what is corner balancing?

[lrayner]

So what exactly is done to "corner balance" a car? I'm finally getting new tires on my Boxster tomorrow and so will be getting an alignment soon. Is it worth it to corner balance it at the same time? Unless I blow up my 944 I won't be autocrossing the Boxster.

[Jad]

For street driving it probably isn't worth it, a good alignment should suffice. Corner balancing makes the car behave the same in left and right hand corners by evenly distributing the weight across the diagonal corners. The factory doesn't do a great job of this as it doesn't make too much difference to the average person under street conditions, with varying loads changing the balance anyway. At the limit, it is very nice to have a car behave the same in both left and right hand corners, unless of course you drive for NASCAR.

[Kim Crosser]

I have been told (caution - 2nd hand/3rd hand information follows!) that Boxsters cannot be corner balanced to any reasonable degree. Check with a Boxster technical expert, but I think you won't find much improvement available.

However, if you are getting an alignment soon, you CAN make a lot of difference if you have them set you up for maximum negative camber on all 4 wheels (probably around -0.5 degrees on the fronts and around -2.0 to -3.0 degrees on the rears). Also, I recommend getting the front toe-in set to ZERO, and the rears set to a very small minimum (like 1/16th). This will help the car turn in much more aggressively and you can find a second or more in AX times with this setup versus the factory tolerances.

If you aren't ever going to AX your Boxster, this isn't that important, and if you are going to just use it as a daily driver, you may want to set it for a little toe-in on both front and rears. Zero toe-in will make it a little "twitchy" on the highway compared to a bit of toe-in on the fronts. The negative camber will help in general and makes it much more aggressive in cornering - period.

[Jad]

Boxsters can be corner balanced, but the tech must know what he is doing. Be sure to tell whoever is doing the alignment what your usage is. A good track alignment isn't that fun on the street and a good street alignment is fast or fun on the track.

[ttweed]

For street driving it probably isn't worth it, a good alignment should suffice.

I have to agree with Jad on this--if you aren't going to autox the Boxster, don't worry about it. You don't even need an agressive alignment if you aren't going to drive it at 10/10ths. A street alignment would be better for tire wear anyway.

That said, I have dutifully paid the extra $275 to have all my race cars expertly corner-balanced (thanks, Steve!), as it can make a difference in the steering balance of the car when turning one way vs. the other, as Jad said. I doubt if your Boxster could be that far out of spec that you would be able to feel the difference, though. The factory does a pretty good job of it, and you would have to have a pretty gross imbalance to notice it in street driving, since you rarely approach the limits of grip in your tires (hopefully).

There can be quite a few different approaches to corner balancing anyway--I know of at least 3 different methods employed by road racers (ignoring the bizarre setups in roundy-round racing) that may result in greater variances than exist on stock cars from the factory. Some people advocate matching the diagonals (weight of RF+LR=LF+RR) while there is another camp that maintains the correct procedure is to achieve the same weight distribution ratio on each side of the vehicle (LF/LR=RF/RR). There is also a dissenting faction who contend that small steering imbalances can be tolerated and corrected by the driver, and that what is most important is maximum braking capability in a straight line, where making sure the two front corners are equal is paramount, so that one side does not lock before the other (LF=RF, and then get the diagonals as close as possible.) The differences in these three methods could easily be larger than any imbalance your car is currently suffering.

Setups are largely effected by personal preferences, tire choice, and the type of tracks that are run, but if you're not racing, why even hurt your brain over such subtleties or pay the extra $$$? Just drive it and don't worry.

TT