Bump Steer with 2 in lift?

[Hayride95]

I recently installed a rough country 2" lift on my stock 95 Hardbody. The kid did not include a drop pitman arm. I am now feeling a pretty substantial pull to the right when I brake. Is this bump steer? I would not have thought that I would have a problem with only a 2" lift? Or do I have a brake caliper pulling? I have pressed slightly on the brake (so as not to cause the front of the truck to dip...bump steer) and I still get a slight pull to the right.

Any help would be appreciated.

Thanks

[icrf]

Bump steer is just that, you hit a bump, the suspension moves in a different arc than the steering, and it pushes or pulls a bit. The problem is usually when the bump is only one tire, affecting the tow of one wheel. If the bump is both tires evenly, like braking, in theory the bump steer on each will cancel out and you wouldn't feel anything.

The only time I noticed any significant bump steer on my truck was going down the interstate that just had a ton of that tar crack patch put on randomly all over the lane. The truck was just wandering like crazy and it was a fight to keep it straight. The other lane was smooth, so I was that ***hole who drove in the left lane for a few miles. A friend of mine in an Xterra was with me and had the same problem. We were both running 3" or so lifts.

While I suppose I wouldn't rule out bump steer completely, I would say something with the brakes is more likely.

[Hayride95]

Ok...had the brakes bled and checked out yesterday and no problems there.
However the brake guy noticed something that seemed odd. At the point where the alignment guy had placed the shims for the alignment (post lift installation) there are three tabs on the passenger side but none on the driver side. The man doing my brakes suggested that if one side of the lift was torqued more than the other upon installation, it could cause this pulling phenomena that I am seeing. Has anyone else had this problem? Also, is it normal to just shim only one side when aligning a vehicle... post lift kit installation.

THanks

[Desert Rat]

the difference in the usage of shims could be a manufacturing variance in the aftermarket upper control arms. Nothing to be alarmed about, but do ensure that you still have sufficient threads holding the UCA in with the shims. I've seen these kits with lots of shims in place actually pull the threads on the frame and the UCS separates from the frame.

icrf gave a good explanation of bump steer. For this style of lift a drop pitman arm doesn't work - you'd have to drop the idler arm with it, and doing so would mean the tierods would move in a different arc than the lower control arms, actually resulting in MORE bump steer, and some wonky steering geometry. Dropped arms typically are associated with solid front axle suspensions, not IFS.

The pull can be a lot of things, but since it's limited to when you're braking, you have a caliper on one side grabbing a little more than the other. Are your front tires identical, and are they inflated to exactly the same PSI? Pulling a little bit right isn't that unusual on crowned roads. Does it still pull right if you do this in a left lane?

[icrf]

When you put the lift on, did you touch the torsion bars at all? It's been a while since I've done one, but I don't think you typically do. If not, then I don't think one side should be tighter than the other.

[Desert Rat]

Yes. It's the torsion bar adjustment that provides lift. The new upper control arms are typically a little longer than stock and enable you to get within camber specs after lifting.

In most cases when lifting the torsion bars need to be reindexed by a couple splines. Ideally when properly adjusted you can get your index finger between the pad on the Upper A arm and the bumpstop. Height adjustments require an alignment afterwards. Toe in can be done in the driveway yourself, but camber/castor is best done with instruments in a shop.


Lots of good how-tos on my site at the link below:
http://www.nissan4wheelers.com/forum/ho ... -read-only