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GM's official T-Bar adjustment procedure


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Ok, y'all. Here it is. This is the actual offical method of getting those torsion bars adjusted perfectly. No problem, piece of cake! You'll want to rush out immediatel and do this! :fume: You ready? Ok, here we go. To ensure some brevity, I did edit out some intro stuff at the beginning:

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Measure fender wheel-opening heights, front and rear, to quantify vehicle lean. Fender wheel-opening heights are related to, but distinct from, trim height (a.k.a. Z and D height).

 

The front wheel-opening height is known as P height, and the rear wheel-opening height is know as R height. The P and R heights are not set at the factory, nor is a specification given for them. However, they are the most direct and repeatable measurement of what a customer would see as the vehicle leaning. Perform the following before measuring the fender wheel-opening heights:

 

Make sure the vehicle is on a level surface...

 

P Height and R Height Measurements:

 

P height and R height are measured the same way. They are the distance from the ground to the highest point on their respective wheel-opening, going through the center of their respective wheel.

 

If the difference left to right, P and or R height is 12 mm or less no repairs are suggested as the vehicle is within specification. If the difference left to right exceeds 12 mm follow 1 of the 3 diagnostics below.

 

If P height is more than 12 mm different left to right, and R height is more than 12 mm different from left to right. Check Z height and D height. See Trim Height Inspection Procedure. If Z height is out of spec and D height delta is greater than 12 mm, adjust Z height until it is within spec and P and R height deltas are less than 12 mm. If Z height is within spec but D height delta is greater than 12 mm, adjust Z height to reduce P and R height deltas to less than 12mm, staying within the Z height tolerances. If this is not possible, check front eye of rear leaf spring for matching color-coded tape or paint. Both sides should be the same color. If not, switch springs side to side. If so, replace leaf spring on lower side only. Recheck Z, D, P, and R heights. If Z height is out of spec but D height delta is less than 12 mm, adjust Z height until it is within spec and P and R height deltas are less than 12 mm. If this is not possible, shim the front fenders and box as needed. If Z height is within spec and D height delta is less than 12 mm, adjust Z height, within tolerance, until P and R height deltas are less than 12 mm. If this is not possibile, shim body and/or pick-up box until P and R height deltas less than 12 mm.

 

If P height is within 12 mm left to right, and R height is more than 12 mm different from left to right, check Z height and D height. See Trim Height Inspection Procedure. If Z height is out of spec and D height delta is greater than 12 mm, adjust Z height until it is within spec and P and R height deltas are less than 12 mm. If Z height is within spec but D height delta is greater than 12 mm, adjust Z height to reduce P and R height deltas to less than 12 mm, staying within the Z height tolerances. If this is not possible, check front eye of rear leaf spring for matching color-coded tape or paint. Both sides should be the same color. If not, switch springs side to side. If so, replace leaf spring on lower side only. Recheck Z, D, P, and R heights. If Z height is within spec and D height delta is less than 12 mm, shim body and/or pick-up box until P and R heights are within 12 mm left to right.

 

If P height is more than 12 mm different from left to right, and R height is within 12 mm left to right. Check Z height and D height. See Trim Height Inspection Procedure. If Z height is out of spec and D height delta is greater than 12 mm, adjust Z height to spec. Recheck P, R, and D heights. If Z height is within spec and D height delta is less than 12 mm, adjust Z height, staying within tolerance, until P height delta is less than 12 mm and R height delta is less than 12 mm. If this is not possible, add fender shims as necessary to make P and R height deltas less than 12 mm. If Z height is out of spec and D height delta is less than 12 mm, adjust Z height until within spec and P and R height deltas are less than 12 mm. If this isn’t possible, check D height with Z height in spec. If D height delta is greater than 12 mm, then check front eye of rear leaf spring for matching color-coded tape or paint. Both sides should be the same color. If not, switch springs side to side. If so, replace leaf spring on lower side only. Recheck Z, D, P, and R heights. If Z height is within spec and D height delta is greater than 12 mm, shim front fenders to get P height delta less than 12 mm.

 

After all adjustments are done, perform a front-end alignment and check headlight aim.

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:flag:

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I don't see any mention of torsion bars in that.  All I see is leaf springs.

 

 

 

When I pasted the instructions, I left out the title in my copy selection. However, it is part of the P Height.... Beyond that, don't get me lying.

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We had that in our engineering class the other day. It's too simple. just take the tangent of the two angles made with the passenger and driver's seats and the floor, multiply by 9.82 and then add the correct amount of headlight fluid as calculated by the equation. Now how easy is that. Or maybe that was the equation for bra removal. If not it's close. :flag: Now that's how you do it. :fume:

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Can you repeat all that again :cool:  :cool:  :D  :crackup:  :D  :D

 

 

 

HEH! The next time I'm challenged for not adjusting my T-BARS (I don't have a heavy brush guard, and I don't know what a snow plow is), I'm just going to quote that article. :)

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Hey man, what the heck are the Z and D height and adjustments and where are the trim adjustment instructions? My truck is pretty out of whack on all four corners. I could use a little more enlightenment if you have time. Thanks..

 

These are my trucks' measurements:

Fr. pass - 35 3/8"

Fr. driv - 34 1/2"

Rr. pass - 38 1/16" (taken with tape flush against wheel inside flare)

Rr. driv - 37 5/8" "

 

Its pretty effed up so I was gonna take a swing at adjusting it before the dealer plays with it. Thanks for any help..

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