cadillacbob Posted August 2, 2009 Report Share Posted August 2, 2009 I am posting today to request one of the GM tech guys to post the pages from the service manual on how to measure the 'Z' trim height... I had downloaded the pages off of the GM tech service bulletin web site, but I don't have access anymore because I don't work in a car plant...and I lost my pages I am certain it was the first measurement that GM recommended an alignment tech do/measure before doing an alignment... I am certain that it was a measurement of the difference in height from the ground of the lower ball joint and the lower controll arm mounting bolt...As usual THANKS in advance...Maybe we could make this a 'sticky'???...Bob Quote Link to comment Share on other sites More sharing options...
BigCountry Posted August 3, 2009 Report Share Posted August 3, 2009 I am posting today to request one of the GM tech guys to post the pages from the service manual on how to measure the 'Z' trim height...I had downloaded the pages off of the GM tech service bulletin web site, but I don't have access anymore because I don't work in a car plant...and I lost my pages I am certain it was the first measurement that GM recommended an alignment tech do/measure before doing an alignment... I am certain that it was a measurement of the difference in height from the ground of the lower ball joint and the lower controll arm mounting bolt...As usual THANKS in advance...Maybe we could make this a 'sticky'???...Bob Superlift has it in their lift kit instructions if you wanna dig around on their site. Quote Link to comment Share on other sites More sharing options...
cadillacbob Posted August 3, 2009 Author Report Share Posted August 3, 2009 (edited) found this on another Chevy site... OUR SS trucks are 3 1/2" +-1/4' Trim height is a predetermined measurement relating to vehicle ride height. Incorrect trim heights can cause bottoming out over bumps, damage to the suspension components and symptoms similar to wheel alignment problems. Check the trim heights when diagnosing suspension concerns and before checking the wheel alignment. Perform the following before measuring the trim heights: Make sure the vehicle is on a level surface, such as an alignment rack. Remove the alignment rack floating pins. -Set the tire pressures to the pressure shown on the certification label. Refer to Label - Vehicle Certification in General Information. -Check the fuel level. Add additional weight if necessary to simulate a full tank. To ensure proper weight distribution make sure the rear storage compartment is empty. Close the doors and hood. Z Height Measurement Important K models only the Z height must be adjusted before the alignment. The Z height dimension measurement determines the proper ride height for the front end of the vehicle. Vehicles equipped with torsion bars use a adjusting arm in order to adjust the Z height dimension. Vehicles without torsion bars have no adjustment and could require replacement of suspension components. Important All dimensions are measured vertical to ground. Cross vehicle Z heights should be within 12 mm (0.47 in) to be considered correct. <<See attachment for image to acompany following instructions.>> 1. Place hand on the front bumper and jounce the front of the vehicle. Make sure that there is at least 38 mm (1.5 in) of movement while jouncing. 2. Allow the vehicle to settle into position. 3. Measure from the pivot bolt center line (2) down to the lower corner (5) of the lower steering knuckle (1) in order to obtain the Z height measurement (4). 4. Repeat the jouncing operation 2 more times for a total of 3 times. 5. Use the highest and lowest measurements to calculate the average height. 6. The true Z height dimension number is the average of the highest and the lowest measurements. Refer to Trim Height Specifications . Z Height Adjustment 1. For vehicles equipped with a torsion bar suspension turn the bolt (1) that contacts the torsion arm as needed. One revolution of the bolt (1) into the nut increases the Z height by approximately 6.0 mm (0.2 in). 2. For vehicles without torsion bars, replace damaged or worn components as necessary. 3. If these measurements are still out of specifications after adjustment or are not equipped with torsion bars, inspect for the following: Sagging front suspension. Refer to Torsion Bar Replacement in Front Suspension. Collision Damage SPEC MEASURMENTS: 92mm (3.5") ideal ---------------------------- I don't know if this helps or answers your question but lets you know what GM checks for and how to check if your vehicle is "within spec" for what it's worth. I will look for a pic...Pic is not off of GM Service bulletin site....but it clarifies the directions... Edited August 3, 2009 by cadillacbob (see edit history) Quote Link to comment Share on other sites More sharing options...
chris B Posted August 4, 2009 Report Share Posted August 4, 2009 Thanks bob Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.