How I Corner Weighted My Honda S2000
By Rob Robinette
Corner weighting, sometimes referred to as "corner balancing," "weight jacking," or "scaling," involves adjusting the spring perches of a car to get a balanced diagonal weight on the tires. Ideally the car should have 50% of its weight on the Left Front and Right Rear tires, and 50% on the Right Front and Left Rear. If your car's corner weights are not equal then its handling will be unbalanced--it will turn better in one direction than in the other (all other things being equal). If your car has coil over adjustable shocks you should consider renting/borrowing/buying some scales and corner balancing your car. It's a lot of work but in the end it's worth it.
On The Scales
I used this Microsoft Excel spreadsheet I created to do the following corner weight calculations: Corner_Balance.zip The spreadsheet's second page has a good article that goes into more detail of how and why to corner balance a car. You can see the article here: Grassroots Motorsports » Understanding Corner Weights This spreadsheet will also give you an estimated center of gravity height if you raise the rear of the car 10 inches or more and re-weigh it. The CG height values shown below are totally fictional.
You can also use this web page to calculate your corner weights: Corner Weight Calculator if you don't use Microsoft Excel. You can estimate your car's center of gravity (CG) height by using this page: CG Height Calculator
I used these scales to weigh the car: Intercomp SW500 EZ Weigh Scales
The following are screen shots from the Corner_Balance.zip Excel spreadsheet. Note the "Conditions and Changes Made" box in the "Ride Height" section of each spreadsheet.
First some baselines. Here's a box stock 2006 Honda S2000 with 5/8 of a tank of gas, and no driver or passenger:
Now here's the same stock S2000 with a 215lb driver in the seat:
I was really surprised to see how far off the stock S2000 was from a balanced Cross Weight. With the stock setup the car should have more grip in left hand turns than in right turns.
Before putting your car on the scales you need to power up the scales and zero them with no weight on them. Also double check that the scales are connected properly--you can really screw up your suspension settings if you have any of the scales connected improperly (i.e. front left and right swapped).
You need a nice, flat and level surface for the scales. I highly recommend using a laser level to confirm the 4 scales are level to one another. Even 1/4 inch difference will make a difference, especially if you have stiff springs on your coil overs. I used a laser level to project a horizontal line above the scales and then stood on each scale and placed a ruler on the top of the scale to take a reading. All 4 scales must be within 1/8 of an inch. I used newspaper to shim one of my scales up 1/4 of an inch--that's why I stood on the scale when measuring, to compact my shim material.
Check your tire pressure and bump it up to the hot pressure you run on the track. I use 2x6 wood planks as ramps to drive the car onto the front ramps then jack up the rear and lower it onto the rear scales. It's difficult to position all 4 scales so you can just drive up on all of them at the same time.
Once you get the car up on the scales you'll need to roll the car back and forth a few inches several times, being careful not to push it off the scales, to unload the suspension (as the car is lowered onto the scales the tires will need to spread out to unbind the suspension).
The first spreadsheet below is what I started with. This is my 2001 S2000 with 1/2 tank gas, 216 lb driver, no passenger, spare tire removed, top up, Magnaflow mufflers (-20lbs), Braille battery (-15lbs), ride height lowered approximately 1 inch, all 4 Bilstein PSS9 coil over shocks set to same length.
I put the car on the scales and input the four corner weights into the spreadsheet (the blue numbers in the left "Corner Weights" section. You can see in the "Target Corner Weights" section that the Left Front and Right Rear need 51 lbs of additional weight to balance the car. You would do that by extending the LF and RR coil overs:
You can see that the car's Cross Weight percentage is very close to the stock S2000. This car will benefit from corner weighting to a 50% Cross Weight.
This was my first adjustment: Four turns of positive coil over shock preload to the Left Front, and one positive turn to the Right Front. I added the turn to the RF simply to raise the ride height of the front of the car. I started with the Left Front because I wanted to raise the ride height of the car by about 1/4 inch so most of my adjustments were positive--they raised the car. If you don't want to change your ride height then a more balanced approach would be appropriate such as making small adjustments to all 4 wheels--add preload to LF and RR (extend coil over), remove preload to RF and LR (shorten the coil over).
Its important to measure and note your ride heights after every change. I saved a copy of the spreadsheet for each adjustment so I have a history of each adjustment. You can see on the right side of the spreadsheet's "Target Corner Weights" section that after this adjustment we still need to add 39lbs to the Left Front and Right Rear.
I still needed more weight on the Left Front and Right Rear so I added + 4 turns to the Right Rear:
I still needed more weight on the LF and RR so I added +4 to the LF:
I still needed more so I added +2 to the RR and drove the car for a week to let the suspension settle:
I decided to disconnect the front and rear sway bars to see what difference that made. It changed the wheel weights by 10 pounds at each wheel:
I finally went too far when I took two turns off the Right Front (went from +1 overall to -1):
I put + 3/4 of a turn back on the Right Front and ended up very close to ideal. I installed McMaster-Carr adjustable end links for the front and rear sway bars and installed them with my girl friend sitting in the driver's seat to load the suspension. Adjustable end links are more important for cars with upgraded (stiffer) sway bars because they can exert a lot of force to the suspension.
Here's my final results:
Here's the car with the same settings but empty:
I took the newly corner balanced S2000 to a Summit Point Raceway Friday at The Track (FATT) event and it handled superbly. Corner weighting your car is hard work but it makes all that high dollar suspension work together the way its supposed to.
Rob Robinette