View Full Version : Neutral suspension setup

12-11-2014, 01:42 AM
By neutral I mean reduce understeer and increase oversteer to make them about equal. I think right now I actually increased my oversteer. I haven't really pushed my car to the limits to really test it after I installed CPR X bar.will try to do tmr, but soft winter tires now.
I clearly felt that car behavior changed when I got CPR lower front bar which stiffened up front end a lot. I had couple of "holy sh@t" moments during my second Dragon Tail run, when I almost flew off the cliff during night run. Did not like that behavior.
Anyway, since then I added Madness top strut bar, which is more for looks, compared to lower bar and added X bar where back seat used to be. I'm thinking on giving up on front lower bar to reduce understeer and Im hitting it pretty often at gas station hatches, dead squirrels,gravel driveways ect.
In the future Im thinking removing lower front bar, but adding RRM chassis braces, adding Koni shocks in the back, maybe adding one more bar that bolts on the bottom of X (was an option from Ron).
What do you think guys, which combo on front/back will give most neutral feel/behavior, what setting on rear Konis?
I also have STS rear sway bar and car is dropped 1" front 1.35" back.

Michael T
12-11-2014, 08:08 AM

Saw your mod list in your sig.

12-11-2014, 10:24 AM
I just installed my CPR lower bar, but have not been to an Autocross or otherwise tested it yet. The only reason I bought it was Ron with CPR said it would "reduce" understeer, which is what I needed!!! Hope you are wrong on this one!

12-11-2014, 11:16 AM
I got to play with a few different setups last season and here's what I'd recommend after trial and error. note this setup is awesome on the track but also a little sketch on roadways until you are used to it.

Rearbar: J&J 28 or 30mm RTB
koni rear shocks: 3/5 firmness
RRM chassis braces: normally I like a soft front end and firm rear, but the chassis braces do one thing very well and that is help keep the contact patch square coming out of corners and make the power delivery more predictable. so that is a compromise that made me quicker even if it induced some under steer. My next suspension mod will be a rollcage or x-bar.
I'm on neuf springs

This setup is about as neutral as I can dial in, with -2 dry camber up front and still be able to daily her. You can rotate easily on let-off if that is your driving style, but it is also great for a fast rotation apex with ability to get on it sooner out of the corner and choose your gates.

Then it is just down to tire pressures and temps to dial it in from there.

You might ping jack & sue too... They have a winning setup and and a ton more seat time.

12-11-2014, 11:53 AM
I just installed my CPR lower bar, but have not been to an Autocross or otherwise tested it yet. The only reason I bought it was Ron with CPR said it would "reduce" understeer, which is what I needed!!! Hope you are wrong on this one!
Possibly, I'm new to suspension alterations, but from what I learned so far stiffer end slides first. I'm gonna re-torque my X bar and take it for a spin after breakfast and see how it goes.

12-11-2014, 01:08 PM
Re-torqued my X-bar, now nice and tight, took it for a spin. Much better. Pushed it on local twisty back road with 15 mph turns, now back wants to slide sideways, but holds there in fast tight turns in you let throttle go. I guess that is what I want. That was on 195/45/16 winter tires, when I came back car showed 36 psi front, back 32 and it varied, so need to adjust pressure too, tire shops never listen to what pressure you want...
So, if I add RRM Corsa braces and Konis to the back it should keep it that way?

12-11-2014, 02:46 PM
but from what I learned so far stiffer end slides first. Back when I used to do SCCA road course, the crew chief would never put a bar up front and we ran 2 bars out back - this was on front drive VW's so similar suspension design in struts up front, twist axle out back.. For some cars that had a factory front bar, off it came..

This was all towards getting less understeer, oversteer did increase which could then be tuned some based on size of the rear bar(s) added


12-11-2014, 02:59 PM
I noticed an immensely more neutral corner behavior in my Roush when I stepped down to a smaller front sway bar from the SVT Contour. Kind of apples to oranges, but I think it applies in regards to less front stabilizer = better bite.

12-11-2014, 03:48 PM
It's going to vary from car to car, even with similar suspension setups. With this car a good alignment, getting front and rear toe in check, is a huge (if not the biggest IMO) first step. After that adding a stiffer rear bar is going to help, but is in essence just adding to the rear spring rate.

12-11-2014, 04:16 PM
Taking off the front will help reduce understeer. The end of the car that is stiffer will slide first. Chassis bars do help, slightly, but are really only good as a fine tweak to your setup after you have done everything else. People will always has how much more it helps the car because the front end feels stiffer and more responsive but nearly all production cars that's not where you need to focus your attention. The suspension is setup to understeer from the factory because it is much safer then to have a snappy rear end. Work in progressions and change one thing at a time. This will allow you to know what to change if a part causes the car to do something you do not want it to do. Also remember as your speed increases your car will naturally become more rear bias so if you make the car balanced at slow 20 mph corners then it will want to oversteer on the faster 45 mph corners; I'm going off of posted curve speed limits for reference. You can also drastically change the balance of the car with small driving changes. Try rolling onto and off the brake and throttle a bit more to help keep it balanced. Hope this helps.

12-11-2014, 05:39 PM
As far as I know, the best practices for this car haven't been fully figured out yet.

I've been tweaking my setup for a while now and haven't gotten to the perfect setup yet. I need to try more parts (aka spend more money) to find the perfect configuration.

So far what I've learned is that rear ride height makes a huge difference on the car's balance (this applies if you have coilovers). Increase the rear height (assuming the front height stays the same) and get more oversteer.

My current hypothesis is that the this car actually needs a front sway bar to maximize front grip at the limit. To balance out the increased stiffness of the front sway, need an even stiffer rear torsion bar.

I've tried these mods:
Neu-F 28mm torsion bar
CPR 30mm torsion bar (tapered to fit stock brackets)
CPR front lower bar
RRM Chassis Bars
Bilstein Coilovers
Whiteline Caster bushings to get to 3.9 degrees of Caster
-1.75 Camber & -2.0 Camber
0 Toe & -0.06 Toe

All of these changes were incremental improvements (especially the torsion bar & coilovers) but I'm still not happy with the front suspension. It does crazy stuff at the limit, reducing front grip and inducing understeer.

12-11-2014, 07:42 PM
Next oil change I will remove front lower bar and see what happens on same road. Regarding alignment, my rear got shims and should be close to 0 toe now and front has camber bolts set to -1 degree and 0 toe.
Found specs of my springs: Color: Blue; Lower rate: 1.0-Inch Front, 1.35-Inch Rear ; Spring rate: 280F & 230R

12-11-2014, 08:18 PM
Hmmmm...getting this high centered front engine front wheel drive neutral.
Good one!
I am embraceing the understeer. Just a different driving style. I like my twitchy
over steering Sprite. I can see where I can even induce understeer with suspension
changes. BUT.....the thing has 50/50 weight distribution.
These puppies are front end loaded. Nature of the beast. In too fast? Crank the wheel
and let the scrub begin. Hope it slows before you are off and WOT when ya can.
Fun stuff.
I embrace it's style.
Still, I did add chassis braces and a upgraded torsion bar and Koni shocks.
Still understeers. Just tighter feeling.
It is a LOT better under heavy braking with the mods.
The dang thing corners like it is on rails. Just gotta find that right speed
going in.

12-12-2014, 08:35 AM
Regarding alignment, my rear got shims and should be close to 0 toe now and front has camber bolts set to -1 degree and 0 toe.

Generally, less negative front camber = less front bite (more understeer). This can be balanced with spring rates but not with what you have installed.

12-14-2014, 11:47 PM
What would be DD friendly front camber?( Not to chew up tires fast) - 1.75?

12-15-2014, 08:56 AM
Frankly, I've been using -2.5 degrees on the front since April with even wear. That said, I autocross the car some with my daughter so the cornering wear may have an effect on the even wear.