Why am I all over the road?

[grenda]

I have a 94runner with fj coils in the rear and new skyjackers in the rear sitting on 33x12.5 maxis bighorns. While I'm on the freeway it seems to drift quite a bit mostly side to side especially when there are ruts in the freeway. I have had a recent alignment and will be replacing front shocks soon but any ideas on how to correct this?

 

[SV_Dude]

Is this your first vehicle with larger meaty tires? That is pretty common with a setup like what you have. Do you have any weird feel in your steering? Any vibrations while driving?

 

[grenda]

Yes it is the first vechile with bigger tires and such. No vibrations or shaking while driving and after pushing the front bumper front shocks feel good so I have no clue?

 

[mikebontoft]

probably have really low caster now... which is an alignment angle. Higher caster increases high speed stability and vice versa.

 

[GonOvr]

Alcohol does crazy things to your driving skills.

 

[BucknutBob]

Another thing to consider is the alignment itself--most shops aren't experienced with alignments on oversize tires, and they actually make the settings worse because they follow factory specs. You may want to have it double-checked by a shop that specializes in 4x4s.

 

[SV_Dude]

Another thing to consider is the alignment itself--most shops aren't experienced with alignments on oversize tires, and they actually make the settings worse because they follow factory specs. You may want to have it double-checked by a shop that specializes in 4x4s.

What needs to be different and why?

 

[sam24th]

I would be willing to bet your caster is probably too low also. I had that issue with my 4runner when I first purchased it. The caster had been set to about 2 degrees, I had the shop set it to 3 degrees which is the factory specs and it still wandered around a little bit. I did a little searching around and found most guys run as close to 4 degrees as possible, so I had the shop reset the caster and it feels much more stable and less wandering around now. Might also want to check your idler arm and see if there is play in it.

 

[KidVermicious]

Your caster is the angle of your steering knuckle, front to back. Draw a line through the upper and lower ball joints: if that line tilts forward when viewed from the side it's positive caster, and if it tilts back it's negative caster. Negative caster puts the center of steering in front of the traction patch of the tire, which is what makes your steering wheel return to center when you let go of it and lets you track straight when you're going down the road (think just like the caster wheels on a shopping cart). I suspect your problem is bad caster angles due to the lift in the rear - if you're stinkbugging even a little that's going to throw your caster off and cause the tramlining you're feeling.

The bigger tires make it worse, wide tires always tramline like that.

 

[fourwd1]

It's the lift you install to fit those larger tires that throws the caster out of spec.
Also check the toe. With the bigger tires it helps to set the toe IN a bit more.