Alignment after Leveling

newdude · March 10, 2022

1 hour ago, SilveradoRST said:

Sorry to hi-jack but this got me thinking. I had the GM Trail Boss Accessory Suspension installed back in Feb '21. So the dealer (further away from me) did the lift and alignment. They also did the power steering controller calibration as stated in the instructions. Fast forward months later, I felt my steering wheel was off-center. Constantly had to hold the wheel slightly left to track straight.

I went to my local dealership and had them do an alignment again, they said the toe was off a bit. The wheel is centered now but I get a bit of wandering, not terrible. I did mention to my local dealership I had the Gm 2" lift done at another dealer when I went in for the alignment. Is this something they would have know by looking up the VIN? Because an authorization code, VIN and a call to Techline was needed to do the power steering controller (per Lift Kit Instructions), is my VIN in the GM system now reflect that I have the 2" lift? Or am I completely wrong, VIN will show I have an RST and I'll have to always remind the dealer to use +Z7X when getting an alignment done?

For future calibrations, yes its documented in GM's system for programming. If the installing dealer attached the install to your VIN it would show in the service history as well.

What it won't do is update the build sheet. Any time you have it aligned, I would make sure they use the +Z7X specs.

The instruction sheet for the GM lift says at the bottom to always align with the +Z7X specs after install and for future alignments.

newdude · March 10, 2022

Just now, Grumpy Bear said:

I'm going ask a question before I step in IT. Does this lift change the frame rake angle? Ever measure it?

I ask because when I did my lower via the back end it of course changed the frame rake when also changes the caster angle by the EXACT same amount. These numbers in this chart reflect the exact change in frame rake which means the 'ideal' caster angle is "Ideal' for GM in that changing the spec means no alignment required.

IF that sounds absurd I direct you to the TSB on the 2.4 ring and piston replacement that states that even at the 150K warranty limit to NOT hone the cylinders.

Or to the GM memo on further reducing of the OCI beyond the 2014 OLM recalibration to 7.5K.

Recalibration of the ABS to 'Band-Aid" a brake vacuum pump. No need to go on, eh?

Point is there is nothing in a lift or lower that would change the 'ideal' caster value Think about it. They have a habit of moving a spec instead of doing the work. IMHO of course.

The recalibration of the power steering adjust the 'assist' to reflect the higher input effort required to overcome an extra degree of two of caster.

You are probably on to something however, the GM 2 inch lift is both front AND rear lift. So I don't "think" the rake should change? Control arms don't change, the struts are replaced with taller struts, blocks in the rear.

Grumpy Bear · March 10, 2022

12 minutes ago, newdude said:

You are probably on to something however, the GM 2 inch lift is both front AND rear lift. So I don't "think" the rake should change? Control arms don't change, the struts are replaced with taller struts, blocks in the rear.

That makes some sense. Be worth measuring before and after next time you do one. Thanks for all the great input you willing give. It IS appreciated.

Black and Blue Z71 · March 10, 2022

Great info all around. I'll be sure to keep everyone updated when I get the truck looked at on Monday.

Byrds8 · March 11, 2022

What necessitates the need for steering re-calibration? I put the Eibach struts, springs and shocks on mine. Got just under 2" on the front and even a slight bit on the back. They had to align it three different times to get the steering wheel centered. However, it does seem its a lot more touchy than it was prior. It seems to track straight but if you bump it ever so slightly one way or the other it goes off that direction.

Edited March 11, 2022 by Byrds8

rbdjr · March 11, 2022

21 hours ago, Grumpy Bear said:

Why would anyone tell anyone else that a spec out of spec it okay?

Needs MOOG extended caster bolts installed and your alignment man replaced.

Front end specs are dependent on Ride Height of the car, the moment you change the ride height throw the original specs out, these trucks have different specs for different option codes and spring weight rating and suspension. So that’s why I said that, if it handles and tracks good its FINE, no tire wear and he will be happy. The pre alignment road test is the most important to see and feel whats the vehicle is doing on the road,handling and tracking, this will determin if and how much you will need to make caster adjustments. The Pre road test is more important than the post road test. I have done alignments all my life, Caster is not a tire wear angle it’s a Stability angle and Handling/Tracking, can be used to correct for road crown correction, I said if it handles properly don’t worry about it, many cars on the road have caster WAY out of spec and they still track and handle well. Stop over and see me, I will invite you to the school where I teach and we can show you on our Hunter Hawk Eye Alignment machine and help you understand my recommendations.

I personally like 4 deg caster on both sides, 0 deg camber, .010 toe total slit on each side. this way I can get close to 100K miles on quality tires. I also was able to get those adjustments from mine with a 2” top strut spacer in front and 1” spacer in rear and I have plenty adjustment to move it around, many different spring rates and suspension.

Edited March 11, 2022 by rbdjr

SilveradoRST · March 11, 2022

1 hour ago, rbdjr said:

Front end specs are dependent on Ride Height of the car, the moment you change the ride height throw the original specs out, these trucks have different specs for different option codes and spring weight rating and suspension. So that’s why I said that, if it handles and tracks good its FINE, no tire wear and he will be happy. The pre alignment road test is the most important to see and feel whats the vehicle is doing on the road,handling and tracking, this will determin if and how much you will need to make caster adjustments. The Pre road test is more important than the post road test. I have done alignments all my life, Caster is not a tire wear angle it’s a Stability angle and Handling/Tracking, can be used to correct for road crown correction, I said if it handles properly don’t worry about it, many cars on the road have caster WAY out of spec and they still track and handle well. Stop over and see me, I will invite you to the school where I teach and we can show you on our Hunter Hawk Eye Alignment machine and help you understand my recommendations.

I personally like 4 deg caster on both sides, 0 deg camber, .010 toe total slit on each side. this way I can get close to 100K miles on quality tires. I also was able to get those adjustments from mine with a 2” top strut spacer in front and 1” spacer in rear and I have plenty adjustment to move it around, many different spring rates and suspension.

Wouldn’t out of spec caster eventually cause increased wear and tear on the suspension and power steering components?

rbdjr · March 11, 2022

7 hours ago, SilveradoRST said:

Wouldn’t out of spec caster eventually cause increased wear and tear on the suspension and power steering components?

Not the caster on his truck, not even close, maybe in extreme cases, but I’m sure you would feel some handling conditions, wander, pull, steering wheel returnability etc

Black and Blue Z71 · March 14, 2022

Hey all, just wanted to provide an update. Went to the dealership and had them look at my alignment. As previously mentioned, it seemed to be aligned to Trail Boss specs. Service Tech was able to dial it in to oem specs. He also noted that the caster was no where near maxed. Drive it about 35 minutes home, mostly highway and everything feels solid and tight. Thanks for all the input fellas!

newdude · March 14, 2022

3 minutes ago, Black and Blue Z71 said:

Hey all, just wanted to provide an update. Went to the dealership and had them look at my alignment. As previously mentioned, it seemed to be aligned to Trail Boss specs. Service Tech was able to dial it in to oem specs. He also noted that the caster was no where near maxed. Drive it about 35 minutes home, mostly highway and everything feels solid and tight. Thanks for all the input fellas!

Good to hear they got you squared away and nice to see an update on this.

Edited March 14, 2022 by newdude

timothycan · May 9, 2022

On 3/9/2022 at 8:32 AM, Black and Blue Z71 said:

Hey all, recently put Pro Comps 1.5 leveling kit on my 2020 Silverado 1500 z71. Got it aligned after and the shop said my caster was almost maxed out from the factory and were only able to make some adjustments. I put the print out below. Is this normal or cause for concern? Appreciate any insight.

Good evening. I wanted to check in and see if you were able to get our truck aligned. I am running into the same problem. I have a 2021 GMC Sierra SLT 1500. Just added a BDS 4 inch Suspension lift and the install shop, recommended by BDS, could ot get the truck in alignment. I do not have a print out or remember what the descrepancies were, but from what I say, looked alot like yours. So just checking with you. My truck is still at the shop. Thanks.

Black and Blue Z71 · May 9, 2022

Hey, yes, the dealership was able to fix my alignment. Driven roughly 500 miles since I last updated the post and all is good. I had a 1.5 leveling kit installed and the shop used Trail Boss alignment specs which put the truck out of alignment. Possibly the shop is using AT4 specs for your truck? Good luck!