Bump steer?

[lexluthr69]

My '01 GT still retains the stock suspension components, so I'm not lowered any at all (besides any sagging of course). I've always associated bump steer with lowering our vehicles. Is it still possible to encounter bump steer with stock suspension?

If I drive over smooth road surfaces, or even relatively smooth, everything feels fine. But if I drive on a road that has not been paved in a while, or paved well, and there are grooves in the surface from the constant pressure of driving on the road, the car tends to want to steer itself. Is that even considered bump steer? Maybe my tie rod ends are shot? Before I get a jack up under it, I thought I'd see what ya'll thought.

Luke

 

[blacksheep-1]

Maybe, but I don't think so.
First off, there are some suspension guys on this forum that have more experience than me, Secondly, I've been doing this for over 30 years. Normally bump steer is associated with suspension movement, generally under braking. Basically, measure the tie rod ends from the center of the car at neutral height. Then have someone jack up the frame or push down on the car, the measurement will change with the arc of the tie rods. This causes toe in or out, the same thing can happen to one side or the other individually as well. Bump steer can be minimized but it can't really be totally taken out of the car.
Maybe what is happening is too much toe in, this lets the car "hunt" or point more quickly, toe out reduces this tendency. Again ,these change as the car rises, or lowers itself. Caster, can also effect the tendency to hunt as well, the more positive the caster, the less the car will want to change course.
Jack the car up, check all the suspension points, ball joints, upper strut mount, tie rod ends,steering rack bolt/bushings, etc. if they are all tight, and the tires are inflated the same then it might be time to check the alignment.

 

[lexluthr69]

Excellent! It's actually the response I was hoping to get. I'm actually pretty familiar with suspension geometries, but it's mostly applicable to trucks. I was very afraid that our Mustangs would have some peculiar tendency or known issue that I would have to find a fix or work around for.

If the hard parts prove to be true, than I'll definitely be leaning towards an alignment. The condition is most easily described as being very similar to driving over a draw bridge with the steel grating in the road surface. That feeling you get as if the road is trying to shimmy back and forth and drag your wheels every which way. That's how it feels on less than quality road surfaces here in VA, and there's more than just a few. I actually know which roads to avoid when driving to and from work.

Thanks again!

 

[BennyBlown2v]

That's just wander or poor groove feel - could be associated with dogtracking, but heavily crowned roads (like ones that haven't been paved in a while) can give the illusion of dogtracking.

 

[tomustang]

Is it still possible to encounter bump steer with stock suspension?

No because bump steer is only in affect when you modify the paremeters of your suspension when lowered, what you are talking about is what Benny said, which is the tire following the track of the road

 

[Jakes]

No you do not have bump steer. Stock suspension is actually engineered quite well.

The tracking you are feeling is normal for cars with wide tires. The wider they are, the more they want to follow the groves worn into the pavement. Groves in most cases you can't see but the tires know are there. There is a name for this phenomenon but I can't think of it right now.

Keeping your tires inflated properly will help this problem, so that's one thing you can check.

 

[tomustang]

There is a name for this phenomenon but I can't think of it right now.

Tramlining

 

[lexluthr69]

Up until about 2k miles ago, the occurences of this were very few and far between. I believe it is indeed tramlining, but with stock tire size (properly inflated), it may be an alignment issue as well. We shall see. I'm about to head out of country for a year, so it's not necessarily on the top of my list right now.

thanks for the info ya'll. I feel much more comfortable with the situation now.

Luke

 

[stangg01]

Shocks?