1987 Suburban v1500 - what separates the v1500 and v2500?

MrDSmith · Mar 22, 2024

Hello folks, I'm the (very) proud, second owner of this fine vehicle. It has been used and driven nearly every day of its life for 36 years, but well maintained. 5.7L V8 350 TBI.

I am having some work done on the vehicle to prepare it for the next 100k miles of use, and it has been advised to replace the original leaf springs due to sagging/shape/age. Since I would like to be able to tow and move cargo every now and then, the topic of beefier leaf springs came up and I thought I'd come here for some advice.

I live in the mountains on dirt roads, and would love to be able to use this vehicle to tow ~5,000lbs of equipment on some logging roads on occasion (once per month, at most, for 10-20 miles). I assume this would be no issue were I to own the v2500, but wonder if I'd be pushing this 1/2 ton vehicle too much in it's stock configuration.

Generally, I am curious to know what all makes the 2500 a 3/4 ton for this model year. Is the frame thicker on the 2500? Are the brakes and axles the same? Surely, the v2500 would have beefier leaf springs. What about the gear ratios?

While I am tempted towards slightly stronger leaf springs, I assume it would take much more than that to achieve the stability and strength of the 3/4 ton v2500 Suburban, and I'm not sure I would want the added lift and change to it's road handling.

So, with all that being said, I am leaning to using OEM spec'd leaf springs from Dayton and possibly replacing the bump stops with blue SumoSprings to help with leveling when I do tow/haul (which I'd probably try to keep under 3k lbs). Any feedback, though, would be much appreciated.

Thought you all might like to see a pic, so here is a shot from one of my game cameras. Everyone in town loves seeing her drive by.

MrDSmith · Mar 22, 2024

Found a document from GM which seems to have answers to many of my questions.

Do I understand correctly that the main differences on the 1987 v2500 Suburban (gas) are:

v2500 vs v1500

FRONT AXLE CAPACITY
3,800lbs vs 3,600lbs

REAR AXLE CAPACITY
6,000lbs vs 4,000lbs

REAR LEAF SPRING CAPACITY
3,000lbs each vs 2,000lbs each

REAR SHOCK ABSORBER DIAM
32MM vs 25mm

BRAKE ROTOR DIAM.
12.5" vs 11.86"

BRAKE DRUM SIZE
13" x 2.5" drum vs 11.15" x 2.75"

STEEL FRAME STRENGTH calculated via section modulus
3.88 vs 3.57 (not sure what real-world difference this translates to)

STOCK WHEEL SIZE
16" x 6.5" vs 15" x 6"

GVWR
8,600lbs vs 7,000lbs

Interestingly enough, this document also claims that the towing capacity is up to 9,500lbs "when properly equipped."

Bextreme04 · Mar 22, 2024

MrDSmith said:
Hello folks, I'm the (very) proud, second owner of this fine vehicle. It has been used and driven nearly every day of its life for 36 years, but well maintained. 5.7L V8 350 TBI.

I am having some work done on the vehicle to prepare it for the next 100k miles of use, and it has been advised to replace the original leaf springs due to sagging/shape/age. Since I would like to be able to tow and move cargo every now and then, the topic of beefier leaf springs came up and I thought I'd come here for some advice.

I live in the mountains on dirt roads, and would love to be able to use this vehicle to tow ~5,000lbs of equipment on some logging roads on occasion (once per month, at most, for 10-20 miles). I assume this would be no issue were I to own the v2500, but wonder if I'd be pushing this 1/2 ton vehicle too much in it's stock configuration.

Generally, I am curious to know what all makes the 2500 a 3/4 ton for this model year. Is the frame thicker on the 2500? Are the brakes and axles the same? Surely, the v2500 would have beefier leaf springs. What about the gear ratios?

While I am tempted towards slightly stronger leaf springs, I assume it would take much more than that to achieve the stability and strength of the 3/4 ton v2500 Suburban, and I'm not sure I would want the added lift and change to it's road handling.

So, with all that being said, I am leaning to using OEM spec'd leaf springs from Dayton and possibly replacing the bump stops with blue SumoSprings to help with leveling when I do tow/haul (which I'd probably try to keep under 3k lbs). Any feedback, though, would be much appreciated.

Thought you all might like to see a pic, so here is a shot from one of my game cameras. Everyone in town loves seeing her drive by.

Axles, springs, and T-case are about the only differences between the 1500 and 2500 squares. I use my K25 pickup for towing/hauling a few times a year and hauling my travel trailer through the PNW highways and logging roads during the hunting season. I use my 2011 K1500 Suburban to tow the travel trailer on family outings the rest of the year. Travel trailer is 4500lbs empty and 6800lbs gross with a load leveling hitch system.

My K25 has 61" 5-leaf rear springs from a 97 K2500 Suburban on it and it has no issue with a 700lb tongue weight trailer and I regularly haul several thousand pounds worth of materials(I've had an entire pallet of railroad ties in it and 2 wet yards of 3/4 minus gravel in it several times).

It is equipped with a 350/TH400/NP205 and a 14BFF rear axle with 4.10's and the big 13" rear drum brakes. It has no issue with the weight. You can easily bolt on the stock V2500 springs and have the weight capacity to tow, the problem is going to be that your 1500 is most likely a stock 700R4/NP241 with a 10 bolt rear axle. The 10 bolt can survive towing the 5k fine, but you will likely need to gear it down some. You'll also want to get a big external cooler for the transmission and make sure the tires and wheels are rated for the extra amount of weight you are planning on putting on them. @Vbb199 has a TBI 1500 suburban and uses it to tow his off road S10 Blazer pretty regularly. I seem to remember he re-geared his axle and had 2500 springs on it without too many issues.

MrDSmith · Mar 22, 2024

Bextreme04 said:
Axles, springs, and T-case are about the only differences between the 1500 and 2500 squares. I use my K25 pickup for towing/hauling a few times a year and hauling my travel trailer through the PNW highways and logging roads during the hunting season. I use my 2011 K1500 Suburban to tow the travel trailer on family outings the rest of the year. Travel trailer is 4500lbs empty and 6800lbs gross with a load leveling hitch system.

My K25 has 61" 5-leaf rear springs from a 97 K2500 Suburban on it and it has no issue with a 700lb tongue weight trailer and I regularly haul several thousand pounds worth of materials(I've had an entire pallet of railroad ties in it and 2 wet yards of 3/4 minus gravel in it several times).

It is equipped with a 350/TH400/NP205 and a 14BFF rear axle with 4.10's and the big 13" rear drum brakes. It has no issue with the weight. You can easily bolt on the stock V2500 springs and have the weight capacity to tow, the problem is going to be that your 1500 is most likely a stock 700R4/NP241 with a 10 bolt rear axle. The 10 bolt can survive towing the 5k fine, but you will likely need to gear it down some. You'll also want to get a big external cooler for the transmission and make sure the tires and wheels are rated for the extra amount of weight you are planning on putting on them. @Vbb199 has a TBI 1500 suburban and uses it to tow his off road S10 Blazer pretty regularly. I seem to remember he re-geared his axle and had 2500 springs on it without too many issues.

That is good information, thank you.

Did you also get a chance to look at my second post, just above yours? I think I started worked on it just as you were posted, so I think it popped-up just after you posted.

Bextreme04 · Mar 22, 2024

MrDSmith said:
That is good information, thank you.

Did you also get a chance to look at my second post, just above yours? I think I started worked on it just as you were posted, so I think it popped-up just after you posted.

I did. The differences are the axles and springs. Stock 1500 is a three leaf spring on a 10 bolt rear axle. Stock 2500 is a 5 leaf on a 14 Bolt Semi or Full float axle. 13 x 2.5" is the heavy duty rear brakes and the 12.5" front disk is the standard 10 Bolt front axle with the HD 8 lug outer hubs. You can get a full 3/4 ton axle set around her for $350-500.. or even a full 3/4 ton suburban for not much more than that and just take the whole drivetrain if that's what you want to do, but honestly it sounds like you won't be doing a lot of towing or anything very heavy duty.. you should be fine with just a good external cooler and 2500 rear springs. Make sure you have good tires and wire in a good quality trailer brake system and you should be good.

MrDSmith · Mar 22, 2024

Bextreme04 said:
I did. The differences are the axles and springs. Stock 1500 is a three leaf spring on a 10 bolt rear axle. Stock 2500 is a 5 leaf on a 14 Bolt Semi or Full float axle. 13 x 2.5" is the heavy duty rear brakes and the 12.5" front disk is the standard 10 Bolt front axle with the HD 8 lug outer hubs. You can get a full 3/4 ton axle set around her for $350-500.. or even a full 3/4 ton suburban for not much more than that and just take the whole drivetrain if that's what you want to do, but honestly it sounds like you won't be doing a lot of towing or anything very heavy duty.. you should be fine with just a good external cooler and 2500 rear springs. Make sure you have good tires and wire in a good quality trailer brake system and you should be good.

Thank you.

MidneightReider · Mar 22, 2024

MrDSmith said:
Hello folks, I'm the (very) proud, second owner of this fine vehicle. It has been used and driven nearly every day of its life for 36 years, but well maintained. 5.7L V8 350 TBI.

I am having some work done on the vehicle to prepare it for the next 100k miles of use, and it has been advised to replace the original leaf springs due to sagging/shape/age. Since I would like to be able to tow and move cargo every now and then, the topic of beefier leaf springs came up and I thought I'd come here for some advice.

I live in the mountains on dirt roads, and would love to be able to use this vehicle to tow ~5,000lbs of equipment on some logging roads on occasion (once per month, at most, for 10-20 miles). I assume this would be no issue were I to own the v2500, but wonder if I'd be pushing this 1/2 ton vehicle too much in it's stock configuration.

Generally, I am curious to know what all makes the 2500 a 3/4 ton for this model year. Is the frame thicker on the 2500? Are the brakes and axles the same? Surely, the v2500 would have beefier leaf springs. What about the gear ratios?

While I am tempted towards slightly stronger leaf springs, I assume it would take much more than that to achieve the stability and strength of the 3/4 ton v2500 Suburban, and I'm not sure I would want the added lift and change to it's road handling.

So, with all that being said, I am leaning to using OEM spec'd leaf springs from Dayton and possibly replacing the bump stops with blue SumoSprings to help with leveling when I do tow/haul (which I'd probably try to keep under 3k lbs). Any feedback, though, would be much appreciated.

Thought you all might like to see a pic, so here is a shot from one of my game cameras. Everyone in town loves seeing her drive by.

As far as the 87-91 Suburbans go there's quite a bit of difference.

Usually a 1500 will have a 4 speed 700R4. Not that a 700R4 is weak, but they did come in S10s and are considered medium duty at best. The 2500 will usually have a 3 speed TH400 which is a heavy duty transmission.

The 1500 will have a 10 bolt rear axle. Someone will argue undoubtedly but 10 bolts are not designed to tow all the time and they will wear out. The 2500 has an 8 lug 14 bolt full floater which means it has more bearing surfaces, bigger axleshafts, a much larger gear set, bigger brakes, and is damn near indestructible under normal conditions.

The frames in a 2500 are stronger. The springs are stronger. Often they were ordered with factory HD tow packages. They have a larger radiator to combat overheating. Many of them were ordered with forged internals like the big RV engines.

Yes, like it or not there is a big advantage to having a 2500 if you are going to tow a lot. It's pretty much why they exist.

MrDSmith · Mar 22, 2024

MidneightReider said:
As far as the 87-91 Suburbans go there's quite a bit of difference.

Usually a 1500 will have a 4 speed 700R4. Not that a 700R4 is weak, but they did come in S10s and are considered medium duty at best. The 2500 will usually have a 3 speed TH400 which is a heavy duty transmission.

The 1500 will have a 10 bolt rear axle. Someone will argue undoubtedly but 10 bolts are not designed to tow all the time and they will wear out. The 2500 has an 8 lug 14 bolt full floater which means it has more bearing surfaces, bigger axleshafts, a much larger gear set, bigger brakes, and is damn near indestructible under normal conditions.

The frames in a 2500 are stronger. The springs are stronger. Often they were ordered with factory HD tow packages. They have a larger radiator to combat overheating. Many of them were ordered with forged internals like the big RV engines.

Yes, like it or not there is a big advantage to having a 2500 if you are going to tow a lot. It's pretty much why they exist.

Gotcha. This is all very helpful for someone like me who is just starting out, thank you.

skysurfer · Mar 22, 2024

I believe the V2500 came standard with the 14b semi-float rear axle, while the C2500 had the full-float.

An option to changing the rear springs would be to add some helper bags. I’ve had Ride-Rite helpers on mine for 20+ years with no issues except I went through some poor quality onboard air pumps before buying an ARB unit. Of course, that doesn’t address the issue of the 1500’s smaller brakes, but at least you’ll be riding level while towing without altering the factory ride the rest of the time.

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Fat 454 · Mar 25, 2024

Hi only real difference between the rated trucks that you cannot change with bolt-ons ( diff, axles etc. ) is the frame itself. Modulus refers to the flexibility or "bending" resistance of the frame when under load. This is a standard structural engineering term, and you can look it up easily for a more technical definition.

The trucks rated for heavier work ( C2500, C 3500 etc. ) were given a "stronger" frame than the C1500, which combined with the other bolt on components rated the trucks for loading. In the real world, this frame strength came from either thicker material, a deeper "C" section, or a combination of both. I'm sure someone more knowledgeable than me on the board will have all the specs.

What i'm getting at is that if you have a C1500 frame, and bolt on all the heavier goodies, still be prepared for frame twisting and cracking under hard use. This will probably be accelerated in fact if you do this. A good place to go to address this is the rock crawling forums. There is a load of info out there about frame flex ( especially on long beds, suburbans etc. ) and the big one - tearing out the steering box mount. Boxing the frame is a good preventative starting point - do this before something breaks - around the steering box and spring hangars. Off road design ( ORD ) sells kits, and there are lots of YT videos.

Good luck.

Hunter79764 · Mar 25, 2024

I've got an 87 v2500 myself. As noted above, all of that is true. If you are going to tow frequently and/or in rough conditions, some of the 3/4T parts would certainly help. That said, 5000 lbs isn't terrible if you keep it all sane. A trans cooler on a 700R4 is ALWAYS a good idea, especially on heavier trucks and/or tow duty. Brakes are a concern, depending on how and where you are towing. If you have trailer brakes, that helps a ton there if you can set them up and use them properly. You mention logging roads, so I'm assuming you aren't trying to take 5000 lbs up and down mountain passes at 70 mph...

From there, if you find yourself not having the beans to get where you need to go, consider swapping axles to a 14 bolt semi float with lower gearing, and either regearing the front or just replacing with a 3/4Ton entire front axle as well, with matching ratio. Higher number gears will make it easier to take off etc, and greatly reduce the load put on the transmission etc. If you don't want to replace the front entirely, I believe there are some years of 14 bolt SF rears with 6 lug wheels, so you don't have to change everything over to 8 lug.

If you think it is too "squatty", you can do the 3/4t springs, but be aware that they may be longer, requiring you to adjust your hangers. Air bags are great on every vehicle I have used them on, so that's certainly an option too. Or, call one of the higher end spring manufacturers and tell them what you want. If you don't mind the price, I don't think I've ever heard anything negative about custom springs, and they would have you riding better unloaded while still having the support to load it up.

Grit dog · Mar 27, 2024

skysurfer said:
I believe the V2500 came standard with the 14b semi-float rear axle, while the C2500 had the full-float.

An option to changing the rear springs would be to add some helper bags. I’ve had Ride-Rite helpers on mine for 20+ years with no issues except I went through some poor quality onboard air pumps before buying an ARB unit. Of course, that doesn’t address the issue of the 1500’s smaller brakes, but at least you’ll be riding level while towing without altering the factory ride the rest of the time.

You must be registered for see images attach

^What he said.
If you drive off road a lot I’d personally keep half ton springs if you’re only occasionally loading it down for short periods of time. The ride will be much better.
I like sumos or Timbrens in the right circumstances. This may be it for you, but not imo. Although it’s arguably the cheapest option. At that point, boot on helper springs are equally as cheap. Every option has its +\-
Towing 5klbs occasionally and short distances is not an issue at all if the truck is mechanically sound. Just be easy on the truck and stay out of OD.
Nice burb and super cool it’s still 100% in service daily!

Grit dog · Mar 27, 2024

And you said towing on logging roads. So low speed. Keep the trans cool and use low gears or even low range if necessary if it’s real steep climbs.
Id keep the light duty rear springs still for ride quality whether you replace them or not. Make sure they’re actually sagging though. Perfectly good OE rear springs on a burb half ton 4x4 always look like the ass is dragging due to the taller front axle/springs and the way squarebody fender openings are lower in the rear.

1987 Suburban v1500 - what separates the v1500 and v2500?

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