About to buy a trailer, now not sure if my truck can pull it

swathdiver · August 2, 2021

2 hours ago, pokismoki said:

you need a MAXTow WT truck option. our little 5.3's aren't built to tow with our cooling system. your gear ratio sucks, but if you went with a 5th wheel trailer you could do it safely in 3.08

if you have the 8 speed transmission your fine, its just not a good ratio for the 6 speed trucks

Why not?

pokismoki · August 2, 2021

15 minutes ago, swathdiver said:

Why not?

the cooling system is very small, it barely keeps up with no headroom for power adders

ive done data log on a 1/8th mile at wot and the heat from one pull was very high, throw a big trailer and driving up the Grapevine in CA. is doeable but its at the limits. you guys deffinatly need 175 t-stats and reprogram the fans to keep the temps down

Edited August 2, 2021 by pokismoki

swathdiver · August 2, 2021

1 minute ago, pokismoki said:

the cooling system is very small, it barely keeps up with no headroom for power adders

Wow, mine is the same as a 2500 save for the electric cooling fans versus their engine driven clutch fan and exactly the same as my 6.2 NHT Sierra. Guess they cheaped out on the K2s?

M1ck3y · August 3, 2021

5 hours ago, swathdiver said:

Why not?

If your referring to the 8sp vs 6pd comment its because the 8spd has a numerically lower ratio in every gear. A 3.08 in the 8spd will perform better and the engine won't have to work as hard compared to the 6. I could be wrong but a 3.23 in the 8spd has a lower ratio everywhere then a 3.73 in the 6pd.

But now that I think about it... I'm pretty sure you can't get a 3.08 in the 8spd form the factory. It's only 3.23 or 3.42, lol.

pokismoki · August 3, 2021

5 hours ago, swathdiver said:

Wow, mine is the same as a 2500 save for the electric cooling fans versus their engine driven clutch fan and exactly the same as my 6.2 NHT Sierra. Guess they cheaped out on the K2s?

I tell everyone the 2500 is a better truck for doing truck stuff, like towing and blue collar work, 1500 are comfy commuters and towing maybe 100 miles in a day twice a week. more than this the wear and tear really kicks in

i love the mechanical fan design so much better than the electric fans. to maintain 175 degrees on the motor in the K2, I runs the fans at 50% all the time, they wont turn off, because thats what it takes to cool the motor with the tiny radiator. might as well have installed a mechanical fan thats always pulling air.

Edited August 3, 2021 by pokismoki

swathdiver · August 3, 2021

11 hours ago, M1ck3y said:

If your referring to the 8sp vs 6pd comment its because the 8spd has a numerically lower ratio in every gear. A 3.08 in the 8spd will perform better and the engine won't have to work as hard compared to the 6. I could be wrong but a 3.23 in the 8spd has a lower ratio everywhere then a 3.73 in the 6pd.

But now that I think about it... I'm pretty sure you can't get a 3.08 in the 8spd form the factory. It's only 3.23 or 3.42, lol.

The nice thing about having more gears is that you have more options to choose the best final drive ratio for towing.

GM recommends towing in 4th gear with a 6-speed for optimum cooling. If one has 3.42 ring and pinion this is a 3:94:1 final drive. If one has a K2 with an 8L90 and 3.42 gears, their final drive in 5th gear will be 4.34:1 or 4.1:1 with a 3.23 axle ratio.

M1ck3y · August 3, 2021

40 minutes ago, swathdiver said:

The nice thing about having more gears is that you have more options to choose the best final drive ratio for towing.

GM recommends towing in 4th gear with a 6-speed for optimum cooling. If one has 3.42 ring and pinion this is a 3:94:1 final drive. If one has a K2 with an 8L90 and 3.42 gears, their final drive in 5th gear will be 4.34:1 or 4.1:1 with a 3.23 axle ratio.

I didn't know they had a recommended gear.. But Cooling is the same regardless of the gear your in as long as tow/haul mode is active (electric fans) Personally I wouldn't touch manual mode unless you really need to gear down going up/down a grade. Your just wasting a lot of fuel, creating more heat, and more wear and tear by cruising at a higher rpm.

Edited August 3, 2021 by M1ck3y

swathdiver · August 3, 2021

1 hour ago, M1ck3y said:

I didn't know they had a recommended gear.. But Cooling is the same regardless of the gear your in as long as tow/haul mode is active (electric fans) Personally I wouldn't touch manual mode unless you really need to gear down going up/down a grade. Your just wasting a lot of fuel, creating more heat, and more wear and tear by cruising at a higher rpm.

No, it's not the same. You are forgetting about the cooling of the transmission and engine oil. @intheburbs has spoken with the guys who designed these things to tow across Death Valley fully loaded. Maybe he can shed more light on this as he has forgotten more than I'll ever know about towing.

pokismoki · August 3, 2021

yeah makes sense pulling in 4th or 5th, you insrease the water Pump speed to the radiator. this helps cool it down,

Ross McKenrick · August 3, 2021

I don't know about gear ratios or transmission cooling, but I want to share that I bought a Little Guy Max teardrop trailer with the following specs (dry weight 3010, tongue weight 310, GVWR 4000-4200):

I then tried to pull it with a 2018 Toyota Highlander which has a rated towing capacity of 5000 lb. I tried pulling the trailer with it in Oregon, Nevada, Utah and Colorado. I was very unhappy with the reserve power--I was that guy driving at 60 mph going uphill with the four-way flashers on. Also, I was uncomfortable trying to pull the trailer through remote state parks -- up and down fairly steep unpaved roads to get to the nice camp sites. After about 2000 miles of towing, I had the car serviced and the front brakes were shot, the rear shocks were leaking, and the transmission (fluid) needed servicing.

I traded the SUV in for a 2021 Silverado with a 3.0L Duramax diesel with a 10-speed transmission and the trailering package. Towing capacity of approx 9600. What a relief! Now I can accelerate going up hills if I want to and I can pull the trailer through pretty tough unpaved roads without worry.

As a fairly new truck / trailer person, I recommend getting a truck with 2x the towing capacity of your trailer GVWR.

Hth.

M1ck3y · August 3, 2021

46 minutes ago, swathdiver said:

No, it's not the same. You are forgetting about the cooling of the transmission and engine oil. @intheburbs has spoken with the guys who designed these things to tow across Death Valley fully loaded. Maybe he can shed more light on this as he has forgotten more than I'll ever know about towing.

Nope I'm not. When you hit tow haul mode the computer runs everything wide open. At least on trucks equipped with electric fans. This includes transmission and engine oil cooler. Mechanical fan equipped trucks most likely operate differently.

M1ck3y · August 3, 2021

35 minutes ago, pokismoki said:

yeah makes sense pulling in 4th or 5th, you insrease the water Pump speed to the radiator. this helps cool it down,

Yup, you'd need more cooling because your create more heat, more energy, more power.

M1ck3y · August 3, 2021

Cam chime in here!?

I'm happy to be wrong or right. But as someone who as actively seen the data, can you please share what takes place during tow/haul mode.

malibu43 · August 3, 2021

Lots of good discussion here folks. Thanks for all the replies.

So we went ahead and bought the trailer yesterday. Again, we talked it over quite a bit and agreed that no matter what, a trailer of this size is part of the plan for our family. So the towing vehicle thing is going to have to sort itself out, whether it's do nothing, re-gear, or trade in for a vehicle with the right towing capacity. Not all those options are created equally in terms of financial feasibility, but we'll worry about that later...

I called two local places yesterday and they both quoted $1400 per axel to re-gear. So, my next question is: Is there anything besides the differential gear that differentiates my truck (in the orange box) from a truck that falls into the green box?

This table is from the 2015 Silverado Trailering Guide I found somewhere here on this forum. The same table is in my truck's owners manual.

M1ck3y · August 3, 2021

3 hours ago, malibu43 said:

Lots of good discussion here folks. Thanks for all the replies.

So we went ahead and bought the trailer yesterday. Again, we talked it over quite a bit and agreed that no matter what, a trailer of this size is part of the plan for our family. So the towing vehicle thing is going to have to sort itself out, whether it's do nothing, re-gear, or trade in for a vehicle with the right towing capacity. Not all those options are created equally in terms of financial feasibility, but we'll worry about that later...

I called two local places yesterday and they both quoted $1400 per axel to re-gear. So, my next question is: Is there anything besides the differential gear that differentiates my truck (in the orange box) from a truck that falls into the green box?

This table is from the 2015 Silverado Trailering Guide I found somewhere here on this forum. The same table is in my truck's owners manual.

Your cooling system is different. The 5.3 with the max tow gets the 8spd with 3.42 and the same cooling system the 6.2 has. Suspension is most likely different, shocks maybe leafs too.

I don't actually know your cooling system is different but that seems to be the consensus on here. I could do some searching on Google and post a link to the information. But so can you.

*edit*

Wow the 5.3 got 3.73's with the 8spd? That must be a fun truck.

You'll also have a smaller axle then the max tow (9.76)

Edited August 3, 2021 by M1ck3y