The mystery continues...
Bumpsteer is when your driving on an uneven road or drive over a bump
and your car decides to jerk to a side. This becomes annoying and dangerous
especially in wet driving.
There have been plenty of solutions but few that work, some even making things worse. Here are some possible solutions or theories on what can help...
My 87 GT (stock height& suspension) was all over the road. I repaced all tie-rod ends (inner & outer) and got new tires. There is still bumpsteer on larger bumps over 45MPH but its obvious that old equipment doesn't help. It rides safer than it did.
Before you start, consider:
Worn Suspension: Your 10+ year suspension parts probably have to be changed. Any movement from these parts will worsen your ride. Check Ball Joints, Tie rod ends, Sway Bar link bushings.
Tires: Uneven, worn tires do not want to drive strait. New tires will make a big difference compared to "Baloney skins with a sewn plaid patch on the sidewall."
Outer Tie Rod Ends (from parts upgrade section)
Around 94? Ford changed the Outer Tie Rod Ends (longer ends) to help keep the Rods (steering linkage) parallel with the lower control arms, reducing bumpsteer. I believe the length difference is not the rod to the rack but the smaller pivoting stud that bolts on to the spindle. Unfortunately I didn't know this last year when I replaced all inner & outer tie rod ends (tried to reduce annoying bumpsteer, and still trying). I don't have any proof of the benefits but it seems to be recommended, on all the mustang tech sites, to upgrade to the later rods. Still unsure if the updated rods have replaced the shorter ones.
It has been claimed that a car that is experiencing bumpsteer is aligned with too much or Positive Toe (Toe Out). I've seen posts on the Tech Boards from 'alignment specialists' that the factory settings have too much Toe and you should ask to have your car aligned with Toe In. I have no Idea if this is true, it sounds good, send me e-mail of personal experience with this if you've done this. I have also seen a service bulletin from Ford that they have changed alignment specifications on 87-94 Mustangs but I couldn't find them. Otherwise obviously ask your alignment mechanic if this will help or send you flying off the road.
I have Some sources say replacing your racks bushings to Offset rack bushings help lower your rack keeping it parallel with the control arms. From what I've seen it increases bumpsteer on stock suspensions and might work slightly in lowered mustangs.
aluminum Rack Bushings (not offset!) are claimed to give you more stability due to being more rigid than only rubber (stock). Check out article in Maximum Motorsports(link lower in page).
Larger tires will also contribute to Bumbsteer.
Example Stock tires: 225 60R15 & getting the wider 235 60R15.
Go to the Maximum Motorsports Website and read their very informative article on bumpsteer. Click on the MM Magazine Articles link then when that page loads click on the Steering Stats link.