Front Sway Bar?
 

Does anyone run a Large Front Sway Bar? Just curious. Maybe a GT3 sway bar? I'm assuming the fit?

Does it make it understeer?

Looking to build a C-Stock Autocross car

We will need more info!! what tire/size?? what spring/shock combo?

We run a LOT of Boxsters with SCCA. 99% of them are running the GT3 bar for more adjustment to conditions/driver.



B

Running typical 17" Boxster tire set up... And stock springs.... Plan on buying some adjustable Koni Shocks.

Still. If everyone else is running GT3 Sway Bars, then thats probably the way to go....

I did say i was building a C-Stock Boxster. Therefore implying stock rim size/width and stock springs.

I believe the GT3 bar is stiffer than stock (even at the softest setting), which will increase Understeer.

I'm not familiar with C-stock rules :) Most of our cars are in prepared classes BSP/FP/XP

That being said.. stick with the stock bars and buy some BoxsterS bars (MO30) I typically carry with me 3-4 rear bars and just swap them out until I have a stock shocked car balanced the way I want it. The rear takes 10min to swap out.. the front takes a little longer.

Bars I go to the track with (and AutoX)

Tarrett
MO30
Stock

I believe you can backdate/update in C-stock?



B

for what it's worth.... I have an old sheet from Ira at Tarett and it shows the front GT3 bar at softest - is 50% stiffer than stock S bar.

kj

I was looking for that information today! I knew I had seen a list comparing the stiffness of the various roll bars that are available.

Any chance you could scan it and share with us? :D

That is if you're already Understeering... But it could potentially just reduce oversteer, and body roll as they are designed to do...

I would normally, but it's from a known source and Ira created it. I really don't want to step on toes and duplicate without permission.

However, I'm pretty sure Ira would be okay to give out to people who ask.... he's really very generous that way. It's called "Boxster Sway Bar Stiffness Ratings"

... sorry if it's inconvenient.

kj

So if the GT3 bars are a recommended upgrade, where is a good place to get them from - direct from Porsche or e-bay or?

Porsche 996 & 997 Hollow Adjustable Sway Bars

FYI,
I may be running in a different competition class next year that requires Porsche sways. If I do, my Tarett F/R bars & drop links may be for sale. PM for more info.

Depending on price, I would be interested...

The GT3 bar is the Tarett front bar

No, a stiffer front bar will increase understeer. The only unusual case where it MAY not, is on a high CG, front-heavy car, with poor camber control ( like a 60's muscle car ). In which case the reduced roll (and reduced positive camber), adds more to the front grip than the increased weight transfer (from the larger bar) removes . A Boxster certainly doesn't fit into this catagory.

There are plenty of books that explain the affects of weight transfer in detail.

Ira emailed me the GT3 bar versus the stock bar info. I'll post it up shortly.

I will tell you running the short drop links with the GT3 bar, decreases the effectiveness of the bar in corner. As you input more steering wheel, it UNLOADS the outside tire in the corner :barf:

He was at our shop late last week test fitting some new parts :) I don't have to ask for permission :)


Bhttp://986forum.com/forums/uploads01...1323985398.jpg

Brad,
That chart is great, thanks for posting.
A couple questions:
- Do you have a common comparison for the H&R rear bar?
- Can a Cayman front bar be fitted to a 986?

The CaymanS bar will not fit :(

I have personal "butt" experience with the H&R rear bar, but I do not have numbers in comparison for it. I do know it is stiffer on full soft than the Tarett rear on full stiff. I have taken them out of several of our race cars. Just too stiff for some of the open diff cars.

My biggest issue right now is the rear drop links everyone sells for the rear bars. They are too short. Take a look under a Cayman Interseries car and notice the rear "pry bar" they have going on. The rear links are way way to short for those cars. Everyone sells a replacement heim based drop link for STOCK replacement. Stock replacement is GREAT for STOCK shocks/springs at euro or USA ride height, but when you lower the car, the upper link mounting point goes UP in the chassis!!! and in turn it points the rear bar into the SKY!!

B

How about on a Boxster S with a lsd?

Thanks for the chart! What short drop links??? Stock ones?

The stock ones won't work either.. all the aftermarket links are based on these!!

Run the LSD with one link removed and zip tied up to the toe link (they move at the same rate) and test the car without the rear bar. LSD's inherently induce understeer that has to be dialed out. I leave the nut on the floating drop link and run the car for a session with the bar disconnected, then quickly reconnect it for the next session for side by side comparison.


The rear links being sold are a compromise.


B

Interesting, so you recommend actually downgrading the rear if the car has an LSD?

I'm a HUGE fan of adjust-ability. We dial our cars per track (its what we do in professional racing, so I do it in club racing also) **Most** of the pro drivers I work with/drive with don't run a rear bar but have a LSD (it means you are very close on spring rate and have the car balanced with slight oversteer) We change springs and tenders until the car is balanced without the bars, then use the bars as a course adjustment and the shocks as a fine adjustment.

Try it. You have nothing to lose by removing a drop link from the rear bar and placing it away from the bar. Run the car and see if you like it. If you don't like it, reconnect it~! Pretty easy. I promise less wheel spin on open diff cars :) if you dis-connect it.

I disconnect the front and rear for racing when it is raining, so I do know what it feels like to drive without the sway bars - just never tried it in the dry on just the rear to improve lap times...

I worked all year on testing different configurations and came up with this exact same conclusion. Thanks for letting the cat out of the bag dude.:mad:

I have a GT3 front sway bar, GT3 adj control arms, tarret drop link clones.
I also have TIEN springs -- 500# and 692# in pairs

I was building a Boxster S track car and collecting parts -- but never built the car.

email mike@lonestarrpm.com or PM
thx

Mike