HD Front End Top Out?

[hello_im_justin]

Hey everyone! Just picked up a 26 ZR2 HD and just wanted to ask a question here to see if anyone else has the same experience or if I should be scheduling a service appt. I did try searching for this and I found threads of clunks in the rear, but didn't see anything about this. When going over speed bumps at anything quicker than a snail's pace, the suspension unloads and I get a pretty good deep sounding clunk out of the front driver's side. Sounds like the shock is topping out. Only on the driver's side. I have not done any torsion bar adjustments or anything like that, all stock. I did a bunch of reading on these shocks and I thought I read that they have internal valving to act as a top out control so when I heard this clunk I was a little concerned. My previous truck was a 2022 AT4 HD that I kept at stock height and just installed some cheap-o Bilstein 5100s and I did not experience this type of clunk. Is this typical behavior on the ZR2 since it is lifted or should I be looking to schedule this thing in to the dealer? Really not looking forward to that since I always seem to either get "couldn't hear nothin" or "yeah, that's normal" treatment. TIA!

 

[AXE]

Jack it up on that corner and see if you can move the steering and suspension around and see if anything is loose. Check the sway bar, tie rods, ball joints, and shock, even the brake caliper. An easy way to test the shoock is to take ii off and see if there is resistance through the stroke.

That clunk was common on my previous lifted Duramax trucks, but doesn't happen on the ZR2. I maybe get a hint of it going over steep speed bumps when you drop off the top.

 

[hello_im_justin]

Will do, thank you. Not looking forward to taking that shock off as it seems they attached some sturdier clips to the tops of the mounting bolts

 

[AXE]

Will do, thank you. Not looking forward to taking that shock off as it seems they attached some sturdier clips to the tops of the mounting bolts

I pulled the rears on my 1500 to install some skids and they are stout. Had to use a small jack to push them in to get the bolt back in place. Might be easier if you have a lift. Maybe it's easier to talk with the dealer first.

 

[hello_im_justin]

Yeah I'm thinking that's the move. I jacked it up and everything seems tight. Sliiiiight play in the steering, like only enough to get a click sound, but I am attributing that to normal movement. I really don't want to take that shock out for fear the dealer will see wrench marks and blame the noise on me. Guess I'll get to know my new service advisor... Truck only has 300 miles on it so I should go use that warranty. Dealers are just such a pain for me since I spent my teens and twenties working at one. Including being a service advisor... Joy.

 

[AXE]

Yeah I'm thinking that's the move. I jacked it up and everything seems tight. Sliiiiight play in the steering, like only enough to get a click sound, but I am attributing that to normal movement. I really don't want to take that shock out for fear the dealer will see wrench marks and blame the noise on me. Guess I'll get to know my new service advisor... Truck only has 300 miles on it so I should go use that warranty. Dealers are just such a pain for me since I spent my teens and twenties working at one. Including being a service advisor... Joy.

It's a haul for you from Mesa, but I have used Sands Chevrolet in Glendale for most of my work and get good results. MIDWAY Chevrolet aint too bad either. I've had the same service advisor since 1997 when I bought my first S10 ZR2 from them.

 

[Mighty Peace]

Quick question, is this what the Cognito Front Shock Extenders for the HD ZR2/AT4x will help with? Anyone have these installed already? Worth it? I know they are no much money ($139 Canadian + 1 hr install time) and was going to get them to put on my new HD ZR2 when its delivered to the dealership.

 

[hello_im_justin]

I bought these and put them on my truck and yes, it got rid of my top out. I do wonder about long term effects on the ball joints being that they are going to travel farther than GM intended with limiting the shocks, but I feel like I am saving the shocks by not having them slam to full extension over every speed bump.

 

[Mighty Peace]

Guess if the factory upper ball joint wears out sooner or when they do, then the option to put in the Cognito UCA's would be the way to go over the factory ones as you can just replace the ball joint rather than the entire factory upper control arm.

 

[hello_im_justin]

Guess if the factory upper ball joint wears out sooner or when they do, then the option to put in the Cognito UCA's would be the way to go over the factory ones as you can just replace the ball joint rather than the entire factory upper control arm.

Honestly, I'd probably just replace the factory arm again. I've seen a post on another forum where they were gathering all the part numbers to piece together the entire ZR2/AT4X lift kit and the prices on the arms were ridiculously cheap. Better than going with Cognito and having to cut out the droop stops on the frame.

 

[AXE]

Quick question, is this what the Cognito Front Shock Extenders for the HD ZR2/AT4x will help with? Anyone have these installed already? Worth it? I know they are no much money ($139 Canadian + 1 hr install time) and was going to get them to put on my new HD ZR2 when its delivered to the dealership.

Just run it and see. Why chase something that more than likely isn't a problem.

 

[Mighty Peace]

You are correct . I was debating and just thought with the truck being new and clean and the part being $138 and 1 hour labour to install to just get done then. I have about 3 weeks to go before my build date, so I got lots of time to contemplate and read other owners comments about their trucks and ride.

 

[kylant]

the dssv shocks are the limiters for the front suspension travel. at full extension the UCA is not anywhere close to touching the service perch. with the cognito shock spacers in, the UCA still does not touch the perch, but it is very close. IMO, you do not want the shocks being the limiters. i see no ill affects running them. i do.
the stock UCAs are cheap. better off just replacing them if a ball joint wears out as opposed to replacing with cognito. cognito is the only one that makes an arm for the ZR2/X and cognito's ball joints are garbage. i had to replace one on my buddy's truck with less than 10K miles on it. also, they require cutting the perch. cst says their regular HD arms work, but have to cut the perch as well. kryptonite is not so sure, they do say they will not work with the dssv shocks though

 

[hello_im_justin]

the dssv shocks are the limiters for the front suspension travel. at full extension the UCA is not anywhere close to touching the service perch. with the cognito shock spacers in, the UCA still does not touch the perch, but it is very close. IMO, you do not want the shocks being the limiters. i see no ill affects running them. i do.
the stock UCAs are cheap. better off just replacing them if a ball joint wears out as opposed to replacing with cognito. cognito is the only one that makes an arm for the ZR2/X and cognito's ball joints are garbage. i had to replace one on my buddy's truck with less than 10K miles on it. also, they require cutting the perch. cst says their regular HD arms work, but have to cut the perch as well. kryptonite is not so sure, they do say they will not work with the dssv shocks though

Yeah I’ve read about Cognitos bad batch of ball joints and I really don’t like how they don’t just update their arms so you don’t have to chop the frame. The factory arms are like $100 a piece. I would way rather replace with factory if I ever needed to. I am really happy with the Cognito spacers though. The truck rides much better with the extra down travel and no clunk.

 

[AXE]

Kryptonite!

 

[hello_im_justin]

Kryptonite literally says on their site that their arms will not work with dssv shocks. And even if they did, $700 for arms or replace 1 for $100…
Maybe if I needed shocks at the same time I needed arms, maybe I would consider it. But I’ve got a backup set of dssv’s from a friend who went all out on his at4xhd so I’m good on shocks for at least 80k miles. And I may not even have the truck that long, who knows lol

 

[AXE]

I've only used their ball joints and tie rods on past applications. I know they make some nice bits.

 

[hello_im_justin]

I’m sure they make quality stuff

 

[PaleRider]

Mine since day 1 has a "click" from the ISS or steering gear. Only when crossing center to left, or on uneven terrain. Usually only present initially and then goes away. Of 3 other zR2 HDs I've driven, 2 did the same.

There is a recall about to drop for the steering gear. May or may not be related.

 

[AXE]

Mine since day 1 has a "click" from the ISS or steering gear. Only when crossing center to left, or on uneven terrain. Usually only present initially and then goes away. Of 3 other zR2 HDs I've driven, 2 did the same.

There is a recall about to drop for the steering gear. May or may not be related.

The ball joints and linkage with grease zerks are notoriously dry at delivery. Could be part of the issue. I have one of my tie rods that seems to be losing more grease than the others. Might have to have them replace the rod or boot.