New to towing questions

Hi, I am a relatively new Avalanche owner as of March this year (2008 Z71 5.3L 1500 4x4 with tow package and 3.73 axle, ~55K miles) and I just bought a used travel trailer along with an Equalizer sway/weight distributing hitch and a Hopkins 47294 Agility proportional brake controller.  Its a 2002 Keystone Bobcat 280EB (28 or 29') with no slide outs, listed at 5,060 lbs dry weight and 6,200 lbs GVWR.  I took the setup to the scales today and the trailer weighed in at about 5,800 with full water and propane, the truck weighed in at 6,000 lbs with a full tank of gas and the hitch connected.  Add in my family (about 500 lbs total), and I am at a combined GVW of 12,300 lbs.  If I can limit my gear in the trailer to 400 lbs and 300 lbs in the truck, I can stay within the 7,000 lb truck; 6,200 trailer, and 13,000 lb combined GVWRs.  When I drove it home (Chicopee, MA to Berlin, CT), it seemed to tow well, felt safe, and did not appear to sag at the hitch.  The camper was dry at the time, but I did have the full family in the truck.  It had a hard time maintaining 65-70 up some grades, but otherwise seemed fine.

So anyway, as I get this trailer setup for trips next year (mostly in the northeast to dog shows, but also a 2-week vacation driving out to AZ in June), I was hoping those with experience towing here could share some of their wisdom, and what things I can add to optimize my towing setup (without spending several hundreds of $$).

1)  In general, would this setup put to much of a strain on the truck being right at the GVWR when loaded?  For those who tow a camper, how many pounds of extra cargo do you usually end up bringing?  Any tricks to reducing weight (I did figure I could lose about 150 lbs towing without the tailgate or hard covers if needed)  

2)  From reading this forum, it seems like the first thing I should do is get an auxiliary transmission cooler.  I've work on many cars, and should have no problem installing this myself.  What recommendations/advice might you all have on this?  Is a passive one enough, or should I get a fan assisted one?  Is it best to install pre or post radiator?  Driving in the heat of the desert southwest in summer does have me concerned.

3) While I am doing (1), should I thoroughly change/flush the ATF, or just just replace/add what I lose?  The fluid is still a good color, doesn't look burnt, and I know many people have opinions on whether to ever flush/change the ATF at all.

4)  I think my suspension handles the load OK, but if i begin to doubt it, what kinds of things would help? New heavy duty shocks?  I saw someone mention these Timbren things, but I am not sure how they work (and they seem awfully expensive for what looks to be rubber bumpers).  Are they worth it?

5)  I have also read about people tuning their engine with an OBD tuner to get some additional HP.  Does this make a difference?  What are the drawbacks, decreased mileage, engine wear, etc.?

Any other input or advice would be appreciated!  Thanks in advance!

BTW, I love this truck.  Wish I had gotten a new one years ago when they were still making them.

First welcome to the club and Avalanche ownership..


1)  In general, would this setup put to much of a strain on the truck being right at the GVWR when loaded?  For those who tow a camper, how many pounds of extra cargo do you usually end up bringing?  Any tricks to reducing weight (I did figure I could lose about 150 lbs towing without the tailgate or hard covers if needed)

You didn't say what motor you have but it will tow your trailer just fine but like you experienced it may have a tough time on the steeper grades. If you can live with that and don't tow to often your good to go. If you can't then swap the gears to 4.10's, that will help on the hills but you may lose a mpg or two cruising.


2)  From reading this forum, it seems like the first thing I should do is get an auxiliary transmission cooler.  I've work on many cars, and should have no problem installing this myself.  What recommendations/advice might you all have on this?  Is a passive one enough, or should I get a fan assisted one?  Is it best to install pre or post radiator?  Driving in the heat of the desert southwest in summer does have me concerned.

Definitely need a trans cooler if your towing, especially in hot weather. It's one part you almost can't go to big, Summit Racing has a lot of choices. They typically go in after the radiator, and fan assist if it's not mounted in the air flow.

3) While I am doing (1), should I thoroughly change/flush the ATF, or just just replace/add what I lose?  The fluid is still a good color, doesn't look burnt, and I know many people have opinions on whether to ever flush/change the ATF at all.

Unless you know the history on the vehicle I would change it and use a good synthetic (I use Royal Purple). If towing if the interval is 50,000. Do not have a shop or dealer use the (back flush) method. Find a shop that just does the (fluid exchange), they disconnect the top trans line and put new fluid in as the old comes out at the same pressure and direction so you get a complete oil change. And then drop the pan and change the filter. Some oil change shops have the machine to do it.


4)  I think my suspension handles the load OK, but if i begin to doubt it, what kinds of things would help? New heavy duty shocks?  I saw someone mention these Timbren things, but I am not sure how they work (and they seem awfully expensive for what looks to be rubber bumpers).  Are they worth it?

There are extra load devices like springs and air bags, but if your not seeing a big drop with your load then you may not need  them. You'll have to decide after towing. Bigger sway bars can help when fully loaded and make it safer. If you need shocks get the Bilstein 5100's they are self adjusting, you may already have the factory Bilstein's on your Z71 they would be yellow..


5)  I have also read about people tuning their engine with an OBD tuner to get some additional HP.  Does this make a difference?  What are the drawbacks, decreased mileage, engine wear, etc.?

There are good hand held tuners that can help with performance an towing. They do make a difference, there's a sponsor here for Diablo Sport that is good. They won't hurt anything but depending on how you tune it you may have to put in premium and/or mileage may drop a little.


There are also allot of other mods you can do to help with the performance like, cat back exhaust, headers, air filter. They will help make sure your motor is doing all it can, some have even added a supercharger.

With your towing package I think you have a auxiliary transmission cooler already.

MS03 2500 said:

With your towing package I think you have a auxiliary transmission cooler already.

Click to expand...

Maybe... But might want to up size it they are pretty small from the factory..

Flex-a-Lite makes a cooler with brackets fit for the GM trucks/SUV, if you want less work/more money than a universal.
https://www.flex-a-lite.com/direct-fit-translife-transmission-cooler-for-99-12-gm-trucks-and-suvs.html

I did notice when helping my cousin that his 2005 1500 Silverado has the same factory aux cooler as my 2002 2500 Avalanche, for whatever that info is worth.

The upgrade that I would suggest would be a Trans Temp gauge, this will tell you if those hills are an issue and if you are danger of overheating your trans. (will also tell you if an upgraded cooler would be necessary).  Us 2500 guys have it easy ours had the factory dash trans gauge.  I have heard of guys upgrading to the 2500 gauge cluster on their 1500, but I image that isn't cheap.  If you are thinking about changing your fluid anyway, you could install aftermarket gauge for less, just have to add a bung to your pan (also makes a great drain plug)  I did this on my 4L60E in my 99 Jimmy when I was towing a large popup.

About the easiest way to do it is to a fan to the cooler. Warning it's a pdf file

http://www.haydenauto.com/upload/HaydenAuto/Documents/Cat_Imperial/2007-imperial-trans-oil-coolers.pdf

I suggest adding the tranny cooler.  I have an 04 with the 5.3L and had an aux. put in.  My Travel Trailer dry weight is 5900 lbs., probably around 6500 loaded. I also had a pair of heavy duty rear shocks installed which helped bounce a LOT.

I have the Z71 2WD and the little GM tow package (i.e. trany cooler & 3.42 gears). I pull 5,000 Lbs dry for years.... my other AVY's all had the Tow package as well (with various gears from yr to yr - never new why?). Our summers are not like some usa states (i'm a canuk)... it gets to be maybe 80F or 90F ish in northern Ontario summers with super high humidity... and the Engine temp has never moved from the the normal temp position yet...never, not even by one degree on any of the vehicles under any condition. Very stable cooling system. My Trany moves from 0 c to about 90 C max in hill areas, nominally is at 75 C ish or less. Very steady & dependable. Cooling is the one area the GM stock I find very solid and dependable. Braking and suspension... another chapter ( I added airbags and an emergency anchor on a chain to stop me    )