Non Standard AT4 Level - Bilstein + ReadyLift + 34s (w/pics)

DrNick · March 6, 2024

Hey all. I know there's a ton of info out there about leveling kits for T1 trucks, but when I was researching for my truck I didn't seem to find much info on some of the options and combinations I was considering so hopefully this might help someone else in the future.

* TL;DR at the bottom of the post.

Here's my rig in stock trim. 2022 Limited GMC AT4. This spot isn't exactly level, but it's close enough that it doesn't register on the truck's angle sensor. I suck at taking pics, but I wanted to show the changes from the different steps of this process. Story time.

I've had a 4WD GMC or Chevrolet truck (usually in Z71 trim) from each generation starting with my 1993 and they seem to be getting better with each generation. I love my 22 Limited AT4, but couldn't stand the Rancho shocks. Especially when towing. All the trucks I had before my most recent 2017 had OEM Bilstein shocks, and to me that's the feel I expect for a GM truck. I had a set of Bilstein 5100s on my 2017 Z71 which provided enough front end lift to run the tires I wanted along with handling improvements, so I knew I wanted to go that route again. In retrospect I should have looked closer at the 6112s for the front, however I'm not 100% confident I wouldn't have been in the same boat as my 5100s didn't actually provide the advertised increase in ride height (more on that later) and given they include springs it would have been more difficult to find something to pair. The stock tires also left a lot to be desired. At 25k miles they were already unreasonably loud to the point passengers would complain and they stopped balancing properly at about 20k miles. After a year with this truck I was ready for new shocks and tires.

I enjoy SCCA RallyX and tow my RallyX car / gear for race weekends. The plan was not to level the truck as I wanted to keep some rake to help with towing. Since a true 33" tire wasn't available in the tire I wanted to run, I decided on a 295/70/18 or a touch over 34". I had seen some guys running similar sized tires with not much lift, so I thought I had a good shot to get by with a set of Bilstein 5100s. I also snagged a set of the Bilstein B8 upper control arms to give the best shot at keeping a decent ride and OE alignment specs.

First step was the Bilstein 5100s and UCAs with the stock tires. The 5100 series claims +1.1" of ride height in the front. Unfortunately I only gained 7/8" (FL) and 15/16" (FR), but it was close enough. The rears saw negligible height increase.

* Side note: previous 5100 sets ran on other trucks provided 4 different height adjustment levels, where as the current set of 5100s only have 3 (stock, + 0.5", and +1.1"). I really like the Bilsteins, but it would have been nice to get the advertised lift, and have a setting in between the 2 lift settings like previous generations which would have been perfect for me. I was also bummed about the height difference from side to side as the truck sat perfectly level prior to the change in struts, but these are small gripes.

Bilstein 5100s + B8 UCA on stock tire.

The Bilsteins added a noticeable amount of lift in the front along with ride and handling improvements that were immediately noticeable. They are worth the change even if you're not wanting to add any height IMO. Stock tires had to go. I've tried a few different options over the years and have had the best luck with the BFG A/T KO2. They didn't have the size I wanted, but the 295/70/18s were close. If nothing else it was nice to have a tire that balanced and wasn't distractingly loud. It was close, but they did rub a touch. It was only at full right lock in reverse, and when hitting some large bumps at speed, but I don't tolerate rubbing tires.

Bilstein 5100s + B8 UCA on BFG 295/70/18 tires.

In spite of the few instances of rubbing and slightly heavier tire, I really liked the strut / shock and tire changes. The tires added approximately 1 inch of overall height. The goal was to keep some rake while eliminating rubbing. I wasn't sure what I could pair with the 5100s to hit the sweet spot while staying within spec in the front, and unfortunately I didn't see many options in the 1/2 to 1 inch lift range. It seemed like most of the level kits above 1 3/4" used a combination of upper and lower spacers, so I thought that the added length of the front struts might be a possible substitute for the lower spacer. The idea being the 5100s might allow for the simple addition of an upper spacer to replicate other leveling kits.

Here's the final product.

Bilstein 5100s + B8 UCA + Ready Lift 1.5" upper spacers on BFG 295/70/18 tires.

Driving Impressions: As stated previously, handling and overall ride are significantly improved. I had a few weeks to drive the truck with the Bilsteins and stock tires to judge how they affected things. The added height in the front from the spacers either didn't have a significant effect and/or is negated by the Bilsteins. The only noticeable difference in the tires on the road are that the new tires balance properly and are quiet. I've had plenty of experience with these tires to know what to expect. I would have liked to try out the KO3, but they're not really available at the moment.

Suspension Height differences: While the truck sat level from side to side originally, there is around 1/8" of difference from the right to the left now. Due to the difference, the figures I post are the average of the right and left. All measurements were from the ground to the bottom of the fender directly above the center of the wheel. Measurements were taken before and after the tire change which resulted in an increase of overall height by approximately 1 1/8" over the stock tire. I have the exact measurements on all 4 corners at each stage and have subtracted the increase due to tires. The final product sits nearly level depending on level ground. I'm hoping for a touch of settle.

- Front:

- Bilstein 5100 struts set @ 1.1" lift: + avg 0.9" (29/32") over stock.

- 5100s @ 1.1" + Ready Lift 1.5" upper spacer: + avg 2.15" (2 5/32") over stock.

- Suspension mods + BFG 34" tires: + avg 3.375" (3 3/8") over stock.

- Rear height was increased by 1.125" (1 1/8") over stock attributed mostly to tires.

The current plan is to allow everything to settle over the next couple of weeks and re-measure when I retorque bolts and check the alignment. I would like to and am considering dropping the 5100s to the middle setting (+ 0.5" lift). If I do this and there is no rubbing I will update this thread in the future. There's probably much better ways to go about this, but so far so good. Hope there is some useful tidbits for someone down the line. If you got this far, thanks for reading.

TL;DR - Approximately replicated other leveling kits that include top and bottom spacers + UCAs with Bilstein 5100s, B8 upper control arms, and Ready Lift 1.5" spacers. Results is an average of 2.15" of front lift allow 295/70/18 BFG KO2 tires (approx 34.3" dia) to be ran w/o rubbing. Truck aligns to factory specs, better handling, better overall ride, negligible increase in CV angle, and nothing in front end required significant tension to install.

Edited March 6, 2024 by DrNick

fondupot · March 8, 2024

Looks good!

RedLT · March 13, 2024

On 3/5/2024 at 6:36 PM, DrNick said:

Hey all. I know there's a ton of info out there about leveling kits for T1 trucks, but when I was researching for my truck I didn't seem to find much info on some of the options and combinations I was considering so hopefully this might help someone else in the future.

* TL;DR at the bottom of the post.

Here's my rig in stock trim. 2022 Limited GMC AT4. This spot isn't exactly level, but it's close enough that it doesn't register on the truck's angle sensor. I suck at taking pics, but I wanted to show the changes from the different steps of this process. Story time.

I've had a 4WD GMC or Chevrolet truck (usually in Z71 trim) from each generation starting with my 1993 and they seem to be getting better with each generation. I love my 22 Limited AT4, but couldn't stand the Rancho shocks. Especially when towing. All the trucks I had before my most recent 2017 had OEM Bilstein shocks, and to me that's the feel I expect for a GM truck. I had a set of Bilstein 5100s on my 2017 Z71 which provided enough front end lift to run the tires I wanted along with handling improvements, so I knew I wanted to go that route again. In retrospect I should have looked closer at the 6112s for the front, however I'm not 100% confident I wouldn't have been in the same boat as my 5100s didn't actually provide the advertised increase in ride height (more on that later) and given they include springs it would have been more difficult to find something to pair. The stock tires also left a lot to be desired. At 25k miles they were already unreasonably loud to the point passengers would complain and they stopped balancing properly at about 20k miles. After a year with this truck I was ready for new shocks and tires.

I enjoy SCCA RallyX and tow my RallyX car / gear for race weekends. The plan was not to level the truck as I wanted to keep some rake to help with towing. Since a true 33" tire wasn't available in the tire I wanted to run, I decided on a 295/70/18 or a touch over 34". I had seen some guys running similar sized tires with not much lift, so I thought I had a good shot to get by with a set of Bilstein 5100s. I also snagged a set of the Bilstein B8 upper control arms to give the best shot at keeping a decent ride and OE alignment specs.

First step was the Bilstein 5100s and UCAs with the stock tires. The 5100 series claims +1.1" of ride height in the front. Unfortunately I only gained 7/8" (FL) and 15/16" (FR), but it was close enough. The rears saw negligible height increase.

* Side note: previous 5100 sets ran on other trucks provided 4 different height adjustment levels, where as the current set of 5100s only have 3 (stock, + 0.5", and +1.1"). I really like the Bilsteins, but it would have been nice to get the advertised lift, and have a setting in between the 2 lift settings like previous generations which would have been perfect for me. I was also bummed about the height difference from side to side as the truck sat perfectly level prior to the change in struts, but these are small gripes.

Bilstein 5100s + B8 UCA on stock tire.

The Bilsteins added a noticeable amount of lift in the front along with ride and handling improvements that were immediately noticeable. They are worth the change even if you're not wanting to add any height IMO. Stock tires had to go. I've tried a few different options over the years and have had the best luck with the BFG A/T KO2. They didn't have the size I wanted, but the 295/70/18s were close. If nothing else it was nice to have a tire that balanced and wasn't distractingly loud. It was close, but they did rub a touch. It was only at full right lock in reverse, and when hitting some large bumps at speed, but I don't tolerate rubbing tires.

Bilstein 5100s + B8 UCA on BFG 295/70/18 tires.

In spite of the few instances of rubbing and slightly heavier tire, I really liked the strut / shock and tire changes. The tires added approximately 1 inch of overall height. The goal was to keep some rake while eliminating rubbing. I wasn't sure what I could pair with the 5100s to hit the sweet spot while staying within spec in the front, and unfortunately I didn't see many options in the 1/2 to 1 inch lift range. It seemed like most of the level kits above 1 3/4" used a combination of upper and lower spacers, so I thought that the added length of the front struts might be a possible substitute for the lower spacer. The idea being the 5100s might allow for the simple addition of an upper spacer to replicate other leveling kits.

Here's the final product.

Bilstein 5100s + B8 UCA + Ready Lift 1.5" upper spacers on BFG 295/70/18 tires.

Driving Impressions: As stated previously, handling and overall ride are significantly improved. I had a few weeks to drive the truck with the Bilsteins and stock tires to judge how they affected things. The added height in the front from the spacers either didn't have a significant effect and/or is negated by the Bilsteins. The only noticeable difference in the tires on the road are that the new tires balance properly and are quiet. I've had plenty of experience with these tires to know what to expect. I would have liked to try out the KO3, but they're not really available at the moment.

Suspension Height differences: While the truck sat level from side to side originally, there is around 1/8" of difference from the right to the left now. Due to the difference, the figures I post are the average of the right and left. All measurements were from the ground to the bottom of the fender directly above the center of the wheel. Measurements were taken before and after the tire change which resulted in an increase of overall height by approximately 1 1/8" over the stock tire. I have the exact measurements on all 4 corners at each stage and have subtracted the increase due to tires. The final product sits nearly level depending on level ground. I'm hoping for a touch of settle.

- Front:

- Bilstein 5100 struts set @ 1.1" lift: + avg 0.9" (29/32") over stock.

- 5100s @ 1.1" + Ready Lift 1.5" upper spacer: + avg 2.15" (2 5/32") over stock.

- Suspension mods + BFG 34" tires: + avg 3.375" (3 3/8") over stock.

- Rear height was increased by 1.125" (1 1/8") over stock attributed mostly to tires.

The current plan is to allow everything to settle over the next couple of weeks and re-measure when I retorque bolts and check the alignment. I would like to and am considering dropping the 5100s to the middle setting (+ 0.5" lift). If I do this and there is no rubbing I will update this thread in the future. There's probably much better ways to go about this, but so far so good. Hope there is some useful tidbits for someone down the line. If you got this far, thanks for reading.

TL;DR - Approximately replicated other leveling kits that include top and bottom spacers + UCAs with Bilstein 5100s, B8 upper control arms, and Ready Lift 1.5" spacers. Results is an average of 2.15" of front lift allow 295/70/18 BFG KO2 tires (approx 34.3" dia) to be ran w/o rubbing. Truck aligns to factory specs, better handling, better overall ride, negligible increase in CV angle, and nothing in front end required significant tension to install.

Looking good!

SierraStorm21 · March 16, 2024

Great write up. I just got my AT4 back from the shop today from having the the Bilstein 5100 set all the way around done. Did the 1.1" setting in the front as well. I'm still on stock 33's (275/60/20) and I seem to have lost my measurements that I took a few weeks ago prior to this. I've only driven maybe 8 miles since getting it back and I'm 39" in the front and 40.6" in the rear to the bottom of the wheel well. Overall it looks significantly better. As for ride, hard to tell yet.

Once it settles in I'll do another set of measurements. Need to adjust the headlights to compensate and I'll take some pictures tomorrow on level ground too.

SierraStorm21 · July 17, 2024

On 3/5/2024 at 4:36 PM, DrNick said:

- Front:

- Bilstein 5100 struts set @ 1.1" lift: + avg 0.9" (29/32") over stock.

- 5100s @ 1.1" + Ready Lift 1.5" upper spacer: + avg 2.15" (2 5/32") over stock.

- Suspension mods + BFG 34" tires: + avg 3.375" (3 3/8") over stock.

- Rear height was increased by 1.125" (1 1/8") over stock attributed mostly to tires.

The current plan is to allow everything to settle over the next couple of weeks and re-measure when I retorque bolts and check the alignment. I would like to and am considering dropping the 5100s to the middle setting (+ 0.5" lift). If I do this and there is no rubbing I will update this thread in the future. There's probably much better ways to go about this, but so far so good. Hope there is some useful tidbits for someone down the line. If you got this far, thanks for reading.

TL;DR - Approximately replicated other leveling kits that include top and bottom spacers + UCAs with Bilstein 5100s, B8 upper control arms, and Ready Lift 1.5" spacers. Results is an average of 2.15" of front lift allow 295/70/18 BFG KO2 tires (approx 34.3" dia) to be ran w/o rubbing. Truck aligns to factory specs, better handling, better overall ride, negligible increase in CV angle, and nothing in front end required significant tension to install.

Do you remember what the stock ride height difference was originally? I ask because I've done the Bilstein 5100's all the way around, position 3, like you have and the difference is 2" between front and back. With my 34's I'm at 41.5" in the back and 39.5" in the front. I lost my original measurements somewhere and don't remember the stock rake. Just seems like it's more than it should be.

I've jacked up the truck to look and make sure the shop did it right, given my other thread about the lack of replacing the nut on the UCA, but it appears right.

I even went down to the local GMC dealer to measure the rake on their new stock AT4 and AT4X. The X had a 3" rake from back to front while the AT4 only had a 2. I couldn't get inside to see what mileage was on either rig as the sales people were busy with other folks.

Does anyone know their rake or could measure it on their stock AT4?

terranceclothtowel · November 14, 2024

This looks great! I'm considering a similar set up and have a few questions.

Do you notice any difference in performance, like handling or acceleration?

I find mixed reviews on whether or not the truck needs re-programming to make the speedometer and odometer accurate. Did you have it re-programmed, or is that something most people aren't doing?

Do you know if running 34s voids the warranty?

Syclone3MT · December 5, 2024

Bilstein 6112 set at 1.2" level but netted about 1" with my 3.0 Diesel, rough country upper control arms. Fuel Vector 17x8.5 +7mm wheels with BF K03 285/75/17 tires. Tires measure just shy of 34".