bushings, rear toe elims, T2 front sway bar, stock rear bar. Worked great for me.

Everyone who hasn't should read the following, all by Carroll Smith:

Prepare To Win
Tune To Win
Engineer To Win

YUP;)

Ok guys, I thought about why I sounded stoned or something. When I wrote "camber gain" I was refering to the increase in the amount of neg. camber. With that in mind does my post sound any better? If a guy tells you to put some MORE camber in the front wheels do you straighten them up or lean them in? If I'm still out to lunch let me know and I'll splash more rum on the brain cells.
John

When racecar guys talk of adding camber they always mean negative camber; tilting the wheels inward more.

Camber gain on the other hand is the fact that an unequal double wishbone suspension has camber which becomes more and more negative as the suspension is compressed. Strut suspension geometry is completely different and has no camber gain. What the camber is set at is what it is regardless of ride height. Because of this fact strut suspensions usually require more static negative camber, assuming you can even get it.

You actually get some camber change as the control arm swings up and down because of the arm forshortening. Picture your car with no engine and trans and the wheel has a huge amount of positive camber. The same thing would happen if you could compress the strut far enough. Thats why its better to have your lower arms slanting down to the outside if you can so you can get a little tiny bit of more neg camber as it swings up. It also puts your roll center in a better location.

It's all coming back to me now
Keep me honest,
John

Not with a true strut unless the car has suspension travel measured in feet. the strut itself is the upper "arm" of the suspension since it locates the top of the upright. Since the strut itself travels in a straight line so does the top of the upright and thus there is no camber change. The strut body moves in only a tiny arc as the suspension goes from full droop to full bump. Because of this you cannot change the camber throughout motion of the suspension.

Now if you could get the outer balljoints of the lower arm to be pointed sharply downward when the car is at static ride height then you could generate a very small amount of negative camber change since the lower joint would effectively move away from the chassis as the suspension responds in bump. The downsides are that when the suspension goes into droop you would have terrible camber settings, using the lower arms at this angle would impose a terribly high roll center (and be nearly impossible to mount on a stock type car anyway) and the tires would have large amounts of scrub during movement of the suspension. All these reasons is why you don't try and do that with a strut, the negatives outweight the positives.