Setup ideas- went from understeer to oversteer

[Zombie killer]

General suspension mods : FE4 suspension, 1" lowering springs, adj BMR sways bar set, some upgraded bushings but NOT cradle bushings. Maxi-brace SFC installed. Other BMR suspension pieces upgrades.

I was running the OEM rims and factory Pzeros and always had understeer and just drove it last year like this during 7-8 autoX events. I made some changes recently where I added camber plates and upgraded my rims to 10.5" and went with PSS 285s on all 4 corners. Made my first autoX this past weekend and the front grip was unbelievable compared to what I was running before. I was having trouble with the rear end jumping out on me on tight turns. It was like the front end would grip so violent that the rear end felt like it wanted to jump around. I ended up adjusting the rear sway bars softer and softer until I had no more adjustment. It helped some in the tight turns but stil not neutral feeling. In some of the high speed sweepers where it would transition from one side of the lean to the other side the rear end would slide out on me with little warning. I don't know if it's the tires reaching their max grip in the rear and I can't recognize their limit or if it's the rear setup needs something adjusted to help. I am looking for suggestions from someone who has been there and knows what to do and can point me in the right direction with what I have now. I am not interested in coil overs at this time since I do not want to get frustrated trying to learn too many new parts at one time.

My suspension alighnment now:
FRONT
-1.5 camber -1.5
6.7 caster 6.7
.04 toe .02

REAR
-.6 camber -.8
.14 toe .14
.28 total toe
.0.00 thrust angle

I am running my camber plates at zero so I have plenty of adjustment to go more negative but the front is hooking hard now so I haven't added more negative camber at this time. I have elongated the subframe holes to gain more caster and can get more caster on one side but I have maxed out them even at 6.7. My rear camber is maxed out so if I am going to need any more rear camber then I will need to locate some bigger camber bolts than OEM ones I suppose.

I like the new front grip but need the rear to stay planted more in the faster parts of the autoX course. I am sure some driver mods are needed to relearn how to "feel" when the traction threshold is about to be broken.

[Rob@WretchedMS]

Where do you have the swaybars set?

[Apex Motorsports]

Originally Posted by Rob@WretchedMS

Where do you have the swaybars set?

This.

[Norm Peterson]

Since you have run out of rear sta-bar adjustment, the next fairly easy thing to try would be a change in rear camber. Maybe -1° or possibly a little more. This tweak is still in the same direction of trying to help the end that needs help "catch up" to the end that suddenly got a lot better.

Stiffening the front bar setting is another option, although to do that is to throw front grip away to bring that end down to the level of what the rear is providing. If you have to do this, then you have to, but doing things that bring up the rear grip should still be what you try first.


Norm

[Zombie killer]

Originally Posted by Norm Peterson

Since you have run out of rear sta-bar adjustment, the next fairly easy thing to try would be a change in rear camber. Maybe -1° or possibly a little more. This tweak is still in the same direction of trying to help the end that needs help "catch up" to the end that suddenly got a lot better.

Stiffening the front bar setting is another option, although to do that is to throw front grip away to bring that end down to the level of what the rear is providing. If you have to do this, then you have to, but doing things that bring up the rear grip should still be what you try first.


Norm

You hit the nail on the head. I want to see what I can do to get the rear to grip better than it does now without trying to lessen the grip on the front to equal it out. If I must I will but trying to see what others have done before me.

Right now my rear sways are set full soft. My front sways are also set full soft. I ran out of time and runs to start working on going stiffer on the front sways and to be honest , I didn't want to lose that front grip. It totally hooks up front and I was enjoying the hell out if it. But after a few tail happy turns and one looping spin out I knew either I had to change the setup or change my attitude on how aggressive I would make the turn in.

I wanted to try rear camber but not sure how far to go. I still enjoy a good run down the 1/4 mile so traction is not something I want to lose there.

[JDP Sales]

Here's a chart that should help dial you in.


Also keep in mind that you need to keep some throttle down sometimes to keep the weight settled and to keep the rear from stepping out. Many will enter a slalom going on and off of throttle and end up oversteering or taking out a cone at the end. If you give steady throttle all the way through, it will keep the weight on the rear and the car balanced.

Best regards,

Tyler
888-308-6007

[Rob@WretchedMS]

is it normal oversteer, or 'snap' oversteer?

Snap oversteer tends to not happen on corner entry/mid corner, but just as the power is being applied and you are starting to turn the steering back towards center it snaps the rear end loose.

Normal oversteer will happen on entry and mid corner and not be as dependent on the gas pedal (however putting power down will make the oversteer worse, it is typically much more predictable.)

[Zombie killer]

Originally Posted by Rob@WretchedMS

is it normal oversteer, or 'snap' oversteer?

Snap oversteer tends to not happen on corner entry/mid corner, but just as the power is being applied and you are starting to turn the steering back towards center it snaps the rear end loose.

Normal oversteer will happen on entry and mid corner and not be as dependent on the gas pedal (however putting power down will make the oversteer worse, it is typically much more predictable.)

1) I will pay more attention to where and how it happens at my next event but I think the oversteer I was experiencing was mainly mid corner as I was getting ready to start applying the power. I do good on the normal speed slaloms and also with some of the slower more abrupt turns but the faster chicago boxes and the like where I am flying in hard and accelerating hard is where I unsettle the car and feel the tail slide around. It is more than 15 degrees and sometimes I can power out and keep the movement going forward but I know it is slowing my times down. And in some of the longer high speed slaloms (near 45-50 mph) the rear end gets to swinging out and by the 3rd turn (cone) I have begun chasing the *ss end. 90% of the time I can catch it enough but I see myself buying a stupid "timing light" if I take one out at the line. LOL!

2) I have purchased full poly cradle bushings but have not installed them yet. The STU class that I was running in doesnt allow solid bushings in this SCCA Solo, didnt want to bump up to ESP just for the use of a solid bushing. But the SCCA CAM class that I participated in this past weekend does allow solid bushings. The problem lies in that not all the SCCA local regions that I have participated in run a CAM class. I probable will install the poly bushings and forgo the solid ones at this time so that I can still run a street tire class. I dont want to compete with cars running R compound tires just because I have the solid bushings installed.

[Zombie killer]

Originally Posted by JDP Tyler

Here's a chart that should help dial you in.


Also keep in mind that you need to keep some throttle down sometimes to keep the weight settled and to keep the rear from stepping out. Many will enter a slalom going on and off of throttle and end up oversteering or taking out a cone at the end. If you give steady throttle all the way through, it will keep the weight on the rear and the car balanced.

Best regards,

Tyler
888-308-6007

Thanks Tyler. I will also mentioned that I was running on less than a half a tank of fuel as I normally do. But that was because of the understeer condition that I was accustomed to before. Before I was trying to get the rear end to step out some to help me turn but maybe now I may try to add some extra weight to plant the rear more. Not sure if the extra weight would slow my times more than the oversteer condition but it may be worth trying to see. I may ask if the race director will let me use sand bags for weight if I placed them in the lower portion of the trunk around the battery. That way I could add or subtract weight as needed and see the effects without having a full tank of gas during the whole event.

[Zombie killer]

Originally Posted by Justin Moreno

Well you have done everything you can to increase rear grip with what you have.

I would focus on eliminating deflection in the rear. Is there a reason you haven't done subframe bushings? The rear whipping out when you change directions sounds like too much compliance in the bushings. When the rear tires are creating significant lateral force, the sub frame is battling against the centrifugal force of the chassis, due to inertia. The subframe is being pulled to the inside of the turn (grip), and the chassis is swinging towards the outside. The subframe bushings are complying, and there is a misalignment of the chassis and subframe. Note that the more displaced the chassis is relative to the subframe, the stiffer the bushings will get (similar to a bump stop).

Now when you switch directions, the chassis will accelerate to the other side, and depending on how hard it swings, there will essentially be an impact between the subframe bolts and the subframe, because as the chassis accelerates to the other side, the bushings comply until they suddenly become stiff due to compression. The impact is what breaks traction.

Solid bushings won't allow any displacement of the subframe to the chassis, and therefore no "impact" to break traction.

Sounds like my first move is to replace those OEM bushings. I will say that the front camber plates I installed have made a world of difference. I havent run anything but one fast autox course so far but it seems ok by my tire temps. My tire temps are even on the outside & middle, and my insides are running about 3-5 degrees hotter. Funny thing, my left to rights side temps did vary about 5-7 degrees between the sides last weekend and I was wondering why that is so on a autoX. Didnt make sense to me as usually they are pretty consistent and I ran my tire pressures the same. All I could figure was that maybe I was favoring one side more than the other on how aggressive I was turning in.

Obtw, love the camber plates man.

[woodside783]

I have the same problem you have. Going to put solid ones in it is the only thing I have not tried yet

[Zombie killer]

Here is a go pro video of one of my autoX runs where I lose rear traction. I am under power at all times but the *ss end will wiggle and sometimes I catch it and sometimes I dont.

I didn't figure out how to imbed a YouTube video so here is the link instead.
http://youtu.be/-Fpzp3zSnf8

[Rob@WretchedMS]

I'm not sure if that is oversteer as much as engine braking causing the rear tires to break free. It looks like it starts to come around as you go through the right hander when you are out of the gas, (it's hard to tell what the RPM's are though) and you get back in the gas before it's planted again so it just continues to go around the other way at the next set of cones.

Do you have more video's?
Any with the steering wheel or front tires in the picture?

[Rob@WretchedMS]

Just found another one of yours on your youtube page, with the camera on the right rear, and it looks like the yellow painted lines are what got you on that run

What were the surface temps that day?