Bump steer help.

[Motor_Freak]

Hi guys!
Any advice on bump steer kit? I have electric power steering assist installed.
Car is jump left/right on bumps on higher speed.
TIA!

[NAZ]

Is the bump steer from the front or rear, or both? You don't provide enough info about your build or the symptoms to know what you're dealing with.

Mine had bump steer built into the front suspension and I used the FFR bump steer kit #27593 to dial out bump steer. I didn't like the kit design so I modified it to meet my needs by using an adjustable Pinto tie-rod to heim joint adapter, part number 91636055-PINTO from Speedway Motors https://www.speedwaymotors.com/Adjus...91636055-PINTO and steel cone spacers to adjust the tie-rod end height. Be sure to use a fender washer on the top of this (or any heim joint attachment) to prevent a failed heim joint from separating and causing loss of control. The Pinto adapter has a 7-deg taper so you have to drill out the steering arms and use a taper reamer to install the adapters.

I use a Longacre Racing bump steer gauge but there are other good ones out there. Buy a quality gauge -- don't try to make your own Rube Goldberg design.

As for rear bump steer, if you have a solid axle and you adjusted ride height without regard to the angle of the LCAs you can cause bump steer and roll steer. I've been bringing this up for a long time and have yet to find anyone that really understands how indiscriminately adjusting ride height can affect handling. If you have a FFR three or four link the lower control arms should be parallel to the ground (no angle up or down hill) for best handling. The farther away from this the more adverse handling you will induce.

[HVACMAN]

Hi guys!
Any advice on bump steer kit? I have electric power steering assist installed.
Car is jump left/right on bumps on higher speed.
TIA!

Tim WhittakerIMG_0149.JPGIMG_0150.JPG

[NAZ]

Tie Rod.jpg


If you look close above the heim joint you'll see a conical spacer, half-nut, fender washer, and a lock nut. The conical spacers provide max rotational travel of the heim joint and the fender washer prevents the heim joint from separating if it should fail. Without something to prevent the joint from separating it's possible to have the joint housing slip over the spherical inner and that could lead to a crash.

[i.e.427]

What are the specs on the front end alignment? Without that, it's a shot in the dark.

[Tim Whittaker]

The one offered by Kootenai Valley is stainless with a chrome bearing. Barrel cam be polished to a mirror finish if desired. Comes with bump steer stud and heim seals. I had a special running and currently am out of stock. Hope to have in stock soon.

[Motor_Freak]

Thank you!

[TxMike64]

Do all of these cars have bumpsteer as designed? Or is it a function of yall's right heights?

[Motor_Freak]

This is my current setup. As far i understand bump steer kit makes steering arm parallel with lower arm.
Looks like mine are pretty close to be parallel right now.
Any thought? Thanks!

[NAZ]

A complicated subject that's difficult to explain on a forum. But part of the fun in building these cars is learning new stuff, so I encourage you to seek out all the information on the subject of suspension system design and set-up.

Bump steer is not corrected by adjusting the tie rod to be parallel to the lower a-arm on the front suspension -- wish it was that simple. Bump steer is caused by the tie rod moving in a different arc than the ball joint plane. Bump steer on IFS & IRS systems is a very complex subject and you will want to get grounded by first understanding how these suspension systems work to fully understand bump steer causes and what is required to minimize it. And it goes well beyond simply knowing the caster / camber set-up specs and there is no way to simply look at all the components and determine how much bump steer you're going to have. We measure bump steer in thousandths of an inch per vertical wheel travel.

There are numerous articles and explanations on bump steer so I suggest you GTS (Google That Stuff) for everything you can find on the subject of front end suspension set-up and tuning. To fully understand bump steer you need a basic understanding of how unequal a-arm suspensions work. It's a complex subject but the more you understand the easier it is for you to dial-in your suspension. You can get very close to zero bump steer with the FFR front suspension on the 33 HR but for every adjustment you make on that suspension you will also be making changes to other areas. So you need to understand the interdependencies before you start making adjustments.

But once again, not ALL bump steer is created at the front of the car so GTS bump steer and rear suspension systems. If you have the IRS, bump steer is adjusted very similar to that on the front end. If you have a 3-link or 4-link solid rear axle it is much simpler and usually caused by indiscriminate setting of ride height.

If all this was simple, everyone would be capable of doing it. Education on the subject is key to making a good handling car. And the more you understand about how a suspension system works and how to set them up, the more you will learn about the FFR design limitations you will be working around.

[Tim Whittaker]

Mtor_Freak,

If you want to give me a call, I can help explain and how to check. I have new kits in stock next week.

[Motor_Freak]

Mtor_Freak,

If you want to give me a call, I can help explain and how to check. I have new kits in stock next week.

sounds good, thanks!

[HotrodMike]

The one offered by Kootenai Valley is stainless with a chrome bearing. Barrel cam be polished to a mirror finish if desired. Comes with bump steer stud and heim seals. I had a special running and currently am out of stock. Hope to have in stock soon.

Good afternoon Tim,
Do you have any of the bump steering kits available? If so I need to purchase one please advise.

Best regards,
Michael Stephens
310 874-7403

[lance corsi]

Scrub radius can often carry the same symptom as bump steer. An imaginary line drawn thru the ball joints should intersect the tire patch in the center. If it doesn’t, the tire will react adversely over bumps.