Off-Road Suspension and Snow Plow Prep Packages

newdude · February 2, 2017

Has anyone checked the "upcharge" of the options separately & when ordered together? I know in the past 1 of them was discounted quite a bit when ordered together since some of the components are common (skid plates for 1). It may not be the case since the Z71 doesn't appear to have HD torsion bars (can anyone confirm this?)

The torsion bars on my '17 gasser w/ VYU has these labels: AA7 (LH) & AA8 (RH).

Correct, Z71 does not get any higher rated torsion bars on its own. If you have 4x4 or Z71 and VYU, you get the higher rated bars. No VYU, no higher rated front bars.

Delta Hotel · February 8, 2017

Does a Z71 ride any higher than a comparable 4x4? (1500 or HD)

It does appear so....

redwngr · February 8, 2017

Snow plow option info here:

https://www.gmupfitter.com/files/media/photo/773/2017_LD_Snow_Plow_11_18_2016.pdf

One of the reasons GM uses torsion bars is for ride height adjustment. Plow weight decreases height and can it be adjusted back to normal. When plow is removed for the summer, ride height can be lowered to standard to maintain ride quality.

revrnd · February 9, 2017

Snow plow option info here:

https://www.gmupfitter.com/files/media/photo/773/2017_LD_Snow_Plow_11_18_2016.pdf

One of the reasons GM uses torsion bars is for ride height adjustment. Plow weight decreases height and can it be adjusted back to normal. When plow is removed for the summer, ride height can be lowered to standard to maintain ride quality.

Does anyone know if there are specs for the "Z" height on the newer models? Those that have done front end work will know what I'm talking about. On the GMT400s we had checking fixtures for setting it on the line, but nothing on the GMT800 & 900 models.

redwngr · February 9, 2017

Does anyone know if there are specs for the "Z" height on the newer models? Those that have done front end work will know what I'm talking about. On the GMT400s we had checking fixtures for setting it on the line, but nothing on the GMT800 & 900 models.

I had the 800 service manuals, and can verify that they included the number.

Maybe someone in the service department will look it up for you -- or perhaps someone on here has the 'Z' dimension and can post.

newdude · February 9, 2017

Does anyone know if there are specs for the "Z" height on the newer models? Those that have done front end work will know what I'm talking about. On the GMT400s we had checking fixtures for setting it on the line, but nothing on the GMT800 & 900 models.

2011-2014 GMT-900 and 2015-2018 K2 Trim Height (Z Height) specs are as follows:

C/K2500-C/K3500 - All cabs/engines

Service Allowed: 128–140 mm (5.0–5.5 in)

Service Preferred: 134 mm (5.3 in)

Cross Z Trim Height, L-R: 0 ± 12 mm (0.47 in)

Cross D Trim Height, L-R: 0 ± 12 mm (0.47 in)

D Height is specified as the measurement from the bottom of the jounce bumper cup, to the jounce bumper pad on the rear axle.

Z Height is specified as using a level from the bottom of the steering knuckle (where the nut holds the lower ball joint stud), take the level and measure from the center of the lower control arm bolts (front and rear), to the point where the level is under them.

Here is a rudimentary drawing I did many years ago on Z Height:

Z Height is the vertical line on the right. The bottom line represents the level used as the "level surface".

revrnd · February 9, 2017

2011-2014 GMT-900 and 2015-2018 K2 Trim Height (Z Height) specs are as follows:

C/K2500-C/K3500 - All cabs/engines

Service Allowed: 128–140 mm (5.0–5.5 in)

Service Preferred: 134 mm (5.3 in)

Cross Z Trim Height, L-R: 0 ± 12 mm (0.47 in)

Cross D Trim Height, L-R: 0 ± 12 mm (0.47 in)

D Height is specified as the measurement from the bottom of the jounce bumper cup, to the jounce bumper pad on the rear axle.

Z Height is specified as using a level from the bottom of the steering knuckle (where the nut holds the lower ball joint stud), take the level and measure from the center of the lower control arm bolts (front and rear), to the point where the level is under them.

Here is a rudimentary drawing I did many years ago on Z Height:

Z Height is the vertical line on the right. The bottom line represents the level used as the "level surface".

Great explanation for those that probably were scratching their head after I mentioned it. The fixture we used was spring loaded on the LCA fasteners (on both sides) & had a finger that touched the knuckle. A pointer was at the other end of the finger & "interacted" with a graduated scale (by model & option). The operator adjusted the bolts until the pointer was in the correct range.

newdude · February 9, 2017

Great explanation for those that probably were scratching their head after I mentioned it. The fixture we used was spring loaded on the LCA fasteners (on both sides) & had a finger that touched the knuckle. A pointer was at the other end of the finger & "interacted" with a graduated scale (by model & option). The operator adjusted the bolts until the pointer was in the correct range.

Noice! I see you retired from Oshawa? Pretty neat. Took me a sec to notice that after reading your reply which was very detailed from an assembly point of view.

The K2 1500 trucks have some differences in trim heights depending on suspension and 2x4/4x4. I guess GM felt the HD trucks it didn't matter so much .

revrnd · February 10, 2017

Noice! I see you retired from Oshawa? Pretty neat. Took me a sec to notice that after reading your reply which was very detailed from an assembly point of view.

The K2 1500 trucks have some differences in trim heights depending on suspension and 2x4/4x4. I guess GM felt the HD trucks it didn't matter so much .

Thanks. That's why I've been looking at the DSA from an "in house" perspective. I recall a problem 1 of my co-workers was dealing w/. I was peripherally involved when the process stopped. Turns out we had 2 vendors & we only had problems when the parts were from 1 of the vendors.