Rear air suspension - shims to adjust height?

[dochummer]

So, just got back from my local GM dealer. I had them check the rear suspension squat issue, and even gave them a print-out of the correct z and d height measurements as well as instructions on what to do with it. They said it was all within normal. He measured the z height and that was fine. I asked him about the d height, and he said that he just measure from all the pivot points to the ground and they were all even, and they even put a level on top of the vehicle, and said it had a slight forward rake. So I asked him about the d height measurement, and he said that there was no fix for the rear, and if I wanted to bring up the front, it would really look funny. (i never questioned the front height...) So I'm back at square one.

Has anybody put shims in above the sensors as a fix? I figured if the sensors were dropped a little, then it would raise the suspension height. Either that, or take it 3 hours to the nearest hummer dealer, and hope they'll fix it...

I guess, last resort...buy a new one?

[dochummer]

So, just got back from my local GM dealer. I had them check the rear suspension squat issue, and even gave them a print-out of the correct z and d height measurements as well as instructions on what to do with it. They said it was all within normal. He measured the z height and that was fine. I asked him about the d height, and he said that he just measure from all the pivot points to the ground and they were all even, and they even put a level on top of the vehicle, and said it had a slight forward rake. So I asked him about the d height measurement, and he said that there was no fix for the rear, and if I wanted to bring up the front, it would really look funny. (i never questioned the front height...) So I'm back at square one.

Has anybody put shims in above the sensors as a fix? I figured if the sensors were dropped a little, then it would raise the suspension height. Either that, or take it 3 hours to the nearest hummer dealer, and hope they'll fix it...

I guess, last resort...buy a new one?

[superbeast]

i was woundering the samething

[kacyk]

Hey Doc, I'm going to Bellevue soon to get my front end lowered. They lowered it on my Pewter H2 under warranty. Basically they made sure the gap between the top of the tire and the fender arch was the same all around. When I first bought the rig the front gap was two inches higher than the rear making it look like a squatting lowrider. I hated that look.

[kacyk]

After they fixed it, the car looks more level

[kacyk]

I will say, however, that after buying the yellow one I took it to the same dealership and they told me also that everything was "normal." I didn't feel like arguing so I'm just going back to the orignal service manager that helped me the first time with a copy of the original repair report. If they did it once, they can do it again!

[Hummertech]

There is a simple procedure we can do at the dealerships to learn your trim hieght at pretty much any height we want. The only problem is that most of you seem to have dealerships that are somewhere on the scale between idiots and morons. If your dealership seems to have a clue to what's going on, then just tell them that you think the rear end looks low, and even if it is within gm's specs, you would be very happy if they could recalibrate the rear trim hieght to a couple inches higher.

[dochummer]

Mine must be idiots, because they insisted that there was no fix for it. I spoke with one of the local tire shops, and they say that they've adjusted the sensors before to level out a ride...but not specifically to raise or lower the vehicle. Do you have instructions on the recalibration that I can give to the dealer to see if they would be willing to do it? I do know that my d height is about an inch low.....

[Hummertech]

OK, here is the procedure, print this up and bring it to them. Tell them to recalibrate the trim height per GM's instructions, except after they achive the measurement needed per GM's instructions, to add an inch or two (however much you want) to it, before they hit learn trim height on the scan tool.

[superbeast]

does it get stiffer riding the higher you go , since they are airing up the bags more ??

[Hummertech]

It shouldn't affect the ride at all, the shocks are what is suppossed to control the stiffness, the springs the height.

[kacyk]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Hummertech:
OK, here is the procedure, print this up and bring it to them. Tell them to recalibrate the trim height per GM's instructions, except after they achive the measurement needed per GM's instructions, to add an inch or two (however much you want) to it, before they hit learn trim height on the scan tool. </div></BLOCKQUOTE>

Hummertech,

If all else fails couldn't we just adjust the torsion bars down up front? Any harm in that?

[dochummer]

Ummm... I didn't see the print out you mentioned Hummertech. Do you still have it?

[Hummertech]

I didn't print out the recalibrating trim height procedure. All Hummer dealers should know about that. It's just doing it a little differently by setting the body an inch higher takes a little thinking outside the box, and I put what I did so if you showed that to someone that it might turn a little light on in their head and make them say, "gee, I guess you can do it like that"

[Hummertech]

Document ID# 1618897
2004 HUMMER H2


--------------------------------------------------------------------------------

Suspension Position Calibration
This procedure noted below should be performed after compressor assembly, air suspension control module, or suspension position sensor replacement. Uneven suspension position can also be corrected by performing this procedure.


Tools Required
CH-47816 Suspension Position Calibration Blocks

Important: Before proceeding with the steps below, ensure:


• There are no stored diagnostic trouble codes stored in the ASCM.

• The vehicle is on level ground.

• There are no occupants in the vehicle.

• The tire pressures are at the recommended kPa/psi.


Raise the vehicle on a hoist.



Install the CH-47816 on to the LR and RR jounce bumper mounting cups.
Lower the vehicle off the hoist.
Depressurize the air suspension system in order to allow the full rear weight of the vehicle to rest on the blocks and rear axle. Refer to Air Suspension Depressurization Procedure .
Turn ON the ignition, with the engine OFF.
Install a scan tool.
With the scan tool select Chassis.
Select Air Suspension.
Select Special Functions.
Select Trim Height Calibration and press the Enter key. The scan tool will flash Calibration In Progress, then display Calibration Complete.
Press the Exit key.
Pressurize the air suspension system until the rear weight of the vehicle is lifted of the blocks. Refer to Air Suspension Pressurization Procedure .
Remove the CH-47816 .
Cycle the ignition switch Off then start and run the engine for 2 minutes. Verify the Air Suspension system is functioning properly.

The only trick is to set the vehicle an inch higher than what the blocks hold it at, before you push recalibrate trim height on the scan tool. Everyone understand now?

[dochummer]

Thanks for the info tech. I guess I'll just have to take it to Kacyk's dealer if he can get his fixed. I think the main thing is that my local dealer just doesn't want to deal with it...

[drmiles]

Hey was reading this thread and thought, since I cranked the torsion bars for my 37's the rear appeared a little too low. Rock rail was level but the gap between the tire and the fender well looked smaller in the rear.

So, I went to the dealer and asked them to raise the rear. The tech did not know at first that the front was higher frome the torsion bar adjustment. Anyway he was able to raise it 1.5", said the sensor max was 2.87volts and mine was up to 2.82. Stated that if you go over the 2.87 max then it will set off a code. The 1.5" helped, Looks a lot better. Everyone keeps asking what lift I have.

At first the ride felt like it does when you turn on the height button. It took about 10 minutes to get use to it. Now I can't tell the diff while driving..

Great Idea, Thanks.

[dochummer]

Dr., how long did it take them to complete the adjustment? I'm wondering if I can call a hummer dealer and just stop buy to have them do it...

[agood1]

Hate to drag up an old thread, but I need to calibrate my suspension. I have the scan tool, but not the blocks. Can you tell me about how tall the blocks are? Can this be done with jack stands set to the desired height and places under the frame? What about using a lift to hold the frame at the desired height?

[DuckTruck]

Great info. fellas.

Well done,

DUCK