Persistent bump steer / wandering with 2" lift

I've done so much to this thing to try and get the ride right with the lifted look. I understand a lifted truck with taller wheels is going to drive worse than stock, but this thing will almost dive off the highway if I take my hand off the wheel. It's a chore to drive for more than a short distance because I have to constantly keep pressure on the steering wheel to keep it straight. It's pulling left as far as I can tell and really doesn't like the highway sloping left. The "good" news is that it doesn't seem to be any play in the steering and it responds well on more level roads and lower speeds. The suspension should have had time to settle since I've been running it for close to a year.

What I've done so far:

1. 2" Ironman lift (leafs/coilovers) with 3/4" aluminum spacer up front to level.
2. LR UCA set to neutral postition (+2 caster).
3. New wheels and tires (255/75/17 @33psi), road force balanced, 17X8.5 6-139.70 -6
4. Alignment done:
-------------------- DRIV____PASS
-- Caster ---------- 2.4 and 3.1
-- Camber --------- 0.1 and -0.2
-- SAI ------------ 11.9 and 12.2
-- Toe ------------- .05 and .09
-- Included Angle -- 12.0 and 12.1

5. No extra weight in the front or rear.
6. "Zip tie mod" which shouldn't make a difference on the road.

I honestly don't know what else to do. I've been looking at replacing the steering rack bushings as a last resort but like I said, it doesn't feel loose, I just don't know of any other options at this point.

The sharp eyed among you will notice I've already posted to /suspension but I wasn't getting much traction over there so I came to the illustrious /2ndGen. You guys are probably smarter and better looking anyway.





EDIT:: USE THESE SPECS!

---------------- DRIV____PASS
-- Caster ----| 3.0 and 3.0
-- Camber ---| -0.4 and -0.4
-- Toe --------| .1 and .1

 

Get it aligned again. Take it to a shop that does ONLY alignments, the specialist, it will cost a lil more but be well worth it. Shoot for 3-3.4* Caster, -0.4* camber, and .1* of toe per side. The toe n caster will help it track better, can camber will provide better tire wear.

My truck goes down the road like a train on tracks, its awesome.

 

Thanks for the reply. Every lift thread I've been in says to shoot for 3, 0, 0 and when I finally get to that it doesn't drive well, big letdown. Will negative camber actually help with tread wear? I was under the impression 0 camber meant it was flat and would wear evenly. And yeah, I've been meaning to get to an actual alignment shop. But between working through normal business hours and the convenience of a chain tire store I just haven't.

I also meant to ask where you normally drive? On the flat or country roads it drives like a dream, but on the heavily sloped highway trying to go straight for a long period of time it's a nightmare. Since it's my DD and I have to hit the highway for 4/5 of my 30min drive everyday I've been miserable.

I updated the post with the actual alignment numbers.

 

The slight negative camber will wear evenly because the tread comes into full contact when you turn or maneuver. I thought the same thing and then did a bunch of reading on alignments after I installed my TC UCAs. I originally had 3*+ of caster on one side and 4*+ on the other after installing UCAs and turning was tough. Now I'm at around 2.x* on either side and it drives really well.

I have seen others suggest numbers similar to @nd4spdbh -- I'm sure those will get you on track.

 

Make sure that both your tires are at the same psi. I had a similar issue, with a 10 psi differance

 

yeah getting the same negative camber on either side will definitely help things, as will a lil more caster n toe. The negative camber (top of the tire in from the bottom) will cause more even wear as when you go around turns the tread rolls under the rim on the outside tire. If you had a perfectly perpendicular tire to the ground, when you go around a turn the outside edges of your tires would wear faster.

 

I wish it was tougher to turn actually, feels like I'm driving a lifted go-kart with power steering. I guess one more trip to the alignment shop couldn't hurt. A few more and I'll hit double digits.

Like, drastically? Because as sensitive as it is it seems like something drastic is needed to fix it.

Just checked em yesterday. Exactly 33psi all around.

 

at 3.4* of caster the turing effort is much greater than when i had it at 1.4* But its not overly too hard, its just right. And toe in will help things from wandering.

 

So ideally my alignment specs should be:
-- Caster = 3.4 and 3.4
-- Camber = -.4 and -.4 (or does the total need to add up to -.4?)
-- SAI = 12 and 12 (guessing)
-- Toe = .1 and .1

Which leads to my next question. Since the shop said my eccentrics were maxed out I'd have to adjust the UCAs to get the caster that high, correct? Using this sheet I would adjust it to the "C" position in the driveway and take it to the shop to have them dial in the rest of the specs on the rack with the eccentrics.

 

That tracks almost exactly with what nd4spdbh mentioned, except for the caster being a little low. I'd guess that's less important when you get your toe/camber in spec.

Now I just gotta decide whether I want to embarrass myself by asking the shop that did it previously to redo it to my new specs for free... or schedule with the local offroad alignment shop and pay $125.

Thanks for your help guys. You really are smarter and better looking than those guys in /Suspension.

 

Alright boys and girls. Looks like some of the information I gave you was slightly wrong. I was going off of a picture of the alignment while it was in progress and it looks like it changed a bit from then. So here are the ACTUAL alignment specs currently on the truck. Highlighted red are the differences from the original post:

-------------------- DRIV____PASS
-- Caster ---------- 2.4 and 3.1
-- Camber --------- 0.1 and -0.2
-- SAI ------------ 11.9 and 12.2
-- Toe ------------- .05 and .09
-- Included Angle -- 12.0 and 12.1

I finally got it on some decent roads yesterday and I'm actually getting a pretty pronounced pull to the left, especially at high speeds. Would that be the Toe?

 

Those numbers aren't too far off, I'm not sure about the included angle, maybe someone else can chime in.

 

It'

Now it makes sense...

It's because cross caster is 0.7*, indicating a difference between the sides. That's why you feel the pull, IMO. I'd recommend getting another alignment.

Really good techs will try to get both sides to match, although it's quite difficult.

An example of one of mine from last year.

 

Also, don't know where you live, but Firestone has a lifetime alignment deal. I think it runs about $170. It's a great service, especially for someone like me. I think I've had 10 alignments in two years time.

 

I usually stay away from 4wheelparts, but they got my alilgnment spot on. I would reccomend them for alignments, as they mainly deal with lifted vehicles. They also have more experience with adjustable UCAs, when some other shops dont. Just my 2cents.

 

I don't like your difference in caster there OP. It is more than .5* difference. Get them to get it closer.

Also. All this talk of alignment, yet no one has seemed to ask what type of tires he is running?

 

Dammit. I even asked the tech if caster being off that much will make a difference before I signed off on it. That fucker said no. I can't believe how hard is it to find a decent alignment shop around here. I've been to 5 different shops and haven't gotten a decent alignment out of any of them.


There's one Firestone shop within a reasonable distance, I'll have to try that lifetime thing out.

 

Mine is off by .6 (2.6 and 3.2) and drives straight as an arrow. Some shops do this intentionally to account for road crown.

 

I take it you're not still on factory UCAs?

 

Yeah, it's all about the technician doing the work. I've met some great techs, and there are lousy ones too.

That's a good point. They definitely play a part. I've read some complaints from some folks running the ST Maxx in the 255 size who come from a 265, etc.

It's a long story, they were JBA UCA's that were not built correctly (BJ angle not set right for lifted, so it was like running a stock UCA). That's in the past...