Difference btwn 2500HD and 3500HD SRW

Another JR · September 29, 2023

On 9/26/2023 at 7:54 PM, Jettech1 said:

From my research and from what newdude said, the 5 leaf spring packs are identical in the 2500 and 3500 trucks. The only difference is the 3500's get the 2 extra springs above the spring pack and the overload bumpers for them. Those 2 extra springs are what increases the payload over the 2500's. I could be wrong as I've been before, but my research says I'm right.

I don’t think that’s correct Jettech based on what MTU said on the post pasted by Pryme. He said the bottom leaf on the main pack, which is shorter, thicker, and does not have its ends clamped with the other four springs and engages progressively, is different and engages (touches the next spring and begins to apply additional spring force) earlier than on the 2500 spring.

The one ton feel stiffer in rear suspension when empty and the overloads do not engage when the truck is empty unless you go over a large bump at speed. In fact, with my 3500 with 2000 lbs in the bed the overloads are still an inch from their bumpers.

MTU Alum · September 30, 2023

The second stage on 3500 engages about one inch quicker than 2500.

#iworkforGM

Dr1ft3r · September 30, 2023

If you install bags on your 3500 it will never touch the overload springs again and it made an immediately noticeable ride quality improvement for me when not loaded down. Obviously, it also improves loaded ride quality too. I run my tires at 70 to 80 psi all the time and the ride is fine. YMMV

Jettech1 · October 1, 2023

On 9/29/2023 at 5:04 PM, Another JR said:

I don’t think that’s correct Jettech based on what MTU said on the post pasted by Pryme. He said the bottom leaf on the main pack, which is shorter, thicker, and does not have its ends clamped with the other four springs and engages progressively, is different and engages (touches the next spring and begins to apply additional spring force) earlier than on the 2500 spring.

The one ton feel stiffer in rear suspension when empty and the overloads do not engage when the truck is empty unless you go over a large bump at speed. In fact, with my 3500 with 2000 lbs in the bed the overloads are still an inch from their bumpers.

How about we compare pics? This is from my 2500 a front and rear pic of my spring pack. Lets see yours if you have the time sir because this topic intrigues me. Not of your overloads on the topside, just basically the same pic from your 3500 spring pack as mine.

Edited October 1, 2023 by Jettech1

Another JR · October 2, 2023

You showed me yours so I guess it’s only fair to show you mine …

Unfortunately I have my pop up camper in the bed, sitting at 1500 lbs with empty water tanks and no food or gear (I’ve weighed it.) Nearly all of that weight (1400+) is on the rear axle. As you can see my secondary springs (not the overloads) are in contact at that weight. One of the pictures looks like maybe there’s a gap but the plastic pad is in hard contact. When the truck is empty there is a gap. My payload rating is 4055 and RGAWR is 7250. Spring pack part number is 84992006. My overloads are about 1.75 inches from the bumpers with the camper on at this weight.

Jettech1 · October 2, 2023

1 minute ago, Another JR said:

You showed me yours so I guess it’s only fair to show you mine …

Unfortunately I have my pop up camper in the bed, sitting at 1500 lbs with empty water tanks and no food or gear (I’ve weighed it.) Nearly all of that weight (1400+) is on the rear axle. As you can see my secondary springs (not the overloads) are in contact at that weight. One of the pictures looks like maybe there’s a gap but the plastic pad is in hard contact. When the truck is empty there is a gap. My payload rating is 4055 and RGAWR is 7250. Spring pack part number is 84992006. My overloads are about 1.75 inches from the bumpers with the camper on at this weight.

Would I be wrong saying your main spring pack looks identical to mine sans the overloads?

Another JR · October 2, 2023

Just now, Jettech1 said:

Would I be wrong saying your main spring pack looks identical to mine sans the overloads?

It’s hard to tell from the picture, but the part number is stencilled in big numbers on the bottom of the spring. They certainly are very similar.

Jettech1 · October 2, 2023

Just now, Another JR said:

It’s hard to tell from the picture, but the part number is stencilled in big numbers on the bottom of the spring. They certainly are very similar.

That's my point. They are identical. You have the 2 overload 3500 helpers on top of your spring pack. But our basic spring packs are identical. Tell me I'm wrong.

Another JR · October 2, 2023

I just realized the rear axle rating on my 2021 3500hd is higher the overall gross vehicle weight rating of my 93 K2500.

Jettech1 · October 2, 2023

9 minutes ago, Another JR said:

I just realized the rear axle rating on my 2021 3500hd is higher the overall gross vehicle weight rating of my 93 K2500.

Here's a weird factoid. We weighed our truck at the CAT scales empty with a full tank of gas and just my wife and I in it. The front axle weighs the same as our 21 Ford Explorer and the rear axle had almost the same exact weight as the 21 Ford Escape that we traded in on our truck. So funny but I love it!!!

Another JR · October 2, 2023

1 minute ago, Jettech1 said:

That's my point. They are identical. You have the 2 overload 3500 helpers on top of your spring pack. But our basic spring packs are identical. Tell me I'm wrong.

Is the part number on yours the same as mine? My guess is it’s not. If you read what MTU wrote, he said the secondary springs on the 3500 engage earlier than those on the 2500 as you add load to the axle. My guess is that mine begin to contact the next leaf under static conditions at around 1000 lbs in the bed while yours don’t contact until some significantly higher weight, giving you a more compliant ride.

I don’t hit my overloads statically until I have over 3000 lbs in the bed, so the overloads are not what is making the ride stiffer at mid-level loads. If the springs were identical the ride would be pretty much the same (except for small truck weight differences. When I test drove trucks the 3500 rear suspension felt noticeably stiffer to me, but that’s subjective.

Jettech1 · October 2, 2023

2 minutes ago, Another JR said:

Is the part number on yours the same as mine? My guess is it’s not. If you read what MTU wrote, he said the secondary springs on the 3500 engage earlier than those on the 2500 as you add load to the axle. My guess is that mine begin to contact the next leaf under static conditions at around 1000 lbs in the bed while yours don’t contact until some significantly higher weight, giving you a more compliant ride.

I don’t hit my overloads statically until I have over 3000 lbs in the bed, so the overloads are not what is making the ride stiffer at mid-level loads. If the springs were identical the ride would be pretty much the same (except for small truck weight differences. When I test drove trucks the 3500 rear suspension felt noticeably stiffer to me, but that’s subjective.

I don't know what the Part numbers are but let's give a shout out to other 3500 owners. Can you take a pic of your rear springs unloaded like I did mine on my 2500 and please post the pics. And let's put this issue to bed once and for all.

Jettech1 · October 2, 2023

9 minutes ago, Another JR said:

Is the part number on yours the same as mine? My guess is it’s not. If you read what MTU wrote, he said the secondary springs on the 3500 engage earlier than those on the 2500 as you add load to the axle. My guess is that mine begin to contact the next leaf under static conditions at around 1000 lbs in the bed while yours don’t contact until some significantly higher weight, giving you a more compliant ride.

I don’t hit my overloads statically until I have over 3000 lbs in the bed, so the overloads are not what is making the ride stiffer at mid-level loads. If the springs were identical the ride would be pretty much the same (except for small truck weight differences. When I test drove trucks the 3500 rear suspension felt noticeably stiffer to me, but that’s subjective.

The PN will be different because you have the extra 2 springs as overloads. But the main spring pack is identical.....we will prove this eventually. Look back at the pics we posted. Although yours was loaded and mine wasn't. They're identical.

Edited October 2, 2023 by Jettech1

Another JR · October 2, 2023

Are you sure the part number 84992006 includes the overload assembly? I honestly don’t know.

i’m just trying to explain what I think MTU (who works at GM) said in his description on the differences in the springs. Maybe MTU can clarify this?

Jettech1 · October 2, 2023

8 minutes ago, Another JR said:

Are you sure the part number 84992006 includes the overload assembly? I honestly don’t know.

i’m just trying to explain what I think MTU (who works at GM) said in his description on the differences in the springs. Maybe MTU can clarify this?

They are definitely different part numbers only due to the overload spring pack that you have on top of the main spring pack. Aside from that, the main 4 leaf spring pack with the overload spring under the 4 mains is identical on both 2500 and 3500's. No extra ends clamped, nothing. Same same. If you look at the pics you and I just posted, we kind of just proved that point.

Edited October 2, 2023 by Jettech1