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Discussion Starter · #1 ·
My 2018 Colorado's rear leaf springs have died. The ride is harsh bottoming out with only a shell on back that weighs 165lbs. Has anyone else experienced this?
Don't want to add helper springs or airbag since the sagging springs will still be there. Looking to replace with new GM springs but i ask myself why. I have looked at aftermarket springs, but they are costly. I think my truck has lost 2 inches in rear height. I have never had a set of springs sag this much.
I haven't seen this problem here so i am in a conundrum.
 

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If you're bottoming out then I would inspect the shocks. I've never heard of any rear leafs failing like that, but a lot of people have made the false assumption that the rear leafs have flattened out just because of the way the OEM springs are designed and they don't think they're supposed to be relatively flat with a "W" around the U-bolts. It would be helpful if you could measure the distance between the fender edge and the center of the wheel hub (to avoid height disparities caused by tire size, etc) to know what your general suspension height is. Before I upgraded my rear leafs, I had run my truck at/near RAWR and GVWR for thousands of miles and never had a problem with the springs losing their arch or height.

So, would be good to get some more info so others can compare their trucks to yours to see if you really have lost quite a bit of height.

Based on my past measurements and some rough estimates, I think the height from the center of the wheel to the edge of the fender was right at 20" and that is with probably 450-500LB on the bed (topper + Decked + stuff in the drawers). From the ground to the edge of the fender was right around 35.5" after adjusting for difference in tire height.

What are your measurements?
 

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Discussion Starter · #3 ·
What topper weighs 500 lbs? When you remove springs and lay them on the ground and they are nearly straight they are sprung! If you think shocks tote the load you are wrong. Shocks stable the springs and control the up and down motion. I cant supply pictures right now but i will soon as new springs arrive. You will be dumbfounded!
 

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What topper weighs 500 lbs? When you remove springs and lay them on the ground and they are nearly straight they are sprung! If you think shocks tote the load you are wrong. Shocks stable the springs and control the up and down motion. I cant supply pictures right now but i will soon as new springs arrive. You will be dumbfounded!
You need to reread my post. You seem to be a bit confused about what I said, how things work, and what the factory springs look like. Do us all a favor and provide the measurements like I did so we have some kind of reference. Thanks.
 

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Discussion Starter · #6 ·
I just asked if others had experienced this. I did not expect to be told to check my shocks and that it is possible that i don't understand how springs work.
Now not to upset you further i am 63 years old and have owned more trucks than i care to mention. I have also built and owned numerous street rods not to be confused with RAT Rods. Shocks are 3 mo old and ranchero. Airlift bags with airlift 2 gen air pump. Airlift does not recommend airbags on diesel colorados but 63 yrs of experience has taught me how to fix what they don't care to. To which the fix works flawlessly.
I am sorry but i was just looking for yes or no answers. Not rough estimates and speculations. Sorry for offending you but I have been solving problems for a long time. I have found it to be very beneficial in problem solving to having conversation with ones that are/have experienced the problems i am trying to solve. Again sorry for offending you.
 

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I saw you didn't want to add air shocks so I didn't jump in earlier. Firestone makes a kit for our truck. I put them on, loved the performance but they sheared the shackle bolts. Imo, totally a design flaw as the bolts were unhardened. Firestone sent me a new set that I'd like to sell if you're interested. I already bought grade 5 bolts for them which should solve the problem. In the meantime I started using sumo springs which are working well enough for me. I miss the adjustability of the air shocks but like the simplicity of the sumos. I don't like the sag from the stock system.
 

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Discussion Starter · #8 ·
I saw you didn't want to add air shocks so I didn't jump in earlier. Firestone makes a kit for our truck. I put them on, loved the performance but they sheared the shackle bolts. Imo, totally a design flaw as the bolts were unhardened. Firestone sent me a new set that I'd like to sell if you're interested. I already bought grade 5 bolts for them which should solve the problem. In the meantime I started using sumo springs which are working well enough for me. I miss the adjustability of the air shocks but like the simplicity of the sumos. I don't like the sag from the stock system.
 

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Discussion Starter · #9 ·
How much sag did you experience? I talked to AlCan springs in Colorado and they said it was a common issue with colorados and tacomas. Have you ever heard of them?
 

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No I haven't. The Colorado does much better than the tacomai I had. It would only take a few hundred pounds and the taco would occasionally hit the bumper stops. The Colorado was fine, I just don't like to see any squat with a load. That's why I preferred the air springs but the sumos do pretty well.
 

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My 2018 Colorado's rear leaf springs have died. The ride is harsh bottoming out with only a shell on back that weighs 165lbs. Has anyone else experienced this?
Don't want to add helper springs or airbag since the sagging springs will still be there. Looking to replace with new GM springs but i ask myself why. I have looked at aftermarket springs, but they are costly. I think my truck has lost 2 inches in rear height. I have never had a set of springs sag this much.
I haven't seen this problem here so i am in a conundrum.
Without measuring, I think that you should check your tire height and your leaves for damage. I eyeballed our 2018 CCLB Z71 in our drive way, and it seems as slightly jacked in the back as ever. And this is with ~60K miles, of which over 20K was pulling the trailer in my pic, over ~80% highway, ~20% secondary roads. My trailer bed load is many hundreds of #, plus a full bed and back seat. Loaded, it slumps 3-4" and rides level.

Subject adjacent, I am guilty of putting off my rear shock replacement. We haven't noticed any loss of handling, and I have yet to hear anyone come up with a trick way to MacGyver removing and reinstalling the upper left bolt that is close to the DEF tank. This fall, I promise....
 

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Without measuring, I think that you should check your tire height and your leaves for damage. I eyeballed our 2018 CCLB Z71 in our drive way, and it seems as slightly jacked in the back as ever. And this is with ~60K miles, of which over 20K was pulling the trailer in my pic, over ~80% highway, ~20% secondary roads. My trailer bed load is many hundreds of #, plus a full bed and back seat. Loaded, it slumps 3-4" and rides level.

Subject adjacent, I am guilty of putting off my rear shock replacement. We haven't noticed any loss of handling, and I have yet to hear anyone come up with a trick way to MacGyver removing and reinstalling the upper left bolt that is close to the DEF tank. This fall, I promise....
I just used a pry-bar and pushed the bolt head up against the DEF tank hard enough to pull the factory shock out and slide the new one. It's not impossible just a bit of a PITA.
 

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…I talked to AlCan springs in Colorado and they said it was a common issue with colorados and tacomas. Have you ever heard of them?
No issues with my stock Z71 leafs for the first 60,000 miles. But I wanted to improve ride (with constant 300+ pounds GFC topper and related gear on the bed) and went to Alcan (Grand Junction, CO) to have a leaf pack made. It mighta been one of the first Colorados they did, because we were aiming for a modest 1.5” over stock ride height but the first fitup was running way high around 3”, LOL. I had visited a scale and provided weight at each corner, but i’m sure there’s a bit of trial and error on an unfamiliar truck. So anyway, they de-arched the leafs a bit and got it down to about 1.75” over stock. I’m happy with their quality and service, and would recommend them. And now they have a data point for a diesel Colorado.

Another side note - I’ll be trying Bilstein remote reservoir shocks on the rear.
 
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No issues with my stock Z71 leafs for the first 60,000 miles. But I wanted to improve ride (with constant 300+ pounds GFC topper and related gear on the bed) and went to Alcan (Grand Junction, CO) to have a leaf pack made. It mighta been one of the first Colorados they did, because we were aiming for a modest 1.5” over stock ride height but the first fitup was running way high around 3”, LOL. I had visited a scale and provided weight at each corner, but i’m sure there’s a bit of trial and error on an unfamiliar truck. So anyway, they de-arched the leafs a bit and got it down to about 1.75” over stock. I’m happy with their quality and service, and would recommend them. And now they have a data point for a diesel Colorado.

Another side note - I’ll be trying Bilstein remote reservoir shocks on the rear.
Thx JDB. I could like a small rear rise. We're returning home thru GJ this Sept. I think I'll call them from California. Maybe I could get new shocks (F&R) installed at the same time. And since we're already on the rack, maybe a slight front lift as well? After all, it's only cubic $, right*?

* Not a diss of what you did. That sounds great. Just me getting ahead of myself...
 

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Just tossing my truck into the discussion here, because I have Decked storage (and stuff in the drawers) and a topper always on my truck and will also be towing an off-road trailer off-road, I ordered and installed a set of Deaver's Expedition leafs which are meant for trucks that constantly carry a load and you want a slight lift. Keep in mind the pics are right after install so the springs hadn't settled at all. As part of the install I also put some Peak 2.0 rear shocks in. Overall, very happy with the results. The OEM springs held up fine until this point, didn't flatten out or sag. I just wanted some lift when loaded up for overlanding trips. In these pics there's about 550LB in/on bed once everything is accounted for.

Here's before:
Wheel Tire Automotive side marker light Automotive parking light Car


After:
Automotive parking light Automotive side marker light Wheel Tire Vehicle


And recently with the trailer hitched up:
Tire Sky Wheel Car Vehicle
 
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Just tossing my truck into the discussion here, because I have Decked storage (and stuff in the drawers) and a topper always on my truck and will also be towing an off-road trailer off-road, I ordered and installed a set of Deaver's Expedition leafs which are meant for trucks that constantly carry a load and you want a slight lift. Keep in mind the pics are right after install so the springs hadn't settled at all. As part of the install I also put some Peak 2.0 rear shocks in. Overall, very happy with the results. The OEM springs held up fine until this point, didn't flatten out or sag. I just wanted some lift when loaded up for overlanding trips. In these pics there's about 550LB in/on bed once everything is accounted for.

Here's before:
View attachment 9509

After:
View attachment 9510

And recently with the trailer hitched up:
View attachment 9511
Love those smaller, rough country trailers. From the rear biased position of your trailer axle, I'm guessing that you have burly hitch weight. Do you know about what it is?
 

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Love those smaller, rough country trailers. From the rear biased position of your trailer axle, I'm guessing that you have burly hitch weight. Do you know about what it is?
I haven't weighed my specific trailer, but the factory hitch weight is listed as 300LB with a 2,200LB dry weight. I suspect the actual tongue weight is closer to 400-450LB. It's heavy enough that one of the most common questions from new owners is basically "Anyone that tows with a (Wrangler Unlimited/4Runner/Tacoma), how do you combat the sag?" heh Trailer has a 3,500LB GVWR so it falls within the tow limits of those vehicles but the tongue weight causes obvious sag for them, especially if they've installed a lift with softer springs.
 
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Discussion Starter · #18 ·
Ok guys here we go the measurement at the bottom of wheel opening lip is 35.25 inches. The measurement that is most accurate is the bottom of the receiver hitch is 13.25 inches. With the bed empty the ride is harsh since truck bottoms out. Shocks are new ranchero the truck is 2 plus inches lower than other trucks i have parked next to and measured.
Tape measure Ruler Tool Rectangle Wood
Tire Automotive tire Tape measure Tread Motor vehicle
Tape measure Ruler Tool Rectangle Wood
Tire Automotive tire Tape measure Tread Motor vehicle
 

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At 35.xx inches your truck is NOT 2+ inches lower than a stock truck. See my measurements above.

Did the ride get worse before or after you installed the shocks? You may also be perceiving coming down onto the overload leafs as bottoming out.

I just feel like you've made your mind up and aren't willing to listen to anyone that says you may be making an incorrect assumption about what is happening. You're stuck on your leafs being bad when that isn't something that really happens with these trucks and don't seem interested in exploring other possibilities. Good luck!
 
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Discussion Starter · #20 ·
At 35.xx inches your truck is NOT 2+ inches lower than a stock truck. See my measurements above.

Did the ride get worse before or after you installed the shocks? You may also be perceiving coming down onto the overload leafs as bottoming out.

I just feel like you've made your mind up and aren't willing to listen to anyone that says you may be making an incorrect assumption about what is happening. You're stuck on your leafs being bad when that isn't something that really happens with these trucks and don't seem interested in exploring other possibilities. Good luck!
 
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