A “Steering/Suspension Myth” (2003 Yukon-XL , 4WD 2500, 8.1)?

[GMCbigblock]

To claify the level of my frustration with this "Myth", I like to share that am about to sell the 'Yukon-XL' as I have almost lost control over my ‘nerve system’ whenever this issue occurs while driving …..as will be explained further as follows….

For background-information; I imported the Yukon-XL ("YXL") from the US in late 2012, and it was declared being in ‘very good conditions’, has done about 130K Miles with no mechanical-failure or issue (CarFax). Honestly & so far; it is so except for ‘one particular issue’ which I recon may be either arising from defaulting AA) “steering box assembly” or BB) the “suspension control mechanizm/setup”! Although the “issue” is hard to explain, I’ll try being informative as much as I recall & can adequately describe …….

The ISSUE:When the "YXL" is driven in a straight road that is bit ‘un-leveled’ or has dents, you will notice that the ‘front-end’ tends to follow the direction of the tiny road’s dents rather than the path am steering it to. It feels as if there is a slight side-pulling force that pushes the nose towards the right-side (i.e. math speaking; it shifts across the ‘X-Axis’ left & right for short, until the road conditions become clear……The YXL's Nose will ‘side-bounce’ & go off center of the path, for few inches left & right then will stabilize). More-surprisingly; when I engage the “4WD mode”, the Burb behaves better & shows ‘enhanced control’ when compared to being in “2WD mode”!

For information, I got it checked by a Suspension-Workshop, and based on their ‘test-drive’ & advice, I replaced the complete Upper Right Arm (severely worn out), together with replacing both sides Lower-Arm’s Bushing (the big & small ones). I replaced the ‘steering-box’ with a used but clean one (close to new). The ‘ball-joints’ were advised to be in ‘very good’ conditions and showed no play (which I view a potential source of the issue). Coincidently; the “service ride control” light came “on”……And, to take the benefit of the doubt, I replaced all existing ‘auto-ride shocks’ with the new ‘standard gas shocks’, and the "YXL" is now softer on the road but the same “issue” persists (Note: after fitting the new shocks, I observe that when going over a “legal street-hump”, the Burb’s Nose dives & bounces up & down more than before)! I was thinking to buy a complete front. Now, I raised the “white flag”…..!!!

Possible causes (as I suspect) could be: 1) There may have been ‘un-compatible’ replacement parts used somewhere in the front suspension assembly? 2) There could be “different front-axle length” between the left & right ones? 3) Could it be a damaged torsion-bar in either side, as the dampening-behavior of one side (Left) is NOT the same as the other side (Right)?

Sorry for the lengthy description….but that is how the “issue” appears to be at my end!! I cannot explain it in better details & with higher level of information; given the “issue” is so weird to be detected & well defined! The "YXL" is ‘reasonably stable’ on the road but it lacks that ‘solid control & safe steering’.

As usually happening in this “great forum”, am looking for some brainstorming, best diagnoses & idea sharing; as am intending to use the "YXL" to travel very soon for about ‘2000-Mile-trip’…..Eagerly waiting for your suggestions to cure this issue & regain that ‘sharp steering & grip’.

 

[Blue85]

I don't know how bad the problem is, but it kind of sounds like the front end is out of alignment or you have a tire issue. If you drove for a while with a really bad steering arm, one or both front tires probably have strange wear on them. When parts were replaced did they align it? You might try swapping the tires front to back and see if the behaviour changes.

I have one of these vehicles and it goes down the road like a dream, so I know they can work. Although many people swap out the Autoride shocks whenever there is an issue, I think they should be retained whenever possible. Losing your active damping control is probably the reason for the increased dive.

 

[jeff in co]

I have the same vehicle too (2004) and it also drive straight and true with 110k on the odometer. I also thought of the tires and/or the particular road you are going down. I know if I go down a grooved highway or ones where large trucks have indented the asphalt, my truck tends to follow the groves. I also think this can be worse depending on the type of tire used.

I'd suggest rotating to see what happens. I would also suspect re-evaluating your front end components to be sure there isn't something else worn that you missed. With the statement "severely worn" throws up a flag the perhaps there are other components that may be in poor condition too.

 

[GMCbigblock]

I don't know how bad the problem is, but it kind of sounds like the front end is out of alignment or you have a tire issue. If you drove for a while with a really bad steering arm, one or both front tires probably have strange wear on them. When parts were replaced did they align it? You might try swapping the tires front to back and see if the behaviour changes.

I have one of these vehicles and it goes down the road like a dream, so I know they can work. Although many people swap out the Autoride shocks whenever there is an issue, I think they should be retained whenever possible. Losing your active damping control is probably the reason for the increased dive.

I have the same vehicle too (2004) and it also drive straight and true with 110k on the odometer. I also thought of the tires and/or the particular road you are going down. I know if I go down a grooved highway or ones where large trucks have indented the asphalt, my truck tends to follow the groves. I also think this can be worse depending on the type of tire used.

I'd suggest rotating to see what happens. I would also suspect re-evaluating your front end components to be sure there isn't something else worn that you missed. With the statement "severely worn" throws up a flag the perhaps there are other components that may be in poor condition too.

Gent's, thanks for the quick replies. I like to add the following important-clarifications:

1) all four tires are new, NITTO.
2) the whole front suspension has been "laser-aligned" and no sign of tire-wear is seen so far; having done more than 6000 miles on them.
3) I need the gas shocks due to sandy conditions, and auto-ride tends to lives shorter in our area!

 

[rob h]

Go thru an extensive front end check, jack it up under the control arm and check all balljoints...that's the only way on these trucks. Look at the inner and outer rod ends and the piman/idler arm. Does it sit higher on one side..?...maybe the one torsion bar is worn more than the other. Then onto the steering box, does it have play...any..? I noticed a few months ago a large amount of play in my 03 2500hd, I was thinking an seeing the steering box so I swapped it out. But that wasn't it, the new one did it too. It ended up being the upper and lower intermediate shaft. I picked up a new upper fom the from dorman and a new lower from the dealer. My play problem was solved.... Also I know when my truck was ifs it drove better to me with the oil filled superlift shocks.





Also tho I solved all front end problems and plasma cut all that crap out and put a 60 right in..lol...

 

[GMCbigblock]

Go thru an extensive front end check, jack it up under the control arm and check all balljoints...that's the only way on these trucks. Look at the inner and outer rod ends and the piman/idler arm. Does it sit higher on one side..?...maybe the one torsion bar is worn more than the other. Then onto the steering box, does it have play...any..? I noticed a few months ago a large amount of play in my 03 2500hd, I was thinking an seeing the steering box so I swapped it out. But that wasn't it, the new one did it too. It ended up being the upper and lower intermediate shaft. I picked up a new upper fom the from dorman and a new lower from the dealer. My play problem was solved.... Also I know when my truck was ifs it drove better to me with the oil filled superlift shocks.


Also tho I solved all front end problems and plasma cut all that crap out and put a 60 right in..lol...

You just pointed the discussion towards an important observation that I found recently....after one of my routine-checks of the Truck's underneath, I noted that the right & left screws of the "torsion-bar keys" are having the same level/height (i.e. one screw sets higher than the other!).....Could this mean that 'one side torsion' is cranked up more than the other one (aiming to compensate for the difference in height & level one side with the other one)? In other words, should both screws have the same height? By all means, how to detect such a possibility, any technique?

As for using oil-shocks with IFS, instead, I may consider using 'adjustable shock' for the front side, to control the nose-dive, as I hate the 'auto-ride' thing on my HD Truck (just don't like the idea to see more wires & e-stuff in that "hard-working shock-dampening place"; facing the sand & heat at all times - close to where the Asphalt's temp in our Region exceeds 180F pre & post Noon times!!).

I'll continue the "thorough check" once I have the Truck back from the Dealer (being now under one job for replacing/renewing the 'Fuel-Pump' before my travel) **

** As a side note on the 8.1 Burb's Fuel-Pump (and am not sure if many are aware of this info., but it's 1st time for me ), I was advised by the Dealer that the Truck has TWO (2) Fuel-Pumps, one in the "Main/Front Tank" and the other one in the "Secondary/Rear Tank"....In this regard, I recall seeing (few months ago) a message on 'Tech1' diagnose-device stating "insufficient fuel supply"; despite the fact that the Truck was running fine but with slight-feeling of 'less pulling power' at higher engine's RPM. Anyway, both Pumps will be replaced!

 

[Fred_M1010]

Another factor that can affect sideways wandering, is excessive negative offset in the wheels (too much scrub radius).
It rarely causes much trouble by itself,
(many aftermarket wheels gives to much scrub radius with most tires, but looks seems to be more important than function )
but when you add play in a worn joint in the front suspension, it can cause a lot of wandering in the ruts.

If the torsion-bars are cranked to lift it and you have near zero toe (or a worn joint somewhere),
you can get a slight toe-out when the suspension compresses.
That can make the truck wander a lot.
The fact that it behaves better in 4wd also indicates that, cause in 4wd the front of the front wheels are pushed inwards.


And regarding the torsion bars, check if the truck has the same height both left and right.
Measure both front and rear, and don't measure to the fenders, they can have a poor fit.
Measure from the ground to the frame instead.

 

[GMCbigblock]

Fred....You made me questioning my current "tire/wheel setup", as am now using the 18x9 wheel size (as I recall) fitted with NITTO "Dura Grappler" (LT275/65R18) - as shown in the attached photo. It's really giving good grip & runs smooth, stable & quite!

But am ready to switch back to the OEM setup if takes.

For info, yesterday I had a chance to pass by the Dealer while the Truck was on the Jack, and did a 'quick visual check', assisted by one of their technicians to help doing 'quick physical check' of the wheel's tolerance-play & generally assess tightness of the rod/steering assemblies etc...."Nothing resulted" which is good & not good in the same time (the puzzle continues)!

Thus; I'll try fitting the OEM wheels & tires (with alignment) if it will help (but I'll have to wait for a friend of mine!!), next will target re-doing a "thorough check" of the front-end (if the "issue" persists)!

 

[GMCbigblock]

** Correction:

- The Tire size is (LT275/70R18 E125R)

- Overall Diameter (33.23)

 

[diesel4me]

Negative caster will encourage wandering and make the tires more likely to follow the cracks in the road ,pull to the gutter side on a crowned road,etc...tires can mimic these problems too...maybe borrow 4 tires and rims off a stock truck and see how it drives then before spending any money..

 

[GMCbigblock]

Cool & surely I'll have to go thru this approach before pulling any coin out of my wallet.....

But since am having very limited time before I hit the road tomorrow, am gonna do that soon upon return from my travel (planned by 1st of September).

Will post the feedback by then!