K2500 Suburban with K1500 Rear Leafs

Howdy,

I know this will work from a functional standpoint because folks go the other way frequently. My 98 K2500 Suburban mainly hauls people (we use all 9 seats about quarterly and 6 frequently) and light stuff so I'd like to soften out the rear ride. I was thinking 1500 leafs to start with and adding an airbag helper set eventually as I sometimes tow cars on a flat trailer.

Any gotchas I'm missing in terms of physical installation or practical usage?

Thanks

It will soften up the ride for sure; I already feel like a 1500 'burb is mushy so personally I would avoid it. It's also going to drop the rear ride height so your front end will be in the air.

Richard

If you get your tongue weight right, towing with K1500 springs isn't a problem. I towed my 3000+ Jaguar on an open flatbed trailer behind my '99 K1500 Suburban.

I thought the 1500 HD and the 2500 LD use the same springs - 4/1. Only if you go to the regular 1500 springs you'll get a 3/1 pack. If the 2500 is a HD then it's a 5/1?

https://www.sdtrucksprings.com/index.php?main_page=product_info&products_id=7365

someotherguy said:

It will soften up the ride for sure; I already feel like a 1500 'burb is mushy so personally I would avoid it. It's also going to drop the rear ride height so your front end will be in the air.

Richard

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Yeah, what Richard said. You are going backwards if you go this route. Helper airbags are going to be a pain when you need to air them and can't find a service station with a working air compressor machine. And eventually, they will fail altogether.

If you are ridding with 6-9 people in the truck, I would imagine it already rides smoother than when loaded for sure, no? But a 4 leafpack from a 1500 with 9 people AND a car trailer is most surely going to get overloaded. I suppose you will be okay with an airbag system. It just seems counterintuitive.

The 1500 Suburbans have a 4 leaf pack and I think the 2500 Suburbans have a 6 leaf pack? Maybe get some "off the shelf" 5 leafpack? Or the 2500 Light Duty, as was suggested. I think those were also 5 leaf pack.

IIRC the Suburban 1500 pack is 5 leafs, but the added weight of the fullsize SUV body vs. a pickup still leaves you with a mushy-ish ride. They're shorter in length than pickup springs, but I don't know the actual spring rate. Just owned several GMT400 1500 Suburbans and always found the ride a little soft.

When comparing to pickups it's important to remember the SUV's do not use the same springs at all. Suburbans have their own springs, fullsize Blazer/Tahoe have their own, and pickups have their own. They're different lengths and do not swap out. So the # of leafs does not necessarily correlate to pickups, either.

Richard

Not too worried about the drop in the rear ride height, this thing still has a stock front end and is down by the bow already. However if I got from jarring empty now and still too firm when just the family is in it, to soft when empty and bottoming out when the family is in it; that's not acceptable. It rides it's best as noted when full of 9 people and/or when the back is loaded with stuff. Wish there was a more middle ground, remove a leaf from the pack?

Not to change your direction here, but what kind of shocks are you running? Do you think an adjustable shock might be an alternative option? Just thinking out loud - it might cost less vs. 2 replacement leafs and a bag kit.

Removing a leaf doesn't sound like a bad idea...but do so at your own discretion. I'm not sure how your truck will behave during emergency maneuver while it's fully loaded (depending on which leaf you pull).

Apples to oranges, but I pulled an overload spring out of a dropped pickup and bought an add-on air bag kit to assist.

Adding bags gave my truck an amplified "variable rate," effect - if that makes sense. It was very noticeable on the highway. Just a couple PSI in an unloaded truck kept close to its usual ride on regular bumps and potholes, but firmed up the closer it got to bottoming out. Before, if I was partially loaded or hit those low-swooping dips, I'd be bopping bumpstops and long trips would feel even longer. The manufacturers' minimum pressure in an unloaded truck rode rough for me, just running by feel.

Hope all that helps!

CTX-SLPR said:

Not too worried about the drop in the rear ride height, this thing still has a stock front end and is down by the bow already. However if I got from jarring empty now and still too firm when just the family is in it, to soft when empty and bottoming out when the family is in it; that's not acceptable. It rides it's best as noted when full of 9 people and/or when the back is loaded with stuff. Wish there was a more middle ground, remove a leaf from the pack?

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Suburbans are typically level from factory, or close to it. If you swap springs as planned, you'll be nose-up and trust me, you won't like it.

Richard

I've never driven a GMT400 2500 Suburban, but do daily drive a GMT800 2500 suburban. I could not remember what leaf springs these have, but just looked and it's a 5 leaf pack. I can pack the wife and kids in there and may get a little better damping, so marginal better ride. I've towed a 4,500 trailer, same effect, but not at the same time thus yet.

I don't have complaints as far as ride quality; seems to ride "maybe" just a hair smoother than my 99 Silverado ECSB 1500 truck that I used for 12 years a daily driver, and that has 3 leaf pack. My other truck is a '00 GMT400 K3500 CCLB, and I can't really tell the difference on that one either (6 leaf pack), but the wheelbase is way different and a heavier truck altogether, LOL. My point is that it still rides like a truck, because that's what it is. Aside from putting new shocks, I would *cautiously* swap leafs to a 5 pack and go from there.

I know these trucks have different geometry as far as the rear axle, so you can't directly swap things without a lot of work. Also, SUV vs trucks and OBS vs NBS. So maybe really not useful information. You'd have to compare spring rates directly, which I don't know what they are. But just a comparison between other trucks may give some idea.

Another point is that the LT tires ride harsher than the P series tires. On my 99 Silverado I added a add-a-leaf deal to the back and it rode harsher. Adding a bags of sand to the bed made it ride better. That was on P series tires. Years later I removed the add-a-leaf, but changed to LT tires, and it seems to ride about the same...not sure if changing to P-series tires is worthwhile. I personally don't like P-series tires under load. They seem too soft. All of my trucks have Lts.

Looks like Rockauto shows leaf springs with 5, 6 and 8 packs, and it says it fits C/K1500 and 2500 Suburbans. I would call Husky Spring and maybe they can recommend something:

https://www.rockauto.com/en/catalog...n,7.4l+v8,1303715,suspension,leaf+spring,7544

There are 3 different widths, so I'm not sure how they make up for that? Maybe some sort of bushing?

Good luck.