Bumpsteer.....

Edited: 3/6/2008 6:53:57 AM by thacru78

I know what causes bumpsteer and how to fix it etc. What do you feel is an acceptable amount of bumpsteer. I know Herb Adams says an acceptable amount is .010 to .020 degrees of bumpsteer per inch of suspension travel. I'm not sure how to turn the degrees into actual inches. I know I have 14 inches of travel. I know at 7 inches of lift, the toe is perfect. At full drop, the wheels are off front to back by 1 inch. At full lift, they are off front to back by 1 inch, but the opposite of at full drop. It's hard to explain so I put together a quick paint version. It's a horrible example but if it does the job im happy. I'm on my 20th hour and i'm fixin to call it a night. The change is minimal and you can't even see it without fenders on, not to mention once the fenders are on. What amount of bumpsteer do you think is acceptable. Thanks Max

Im definately not the suspension genious Max is but i always set them up with the toe correct at ride height and then try and get the tierods adjust so that bump is limited as much as possible although with adjustible suspension coupled with stock steering there will always be some.

Yeah. The amount I have right now I don't think will be noticeable by looking at it or that noticeable while driving it. It's not enough to make the tires squel will driving low or aired up. I've definately scene some stock suspension with alot worse than mine. However, I spent $600 on a custom rack and pinion to minimize the bumpsteer. I was just trying to figure out in laymen (SP) terms what is exceptable. With 14 inches of travel it's going to be near impossible to make it perfect. I just don't want to think that what I have is ok and then 3,000 miles later be buying new tires.

I think with 14" of travel the amount of bumpsteer in your system is quite small.

A full inch is a lot. Because the amount of change is consistent, the tierods are the correct length, but are mounted at the wrong angle. If you truck is a front steer system then at ride height the tierods will be high on the chassis and low at the spindle and the opposite if it is a rear steer.

If my calculations are right, you are looking at about 3.5

Max, how did you arrive at that calculation without knowing overall tire/ wheel diameter?
I would think that on a 50" wheel diameter this 1" of difference would be less severe than on a 20" wheel diameter...
Or am I looking at it all wrong?

Those numbers are based on a 30" to 32" tall wheel tire combo. If you are on here asking me about your truck on bags with a 50" tall wheel and tire, I'm fairly sure that you have specified that earlier.

LOL- I think that's a safe assumption!
I wasn't second-guessing you, that question was more to verify that I was going about it the right way!!

It is a 32 inch tire/combo. Thanks for the help Max. Ima play with the rack and pinion more to try and find that sweet spot.

I minimized it to a 1/4 inch by repositioning the rack and pinion. That was the best I could do. It's not even noticeable at all so I think i'm going to go with it. Thanks for the help Max