Bump Steer Definition :

Bump Steer is when your wheels steer themselves without input from the steering wheel. The undesirable steering is caused by bumps in the track interacting with improper length or angle of your suspension and steering linkages.

Most car builders design their cars so that the effects of bump steer are minimal. However, you must still take care to bolt on your suspension carefully so as not to create unwanted bump steer. Make sure that you are always using the correct components for a particular car. Bump steer must be designed into the car and cannot be adjusted out if improper parts are used or if pivot points are moved without considering bump steer design principles.

In order to accomplish zero bump the tie rod must fall between an imaginary line that runs from the upper ball joint through the lower ball joint and an imaginary line that runs through the upper a-arm pivot and the lower control arm pivot. In addition, the centerline of the tie rod must intersect with the instant center created by the upper a-arm and the lower control arm (See diagram below).

The instant center is an imaginary point that is created by drawing a line from the upper a-arm ball joint through the a-arm pivot where it is intersected by an imaginary line that extends from the lower ball joint through the inner control arm pivot. Where the two imaginary lines intersect is the instant center.

Sounds complicated? Really it is very simple. To achieve zero bump the front end must be designed correctly. The tie rod must travel on the same arc as the suspension when the car goes through travel. Simply matching lengths and arcs to prevent any unwanted steering of the front tires.

To exaggerate, if the tie rod were only 10" long and the suspension were 20" long then when the suspension traveled the tie rod angle would shorten much quicker than the suspension arc. In this scenario the tie rod would shorten much quicker through travel than the suspension and the car would toe in drastically over bumps. The shorter arc of the tie rod would pull on the spindle and toe it in through travel.

I. Bump Simplified

When designing a car, if the centerline of the outer tie rod lines up with the centerline of the lower ball joint, and the inter tie rod lines up with the lower pivot point then the length and angle of the tie rod and suspension will be the same resulting in zero bump. Most car builders design their cars in this fashion.

 

[QUOTE]Originally posted by Bieg
[B]

The fact that he is faster than most guys with Modded cars says a whole lot doesn't it.

 

Sure there are. I still maintain though that until you perfect your technique (at least the basics) you really don't know if your modifications are really improving the car or just helping to mask poor technique. The S2000 rewards smooth technique and that is something that many drivers don't have. Skip Barber calls them "Pedal Snappers" and driving like that almost any car will handle like sh1t. If there is one car that punishes pedal snappers more than most it is the S2000.

You run into this "I have to have the latest, greatest" phenom in audio, photography, computers, etc..... You see a new "photographer" that absolutely needs to have the fastest, sharpest lens yet he has not mastered how to hold the camera still or using a tripod. They get so caught up in the gear that they forget that the technique is an important ingredient.

I had a friend who was into audio gear and was quoting the great specs of his Nakamichi Cassette deck (this was years ago) off to me. I said sure is a nice piece but when was the last time you cleaned the heads? He just looked at me with a blank stare until I told him to get me some Q-Tips and alcohol. When he heard what it should sound like he was stunned.

So my main argument against mods is that the car is way better than most of the people driving it and until the driver can outdrive the car it doesn't make much sense to change the car. Improve the driver I say.

That of course is just my opinion.

 

dlq04, meat,

Thanks.

dlq04,

I will print out your post and look at this over the holidays. I am going to try to find a generic front end diagram so that I can better follow your explanation. Maybe the Helm manual has a diagram. I'll look.

 

[QUOTE]Originally posted by littleton
[B]dlq04, meat,

Thanks.

 

Bieg/All: What are your thoughts about the willingness of dealerships (and Honda) to repair problems like trannies, diff's and engines on cars that have been obviously modified. What I am after here is, are you given less consideration (You Pay) for your problem in a modified car than you might be for a stock one. I guess the reality here is you might not even know you had been discriminated against, but you might? Any examples come to mind? Is such treatment fair...either way?

 

dlq04,

Thanks. Will be a good learning project for the holidays.

 

It's going to depend on the mod and the dealership. Legally and in theory, a dealership can't discriminate or refuse to service your car unless they can show that a particular mod caused the problem. For example, if you replace the badges on the car with Rick's badges then Honda can't choose not to repair your diff because there's obviously no relationship between your changing the badges and the diff dieing. It gets a little more gray if the dealer can find a link between the mod and the failure. If you put a supercharger on your car the dealer may choose not to warranty any drivetrain components because of the extra stress the supercharger puts on those components. We've seen a wide variation in where dealers draw the line. Some dealers are pretty cool about mods and warranty and others are the exact opposite. The bottom line is if you mod the car then if that mod can possibly cause failures you may have trouble getting warranty service on the affected components.

 

The law states they have to honor the warranty UNLESS they can show said aftermarket part was the cause of whatever problem you are there for.

That being said good luck trying to get a broken engine, rear end or tranny fixed if you went with forced induction. They would be well within their rights to deny it. This of course makes people resort ot fraud by doing such things as removing the aftermarket parts prior to bringing it back to the dealer.

For those people the cost of modding their car includes a bit of integrity.

 

Happy Holidays to all!