Towing heavy with my C30

[KnockingDiesel]

Hello all,

Been doing some remodeling on the house and using my gmc to pull the dump trailer. I pulled a few stumps and some concrete/block and loaded it into my trailer, I didn’t think too much about the weight since I usually pull it with my diesel. So I get to the land fill and was just under 20,000 lbs over the scales.

It wasn’t exactly effortless but the 20 mile drive to the dump would have had me guessing my load was less than that. On the biggest hill I was at 40 mph in 2nd (3rd technically) with a 50 mph speed limit.

My trailer is about 3,200 lbs and it’s content was 9,400 lbs that’s 12,600 lbs in a 40 year old truck and I think that’s pretty cool. I’ve been pulling trailers since I was a kid and at no point did I feel I didn’t have enough truck.

All that aside what’s the max towing capacity on this truck I couldn’t find too much info but one brochure said 13,500 properly optioned/equipped and others said 11,000.

Either way an SM465 and 454 did better than I thought it would. I have no idea what my mpg was and I don’t think I’d wanna know at that weight.

 

[AyWoSch Motors]

Ah, a fellow New Mexican, nice.
I'm up near Las Vegas.

Impressive load. Good to know it can take it, I just recently bought a Chevy C30 dually. Although mine has a 2bbl 350 and an automatic. Would love to get a big block and a 4 speed.

 

[bucket]

I've pulled similar weights with my '78 C20 Suburban. It does the job just fine. You obviously know the weight is back there and you need to drive accordingly, but it feels confident.

 

[Keith Seymore]

Hello all,

Been doing some remodeling on the house and using my gmc to pull the dump trailer. I pulled a few stumps and some concrete/block and loaded it into my trailer, I didn’t think too much about the weight since I usually pull it with my diesel. So I get to the land fill and was just under 20,000 lbs over the scales.

It wasn’t exactly effortless but the 20 mile drive to the dump would have had me guessing my load was less than that. On the biggest hill I was at 40 mph in 2nd (3rd technically) with a 50 mph speed limit.

My trailer is about 3,200 lbs and it’s content was 9,400 lbs that’s 12,600 lbs in a 40 year old truck and I think that’s pretty cool. I’ve been pulling trailers since I was a kid and at no point did I feel I didn’t have enough truck.

All that aside what’s the max towing capacity on this truck I couldn’t find too much info but one brochure said 13,500 properly optioned/equipped and others said 11,000.

Either way an SM465 and 454 did better than I thought it would. I have no idea what my mpg was and I don’t think I’d wanna know at that weight.

It varies a bit with your rear axle ratio:

11,000 GCWR with a 3.21 gear
13,500 with a 3.73
15,000 with a 4.10
17,000 with a 4.56

The GCWR is established by powertrain, springs and tires (in terms of ride and handling), but there is also a "go/no go" sense check of attempting to launch the vehicle up the 16% grade at the Milford Proving Ground. By you having the SM465 with the creeper gear that test would be no problem.

K

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[Bextreme04]

I pulled my 6k travel trailer out to the coast for elk hunting last year and it felt like there was hardly anything back there. The 4.10's are a great towing gear. I was running 60-65 the whole way on flat land and only really felt it when I had to slow down to 45ish through the coastal mountain range. That's with a freshly rebuilt 350/TH400. I have a new fuel injected 454/4L80e that needs to get stuck in at some point, that should make it an easy 65mph pull all the way through including the mountains. My owners manual says 6k max tow capacity, which seems light for an 8600GVW K25

 

[KnockingDiesel]

Thank you all for the replies!

 

[Salty Crusty]

It ain't about what it will get moving, it's about what it will get stopped!

 

[75gmck25]

There’s also quite a bit of flex in the GVW rating of these trucks. My K25 Camper Special is rated at 8400 lbs GVW, and I run it at nearly that weight fairly often. At full load the bed drops about 2 3/4”, so it’s still almost level.

However, after a demo job for a brick wall we just kept loading the truck until the bed was full, and it ran across the scales at 10,900 lbs total. It was a little slower to stop and there were some creaks from the rear springs, but the 350/th350 and 14 bolt FF didn’t seem to mind the extra weight. I have 10 ply rated 16” tires and usually run them at about 65psi, so they also hold up well.

 

[SquareRoot]

This thread is worthless without pics! Photos or it didn't happen.

 

[Keith Seymore]

It ain't about what it will get moving, it's about what it will get stopped!

We didn't really factor in the brakes when assigning the ratings because we "assumed" the trailer would have sufficient brakes.

K

 

[Salty Crusty]

^ that assumption could cost lives but I guess assumptions have to be made. I won't pull anything I can't stop WITHOUT trailer brakes since more don't work than do.

There are plenty of clutch-butts out there that have no clue about trailers and pulling stuff...borrowed truck and trailer to move, etc. And my experience says that while many will neglect vehicle maintenance, there are many times that number that do zero maintenance on their trailer, just air up the tires when it's hooked up.

 

[KnockingDiesel]

This thread is worthless without pics! Photos or it didn't happen.

I don’t have any pics of the load, other that the scale receipts. But I do of some other stuff I’ve hauled

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I use the truck to tow frequently. New brakes front and rear, new MC and replaced rubber lines. She stops as good as any truck.

Been debating on painting it though. I like the white but was originally dark blue.

 

[KnockingDiesel]

Also came across the brush guard at pick a part and we use it to push cars too.

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[Keith Seymore]

^ that assumption could cost lives but I guess assumptions have to be made. I won't pull anything I can't stop WITHOUT trailer brakes since more don't work than do.

There are plenty of clutch-butts out there that have no clue about trailers and pulling stuff...borrowed truck and trailer to move, etc. And my experience says that while many will neglect vehicle maintenance, there are many times that number that do zero maintenance on their trailer, just air up the tires when it's hooked up.

It's no different than building an incomplete vehicle, like a cab and chassis.

The manufacturer does the math and tell you where the CG needs to end up (both laden and unladen) for you to have a safe handling and braking vehicle. Once the body builder gets ahold of it we have no control of what they do in the field.

We were getting complaints from HD rollback drivers that "they couldn't stop". When we went out to look at the trucks they had two cars on the roll back deck and one hanging off the back. I swear if you put your foot on the rear bumper the front wheels would come off the ground.

"Cant's stop?!" I said. "They should be complaining that they can't steer!"

K

 

[SirRobyn0]

There’s also quite a bit of flex in the GVW rating of these trucks. My K25 Camper Special is rated at 8400 lbs GVW, and I run it at nearly that weight fairly often. At full load the bed drops about 2 3/4”, so it’s still almost level.

However, after a demo job for a brick wall we just kept loading the truck until the bed was full, and it ran across the scales at 10,900 lbs total. It was a little slower to stop and there were some creaks from the rear springs, but the 350/th350 and 14 bolt FF didn’t seem to mind the extra weight. I have 10 ply rated 16” tires and usually run them at about 65psi, so they also hold up well.

I agree, my truck has a dump kit on the factory bed and I've hauled all kinds of stuff in it, but it's usually the gravel that ends up being the heaviest, with figures similar to your brick load. Because the truck doesn't squat much during loading I often think there is less weight back there until I hit the scales. 305 / 700R4 here. The thing that gets me about the 305 is that it is slow, but it's not much different loaded down.

We didn't really factor in the brakes when assigning the ratings because we "assumed" the trailer would have sufficient brakes.

K

Yes, but this is one of the reasons that I like towing with a 3/4 ton truck vs using like say my Jeep Grand Cherokee. At least with the truck I've got bigger front disk brakes and those really big 3/4 rear drums. I figure in a full trailer brake failure situation I've got a better chance getting it stopped, but even still that is something to think about when a guy is loading up his trailer. What happens if you fade the trailer brakes on a long hill? Will you have enough truck brakes to get it stopped?