Mods necessary to tow a car long distance?

[AlecE]

Hi, I am new to this form and have been looking at different mods people do to improve towing capabilities, and I am wondering what I need to do for my truck. I have a 2016 GMC sierra 1500 4WD 5.3 v8 all terrain double cab with the 3.42 gears giving me a supposed tow capacity of 9,200lbs. I plan to tow a midsize SUV with a rough curb weight of 5000lbs and use an aluminum trailer with electric trailer brakes weighing roughly 2000lbs, giving me an estimated trailer weight of somewhere between 7000-7500lbs. I have new 33in load range E tires on 18in stock rims, 2in level kit, upgraded slotted/drilled rotors, and a 5000lb rear Air-Lift that i plan to put on as well. I plan to change all my fluids and belts before the trip since I just hit 90k miles. I want to be able to tow a load like this for 6 to 9 hours straight probably once every 3 or 4 months. I also have a larger boat that weighs roughly 3000 pounds that i tow shorter distances regularly. I don't want to spend a ton of money or time, and i don't think i need or can justify a 2500, but what other mods would i need? I was thinking for sure transmission cooler? I don't really want to buy a new radiator but would that be necessary? also would a regear or a tune ever be necessary, or am i fine because i have the 3.42? Thanks! 

[CamGTP]

A tune or re-gear is not required for what you want to do. Use tow/haul mode and the truck will handle things just fine.

 

If you encounter lots of hill you can put the truck into manual mode and select the best gear for pull the grade.

 

I highly suggest that you either buy the new GM transmission theremostat with a lower temp or bypass the factory transmission thermostat to keep the transmission cooler. The new thermostat lowers the operating temps by atleast 30 degrees and bypassing the thermostat can do the same if not even more. Running the OEM thermostat will let the transmission operate around 190-215 degrees which is gettings pretty warm. Ideally you'll want to keep the temps between 150-180 degrees for optimum fluid life.

 

No need for a transmission cooler, just do the new thermostat or do the bypass mod. I don't have the part number handy but it's on this website somewhere, any GM dealership could get you one.

[AlecE]

Ok, Thanks! I see you live in Minnesota as well, so I was wondering if there is any issues with a doing a bypass or a thermostat in the winter. I am only asking because the transmission coolers I was looking at previously had a thermal bypass for cold weather climates. I don't fully understand why, but the ones without thermal bypass said "not to be used below 32°F"

[CamGTP]

It's a non issue.

 

GM never used a thermostat prior to 2014 on the GM trucks, all of the older trucks with 6L80e's never used one and it was better that way. Those trucks and my 2016 included run around 140-160 degrees in the summer and 110-125 in the winter. The thermostat was added because of emissions, the faster and hotter the fluid got the less friction and possible drag there was. They were trying everything to gain fuel mileage and this was one of the ways.

[AlecE]

Ok, Thanks! I really appreciate the help, I will probably end up getting a new thermostat then. Thanks again!

[CamGTP]

Sounds like a plan, it's a pretty simple job and it's well worth it to try and keep the transmission happy. You can even monitor your current transmission temps during daily driving before and after just to see the difference it makes.

 

If you feel that the truck isn't all that happy after towing that much weight for that long of a distance, then maybe consider regearing to 3.73's. But that cost is pretty large for many. I'd error on the side of caution and only tow between 65-70mph max for fuel mileage and to keep the truck happy. You may find that manual 5th gear is best too.

[AlecE]

Sounds good! thank you!

[mikeyk101]

Since you have the 2" level kit, adding the Airlift bags is a good idea. I added them to my setup. I originally had the Rough Country spacer level but ditched them last year and installed Rancho Quicklift struts to keep the level. (Taking off the spacers was an absolute nightmare but that's another story) I tow a Toy hauler several times a year. Mine is the same setup as yours except I have a crew cab. The toy hauler is around 4500lbs empty and when loaded, comes in around 62-6300lbs. 2ith a weight distribution hitch, I was able to dial in the front axle but rear axle was lower than front. This caused problems mostly only when driving at night with the headlights. These trucks are designed to have a certain amount of sag when heavy loads are in bed or towing. With stock front end suspension, it would normally come out with rear end dropping but still just higher or level with front axle. But you raise front end

 by 2", the sag causes problems. The Airlift bags will be a definite plus in controlling that sag. 

 

And as far as towing with that weight, it shouldn't be a problem. I have towed all over including some pretty decent grades like in Arkansas and Tennessee and it has done fine. Like @CamGTPmentions, definitely use tow haul mode. One thing I found that helps is that right before you get to a steeper grade, drop the shifter from "D" down to "M" and you should be able to maintain your speed. Sometimes I have also had to shift down just one more gear while in "M" to help it out. Once I crest the grade, I drop it right back into "D".

 

The only time I have struggled and ended up having to pull over because of hot engine and trans, I was headed up US 16 into the Big Horn Mtns in Wyoming. That climb is around an 8 degree grade and goes for several miles without any safe turnouts. And I made a major screwup and had filled up in Buffalo with 85 octane gas as it was the cheapest. Too low for using while towing in mountains and probably accelerated the overheating. I should have at least gone with the midgrade. I was also trying to pace a friend who was motoring at a faster pace than I should have while towing. I should have stayed more around 50 mph. Slow and steady wins that race. I also had the OEM transmission thermostat. The transmission and engine temps hit around 260⁰ and a warning on the DIC to pull over immediately to let engine idle and cool down came up.

 

Since learning what I have along with the updated trans thermostat, I've been itching to get back out there to run it again. But that has been the only time where my truck struggled. Every where else, it was just fine.

[CajunFries]

Like the guys above stated with the trans thermostat. You can even just flip the “pill” on the inside (How to ). It’s free and super easy. 
 

I also upgraded my radiator to Mishimoto. I started having over heating climbing hills while towing in the SoCal summer (can get up to about 110-115). It never hurt to have more cooling capability! 

[AlecE]

Thanks! I bought the Airlift kit with the air compressor awhile ago as my truck was squatting even when just towing my boat so I am excited to try that out, I hopefully will have time to install that in the next couple days here. I also just ordered the updated trans thermostat from GM (#86774933 about $60). I choose that over the pill flip, or thermostat bypass because I read some people that say those can cause some issues in cold weather (I live in MN) and I don't feel like risking it. Thank you for all for the advice, I will be towing on pretty flat terrain so it sounds like I would've probably been fine, but i don't really want to risk overheating and cause any damage to my truck. 

[JimCost2014]

Still think you would be fine is stock trim making the trip, only thing that really is going to be hurt is your wallet when you see your gas mileage.

[CajunFries]

3 hours ago, AlecE said:

Thanks! I bought the Airlift kit with the air compressor awhile ago as my truck was squatting even when just towing my boat so I am excited to try that out, I hopefully will have time to install that in the next couple days here. I also just ordered the updated trans thermostat from GM (#86774933 about $60). I choose that over the pill flip, or thermostat bypass because I read some people that say those can cause some issues in cold weather (I live in MN) and I don't feel like risking it. Thank you for all for the advice, I will be towing on pretty flat terrain so it sounds like I would've probably been fine, but i don't really want to risk overheating and cause any damage to my truck. 

If you won’t be climbing big long hills in hot weather, you should be okay. I was pulling about 4500-5000 in 110+degrees with 6% incline soooo yeah. 

[Buckwild27]

I agree you will be ok. Your mileage will be garage and on some hills you might feel like you need to get out and push it up the hill. In the winter Your mileage will suffer a little if you remove and bypass trans thermostat. My 13 has a deeper pan and a bigger trans cooler and it takes about 50 miles to get temp to 100° on the really cold winter days. If you start pulling heavy trailer loads on the regular I would look into swapping gears to 3.73's