2" lift induced 4WD Wobble issue

[Spoolin]

Hey All,

For you suspension guru's out here... I have a 2" lift on my ZR2.
Wasn't until the temps drops and the lakes froze over and started using AWD and 4Hi mode that I noticed that the front end of the truck wobbles pretty seriously when the front end is unloaded (hard acceleration or towing/hauling heavy loads).

Called a local suspension shop and they said it's a "known GM issue" and to just not use Auto mode.

Feels a lot like the knobby tires are hitting the firewall and everything starts to vibrate / wobble, increasing with intensity the more the front end unloads.

Any thoughts on what to look into? Truck also has extended axles which I wonder if that has something to do with it.

 

[amateurhour]

I’m not a guru, but I do have a few questions: First being is this a 1500? What suspension lift was used? Does it have strut spacers, collars, or something else? Why extended axles? More extended than factory trailers boss/zr2?

 

[ZR2BIZON]

I have a 2" lift over stock and have no wobles. It's a peak kit. Nothing on 4hi or 4lo. Everything else on the truck is stock and I removed the sway-bar

 

[The_Q]

It is a known issue with certain Lifts. ReadyLift has the following on their kit "NOTES: Use of Auto 4 Hi feature not recommended. "

I also know that Peak Suspension says this is not an issue with their lift. I've had no issues with either of my ZR2s that have the Peak 2.25" lift.

 

[Spoolin]

I’m not a guru, but I do have a few questions: First being is this a 1500? What suspension lift was used? Does it have strut spacers, collars, or something else? Why extended axles? More extended than factory trailers boss/zr2?

Hey, it is a 1500 ZR2.
Lift is Mazzulla Control arms and axles.
Axles were to fit 35's and to fit inside the flare kit.

 

[Spoolin]

It is a known issue with certain Lifts. ReadyLift has the following on their kit "NOTES: Use of Auto 4 Hi feature not recommended. "

I also know that Peak Suspension says this is not an issue with their lift. I've had no issues with either of my ZR2s that have the Peak 2.25" lift.

I was told that as well. Some of these companies have in small print "not to engage AWD or 4WD", something I wish I would have known prior to doing this.

At speed or when the truck is level it is not an issue, but when under hard acceleration or increased suspension travel it is rather worrisome, enough so that I will probably have to remove the kit.

 

[AXE]

Maybe the axles are going bad since you said it had been fine until more recently. Maybe some splines are stripped and when the suspension extends the splines arent making full contact. May want to pull them and see what you find.

 

[Spoolin]

I have an appointment with a shop in a couple weeks to get the truck on the lift. I would hope the extended axles are/were designed with that in mind but it's a fair assessment of what could be happening.

I'll try to take some video's of it tomorrow just to help paint a better picture.

 

[AXE]

Did you talk to Mazzulla?

 

[Spoolin]

Did you talk to Mazzulla?

I have not, I bought it through a third party vendor (PAX), but that's a good idea.
I'll give them a ring tomorrow morning.

 

[AXE]

Also could be the CV joints binding if they are over extending. Maybe they didn't get enough grease. Here's a video that gives some perspective on how that might occur.

I've had a couple leaking boots that I've replaced, but I've never had a bad CV joint or replaced one. Seems like it would be very common, especially given how much work they do.

 

[amateurhour]

Ahh, a long arm kit! I don’t have any experience with those.
Do you know what the alignment is at? I’m thinking along the same lines as axe and wondering if the angles of the cv joints match when the suspension travels?

 

[Spoolin]

Also could be the CV joints binding if they are over extending. Maybe they didn't get enough grease. Here's s video that gives some perspective on how that might occur.

I've had a couple leaking boots that I've replaced, but I've never had a bad CV joint or replaced one. Seems like it would be very common, especially given how much work they do.

Thanks for the video, that is pretty helpful and I do feel that might be the cause.
Especially since it only happens when the suspension is unloaded.
I am calling Mazzula and Pax today just to see if that is something they have run into before.

 

[Spoolin]

Ahh, a long arm kit! I don’t have any experience with those.
Do you know what the alignment is at? I’m thinking along the same lines as axe and wondering if the angles of the cv joints match when the suspension travels?

I don't know what the alignment is at, I've geared on my trucks before but never on suspension work. Was hoping the shop that did it knew more about it than me and could properly set it up.

 

[Spoolin]

I took a couple video's of it today.
First one is 2WD (normal), second one is AWD (vibration) and the third is 4HI (vibration).

The sound doesn't come through but you are able to hear some of the vibration.

 

[AXE]

Might even be the front drive shaft or transfer case. May want to check fluid in the transfer case.

 

[Spoolin]

Ok, so here's what I found out.

I took the truck to a local off-road shop and was told the CV shaft angle was excessive and both front inner joints / boots were leaking grease.
They suggested a diff drop (spacer) to help alleviate the poor angle of the CV joint.

I called Mazzula and they confirmed that I have their long travel suspension kit and their rep mentioned they are technically not designed for stock coil-over's / suspension set-up. (unsure why, probably above my paygrade/level of understanding) They also mentioned that a diff drop was "snake oil".

To address the issue of the long travel kit not being designed for stock suspension / OEM geometry, Pax Power designed a front end spacer lift that goes on top of the strut assembly to help get the truck level with the back end. (+/- 2")
That spacer lift initially caused some of their trucks to experience front end wobble which they found to be attributed to poor CV shaft angle / axle bind. They believe my truck may have one of those earlier spacers, and they have since revised the spacer to be a tad smaller and that seems to have addressed the angle of the CV shaft / axle bind. They also said a diff drop is not a good idea.

It's Pax is gonna send me one of their newer/revised spacers which I will install and see if that addresses the axle bind.

I will follow up again once I know a bit more.

 

[Nmass94]

Ok, so here's what I found out.

I took the truck to a local off-road shop and was told the CV shaft angle was excessive and both front inner joints / boots were leaking grease.
They suggested a diff drop (spacer) to help alleviate the poor angle of the CV joint.

I called Mazzula and they confirmed that I have their long travel suspension kit and their rep mentioned they are technically not designed for stock coil-over's / suspension set-up. (unsure why, probably above my paygrade/level of understanding) They also mentioned that a diff drop was "snake oil".

To address the issue of the long travel kit not being designed for stock suspension / OEM geometry, Pax Power designed a front end spacer lift that goes on top of the strut assembly to help get the truck level with the back end. (+/- 2")
That spacer lift initially caused some of their trucks to experience front end wobble which they found to be attributed to poor CV shaft angle / axle bind. They believe my truck may have one of those earlier spacers, and they have since revised the spacer to be a tad smaller and that seems to have addressed the angle of the CV shaft / axle bind. They also said a diff drop is not a good idea.

It's Pax is gonna send me one of their newer/revised spacers which I will install and see if that addresses the axle bind.

I will follow up again once I know a bit more.

I hope for your sake that solves the issue, however from my knowledge by adding strut top spacers you're only going to make the CVs steeper.
Diff drops have issues, but they do make cv angles less severe.