GMC AT4 4" BDS Lift Issue

[ullose272]

Its possible with the cv shaft out like that the one of the cv joints could be bottoming internally causing the clunk. What happens when you run it in 4wd

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[TheElementalCashew]

5 minutes ago, ullose272 said:

Its possible with the cv shaft out like that the one of the cv joints could be bottoming internally causing the clunk. What happens when you run it in 4wd

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The installer said to not run it in 4WD until this has been resolved. 

 

That said, I ran in 4WD several times over this past winter and never noticed anything out of the ordinary, other than the clunk in 2WD and 4WD. 

[TheElementalCashew]

A little update, the installer has received a set of CV shaft spacers from BDS that will supposedly correct the issue. Interestingly, the PDF instructions for this lift kit include directions for installing a CV spacer (pages 20-21) and also lists the CV spacers in the lift inventory. I don't recall if they have always included those directions, or if they were a later add-on. Looking at the product page pictures, I don't see a CV spacer in the pictures (which I realize doesn't mean anything). 

 

In any case, the spacers will be going on next Monday, so I'll report back with any updates after that. 

[topgear1224]

A little update, the installer has received a set of CV shaft spacers from BDS that will supposedly correct the issue. Interestingly, the PDF instructions for this lift kit include directions for installing a CV spacer (pages 20-21) and also lists the CV spacers in the lift inventory. I don't recall if they have always included those directions, or if they were a later add-on. Looking at the product page pictures, I don't see a CV spacer in the pictures (which I realize doesn't mean anything). 
 
In any case, the spacers will be going on next Monday, so I'll report back with any updates after that. 

Interesting, I saw in their own truck the gap.

I still don't believe that is the clunk, but maybe it is loading torsionally and that is making it bind then release in the joint.

Kinda like how bad CV angles create vibration at highway speeds in 4hi on 01-06 2500hd trucks.

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[TheElementalCashew]

Interesting, I saw in their own truck the gap.

I still don't believe that is the clunk, but maybe it is loading torsionally and that is making it bind then release in the joint.

Kinda like how bad CV angles create vibration at highway speeds in 4hi on 01-06 2500hd trucks.

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Maybe. I’m not 100% convinced it is the cause either. But I guess we’ll see.

[TheElementalCashew]

I forgot to update this. The installer went to work to put the CV spacers in, only to realize that they had actually already correctly installed the spacers provided by BDS with the kit. So back to the drawing board. I've reached out to BDS myself as well to discuss warranty work. 

[topgear1224]

I forgot to update this. The installer went to work to put the CV spacers in, only to realize that they had actually already correctly installed the spacers provided by BDS with the kit. So back to the drawing board. I've reached out to BDS myself as well to discuss warranty work. 

Did he remove the CV axles to inspect them and then reinstall them? If so is the problem still there

you were saying you could feel it in the floorboard.

I know this sounds crazy but does this only happen at full turn?

You say it's easily reproducible what exactly is the truck doing when you feel it. Like right turn only, going up driveway, speed bumps, one wheel in the air [emoji23]?

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[TheElementalCashew]

I think they only got as far as seeing the spacers were installed. Pretty sure they didn't actually remove the shafts and reinstall. Yes, the problem still exists. 

 

I wouldn't say I can just feel it in the floorboard, but you can feel it throughout the whole vehicle when it clunks. 

 

Yes, generally this would happen at full lock. I can take a more easy angle of slow turn and it usually won't clunk. 

 

Stop the truck. Turn the wheels to the right or left, full lock, as if you were about to pull forward into or back into a parking spot. Moving forward or back, apply gas to start moving. Instant clunk as the turn begins. 

 

I hate parking lots now, because every time I pull into or out of a parking spot, it clunks so loudly I usually get some looks from pedestrians who probably think I hit something. 

[JAEDEE]

Just for reference.  I have a BDS 6 inch lift w/35's on my truck and have no strange noises.

[TheElementalCashew]

5 hours ago, JAEDEE said:

Just for reference.  I have a BDS 6 inch lift w/35's on my truck and have no strange noises.

That's good to hear. I assumed if this was a known problem I probably would have read it on this forum by now. I hope one day I can get my truck to that point. 

[Supercup]

15 hours ago, TheElementalCashew said:

That's good to hear. I assumed if this was a known problem I probably would have read it on this forum by now. I hope one day I can get my truck to that point. 

 

At this point if I were you I would take it to another shop and see if you can get a second opinion - and find the issues, so you can get back to enjoying your truck!

 

Wish you luck on this - know it must be frustrating! 

[topgear1224]

I think they only got as far as seeing the spacers were installed. Pretty sure they didn't actually remove the shafts and reinstall. Yes, the problem still exists. 
 
I wouldn't say I can just feel it in the floorboard, but you can feel it throughout the whole vehicle when it clunks. 
 
Yes, generally this would happen at full lock. I can take a more easy angle of slow turn and it usually won't clunk. 
 
Stop the truck. Turn the wheels to the right or left, full lock, as if you were about to pull forward into or back into a parking spot. Moving forward or back, apply gas to start moving. Instant clunk as the turn begins. 
 
I hate parking lots now, because every time I pull into or out of a parking spot, it clunks so loudly I usually get some looks from pedestrians who probably think I hit something. 

I did verify that the CV axles are in fact the "snap ring" style.

What tire size are you running.

I would think a suspension shop would have at least one GoPro that they could Mount and monitor the suspension to figure out when the noise is occurring if it's happening in a parking lot speed it's not like they're going to accidentally run over their GoPro or lose it.


Honestly at this point I would just take it to the dealer if you can reliably replicate the problem they should be able to tell you exactly what the issue is. being that you bought a BDS kit you do have drivetrain warranty through BDS's third party company if they were to attempt to deny your warranty claim due to the lift.


Best case scenario:

He didn't trim the wheel well properly. Did he remove the front rear mud flap and cut the corner of the sheet metal that's behind the flap?

I've been looking at so many lift kit instructions for these trucks. I don't remember where I found the trimming instructions for ours but I do remember is unique to Chevy vs GMC as far as trimming.

If you have confidence in your driving skills the best way to check this would be to drive on top of something with one side while under full lock apply the parking brake gently release the foot brake to make sure you don't roll down it and then check. kind of like how the Jeep kids like to park all jacked up in parking lots with their wheel two feet off the ground just much less extreme obviously. I wouldn't suggest a light pole like the Jeep kids do but maybe a really high media inside of a parking lot or maybe a large rock on top of that island. Concrete Steps would work nicely as well. The goal would be to put the vehicle under full compression and full lock on one side. (Or as close as you can get with the huge swaybar

also if he decided to torque the vehicle while it was in the air that would lead to weird binding problems as well. final torque occurs on the ground. CV spacers go on the knuckle ends.

Here is the PDF instructions if you are interested.
https://bds-suspension.com/instructions/021683.pdf


Your theory of axles could very well be correct. Here's my stock x 31 at full lock with both the wheels off. you can see how the CV joint rolls over pretty far. This isn't necessarily a problem but it does mean if you have any issues in that outside joint nearest to the wheel you're going to feel it bind and release. I hear AT4/TB have less steering angle attainable. at least according to the GM accessory book that says that they recalibrate the steering locks. I also wonder if he got the inner one seated in that diff still.

worst case scenario:

would be that he installed the lift incorrectly or trimmed one crossmembers incorrectly which means that although it's bolted tight the cross member is actually shifting. this would change the alignment on the fly effectively moving the entire front axle to the left or the right and it would cause all kinds of weird sensations and noises.



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[topgear1224]

Also wonder if your powertrain mounts need to reset that's where they loosen it they run forward and back or whatever on the lift and that sort of resetd them to where they're not binding or anything and they tighten them back down maybe actually feeling a mount max out.

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[Elevation X31]

How do the cv axles come out of the differential with the clips? Do you just have to pull on it, and push it back in for installation? 

[topgear1224]

How do the cv axles come out of the differential with the clips? Do you just have to pull on it, and push it back in for installation? 

Yes but not literally. Basically if you just pull you are going to rip a boot. You have to shock load it.

They have a slide hammer attachment to remove them without damage.

It takes a sudden movement.

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