Lets talk sway bars...gt3, h+r...
 

Im having some trouble deciding on a sway bar kit to use for autoX. Here are some quick specs.

Car: 2000 boxster with a 3.4 996 engine

Wheels and tires: Cup 1 17X9" on all 4, 255 front 275 rear stagger on autoX slicks
Suspension: stock for now

Within the next few weeks, I will be buying a set of K sport coilovers with 450/550 spring rates, but after I choose a set of sway bars.

I like the GT3 front bar, but its extremely expensive. Are the H+Rs and Eibachs too stiff? The pricing is just about what id like to pay for a set.... what is your experience?

For AX, try just adding a M030 rear sway to get the car to rotate more easily. It is not adjustable but often this is all you need to carve the cones effectively.

To run "slicks" effectively you will need coilovers/corner balance and LCAs to get -3 degrees camber in the front. Without these setup changes the outer shoulders on soft compound tires will shred like they are in a cheese grater. I personally favor PSS9s with standard issue springs over Ksport 450/550 springs to get all that 3.4L power down early. Wheel spin on corner exit is undesirable in AX.

Many complain that the H&R rear bar is too stiff, but I like it on the soft setting for AX. Really helps rotate the rear & it's half the price of a Tarrett bar + drop link setup.

hr bars are solid and really heavy compared to the gt3 offerings.

At 255 F / 275 R, that is not a lot of stagger, which is just about right given the lmited front camber that you have available. That is, due to camber limitations, you are not able to get the most out of the front rubber, so if you have a lot of stagger, it would inherently understeer.

The GT3 front bar is good and light, and has plenty of adjustment. Definitely worth it. The 450 / 550 spring rates will change the balance, so you will be tuning balance front to rear after installing those spring rates.

The GT3 front bar will limit body roll, which limits camber change in roll, which will actually decrease understeer to a point, but if you go too stiff, the front bar will start to increase understeer.

The new 450#/in springs are probably about twice as stiff as stock, so you may want to reduce front bar stiffness after changing springs. I would strongly suggest doing the front bar first and tune on that before making any rear bar changes. Too many variables at one time is not a good thing.

The KSport coil-overs come with camber plates so he will be able to get about -3.2 degrees of camber in the front without LCA's. If you need any more than that though, you will need the GT3 arms.

In that case, you can expect to be a bit tail happy with those tire sizes. It could work OK for auto-x, but watch out for the back end coming around.

Thanks for the input guys. I have some other projects going on at the same time, so im on a limited budget.

I wanted the K sports since they come with camber plates, and so I can avoid having to spend $1000 on gt3 lower control arms to get -3 deg camber.

The gt3 front bar is also cost prohibitive for now, but I got a great deal on an used H+R sway set. Ill install the rear bar first on its softest settings, and take it from there. I can always sell the front bar and buy a gt3 bar this winter...

I wonder if you can slot the shock towers a little more in the front :eek: to allow some more camber

Im not too concerned about tail happy. Ill just turn the autoX event to a formula D event...

there's someone on this forum selling used tarett front camber plates that might be in your budget. there's also a thread here about someone who did modify the upper strut mounts for more camber.

+1 on the K-Sport coil overs. Withe the camber adjustments, I run reasonable camber on the street, then go -3.4ish for autocross. Takes only a few minutes to do the adjustment at the event.
I've put about 70K on mine over the last 5 years. Still going strong.

When I adjust camber with GT3 type arms, there is a drastic change in toe. So much that it would be impossible to adjust back in a few minutes. Is this then an advantage of camber plates over GT3 arms - little change in toe?

No, it's the same with camber plates... or any means of camber adjustment for that matter. I had the same thought when I read that... "A few minutes" would be a bit of an exaggeration for resetting toe after a camber change.

I did an alignment using a string system, setting up my front camber at -3.4 and zero toe. That's the AX setup, which is most important. When I slide the camber out to -2.0, I get a bit of toe out, but the car still tracks straight on the highway and tire wear is pretty even across the tire. The goal is to have the optimum racing setup and to get to and from events on R-Comps without killing them on the drive.