Pulling to the right since tires/lift

Friday I had my mods added...see my sig below. Yesterday I had an alignment done. I was told it was slightly off, almost not worth aligning but I felt my steering was off so he did it for me anyway.

It felt better after the alignment but now I find it often pulls to the right. Occasionally it pulls to the left. If I hit a bump in the road, it may jerk to the right slightly. Same with braking..it may brake to the right.

If I am on new pavement or what looks like a smooth, flat surface, all seems fine. When brake, I brake straight.

I thought my problems may be due to the surface of the roads. But it doesn't make sense to me. I also did read on another thread tire pressure may be a factor. I initially had my tires @ 40psi but the ride was pretty rough. I let them down to 33psi and the ride improved. I'm not sure what psi I should have my tires...note that are P rated. I may get some chalk and do the chalk test the next dry day.

I never noticed this prior the mods, so I assume it was not a problem before.

Any thoughts?

 

Start with the chaulk test on the tires.

draw about a 1 inch wide chaulk like across the tires.
Drive a short distance and then look at the lines.

if the more of the center is worn than the edges, you have too much air.
if the edge's are worn more then the center, you dont have enough air.

this will take several attempts. keep track of the pressures as the front
and the rear may differ up to ten pounds. remember our beds are very light.

while keeping track of the pressures, also note how the truck drives at the different pressures.

keep going till you find what pressures give you the best wear pattern
and also the best ride and handling.

Example: on my truck with the 265/75R16 Duratrac's
front 34, rear 24 work best for me.

 

what are your alighment numbers?

 

Yea, I am definitely going to do the chalk test. I just need some chalk lol

Here's the report. I just noticed the tire size listed is the wrong tire size. I actually have 70R18's. I'm not sure if that would make a difference or not.

 

there are much smarter folks here than me on alignment stuff, so don't take this as the gospel. your caster numbers are a bit low, which could be the cause of some of your issues. ideal numbers are around 2.6* - 2.8*. my alignment person insists on there being an offset on the caster to compensate for road crown. since you ride straight and brake straight on even surfaces, your issue may also be related to your caster #s not having an offset to compensate for the crown.

 

Thanks for that Bakerla. I am going to bring it back to the alignment shop and mention what you said.

 

they are most likely going to tell you that they can't get the caster settings any higher without messing with camber. your next step is to get a set of after market UCAs. and those aren't cheap....

 

Your SAIs are widely out of spec, and vary from side to side.

Check:
http://www.familycar.com/alignment.htm

And scroll down to the section on Steering Axis Inclination where it says in part:

Because of this, if the SAI is different from side to side, it will cause a pull at very slow speeds. Most alignment machines have a way to measure SAI; however it is not separately adjustable. The most likely cause for SAI being out is bent parts which must be replaced to correct the condition. SAI is also referred to as KPI

What to do about that? HellifIknow. Hopefully a guru will chime in.

 

ya.... my alignment guy did the same thing on the caster. the left and right on my truck differ by 0.40.

my truck drives and brakes straight.

my alignment guy also added in a tiny bit of toe to help elliminate some bump steer when the suspension compresses.

 

What should the caster numbers look like? In the low 2.x? Others threads I have just read mentioned that.

 

with a 2.5" lift, your caster numbers should be between 2.6-2.8, but if you dont have after market UCA's you woulld be lucky to get it at 2.0.

 

How are other people getting away with it then? Is it hit or miss?

 

i would guess that they get it close enough. i have read that it can vary between trucks.

 

I still say investigate that 14+ degree difference between left and right SAI as teh potential root cause of the pull.

 

Thanks for the replies and the link on alignments...made for a good crash course.

I really don't want to get into new UCAs if I can avoid it. I'm going to take the truck back and see about getting the caster numbers up and check out the SAI.

Oddly enough...yesterday evening I did a 20km round trip in the city with my wife and dog aboard...neither weight much...180lbs total....and I didn't find it as bad.

I also got some chalk and will do the test today. Either way, I'll post my results on the rechecking of the alignment etc.

 

if the guy didnt set the machine for your lift and rim and tire size than the alignment will b off