Sagging front end 2004 Z71

[mysticstiles1]

I just recently picked up a 2004 Z71 Tahoe with 123k on the clock. One of the first things I noticed was the front end seemed lower than other Tahoe's/Suburban's I have owned, and the drivers side was noticeably lower than the passenger side. On past vehicles when I cranked the torsion bars, even minimally, it created a noticeable lift in the front. I crawled under the Tahoe to discover the drivers side torsion key adjuster screw was ******* in pretty pretty much all the way in, the passenger side was ******* in maybe half way. I ended up ordering a set of lift keys, installed them and had the same outcome, I was able to make it look decent side to side by screwing the drivers side in almost all the way, but the passenger side screw is minimally tightened and the front is still low, definetely lookes lower in the front than the rear. I took it apart and tried to index the keys differently, but there would be no way to install them, they are pointed toward the ground.

Is it possible to have a worn out torsion bar? Worn out opening where the in the lower control arm? Are there other suspension components that can cause the front ride height to be low?

 

[scotto0609]

Check the frame and components for collision damage..

 

[mysticstiles1]

No noticeable damage...

 

[Project Denali]

Torsion bars are a spring in a basic sense so they can sag and wear but it is probably dependent on how the truck has been used. I would imagine plowing, or towing heavy loads would be harder on them. I wouldn't imagine that most trucks with 123k miles would experience bad torsion bar/bars but it is possible. Have you measure the heights to each wheel well? That would give you a reference of how different each side is (measure on flat ground of course).

 

[Dannygtrr]

Any update on this? Iv read more of these and I am also getting more sag on driver side.

 

[Twinsoffroad]

Also curious if anyone has a solution for the driver side lean. Mine is about 3/4” lower on the driver side front and rear measured from the fenders. I saw another forum someone mentioned replacing the swaybar links helped which did nothing for me. Might just add a 3/4” spacer on the rear left shock to see how that helps it.

 

[OR VietVet]

Also curious if anyone has a solution for the driver side lean. Mine is about 3/4” lower on the driver side front and rear measured from the fenders. I saw another forum someone mentioned replacing the swaybar links helped which did nothing for me. Might just add a 3/4” spacer on the rear left shock to see how that helps it.

A shock is there to absorb spring action and adding a spacer will have no effect. If it does, I will be completely surprised. The only shock that lifts is assisted with air or some other design.

 

[Donal]

I just recently picked up a 2004 Z71 Tahoe with 123k on the clock. One of the first things I noticed was the front end seemed lower than other Tahoe's/Suburban's I have owned, and the drivers side was noticeably lower than the passenger side. On past vehicles when I cranked the torsion bars, even minimally, it created a noticeable lift in the front. I crawled under the Tahoe to discover the drivers side torsion key adjuster screw was ******* in pretty pretty much all the way in, the passenger side was ******* in maybe half way. I ended up ordering a set of lift keys, installed them and had the same outcome, I was able to make it look decent side to side by screwing the drivers side in almost all the way, but the passenger side screw is minimally tightened and the front is still low, definetely lookes lower in the front than the rear. I took it apart and tried to index the keys differently, but there would be no way to install them, they are pointed toward the ground.

Is it possible to have a worn out torsion bar? Worn out opening where the in the lower control arm? Are there other suspension components that can cause the front ride height to be low?

A Chilton repair manual is available for down load on this site. Scetion 10-4 explains with picts how to inspect, replace and adjust the torsion bars. Remember that previous owners may have modified components and replaced components with non-oem parts and you may have to start with idinitifing (cant spell identifying,) and start over with correct parts to get near factory set up and performance.

 

[Twinsoffroad]

A shock is there to absorb spring action and adding a spacer will have no effect. If it does, I will be completely surprised. The only shock that lifts is assisted with air or some other design.

My bad! Meant to say coil spacers.

 

[Donal]

I just recently picked up a 2004 Z71 Tahoe with 123k on the clock. One of the first things I noticed was the front end seemed lower than other Tahoe's/Suburban's I have owned, and the drivers side was noticeably lower than the passenger side. On past vehicles when I cranked the torsion bars, even minimally, it created a noticeable lift in the front. I crawled under the Tahoe to discover the drivers side torsion key adjuster screw was ******* in pretty pretty much all the way in, the passenger side was ******* in maybe half way. I ended up ordering a set of lift keys, installed them and had the same outcome, I was able to make it look decent side to side by screwing the drivers side in almost all the way, but the passenger side screw is minimally tightened and the front is still low, definetely lookes lower in the front than the rear. I took it apart and tried to index the keys differently, but there would be no way to install them, they are pointed toward the ground.

Is it possible to have a worn out torsion bar? Worn out opening where the in the lower control arm? Are there other suspension components that can cause the front ride height to be low?

Use the search feature to locate many conversations regarding the front suspension of Tahoe and yukon behicles (same as vehicles.) Appears as if some members are reluctant to repost data and information just posted last month.
Well, maybve new informaion (similar to information,) is needed.

The torsion bars are steel bars forged with a hex section on each end to provide holding relative load of torsion. The hex allows for longitunidal movement avoid loads to the length of the bar. the hex is ellipitical as well to avoid additional torsion parasitic loads caused by the torsion load by one end of the bar is fixed at the rear crossmember, but the other end is fixed to the lower control arm which pivots around a different axis than the torsion bar axis. Now the bar is forged from a carbon steel and all steels have an elastic range and when loaded, stretch, twist, or change dimension and when load decreased, return the the unloaded dimension. Steel also has a plastic range and when load exceeds the elastic range the steel yields and when the loads is decreased, the unloaded deminsion is now different. If you want to learn and understand the torsion bar suspension, search for 1957 Desoto cars, memory kicked in make that 1957 . Desoto was the first to design and offer torsion bar suspenson in 1955. ok so back to the future and apply this informatin to your vehicle. The Desoto cars and International travelall vehicle bars pivoted on the same axis as the lower control arm and did not need the ellipitical feature.
NOW The bars may have been over loaded by intention or accident and may not ever return to the as installed dimension and provide new performance.

 

[Donal]

While I am thinking about it. The torsion bars are springs that provide the spring in suspension. Some vehicles use coiled bars steel to provide the spring. All steel have the same modulus of elasticity, some just go into plasitc deformation at lower loads. So, if you measure the length of the torsion bars you see that are about 48 inches in length. If you go to some off brand of vehicle of similar size, you may see the coiled springs and the coils are about 8 inches across. If you leasure the around one coil you will see the llength of the coil is about 25 inches. Both of the springs, bar and coils are loaded in torsion or twisting load when inservice in the vehicle. So one vehicle the suspension height is provided one bar of steel about 48 inches and the other is provided by a bar of steel many times longer, number of coils times the length of each coil. So the Tahoe ride height is provide by a bar loaded in the elastic range. Along comes someone that wants to change the ride height of the vehicle by incresing the load on the torsion bar. Well, small adjustments are made and all is good. Sso let change the ride height even more and we dont have time to jack up the vehicle to unload the bars. We gonna getter done. Soon the bar load is sufficient to take the bar operating load to the plastic range, never to return to the original dimension. So here and now, we have a new owner that thinks wow what beautiful Tahoe. But why does it sag and why does it steer funny and why does the tires wear funny and why do the tires go in at the top when I back up, etc. O the moral. If you want to raise or lower vehicle get the components to make the change. If you need to convert to the coil over option. Go

 

[BlueBurb04]

I'm having the same issue on my 04 Suburban (hope it's ok to post here with a Suburban). Drivers side bar sags. Even with lift keys. I can barely get it airspace between the lower arm and bump stop. And that's with junk yard Z71 bars. (Mine is not a Z71 Called the parts guy at the dealer we use, looking for 04 Suburban Z71 bars (Z71 bars have a much higher torque rating), there is one passenger side left in the country, and the drivers side is discontinued. Ugh. With how popular these trucks are, it makes no sense that the aftermarket doesn't make replacement torsion bars!

 

[OR VietVet]

I'm having the same issue on my 04 Suburban (hope it's ok to post here with a Suburban). Drivers side bar sags. Even with lift keys. I can barely get it airspace between the lower arm and bump stop. And that's with junk yard Z71 bars. (Mine is not a Z71 Called the parts guy at the dealer we use, looking for 04 Suburban Z71 bars (Z71 bars have a much higher torque rating), there is one passenger side left in the country, and the drivers side is discontinued. Ugh. With how popular these trucks are, it makes no sense that the aftermarket doesn't make replacement torsion bars!

Maybe this will help

Torsion Bar Reference :: SuspensionMAXX

SuspensionMAXX Adjustable Leveling Kits. Less expensive than lift kits. Adjustable torsion bar keys, extended sway bar links. Chevy, Ford, Dodge, Toyota, GMC, Hummer and more. Get the "Just Right" amount of leveling lift for your needs with a SuspensionMAXX adjustable leveling kit.

suspensionmaxx.com

 

[Fless]

I'm having the same issue on my 04 Suburban (hope it's ok to post here with a Suburban). Drivers side bar sags. Even with lift keys. I can barely get it airspace between the lower arm and bump stop. And that's with junk yard Z71 bars. (Mine is not a Z71 Called the parts guy at the dealer we use, looking for 04 Suburban Z71 bars (Z71 bars have a much higher torque rating), there is one passenger side left in the country, and the drivers side is discontinued. Ugh. With how popular these trucks are, it makes no sense that the aftermarket doesn't make replacement torsion bars!

You shouldn't have any space between the lower control arm and the jounce (not "bump") stops. See this link for more detail:

Front Bump Stop Issue

Previous owner hacked off the front bump stop cups and I am having a helluva time find some sort of replacement to bolt In. Truck is an 01 Tahoe with belltech drop spindles, Purple Keys and Stock replacement shocks. The front end bounces really bad and sways when going over bumps and dips...

www.tahoeyukonforum.com

 

[Alex_M]

The drivers side lean is super common on a wide range of vehicles at a certain age, and very well documented particularly on full size trucks. This generation Tahoe/Suburban/Silverado has been starting to enter that age in the last few years. The drivers side sag is because of the additional weight carried on the drivers side, ie. the driver and the gas tank.

I have seen many creative solutions. Some folks swap springs side to side, some folks add helper leaves (in leaf sprung vehicles) to the sagging side, some just crank up the drivers side torsion bar (in vehicles with torsion bars like our Tahoe's). For me, the low buck option is to swap the rear springs side to side and crank the drivers torsion bar up. The "correct" repair would be to install all new springs front and rear, but realistically the cost outweighs the benefit on most vehicles of this age, except for some enthusiasts.

For an extreme case, which yours (OPs) sounds like, I would look into getting a set of torsion bars out of the junk yard. Make note of which is driver, which is passenger if they are not marked.

Now, this piece is important. Some, not all, but some GMs of this generation have torsion bars that are factory marked left and right (from the drivers perspective). These are easy to tell because they have an L and an R cast into the end. You cannot swap them side to side. The truck will either set on the bump stops, or it will be almost impossible to get the torsion key installed and once you manage to there will be so much preload (even at the lowest setting) that the suspension will be at full droop/max height all the time.

In my experience if they are not marked left to right then they are the heavier spring rate torsion bars. If you use these the ride will be a bit rougher and a fair bit taller as well. I cannot remember the numbers off hand, but both sets have numbers cast into them. This *may* have been a Z71 option, it *may* have been a factory plow package, or it's even possible that I have unknowingly parted out a half ton truck that someone put 2500 torsion bars in. The last I think is unlikely. If it were me, I would look for a set that were standard marked left and right, and use the lift keys you have.

One other note for others who may find this since I brought up 2500 torsion bars, 2500 stock torsion keys actually lower a half ton truck and vice versa.