Upper control arm contacting frame (stop)

[xXxPARAGONxXx]

When I had the driver’s side front tire/wheel off yesterday to clean the wheel, I noticed that the upper control arm was contacting the frame (stop). I did not take a photo then, but I did take one now with the wheel/tire on and the weight of the truck on the tire.

If that point of contact was rubber, I wouldn’t be too worried, but it’s metal-on-metal. After doing some research, it seems that the previous owner may have cranked the torsion bar to achieve some lift, but in doing so, made the upper control arm contact the frame stop.

By the looks of the photo, is this a reasonable conclusion? Should I be worried that the control arm is bent and needs replacement?

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[Nad_Yvalhosert]

You're spot on that the bars are cranked. Theres little possibility that the UCA's are bent, the frame is much softer than the arms. The frame stops will bend before the UCA's do.

In the mean time, lower the torsion bars. You're gonna need at least a half inch of clearance for suspension jounce. That is if you want to keep the ride height...
Oh, and if you do, make sure you have enough shock travel or the ride quality will be $hit.

 

[xXxPARAGONxXx]

You're spot on that the bars are cranked. Theres little possibility that the UCA's are bent, the frame is much softer than the arms. The frame stops will bend before the UCA's do.

In the mean time, lower the torsion bars. You're gonna need at least a half inch of clearance for suspension jounce. That is if you want to keep the ride height...
Oh, and if you do, make sure you have enough shock travel or the ride quality will be $hit.

I am confused on how I could lower the torsion bars and keep the ride height. I thought lowering the torsion bar would automatically lower the ride height. Torsion bar suspension is new to me, so I'm still learning the ins and outs.

I already have new shocks on the shelf — Bilstein 4600s: 24-025683 for the rear and 24-104050 for the front. Hopefully they will work! I took off the UPC from each box, so I don't think returning them now is a possibility.

 

[Nad_Yvalhosert]

There's generally a 2" rake on our trucks, yes? A set of torsion bar keys is advertised to level the truck and give up to a 2.5" lift. Cranking the bars beyond that, all the way up as it shows in the picture, is about 3-3.5 (or more) inches above stock Z height.

Lowering your truck from the 3+ inches of increased Z height, to get a half inch clearance between the UCA and the frame stop, will actually lower the truck about an inch, back down to the 2" (technically a lifted or "leveled" stance) and give you a dramatically better ride than you have now.

So when I say lower it, I dont mean slam it to the ground, or even back to OE Z height. I mean just a little bit to give you room for suspension travel.

Now whether, or not, that you have OE keys or lift keys, the max travel limit is reached when your UCA hits the frame stop. That means it's too high. Unless you like a bone jarring ride on the frame, I'd still recommended to drop the height to said minimum clearance of a half inch in between the frame stop and the UCA.

Oh, and head in for an alignment ASAP

 

[Schurkey]

Including aligning/aiming the headlights.

 

[wb292]

Not to mention tires coming off of the ground on rough roads when it tops out. Not fun in a curve.

 

[xXxPARAGONxXx]

On a K2500, does anyone know how to measure the Z height? I'm trying to figure out which points to obtain the measurement. I have the service manual, but it's sort of vague.

 

[Blazerbiker]

If the arm is hitting at full droop (when the tire was off) that's fine, it's a droop stop. The key is to have some down travel left in the suspension when it's at ride height. The arm does not move very much that close to the pivot point so a little space there goes a long way. The thing to check is that as you jack the chassis up, the wheel stays in contact with the ground until the chassis is 3-4" above where it normally sits. If it does not, then you either lower the ride height by unloading the torsion bars or start the harder job of getting more droop out of the suspension. That involves changing the droop stop to let the suspension droop more while making sure you have enough shock travel to accommodate the extra droop and that the CVs and steering links don't bind at full droop and full steering. The factory often leaves a little bit on the table since their tolerances vary and your individual parts may give you some room to keep a higher ride height and still have some droop travel.

 

[Steve A]

There's generally a 2" rake on our trucks, yes? A set of torsion bar keys is advertised to level the truck and give up to a 2.5" lift. Cranking the bars beyond that, all the way up as it shows in the picture, is about 3-3.5 (or more) inches above stock Z height.

Be careful using the "lift" keys. Simple geometry says if the control arm pivot points remain the same you can only raise the vehicle a set amount before contacting the droop stop, regardless of which keys are used.

 

[Blazerbiker]

Be careful using the "lift" keys. Simple geometry says if the control arm pivot points remain the same you can only raise the vehicle a set amount before contacting the droop stop, regardless of which keys are used.

That's a good point too, all the keys do is twist the bar for you so that your adjusting screw isn't so far extended.