72 C20 lowering a tow rig

[Mystery_man]

Ok yall all the searching that I have done for lowering this truck does not tell me if it affects the towing capacity.

I want to lower my truck as much as I can without taking away from the towing capacity. Do bags or drop spindles/shakles? I am looking at towing a 36ft gooseneck to take 2 race cars and tools/parts.

Suggestions? I am new to these trucks and have never modified the suspension of a towing truck. I can weld and do most of my work myself or with the assistance of a machine shop.

[Mystery_man]

I think I like bags, but anyone have real world experience with towing with this truck on bags?

[Billyburban]

Originally Posted by Mystery_man

I think I like bags, but anyone have real world experience with towing with this truck on bags?

I have a 70 c10 suburban just put CPP 4inch lowering HD springs in rear with there shocks also there shock relocaters I'm hooking up my 19ft travel trailer to night fingers crossed

[Mike C]

You probably don't want to hear this, but if you are looking at a big trailer with a 1000# pin weight, you should do air bags. But NOT to lower it but to increase load capacity. I left my C20 at full height except for 1 1/2" shackles in the rear at the lower of the 2 settings. This allowed 1500+# in the bed without being on the bumpstops.

But lowering more than a little WILL impact the load carrying ability, and a trailer the size you are talking is probably too much for the platform anyhow. That would be a challenge for my SB/EC Duramax truck.
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[Billyburban]

Originally Posted by Mike C

You probably don't want to hear this, but if you are looking at a big trailer with a 1000# pin weight, you should do air bags. But NOT to lower it but to increase load capacity. I left my C20 at full height except for 1 1/2" shackles in the rear at the lower of the 2 settings. This allowed 1500+# in the bed without being on the bumpstops.

But lowering more than a little WILL impact the load carrying ability, and a trailer the size you are talking is probably too much for the platform anyhow. That would be a challenge for my SB/EC Duramax truck.
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Well I hooked up my trailer last night in my backyard and it didn't drop much at all but not enough room to move around I'll post pics with trailer on the back of my suburban

[Billyburban]

Here's mine the rear has 4 inch HD rear coils an drop shocks with relocaters from CPP generic front suspension heading to CPP tomorrow to get the front suspension an drop spindles

[Billyburban]

The coil still has room to bounce 😁

[brad_man_72]

Billy the axle is clearly sitting on the bumpstop. Not that that has ever slowed me down.4-6 drop sitting on the bumpstops with a full fuel tank in a 1/2 ton.

[Mike C]

My 29' Gooseneck is a 14,000# GVWR with a 9,000# load capacity. Your trailer will weigh close to 8,000# at least, maybe more depending on it's setup. The cars plus the tools and parts will add 5000# more I'd guess? That's a 13,000# load. Heaviest I pulled with my '70 GMC C2500 was probably 7,500# and it did that fairly well. But double that, I have my doubts.

I think my '02 Duramax truck is rated to 16,000# max trailer weight. And there is no doubt that it is a much more robust chassis and driveline. As much as I love these old trucks, my opinion is that's WAY outside of the truck's safe operating abilities. Even more so if you expect to do that lowered.

YMMV but be safe either way.

[Billyburban]

Yea it is I'm going to have to install air bag helper lol. Your truck has an Ls swap ?

[SS Tim]

Agree the basic problem is you probably don't have the capacity to start with.

Here are Chevrolets published max GCW (gross combined weight) ratings for a 72 C/20 pickup.

400 bbc .... 4.10/ 12.5k..... 3.54/ 10.75k

350 sbc .... 4.57/ 10.5k..... 4.10/ 9.6k

Considering a truck that curbs around 4500lb leaves a 8000lb trailer and cargo load at best.

[brad_man_72]

Yup 5.3 swap. Nothing fancy just clean.

[Billyburban]

Originally Posted by brad_man_72

Yup 5.3 swap. Nothing fancy just clean.

Looks nice an clean. You didn't switch over hydro brakes ? You have disic in the front an drums an the rear ? It stops good when towing ?

[special-K]

Let's stay on topic here. How did we get to talking about hauling a smaller camper with a Suburban and all this other unrelated stuff? This thread is about lowering a C/20 pickup and hauling a two-car trailer, and that IS way too much for the capacity even with beefed up springs. This is 1t or heavier territory. Just do the GVW math. You CAN lower a truck in a way to maintain hauling capacity...within limits. The right bags are fine. They were largely used on heavy rigs way before anyone put them under a pickup. Lowering reduces travel and so does weight, so watch for that. Brakes are a consideration along with suspension. Then there is steering parts, frame, cooling, to name a few. Actual weight of tow vehicle comes into play with larger loads, no matter how tough a truck is.

[Billyburban]

Originally Posted by special-K

Let's stay on topic here. How did we get to talking about hauling a smaller camper with a Suburban and all this other unrelated stuff? This thread is about lowering a C/20 pickup and hauling a two-car trailer, and that IS way too much for the capacity even with beefed up springs. This is 1t or heavier territory. Just do the GVW math. You CAN lower a truck in a way to maintain hauling capacity...within limits. The right bags are fine. They were largely used on heavy rigs way before anyone put them under a pickup. Lowering reduces travel and so does weight, so watch for that. Brakes are a consideration along with suspension. Then there is steering parts, frame, cooling, to name a few. Actual weight of tow vehicle comes into play with larger loads, no matter how tough a truck is.

Well I asked a ? Isn't that what this whole community is for sharing in pros & cons about certain subjects even when different they do share characteristics ? It's OK though my buddy at the Pomona swap meet picked up a 1970 Chevy suburban brochure that they gave out when you bought the SUV's so I have all the specs for the C 10 C 20s straight from GM. It says there both rated for 6000 for towing. Some said about the newer trucks being more sturdy but my rear frame I boxed it all in so it's much stronger and stiffer than a brand-new trucks but maybe I'll box in the entire frame completely Back to front.