Jump to content

Rear lift blocks on composite leaf springs?

KRAS

By KRAS
in Modifications, Wheels & Tires

 Share

Recommended Posts

KRAS Enthusiast

KRAS

Posted
Posted

Has anyone been able to crack the nut from an engineering perspective on why you’re not supposed to put a lift block under the composite springs (which my dealer did). Oddly enough- RC & Fabtech don’t have any warnings, just Chevy

and Readylift.  My theories are:

1- steel will continue to flex but not rebound when it hits its load limit but composite/carbon snaps 

2- they are tuned for the trucks specific factory angles

3- GM figured out that this truck looks a lot better at 2”+ taller and wants more money

topgear1224 Enthusiast

topgear1224

Posted
Posted

It's leverage on the spring that's why GM says don't do it. Yes it will snap with hard enough use.

Also because of how it's designed it's really only designed to flex sort of towards the ends and kind of give you a variable spring rate,

whereas the steel one the whole thing can flex and as you flex more of it it's sort of variable.... it's kind of hard to explain.

Anyways now you can get the conversion to steel springs from GM I think it's $600 and that includes both the springs and u-bolts. Just look at the 2021 accessories

Sent from my SM-N975U using Tapatalk

AJMBLAZER Enthusiast

AJMBLAZER

Posted
Posted

I dunno.

 

The surface area of the lift blocks won't be any smaller than the surface area of the spring perch on the axle so not sure what difference it will make.

  • Like 1
Travis26 Enthusiast

Travis26

Posted
Posted

Following this post.  I ordered a Moto Fab 2.5" front 2" rear leveling kit last week.  I'm now contemplating whether or not to install the lift block in the back or not since I have the composite leaf.  I emailed Moto Fab and they say there are no issues using it.

topgear1224 Enthusiast

topgear1224

Posted
Posted

it really just depends on how hard you drive the truck if you're sitting there jumping it all the time you're probably going to snap them.

if you just drive them on the road it'll probably never fail

Sent from my SM-N975U using Tapatalk

Travis26 Enthusiast

Travis26

Posted
Posted

I have a 6,000 lb travel trailer that I tow probably a dozen times through out the year.  I will be installing a Air Lift system before I tow though. That's my main concern. 

Gangly Senior Enthusiast

Gangly

Posted
Posted

As far as I can tell through my research on the boards, there are no known instances of mechanical failure, degradation, or diminished  materials performance as a result of using the blocks with the composite springs.  GM has a reason for what they are saying, but I don't know if anybody outside of GM knows why.  

 

 

Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
On 11/8/2020 at 2:14 PM, AJMBLAZER said:

I dunno.

 

The surface area of the lift blocks won't be any smaller than the surface area of the spring perch on the axle so not sure what difference it will make.

The difference is that extra inch to the compression bump stop. Extend the bumper an inch and all is good. Otherwise the spring can be extended an extra inch. Question is.....how big a jump empty would equal 2000 pounds in the box or who at full load is running the dunes? 

pewterliftedz Enthusiast

pewterliftedz

Posted
Posted

The composite springs have a shim that should be removed before installed a block, Superlift has a kit that provides a new pin to remove the shim

  • Like 1
AJMBLAZER Enthusiast

AJMBLAZER

Posted
Posted (edited)

The composite is thick and looks obviously different. Also I don’t think a magnet will stick to it. 
 

I’d take a picture but my truck is 2 hours away from me. 

Edited by AJMBLAZER
Duramax3oh Enthusiast

Duramax3oh

Posted
Posted

Along a similar path, could there be a problem of using an Add-a-leaf in lieu of rear block? If the composite is made to flex different would mixing that with an AAL be bad?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.4k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,760
    Total Members
    8,960
    Most Online
    MASONV88888888
    Newest Member
    MASONV88888888
    Joined

  • Who's Online   0 Members, 0 Anonymous, 1,552 Guests (See full list)

    • There are no registered users currently online

  • Latest Articles

  • Posts

    • Coastie05
      Replacing 2.7L on 2021 Silverado with 2023 2.7L

      By Coastie05 · Posted

      I’m definitely interested to hear the end result here. 
    • MASONV88888888
      Another 6.2L engine failure!

      By MASONV88888888 · Posted

      My 2025 Silverado 1500 had to receive a brand-new engine (long block) under warranty last month at only around 16,500 miles. Before the replacement, the truck repeatedly displayed "Engine Oil Level Low" warnings, even though the Oil Life Monitor still showed around 50% remaining after about 6,000 miles since my last oil change. After seeing the warning several times, I checked the dipstick with the engine cold, and the oil level was completely normal. The next day, the message escalated to "Add Engine Oil." At first, I assumed it was just a faulty oil level sensor, so I brought the truck to the dealership. After inspecting the engine, they found internal cylinder wall scoring and ultimately replaced the entire long block under warranty. Before this happened, I was planning to install a 4-inch lift and suspension upgrade on my truck. After needing a new engine at just 16,500 miles, I honestly don't see the point anymore. I also contacted GM to ask whether my vehicle qualified for a buyback, but I was informed that it does not at this time. Anyway, this experience has left me with serious concerns about the long-term reliability of this engine. I sincerely hope NHTSA expands the current investigation or recall to include 2025 model and performs a thorough inspection of affected vehicles. My biggest concern is that these engines may fail shortly after the powertrain warranty expires. If GM truly stands behind this engine, then at the very least, please consider extending the powertrain warranty to 10 years for affected owners. That would go a long way toward restoring customer confidence.
    • Grumpy Bear
      OCI, not when but why?

      By Grumpy Bear · Posted

      Without exception but then I'm the odd duck, right? I know what goes into that test, how it is calculated and thus how to beat it. But EPA values are often not beaten by the general public and the government has in past years adjusted the means and methods to come to those values to more closely approximate "Joe Average".    The only real trick to beating that EPA average is don't drive like "Joe Average".    It's the same method you used to profit from "Economic Migration" and in doing so beat the 'stats'. But you, like me, are not "Joe Average".     The thing you don't seem to grasp is this "Purchasing Power Index" isn't forward looking. It doesn't predict what it going to be but looks backward and states what it was. They are not telling us what the THINK, they are telling us what they MEASURED. Example:    Wife says "I'm going to lose 40 pounds by Christmas". May she does, maybe she doesn't but the doctors office who weighed her when she made that statement and again at Christmas only REPORTS what the RESULT was. You and I can banter about what was possible and what aunt Tilly did till the cows come home but the result is the result. Arguing otherwise is.....irrational. That's all I'm saying. This isn't about:      What you are calling a 'Statistic' is a RESULT not a CALCUATION and as a result the RULE. Like gravity as a rule, it can not be broken. 
    • MASONV88888888
      Rattle in the rear!

      By MASONV88888888 · Posted

      Just wanted to say thank you for posting this. Years later, your thread is still helping Silverado owners.   I bought my 2025 Silverado 1500 in January 2025, and I've had what feels like the exact same rattle since day one. After reading your findings, I believe my truck has the same issue with the cable carrier contacting the rear sliding window. To be honest, I had pretty much given up on pursuing the issue. It wasn't until I recently drove another brand's pickup that I realized just how quiet their cabin was—and how noisy mine has been all along. On my truck, the rattle happens on almost any paved road, gets even worse on rougher pavement, and I can even hear it during braking and acceleration.   I actually referenced your thread when submitting my case to GM, hoping they'll recognize this as a recurring issue instead of treating it as an isolated incident. The reason I reached out to GM first is because my dealership told me they would need to keep the truck for at least two days just to diagnose the problem. I was concerned that even after two days, they still might not be able to identify the source of the rattle before giving the truck back to me. I had also asked a few dealerships about this issue during previous service visits, but none of them seemed to know what was causing it or had a solution. That's why I decided to contact GM directly first, hoping they might already have an official repair procedure or guidance for this issue.   I also hope GM eventually comes up with an official fix for this problem. I have a feeling there are many Silverado owners experiencing the same rattle, but most either choose to live with it or simply don't know what the cause is.   Really appreciate you taking the time to document your diagnosis. Your post is still making a difference years later.
    • Buckwild27
      Gas Prices

      By Buckwild27 · Posted

      I have 2 choices. 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...