Bump steer kit

[Todd Haskins]

My 17 year old MK1 has always suffered from wandering on a bumpy road and I am wondering if the installation of a bump steer kit would eliminate this? I see that FFR is having a 25% off sale this weekend and this might be a good time to buy a kit and finally stop this problem if it actually will.

Another issue I have had is the front end feels mushy. I can't imagine tearing down the back stretch of a race track at 100mph. Mine is a stock build with a flaming river rack and solid after market U joint. I did use the rag joint and mustang converted rack for a few years.! The lower A arms came from the Mustang donor and the upper are from FFR. I wonder if the newer parts for the upper arms that are now included with the kits would be a upgrade worth the price and can they be retrofitted to my MK1?

I'm looking to make my car feel more solid and tight. What would you suggest?

[NAZ]

The short answer to will a bump steer kit help is maybe. It depends on the kit and your ability to measure bump steer.

You need a way to measure bump steer so I'd suggest you start with sourcing a bump steer gauge to go with that bump steer kit. There's a simple truism that you can't control what you don't measure. Simply buying a bump steer kit is no guarantee that you won't make the issue worse. For a bump steer kit to be effective it has to be adjustable. That adjustment is typically through shims or spacers. If you don't have a way to measure the effect of your adjustments you're just guessing.

There are two common types of gauges, one uses two indicators and another type uses just one. I prefer the single dial indicator style. And some folks make their own but some I've seen make me skeptical that these cobbled together contraptions are worth the effort the designed put into it. Many will find a store bought gauge expensive for a one-time deal so if you're in that camp perhaps someone in your area has a gauge you can borrow.

[Todd Haskins]

Thanks Naz. I didn't know this was such a project but getting the geometry of the suspension is critical. I'm going to have to find someone that has more experience with this before I proceed.

[NAZ]

Good decision Todd. Get with someone that has the knowledge about tuning suspensions. Your best bet is probably someone that builds and tunes race car suspensions on dirt or asphalt track cars as they will have the experience and knowledge to guide you. Sad to say but I doubt most professional mechanics know a lot about the subject as they simply follow a repair manual for adjusting the suspension. I used to make my living as a Ford Technician so I've worked with many mechanics over the years and have some insight into how well versed the average guy is on outside the box suspension systems.

One other thing I might add is you need to be sure that what you're experiencing is truly "bump steer". If you have a solid rear axle you can also get that darting feeling from roll steer. If you have a sensitive butt you will also feel the car yaw with roll steer. On a solid axle car the lower control arms (LCA) control roll steer. Roll steer is where the solid axle becomes skewed as the car goes around the corner or over a bump. This makes the axle "rear steer" like a forklift. Think about the old push cart you made as a kid with a solid front axle that pivoted on a nail driven through the center of the span. The axle skewed to turn the push car.

If your lower control arms are not both level with the ground at static ride height you will have some degree of roll steer. This can present much like bump steer but is caused by the rear axle not the front suspension. Most cars will have a little of both if not properly setup. If you have a solid rear axle and you've set your ride height without consideration of the angle on your LCA then I'd look there first. All you need to be able to adjust out of that condition is a simple level and a change of ride height. But remember, any adjustment on one point may cause a change in another area so check the pinion angle if making adjustments to the LCA or ride height.