Seeking assistance with troublesome alignment - '18 Silverado 4x4

oscyjack · June 6, 2024

Hey all.

If this is posted in the wrong place, apologies and mods if you wouldn't mind moving it to the right place.

I could be really long winded here, or just kind of give the skinny. But I am absolutely desperate for help in getting my truck properly aligned and driving like it should.

Even when my truck is within factory alignment specs, I seem to constantly either have a pull left or right depending on the road crown, or what I feel is too much steering wander, causing me to have to constantly correct to maintain a lane a freeway speeds.

I bought this truck last august, bone stock with 40k on the clock. 2018 Z71 LT2 CCSB in good shape with no signs of paint/body/framework. The truck had a leftwards pull on the test drive, but I knew I would be building it so I was not overly concerned with that. Since then, I have replaced the following components:

Tie rods replaced with PPE Forged tie rod assemblies
LCAs replaced with Mevotech TTX arms
UCAs replaced with Bilstein B8 UCAs (tubular arms with moog problem solver joints)
Front struts replaced with Bilstein 6112 (extended sku 1.85"-2.7", set at the lowest 1.85" on both sides)
Rear shocks replaced with Bilstein 5160's.
Rear suspension is +1" over stock via +1" non-tapered block, installed with new u-bolts (2.25" overall)
Sway bar links replaced with poly factory design
Hubs replaced with Timkens
Have tried 3 sets of tires, 2 sets of wheels. Current tires are LT(C) 285/70r17 Falken Wildpeak AT4w.
Current wheels are Fuel Rebel 6, 17x9 @ -12offset. The problem was present with stock wheels, and stock wheels with 1" BORA spacers.
Brakes have been replaced, and re-did the job 4 times now thinking maybe I had a pad/caliper hanging up at times.
Parking brakes have been inspected and adjusted
ABS bleed down procedure done numerous times
5x alignments, and I have my own bidirectional tool for the SAS reset/relearn if the shop doesn't do it.
Have played with tire PSI's and f/r deltas, high pressures, low pressures, mixed front/rear.
All bushings received their final torque at ride height with loaded suspension.

Current alignment specs that are still troublesome:

Camber L/R: 0.0/-0.2

Caster L/R: 2.7/2.8

Toe L/R: 0.03/0.05

Steer ahead: -0.01

Thrust angle: 0.03

I have indeed been using the same firestone location for the alignment. And that may be the problem entirely lol. But, based on the specs me-thinks something else might be afoot.

Open to any and all suggestions!

Other potentially pertinent information. When I bought the truck, I did a full maintenance routine. Every fluid is new and high quality. The truck is in excellent shape overall without any form of obvious damage. it is the 5.3 L83 with a 3.08 rear end (plan on 4:10's once I get the steering fixed), stock G80 that works as of now. Stock 6l80 that is serviced and works as it should as of now. I do have a slightly weepy passenger side rear axle seal, no contamination of the parking brake on that side.

Driving characteristics - It feels like my front end and rear end are two different vehicles. The rear tracks well, the front does not. Someone save my bacon

Edited June 6, 2024 by oscyjack

MikeBMW · June 7, 2024

Have you had the rear springs checked to be sure they are aligned?

Buckwild27 · June 7, 2024

I could be wrong but I believe somewhere in my internet rabbit hole travels somebody was talking about how they calibrated the electric steering to fix a similar issue. I have not encountered this myself so don't take this info as gospel.

oscyjack · June 7, 2024

Thank you for the input, I have reset/relearned the SAS numerous times to no complete avail. Though it did make some amount of impact.

oscyjack · June 7, 2024

Correct me if im wrong, but wouldnt that show in the thrust angle and likely reveal itself with an discrepancy between the appearance of both at resting state?

My thrust angle is small and to my eye, the springs are lined up and torqued appropriately.

I do have some progressive leafs to go in, I was hoping to get this alignment nonsense wrapped up first, but, if it were the springs maybe thatd be an unintentional fix haha

newdude · June 7, 2024

23 hours ago, oscyjack said:

I bought this truck last august, bone stock with 40k on the clock. 2018 Z71 LT2 CCSB in good shape with no signs of paint/body/framework. The truck had a leftwards pull on the test drive, but I knew I would be building it so I was not overly concerned with that. Since then, I have replaced the following components:

Tie rods replaced with PPE Forged tie rod assemblies

LCAs replaced with Mevotech TTX arms

UCAs replaced with Bilstein B8 UCAs (tubular arms with moog problem solver joints)

Front struts replaced with Bilstein 6112 (extended sku 1.85"-2.7", set at the lowest 1.85" on both sides)

Rear shocks replaced with Bilstein 5160's.

Rear suspension is +1" over stock via +1" non-tapered block, installed with new u-bolts (2.25" overall)

Have tried 3 sets of tires, 2 sets of wheels. Current tires are LT(C) 285/70r17 Falken Wildpeak AT4w.

Current wheels are Fuel Rebel 6, 17x9 @ -12offset. The problem was present with stock wheels, and stock wheels with 1" BORA spacers.

Brakes have been replaced, and re-did the job 4 times now thinking maybe I had a pad/caliper hanging up at times.

Parking brakes have been inspected and adjusted

ABS bleed down procedure done numerous times

5x alignments, and I have my own bidirectional tool for the SAS reset/relearn if the shop doesn't do it.

Have played with tire PSI's and f/r deltas, high pressures, low pressures, mixed front/rear.

All bushings received their final torque at ride height with loaded suspension.

Current alignment specs that are still troublesome:

Camber L/R: 0.0/-0.2

Caster L/R: 2.7/2.8

Toe L/R: 0.03/0.05

Steer ahead: -0.01

Thrust angle: 0.03

Driving characteristics - It feels like my front end and rear end are two different vehicles. The rear tracks well, the front does not. Someone save my bacon

What is the factory wheel/tire package it came with? 17s? 18s? 20s?

I'd have been curious what was causing the pull on day one as installing everything you've install could be exacerbating the issue. But obviously the truck is past that point. When I say exacerbate, I'm thinking that there could be something bent or misaligned. Even though there are no signs of collision repairs, can't rule it out if they did a really good job to make things look nice and untouched.

I know you've written down your findings for the alignment, but do you have a copy of the printout sheet you could post with the bar graphs showing the before and after?

oscyjack · June 7, 2024

1 hour ago, newdude said:

What is the factory wheel/tire package it came with? 17s? 18s? 20s?

I'd have been curious what was causing the pull on day one as installing everything you've install could be exacerbating the issue. But obviously the truck is past that point. When I say exacerbate, I'm thinking that there could be something bent or misaligned. Even though there are no signs of collision repairs, can't rule it out if they did a really good job to make things look nice and untouched.

I know you've written down your findings for the alignment, but do you have a copy of the printout sheet you could post with the bar graphs showing the before and after?

Thank you for chiming in! Really appreciate it. I'm hoping with our collective noggins, we might get somewhere.

Factory wheels were 18's w/ 265/65r18 iirc.

I surely do! I will post those here ASAP. I should actually have my last two or three. I will try to get them posted chronologically.

I had the same thought regarding the pull, but aside from one remaining LCA to swap out this Sunday (admittedly I did make this post prematurely before I had both in), everything else looks 100% as it should to someone whos been wrenching on GMs since 2000 or so. My sneakiest suspicion is that the remaining side has play in the joint and/or hub, that really doesn't make itself an issue until under load. I live in MI where the roads are reallllllly realllllly shite. I had the frame on a rack after I bought it and it was square, as an aside.

One thing I neglected to mention in my initial post was that I have also included new spindles/knuckles with the install. The passenger side LBJ was 100% stuck. BFH, heat, penetrant and a combo of the three made no headway. So the passenger side is currently basically all new within the last 8 months aside from the CV axle itself. The same will be true on the drivers side after this sunday.

The alignment shop ...states....they saw no play anywhere. And without any extra added pejorative, it is firestone after all hehe.

Edited June 7, 2024 by oscyjack

oscyjack · June 7, 2024

First picture is my before/after UCA install on 10/1/23, second picture is after installing tie rods on 12/8/23, third picture was after i fell into a hole to china driving down a logging road on 1/30/24.

The fourth pic was from this week, 2 days after install of the passenger side: Hub, spindle, end-links, LCA. I used all new GM hardware for each fastener and used by the book torque specs/procedures.

oscyjack · June 7, 2024

This is the most recent alignment in this post here. As well as a beauty shot to keep you interested in helping me lmao

newdude · June 7, 2024

16 minutes ago, oscyjack said:

This is the most recent alignment in this post here. As well as a beauty shot to keep you interested in helping me lmao

Hmm. Each one of those, the toe seems to be going right out of line each time, and in a short period of time.

Steering rack. Any play in the mounting bushings?

oscyjack · June 7, 2024

12 minutes ago, newdude said:

Hmm. Each one of those, the toe seems to be going right out of line each time, and in a short period of time.

Steering rack. Any play in the mounting bushings?

The rack has definitely been in the back of my mind. I sure do miss hydraulics sometimes lol.

I have not checked those for play specifically as of yet, but I can and will do so on Sunday during the drivers side surgery and will report back.

Do bear in mind, only one of those alignments was independent of a parts swap. But, I like where your heads at. And I am not at all afraid to fix what's broken, just need to find it first lol.

Thanks again for your hopefully continued input. Can only bounce this around in your own head for so long lol

Edited June 7, 2024 by oscyjack

rlcole321 · June 8, 2024

Yeah, I saw that too, about the Toe issue, I know when you install new parts like springs, they will "settle" in and drop a little bit and any change in camber (or caster) will effect the toe angle. I'm also old school for frt alignments, because of road crowns and right lane driving, you need 1/2 to 3/4 of a degree more caster on the right side (to keep from pulling right, if it pulls right, add caster to the right, if it pulls left, add caster to the left), also the more caster you have the better the vehicle will track straight. When you mod the suspension then you'll need to "Mod" the alignment spec's too!

oscyjack · June 8, 2024

Tomorrow is surgery day #2 for the drivers side. Made an appointment at a local chevy dealer to do an alignment after. Me hopes they will do it better than firestone, we shall see! Ill report in on tues.

oscyjack · June 10, 2024

Weekend surgery is complete. Both sides are now completely done. The only original components on the front end are the LCA bolts, the lower strut bolts and the steering rack.

I also found an additional steering angle sensor in the scan tool under the brake controller which I did not know was there. I ran all 3 SAS resets, and I have noted an improvement. Alignment tomorrow, will report back.