Aug 5, 2005 update to the Honda Civic Si project car

50/50

Now that the Civic has some tasty adjustable Ground Control suspension, we could do some corner-weighting. Before heading off to the garage, we printed this really helpful corner-weighting story that we found on the Web. (Okay, we knew the story was there because we put it there.)

Since a car should be weighed in as-raced condition, we first needed the right fuel load. The car was flat out of gas, so we bought three gallons—that’s about where we like to run it.

As far as ride heights go, Jay from Ground Control said an 11-7/8-inch hub-center-to-fender-lip measurement up front would be about right. For the rear, he said to knock an eighth of an inch off that figure.

We checked the car before rolling it up onto the ramps, and our left-front was just right. The other three corners were a little high.

With our driver on board, here’s our baseline weights: LF: 766 RF: 778 LR: 513 RR: 396

Our cross-weight was 52.59%. (50% is generally considered to be ideal for a car that turns both left and right.)

To level the front and improve our cross-weights, we dropped the right-front one turn. We then had the following corner-weights:

LF: 778 RF: 767 LR: 501 RR: 411

Our cross-weight was now 51.61%.

The car’s rear was too high, so we figured we’d work on that end next. We dropped the left-rear two turns (to drop ride height and improve our cross-weight) and lowered the right-rear one turn (to drop the ride height).

Now we had the following weights:

LF: 790 RF: 753 LR: 488 RR: 423

Cross-weight was now 50.51%, meaning we were still heading in the right direction.

To fine-tune things a bit, we dropped the left-rear half a turn. That move produced these numbers:

LF: 796 RF: 749 LR: 480 RR: 429

Our cross-weights? A so-close 50.06%. Our left-side weight was 1276 (52.00%) and the rear weight was 909 (37.07%).

The car is going in for an alignment tomorrow, and then we have an autocross on Sunday. We’ll see how it feels.

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