When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
best alignment specs to minimize corner entry to mid corner understeer?
2005 997S
anyone know the best alignment specs to minimize corner entry to mid corner understeer?
The way I understand it, Porsche and many other manufactures dial in some understeer to be "safe" for drivers that are less skilled and appropriate for the general public.
Generally speaking, it appears that my car has some corner entry to mid corner understeer, and is magnified with off camber and is extremely noticeable in an off camber decreasing radius corner.
On throttle, mid corner to exit does tend to step the back out and the chassis dynamics totally change. It might be totally unnatural for some, but as the understeer gets bad, putting power down tends to help.
I don't usually tune cars, but for my Kart, I could widen the front track, increase front tire pressure, add more negative camber (F), maybe even try to add more negative caster or move my seat slightly forward. If none of those things work, run stiffer rear axle and/or widen the rear track (yes, widening the rear track will actually get you less rear end grip and more positive front end grip). Wont even get into front bar adjustments.
The problem for me is that EVERYTHING changes the second you add suspension to the equation and everything I know for the Kart is thrown out the window.
My guess is to add more negative front camber and slightly more toe in? I am just guessing, and have no measurements as to how much.
Anyone know what the ideal specs (not necessarily Porsche spec) might be?
Wow!!! Great info. My only hesitation is that mine insnt a turbo so different weight bias and not 4WD and probably has different front and rear track? ( narrow body vs wide body)? Thoughts?
Increasing front negative camber helps reduce the built in understeer designed into the car by Porsche. With a stock USA 997.1 C2S suspension setup from the factory the spec is 0 to -0.5 deg (-15 minutes +/- 15 minutes). The ROW Performance spec moves that up to -0.25 to -0.75 deg (-30 minutes +/- 15 minutes). You want to be on the higher side of the spec to maximize negative camber so that understeer is reduced.
Note: these specs are degrees/minutes. To convert minutes to decimal degrees divide by 60.
997.1 alignment specs
GT3's are setup closer to -1.5 deg from the factory (-1 deg 30 minutes +/- 5 minutes, or -1.42 to -1.58 degress). Their front LCA's are adjustable so they can go much higher than a stock 997 too.
GT3 alignment specs
So a great starting point is to maximize your front negative camber trying to get as close as you can to the GT3 specs with your stock 997 suspension. You will likely get to about -1.1 or so, maybe higher if your car is lowered and/or the front strut tops are rotated 180 degrees. This is still short of GT3 specs though. To go higher you need GT3 LCA's or some other front camber adjustment mod such as monoball strut top mounts with camber adjustments.
Now what is not being said and should be is your tires. If you are on street tires then your front camber should probably be no higher than about -1.8 or so. Track tires you will want to be at least -2.5 and likely even higher than that. This has to do with the way track tires are angled with built in negative camber. You are trying to maximize your contact patch in both cases. Regardless of street or track tires setup the rear camber to be no more than about 0.5 degree different than the fronts.
I'm on MPSS street tires, -1.7 up front, -1.5 in the rear, and close to zero toe. These specs are slightly more aggressive than stock GT3 settings but way more conservative than a track setup. With this alignment and my other suspension mods I'm very neutral and taking corners like a go cart. Straight line at higher speeds though the steering is very alive, mostly from the near zero toe. If you are on track tires then the track guys are better suited at pointing you towards the "best" alignment settings depending upon tire brand and the track you race at.
Is that a typo or do you really run more negative camber up front than in back? I've always run -1 more in back.
For a performance oriented alignment (like track use) you would want more negative STATIC camber up front than the rears. Normal track setup is something like -2.5 degrees up front vs -2 or even a bit less like -1.8 in the rear. The reason is the rears are a multilink configuration which go more negative during compression. The fronts are mcpherson strut which don't benefit from more negative camber during compression once the strut/arm angle increases over 90 degrees.
.......I'm on MPSS street tires, -1.7 up front, -1.5 in the rear, and close to zero toe. These specs are slightly more aggressive than stock GT3 settings but way more conservative than a track setup. With this alignment and my other suspension mods I'm very neutral and taking corners like a go cart. Straight line at higher speeds though the steering is very alive, mostly from the near zero toe........
Does very alive above means it is a bit twitchy at highway speed ?
My car is currently doing that and I don't like it, how do I avoid it?
Does it make sense to go -1.7 camber in front, -1.5 camber in rear and use the factory toe in spec ? Any idea what effect that will have ? TIA.
