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Abnormally rough ride

reb0957
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reb0957 Enthusiast

reb0957

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I have owned or driven several 3/4 tons over the years. At my core I am a Ram person, and the last Ram 2500 I owned was a 14 gasser with coil spring rear end. I have a SRW F350 diesel 8' bed and a 16 SB Ram 2500 diesel at my disposal to drive everyday. I have noticed my truck is rough but attributed it to short bed and leaf springs. Recently, hopped in my buddies 21 High Country 2500 Diesel and it was way smoother than my AT4. Then I had a couple of customers in the truck for lunch. One a F250 Platinum diesel driver the other a Chevy 2500 diesel owner. Both asked what I have done to my truck to make it ride so rough. My wife routinely gasps from driving down main drag in our town from hitting standard bumps in the road. Granted I live in Louisiana and our bumps are probably not accepted in other states. I am on the factory Goo Years and only have 10.6k miles. I needed the 2500 for the ground clearance while pulling a tractor. I really don't travel far enough most days to get a diesel to temperatures.
Yesterday I got under the truck and didn't notice anything out of place or wrong.
As soon as I bought the truck, I had them lower the TPMS threshold to 40 rear and 45 front. I routinely run them 50psi front and 45psi in rear. There was no need to wear out the middle of tires or run that much pressure not pulling anything.
Could GMC only run 1 front suspension set up and I am feeling this because I am in a lighter gas motor and transmission?
I know this will never be as smooth as a coil spring truck. I just can;t believe it is that much rougher than the diesels.
Any idea what I should be looking for to mitigate this?

I have been researching lift kits. Any recommendation on a set up to fit 35x12.50 that would also help with ride?

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asilverblazer
asilverblazer

Not really comparing, just offering a data point. My 3500 truck, with springs similar to the pictured ones, with air bags, tires at 60 PSI, rides VERY stiff.    More than others? Don't know.

Dr1ft3r
Dr1ft3r

Sorry, I've been AWOL for a while. 5 PSI is the minimum that's supposed to be kept in most bags to prevent the walls of the bags from being damaged, unless the bags have the stopper inside (which I be

Another JR
Another JR

The front torsion springs are different for different truck configurations based on the front axle load.  Do you have a plow package or camper springs?  What is the FGAWR on the door sticker?

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Another JR Senior Enthusiast

Another JR

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The front torsion springs are different for different truck configurations based on the front axle load.  Do you have a plow package or camper springs?  What is the FGAWR on the door sticker?

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reb0957 Enthusiast

reb0957

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13 hours ago, Another JR said:

The front torsion springs are different for different truck configurations based on the front axle load.  Do you have a plow package or camper springs?  What is the FGAWR on the door sticker?

Neither of those are listed on the sticker.

FGAWR is 4800lbs.

CRApex Enthusiast

CRApex

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My last several trucks have been diesels, I purchased a 2024 3500 gas High Country and it drives nice, I would say about the same as the diesel did.

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Another JR Senior Enthusiast

Another JR

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That’s the FGAWR rating I’d expect. To be thorough at diagnosing this from a distance, since you have already reduced tire pressure appropriately, I’d suggest next confirming you have the correct front and rear springs actually installed.  I know it’s very very unlikely GM would install the wrong parts, but it’s easy to check. 
 

I have my original 5600 lb front camper springs in the garage and I have installed the base 5200 lb springs for my model. Later today I’ll put a caliper on them and post the torsion bar diameters. Yours should be smaller diameter than mine if they are actually 4800 lb springs. I’m suggesting this measurement method because my original factory springs didn’t have an obvious part number marking. 
 

The rear leaf springs have the eight digit part number painted on them in large characters on the bottom surface, but I don’t have the table showing part number versus model. The secondary spring gaps when the truck is unloaded should look like these pictures from Jettech’s 2500:

F6C20C0C-63F7-4A0C-8629-36F9E2A26D15.webp.0bff9b9410bd36512e48ebc16535752d.webp1E342F90-ACED-46E5-B493-09066DE55177.webp.b6be8e1cc3bafc7d7f3c180d1b78d0b5.webp


If the gaps are much smaller like these pictures from my 3500, then you have the wrong springs unless you ordered the 3500 rear springs under an option I others have said is now available:

152E7C04-7BFB-43D6-A7D2-3AF5D5AEA394.thumb.jpeg.8927d39f6de93fe693d7432412b84ab2.jpeg8A2E5F31-4583-40AD-B1E7-9C55417CA521.thumb.jpeg.a73c3b86ea6df77a7581143e32b2ae0a.jpeg


If the springs check out, it may be that your shocks are overly stiff, or it may simply be that your expectations are for a softer ride than the truck provides. I know our 3500 gives a fairly stiff ride, especially in the rear seat, but it’s not horrible.  I still have my original Rancho shocks, so I’m hoping for a little improvement when I eventually replace them. 

reb0957 Enthusiast

reb0957

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Posted (edited)
2 hours ago, CRApex said:

My last several trucks have been diesels, I purchased a 2024 3500 gas High Country and it drives nice, I would say about the same as the diesel did.

I would have never said anything, until I rode in a high country with a diesel. On the same roads I am getting beat up on, that High Country was smooth. I expected this truck to be rougher than my plush Ram 1500.

Edited by reb0957
Another JR Senior Enthusiast

Another JR

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The diameter of the 5600 lb spring is approximately 1 and 34/64 inch. 
 

The diameter of the 5200 lb spring is approximately 1 and 32/64 inch. 
 

Here are the front torsion spring part numbers from an MTU post a while back (left/right):

 

4400 FGAWR 84745473/5

4800 FGAWR 84745477/9

5200 FGAWR 84745481/3

5600 FGAWR 84745485/7

6000 FGAWR 84745489/91

 

I believe your rear leaf springs should be part number 84992005. 

 

 

reb0957 Enthusiast

reb0957

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Torsion bar PN is correct. When I went to get this PN, it looks like a pipe wrench was put on the torsion bar stickers.

Rear leafs correct over load spring gap looks correct.

Then I decided to measure my heights: Filled up this morning. Measured form center hub to fender and floor to fender.

Drivers  side Front: Hub: 24" Floor : 40 1/4" Drivers Side rear:  Hub25 1/2"  Floor: 41 5/16" Rake: 1.062"

Passenger side: Front Hub: 24 7/16" Floor: 40 3/8"  Rear: Hub: 25 5/8" Floor: 41 9/16" Rake: 1.187"

Is it safe to assume the dealership leveled this by cranking the torsion bars? Or is this the right amount of rake? Seems very little for a 3/4 ton. If the dealership did crank the torsion bars, nothing else was change. This is probably the issue.

Thoughts?

Another JR Senior Enthusiast

Another JR

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I have provided below my front wheel center to fender measurements for my stock 3500, but I don’t know if the 2500 had the same nominal target height. My guess is that it is intended to be set to the same ride height.  
 

These measurements were just done with a tape measure and are to the nearest 1/8 inch. The truck is empty, but it has a full fuel tank, which makes the left side sit slightly low. Left is 24.25 inches and right is 24.5 inches.  It looks to me like your truck is at almost exactly the same height in front as mine so I suspect your torsion bar settings have not been changed. 
 

Jettech1 Senior Enthusiast

Jettech1

Posted
Posted (edited)
On 10/16/2023 at 1:45 PM, Another JR said:

That’s the FGAWR rating I’d expect. To be thorough at diagnosing this from a distance, since you have already reduced tire pressure appropriately, I’d suggest next confirming you have the correct front and rear springs actually installed.  I know it’s very very unlikely GM would install the wrong parts, but it’s easy to check. 
 

I have my original 5600 lb front camper springs in the garage and I have installed the base 5200 lb springs for my model. Later today I’ll put a caliper on them and post the torsion bar diameters. Yours should be smaller diameter than mine if they are actually 4800 lb springs. I’m suggesting this measurement method because my original factory springs didn’t have an obvious part number marking. 
 

The rear leaf springs have the eight digit part number painted on them in large characters on the bottom surface, but I don’t have the table showing part number versus model. The secondary spring gaps when the truck is unloaded should look like these pictures from Jettech’s 2500:

F6C20C0C-63F7-4A0C-8629-36F9E2A26D15.webp.0bff9b9410bd36512e48ebc16535752d.webp1E342F90-ACED-46E5-B493-09066DE55177.webp.b6be8e1cc3bafc7d7f3c180d1b78d0b5.webp


If the gaps are much smaller like these pictures from my 3500, then you have the wrong springs unless you ordered the 3500 rear springs under an option I others have said is now available:

152E7C04-7BFB-43D6-A7D2-3AF5D5AEA394.thumb.jpeg.8927d39f6de93fe693d7432412b84ab2.jpeg8A2E5F31-4583-40AD-B1E7-9C55417CA521.thumb.jpeg.a73c3b86ea6df77a7581143e32b2ae0a.jpeg


If the springs check out, it may be that your shocks are overly stiff, or it may simply be that your expectations are for a softer ride than the truck provides. I know our 3500 gives a fairly stiff ride, especially in the rear seat, but it’s not horrible.  I still have my original Rancho shocks, so I’m hoping for a little improvement when I eventually replace them. 

Without measuring the actual thickness of the overload bottom spring, why does yours look thinner?  Could it be just the pics?  I think we have established that the 3500's lower spring is closer to the main spring pack.  But I was looking at the pics of mine and yours and I have to say, they look thinner???  I don't know, perhaps the pic.  Your bottom overload looks to be about 1.5 times thicker than the main spring pack.  My overload spring looks to be about 2 plus times the thickness...do you see what I'm seeing?

 

Edited by Jettech1
Another JR Senior Enthusiast

Another JR

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Posted
3 hours ago, Jettech1 said:

Without measuring the actual thickness of the overload bottom spring, why does yours look thinner?  Could it be just the pics?  I think we have established that the 3500's lower spring is closer to the main spring pack.  But I was looking at the pics of mine and yours and I have to say, they look thinner???  I don't know, perhaps the pic.  Your bottom overload looks to be about 1.5 times thicker than the main spring pack.  My overload spring looks to be about 2 plus times the thickness...do you see what I'm seeing?

 

It does look like yours is thicker. I’ll measure tomorrow so you can compare. I can see why they might have done that for the 2500 configurations that don’t have the third stage springs. 

Another JR Senior Enthusiast

Another JR

Posted
Posted (edited)
14 hours ago, Jettech1 said:

Without measuring the actual thickness of the overload bottom spring, why does yours look thinner?  Could it be just the pics?  I think we have established that the 3500's lower spring is closer to the main spring pack.  But I was looking at the pics of mine and yours and I have to say, they look thinner???  I don't know, perhaps the pic.  Your bottom overload looks to be about 1.5 times thicker than the main spring pack.  My overload spring looks to be about 2 plus times the thickness...do you see what I'm seeing?

 

On my 2021 3500 hd cclb srw gas I measured the rear springs thicknesses as follows. This was done with a calipers and metal ruler and I feel I was accurate to the nearest 64th of an inch. I was measuring on the outside of the spring coatings, so take that into account. The primary springs are 3/8” thick, and the secondary spring is 9/16” thick. 
 

This was a p/n 84992006 spring assembly. My RGAWR is 7250 lbs. 

Edited by Another JR
Added part number and RGAWR
asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted

EVERYONE complains how rough mine rides, 2018 CCSB 3500 w/ diesel. I attributed it to the previous owners adding airbags to it plus its not a long bed. My spring pack has the overload spring pack on top, but I'm not sure what the overload spring on bottom looks like (regarding thickness comparison above).

Another JR Senior Enthusiast

Another JR

Posted
Posted (edited)
7 hours ago, asilverblazer said:

EVERYONE complains how rough mine rides, 2018 CCSB 3500 w/ diesel. I attributed it to the previous owners adding airbags to it plus its not a long bed. My spring pack has the overload spring pack on top, but I'm not sure what the overload spring on bottom looks like (regarding thickness comparison above).

Do you have camper springs or a plow package?  That will make the front stiffer. Have you lowered tire pressure when unloaded?  60 psi will ride a lot nicer than 80. (The rear tpms alarm pressure on my truck is 62 psi.)

 

Jettech was talking about the thickness of the four first-stage springs marked with the green arrow compared to the thickness of the second stage spring marked with the red arrow. 

B47A3D26-DC27-4E73-AD9D-81BB6A6A06DE.jpeg

Edited by Another JR
Jettech1 Senior Enthusiast

Jettech1

Posted
Posted
7 hours ago, Another JR said:

On my 2021 3500 hd cclb srw gas I measured the rear springs thicknesses as follows. This was done with a calipers and metal ruler and I feel I was accurate to the nearest 64th of an inch. I was measuring on the outside of the spring coatings, so take that into account. The primary springs are 3/8” thick, and the secondary spring is 9/16” thick. 
 

This was a p/n 84992006 spring assembly. My RGAWR is 7250 lbs. 

I'll get some measurements tomorrow.  This has become quite an interesting topic when it comes to the differences between the two.

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