Towing at the limit

swathdiver · April 1, 2021

2 hours ago, dieselfan1 said:

Call it what you want, it's still a half ton.

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Yeah, so?

pokismoki · April 2, 2021

13 hours ago, swathdiver said:

That is the Maximum Towing Package and in a previous generation, GMT900, came with the 6.2 motor, 3.73 gears and the increased capacity cooling system with an engine oil cooler and external transmission cooler. It has an extra leaf in the rear spring pack bringing the rear axle rating from 3950 to 4200 pounds. The K2s are similar though I do not know what gears they used. Towing capacity is 10,400 to almost 11,000 pounds for the RWD models. The K2s were rated even higher if memory serves.

any chance the MTP has a larger radiator than our K2 trucks with 5.3 motors? I find the stock rad is a bit under performing when towing and at WOT not towing

swathdiver · April 2, 2021

4 hours ago, pokismoki said:

any chance the MTP has a larger radiator than our K2 trucks with 5.3 motors? I find the stock rad is a bit under performing when towing and at WOT not towing

According to ACDelco's parts website, yes, the NHT has a different radiator. It is 21907 versus 21927. I selected a 2017 with the 6.2 of course. Don't see dimensions listed there like they have for mine, maybe Rock Auto has them.

https://parts-catalog.acdelco.com/catalog/catalog_search.php

asilverblazer · April 2, 2021

Towing at the limit half a dozen times a year will never justify the added cost of upgrading trucks. Especially when its an otherwise daily driver.

If the limit is 10000 lbs, the limit is 10000 lbs, I'm not going to stop at 5000 lbs to make a bunch of worry warts feel warm and fuzzy.

If everything is set up correctly, the weight is distributed correctly, brakes are working sway is minimal... go for it.

pokismoki · April 5, 2021

On 4/2/2021 at 2:31 AM, swathdiver said:

According to ACDelco's parts website, yes, the NHT has a different radiator. It is 21907 versus 21927. I selected a 2017 with the 6.2 of course. Don't see dimensions listed there like they have for mine, maybe Rock Auto has them.

https://parts-catalog.acdelco.com/catalog/catalog_search.php

whats the part number for the larger radiator that drops into our 1500 trucks?

swathdiver · April 5, 2021

4 hours ago, pokismoki said:

whats the part number for the larger radiator that drops into our 1500 trucks?

You have a K2 right? If so, it is 21907.

pokismoki · April 6, 2021

thankyou for the help! i bet it cost a pretty penny...

don67 · April 6, 2021

My 2018 Silverado has the same setup as the OP, and one occasion I've towed at the limit (tractor + float).

Braking was fine, as was handling at speeds below 50mph. Above 50mph however felt a little squirrely... not something I'd want to do for hours on end. Especially not with a boxy trailer that catches a lot of sidewind. 7,000 to 8,000 lb is probably the 'comfort limit' for long-distance hauling.

swathdiver · April 7, 2021

On 4/6/2021 at 10:56 AM, don67 said:

My 2018 Silverado has the same setup as the OP, and one occasion I've towed at the limit (tractor + float).

Braking was fine, as was handling at speeds below 50mph. Above 50mph however felt a little squirrely... not something I'd want to do for hours on end. Especially not with a boxy trailer that catches a lot of sidewind. 7,000 to 8,000 lb is probably the 'comfort limit' for long-distance hauling.

Was that with a weight distribution hitch or without?

don67 · April 7, 2021

Without

swathdiver · April 7, 2021

17 minutes ago, don67 said:

Without

Ok, makes sense. Your generation truck requires a weight distribution hitch for loads over 7,000 pounds and is optional below that.

ic3man5 · April 8, 2021

On 4/2/2021 at 12:37 PM, asilverblazer said:

Towing at the limit half a dozen times a year will never justify the added cost of upgrading trucks. Especially when its an otherwise daily driver.

If the limit is 10000 lbs, the limit is 10000 lbs, I'm not going to stop at 5000 lbs to make a bunch of worry warts feel warm and fuzzy.

If everything is set up correctly, the weight is distributed correctly, brakes are working sway is minimal... go for it.

I can only assume this comment is indirectly directed towards me since I'm the only one that mentioned the divide by half rule; so here comes the information to fill in your ignorance:

Tow rating is determined by the following (J2807 Specification):

-0-30 mph in 12 seconds

-0-60 mph in 30 seconds

-40-60 mph in 18 seconds

-must be able to brake from 20 mph to zero in 45 feet with trailer brakes, or 80 feet without.

-needs to be able to maintain understeer as it accelerates on a circular skid pad from 0.1 g to 0.3 g of lateral acceleration.

-needs be able to tow its maximum trailer weight up a specific 11.4-mile uphill stretch of road in Arizona. For this test to be run correctly, it must be at least 100 degrees Fahrenheit outside, and the air conditioning must be on its maximum setting using outside air. The truck must maintain a minimum speed of 40 mph, and it can't throw any error codes or burn any fluids during the test. Grade of test is between 3-7% on the David Dam test.

None of this testing really covers real world testing with long distance or long duration travel. The most stressful test only lasts 15.2 minutes (11.4/45=0.2533). What makes this even worse is the Vehicle Warm-up is Optional or not specified in the test.

So now that we have established a baseline we can see that tow limit specification doesn't specifically cover pushing the truck to its limits in all situations. Multiple people have already stated (including myself) the truck CAN NOT successfully tow extended distances at max tow rating without doing damage. Its already an established fact the TCC is weak in the K2 and is ran too hot to begin with. $300 tranny cooler vs $3000-5000 transmission rebuild because you decided to tow your daily driver a couple times a year at the limit; I know which one I'd pick. Sometimes it pays to be a worry wart and feel warm and fuzzy, but that is just me.

J2807 specification can be found here for further reading:

https://fifthwheelst.com/documents/tow-test-standards-2016-02.pdf

Edited April 8, 2021 by ic3man5

KARNUT · April 8, 2021

Hummm. A truck can’t tow at maximum limits for extended times without breaking down. I did for 20 years with multiple vehicles for a minimum of 100K miles each. My half tons had max payload from brand new until trade in. My trailers were capable of stopping their load and the truck. Diesels were the primary workhorses. The early gassers were 390s,454s, a couple V-10s. Honestly they all were over max limits. Of course that was until the mid 2000s. Payload and tow loads have increased. I would have been within the new ratings.

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ic3man5 · April 8, 2021

11 minutes ago, KARNUT said:

Hummm. A truck can’t tow at maximum limits for extended times without breaking down. I did for 20 years with multiple vehicles for a minimum of 100K miles each. My half tons had max payload from brand new until trade in. My trailers were capable of stopping their load and the truck. Diesels were the primary workhorses. The early gassers were 390s,454s, a couple V-10s. Honestly the all were over max limits. Of course that was until the mid 2000s. Payload and tow loads have increased. I would have been within the new ratings.

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Those trucks weren't at the thermal limits and were essentially built better out of mechanical tolerances and limitations. Your truck 20 years ago more than likely had over 100hp/torque less power, bigger block, lighter, worse brakes, etc. I wouldn't say that is a fair comparison as I used to do the same without issue; now with the EPA and push for efficacy we are reaching more limits in the designs. I've seen my fair share of 4L60s be destroyed because of towing.

KARNUT · April 8, 2021

Those trucks weren't at the thermal limits and were essentially built better out of mechanical tolerances and limitations. Your truck 20 years ago more than likely had over 100hp/torque less power, bigger block, lighter, worse brakes, etc. I wouldn't say that is a fair comparison as I used to do the same without issue; now with the EPA and push for efficacy we are reaching more limits in the designs. I've seen my fair share of 4L60s be destroyed because of towing.

My shop see examples of heavy towing daily. Non of my trucks were stock.

I just stopped towing in the mid 2000s.

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