2023 LTZ 3500 - Leaf springs are bagged!?

[PBNB]

4 hours ago, asilverblazer said:

Why are you raising the front? Its sounds like you are spending a bunch of money to correct the resulting problems from lifting the front and 'wishfully' improving the ride at the same time. Especially since your concerns seem to stem from the rear - at least that's what you talking most about.

 

The trucks are very heavily sprung - and the jounce bumpers in the front (on the lower control arm) are not strictly bump stops but have a role in suspension too.

 

 

Good question! I started off with shocks to deal with the excessive bouncing or lack of rebound control with the Ranchos. Then as I got into it, I found that the new shocks would work better with more travel in both directions. The new shocks have adjustable compression and significant rebound control So by adding a bit of lift to the torsion bars we can open up the range. This led to upper control arms that correct the angles of the control arm as the wheels drop. They also provide more range for alignment. And then there is the differential drop to adjust the CV angles for the lower hubs. 

 

A lot of this comes from others who have done similar and greatly improved the ride. 

 

Then I started to look at the rear to see what 1.5" lift in the front would do to the rake and it appears that I will still have some positive rear rake. That is my OCD kicking in and seeing the what appeared to be a lower rear, I thought I would see what others think. The learning curve on this truck has been steep but working through it

 

It turns out that the measurements I took were not at the correct locations and the truck actually has some rear rake but I had to stand back and look at the frame rather than the wheel wells. I was also looking at the Sierras which have different fenders so they look different and measuring from the hub to the wheel well lip gives a different number than the Silverados.

 

That is how I got here and how I went down this rabbit hole. I don't like the idea of spending money but I have seen the improvements with other trucks so I think it will be a move I can deal with. 

 

I pulled this off GM's website so I could get a better idea of the fender lips that I was working with. They were able to push this down to level and you can see the smaller rear wheel well. I found this helpful to understand my measurements.

 

[asilverblazer]

21 hours ago, PBNB said:

Good question! rebound control with the Ranchos. Then as I got into it, I found that the new shocks would work better with more travel in both directions. The new shocks have adjustable compression and significant rebound control So by adding a bit of lift to the torsion bars we can open up the range. This led to upper control arms that correct the angles of the control arm as the wheels drop. They also provide more range for alignment. And then there is the differential drop to adjust the CV angles for the lower hubs. 

 

A lot of this comes from others who have done similar and greatly improved the ride. 

I'll remain skeptical of the 'greatly improved ride claim for a few reasons:

1. Ride is subjective - what is 'better' to one may be 'worse' to another.

2. People that spend considerable amounts of money to 'improve' the ride are going to be inclined to say they succeeded - regardless of actual results.

3. A layman will never be able to invest the time resources or knowledge into re-designing the factory suspension with any chance of improving it.

 

I agree there is an opportunity for increased travel to allow the shock absorbers more time to influence the action of the springs. Will it be enough? You might gain an additional 1" of full jounce travel for a total of maybe 4". On an average drive - how often is the suspension jouncing more than 2"? So will you be able to take advantage of the additional travel - not without decreasing the spring rate - which you aren't planning on doing. That also all applies to rebound travel too. 

 

Adjusting the torsion bars and/or adding keys only changes the knuckle's position in relation to the factory bump stops. It does NOT change the spring rate - unless you crank it so far that you are pushing the suspension against the stops. 

 

Even changing the shocks will have little impact if there is no movement in the suspension. Because there is no motion for the shock absorber to absorb. Do you know how much the suspension is compressing and rebounding? As noted earlier, your plans will not be changing this.

 

22 hours ago, PBNB said:

Then I started to look at the rear to see what 1.5" lift in the front would do to the rake and it appears that I will still have some positive rear rake. That is my OCD kicking in and seeing the what appeared to be a lower rear, I thought I would see what others think. The learning curve on this truck has been steep but working through it

 

It turns out that the measurements I took were not at the correct locations and the truck actually has some rear rake but I had to stand back and look at the frame rather than the wheel wells. I was also looking at the Sierras which have different fenders so they look different and measuring from the hub to the wheel well lip gives a different number than the Silverados.

Regarding the rake, its actually quite a bit simpler. The higher rear exists only so that when the truck is loaded it would appear to level out. The body can be set around the chassis however the designers choose - which you see in the difference between the GMC and Chevrolet.

 

This aesthetic function can disguise an actual engineering intent. Ideally the truck would sit halfway in its suspension range of motion at all times; but that isn't possible given a loaded truck would be too low and an empty one is too high. The result is the empty truck sits high, because someone might load the truck and it has to be able to carry that weight.

 

Raising the rear of the truck via blocks to solve an aesthetic concern would have little impact to the suspension's performance. (Ignoring possibly overextending original shocks or crushing an extended one)

 

22 hours ago, PBNB said:

That is how I got here and how I went down this rabbit hole. I don't like the idea of spending money but I have seen the improvements with other trucks so I think it will be a move I can deal with. 

What improvements do you see that you trying to replicate?

[PBNB]

9 minutes ago, asilverblazer said:

What improvements do you see that you trying to replicate?

The first improvement that I am hoping for is rebound control. We have some pretty crappy roads and some rural roads that are not paved. The truck was floating over some dips on our last trip. 

 

Lateral rolling is the other improvement I am hoping for. The truck does lean quite a bit when cornering. I don't expect it to handle like the cars I have had with KW suspensions but even our last truck (1/2 ton Toyota) was much better with coils and slightly better shocks. This is our first torsion bar truck so maybe it is supposed to float?

 

When I started this thread I was really puzzled about rake, but I can see that the truck has a few inches. 

 

I had already started down the path of replacing the shocks and had factored in replacing the leafs as well. Not knowing what the truck's first 25k miles entailed and then the measurements I took, started me down the rear leaf questions. I had envisioned a 20,000 lbs. fifth wheel living on the truck for 2 years solid!

 

Aesthetics are not super important on the list but in the end, the way the truck sits will be what we see everyday.

 

 

[Chuck FB]

What you describe in how floaty the truck is and the lean issue in going around corners, that typically is a classic sign of completely bagged out shocks. That with the rather dismal track record in how these factory Ranch shocks seem to last, I suspect any decent set of shocks put on the truck and I don't mean kings or even Fox for that matter but as I mentioned the Bilstein options, that should get the truck back to behaving properly without spending a huge wad of cash. I also was thinking and your truck and because of buying it used it may not cover it but in theory the 36000 mile ( 60000 km ) bumper to bumper warranty for the original owner was supposed to cover shock issues, maybe.  

 

There is one other thing that you definitely should check out on your truck and that is all the hardware and rubber bushings associated with the front sway bar. From the rubber half blocks that clamp the sway bar to the trucks frame, to both ends of both end link rods to make sure a bushing hasn't blown out or that the bolt hardware isn't all loose. You never know when it comes to used vehicles, people have gotten the brain wave to remove one end link rendering the sway bar useless or they removed the whole thing from the vehicle. 

 

Again mine being a gas may seem slightly different but it does have the lower rate torsion bars to match up with the lower engine weight but from my perspective in going around corners and I mean like a sharp turn from a light in town so its a quick sharp turn, it feels like its more on rails than anything and does not have a snap back effect from coming back from a lean because there was little lean of any to begin with. 

[asilverblazer]

1 hour ago, PBNB said:

The first improvement that I am hoping for is rebound control. We have some pretty crappy roads and some rural roads that are not paved. The truck was floating over some dips on our last trip. 

I would start with shocks. Bilstein (5100) are highly recommended by others, including myself. This is relatively cheap and directly addresses your concerns.

 

1 hour ago, PBNB said:

Lateral rolling is the other improvement I am hoping for. The truck does lean quite a bit when cornering.

Maybe stabilizer bar improvements.

 

1 hour ago, PBNB said:

This is our first torsion bar truck so maybe it is supposed to float?

It should perform similarly to other rear leaf sprung trucks. The torsion bars won't make a substantial difference compared to other trucks.

 

The term "float" might be too ambiguous for internet (my) discussions, try being more descriptive using other terms and describing the type, severity, frequency, etc. of motions. 

 

1 hour ago, PBNB said:

I had already started down the path of replacing the shocks and had factored in replacing the leafs as well. Not knowing what the truck's first 25k miles entailed and then the measurements I took, started me down the rear leaf questions. I had envisioned a 20,000 lbs. fifth wheel living on the truck for 2 years solid!

Leaf springs don't wear out in 25k miles. Maybe 250K.

 

The factory shocks aren't the best regardless of brand but also don't expect a huge difference either - refer to my comments above - if the suspension isn't moving the shocks aren't doing anything (good or bad). The springs on an (any) HD truck are very stiff and won't compress easily compared to a half ton. 

 

1 hour ago, PBNB said:

Aesthetics are not super important on the list but in the end, the way the truck sits will be what we see everyday.

Agreed.

[asilverblazer]

8 minutes ago, Chuck FB said:

What you describe in how floaty the truck is and the lean issue in going around corners, that typically is a classic sign of completely bagged out shocks. That with the rather dismal track record in how these factory Ranch shocks seem to last, I suspect any decent set of shocks put on the truck and I don't mean kings or even Fox for that matter but as I mentioned the Bilstein options, that should get the truck back to behaving properly...

 

There is one other thing that you definitely should check out on your truck and that is all the hardware and rubber bushings associated with the front sway bar. From the rubber half blocks that clamp the sway bar to the trucks frame, to both ends of both end link rods to make sure a bushing hasn't blown out or that the bolt hardware isn't all loose. You never know when it comes to used vehicles, people have gotten the brain wave to remove one end link rendering the sway bar useless or they removed the whole thing from the vehicle...

Generally agree but if the truck is under 30K miles, I can't imagine normal wear and tear or worn out parts being the culprit.

 

Defective, abused or missing sure. Without obvious signs of those though, it might be getting used to an HD truck.

[Chuck FB]

46 minutes ago, asilverblazer said:

Generally agree but if the truck is under 30K miles, I can't imagine normal wear and tear or worn out parts being the culprit.

 

Defective, abused or missing sure. Without obvious signs of those though, it might be getting used to an HD truck.

I believe it was on this forum where some said they had the Rancho shocks leaking for example quite early on mileage wise but also have noted some youtube videos of trucks that were not being controlled well in using a speed bump at relatively low speed and in one case the person had created a before and after video with low speed video to show the amount of up/down after effect after going over the speed bump with front and rear axle action, then replacing the shocks and repeating the process again on the same speed bump. Pretty sure it was the Rancho shocks that had been stock and with surprisingly few miles on the truck. 

 

As per this members truck, if the measurements he gave before are an indication I have a feeling a fairly heavy trailer may have been pulled and we have some crappy roads up here in Canada, so hard to say where that truck had been driving and with how much load and stressing the suspension. For all I know that truck could have gone to Alaska or further up into the Yukon and there are some BAD frost heaved roads up there. Anywhere I have happened to be in the states and not claiming there would be no bad roads in the lower 48 but up here in northern Alberta we can have some horrible frost heave highways and as I mentioned in the Yukon and Alaska its perma frost issues that cause the road to crater or heave like moguls on a ski hill, there is a reason why so many travel trailers break leaf springs up there or bend their frame on one trip. I was up there once and watching how some people drove, hardly a brain cell in their head behind the wheel of some RV's LOL. But that is how one can take a vehicle and pound the living piss out of it by driving too fast carrying weight ( going 60+ when they should be going 15 mph over some of that mess ).   

Edited November 22, 2025 by Chuck FB