Suspension Analysis Done.

[superpro787]

can you explain why bump out is better then bump in

[astroracer]

Originally Posted by superpro787

can you explain why bump out is better then bump in

This is a quote from the Longacre site...
E. How Much Bump Steer?

Ideally you should run as little bump steer as possible. Most of the tracks we see today are old and bumpy. Bump steer on these rough surfaces causes the car to be unpredictable.

Some bump out can make the car more stable on corner entry. Bump in is almost always undesirable.

Some people use small amounts of bump out to create entry stability and an Ackerman type effect in the center of the turn where as the bump setting causes the LF to turn a bit farther than the RF as the RF compresses and the LF extends.

My recommendation is to run .005 to .015 thousands of bump out but never allow the tires to bump in.

If you want Ackerman in the center of the turn then add Ackerman while maintaining proper bump. If you use bump to obtain some Ackerman effect the car will be unsettled as it goes over each bump, which will break the contact patch from the racing surface.

If the design of your car does not allow for such precise bump adjustments then more bump out is better than any bump in. However, strive to get the best bump numbers even it if means replacing parts. Excessive bump over .050 can slow your car down.

As you can see both Mike and I's suspensions are falling right into the recommended range... This takes a lot of work to get it right and the benefits are worth it.
Mark

The Longacre site is full of good info...
http://www.longacreracing.com/articles/art.asp?ARTID=13