Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 16 of 16 Posts

·
Registered
2002 gmc envoy_slt
Joined
·
101 Posts
Discussion Starter · #1 ·
About to take a trip from Florida to Idaho using a 2-wheel tow trailer for my wife's Civic.
I looked up the RPO codes ... I see I have a GT5 and G80.
So if I'm right that means I have a locking Diff with 4.10 gears.

I'm pretty short on time, should I get an after market trans cooler??

Is it recommended to not use cruise while towing?

And as for using 3rd gear--going up grades is when to down shift?

Will be giving the throttle body a cleaning this weekend along with installing a K&N filter. Might put in new plugs, but she only has 66k on her and runs great. For preventive maintenance I'm also replacing the fuel filter. Will also make sure I disconnect the battery while doing the work so the PCM resets with the changes and for safety reason as well. :)

thanks in advance for your replies.
-D
 

·
Registered
2004 chevy trailblazer_lt
Joined
·
997 Posts
Experienced tow'ers will tell you to ALWAYS tow in 3rd when pulling any load over about 1000-2000 pounds or so. You should always tow in a gear that gets you the best power band range of the engine for long engine and transmission life, and then simply live with whatever mileage you will get.

It is false economy to try to save a few dollars on gas and burn up your transmission.

To find out for SURE what gear to tow in, you just do this little test: with the load in place and on a level stretch of highway, get a feel for how far down your pedal is depressed in 3. Now shift to D, wait for the torque converter to lock up and see how far down the pedal goes. If you need more pedal, you are outside the best power band and you should go back to 3.

You should always tow in the gear that results in the least pedal depression. (Note, this is NOT the same as the gear that gives you the lowest RPM!) You will inevitably find anything over about 1000 pounds should be pulled in 3rd on level stretches and be prepared to downshift even lower if the engine starts lugging on upgrades.

Otherwise, it will be hard to offer advice on transmission coolers etc., without knowing the weight of your load, your style of hitch and what else will be loaded in your truck. (Don't forget that you need to keep your truck at or below the maximum gross combined weight rating as listed on your door sticker, and this includes the total of trailer PLUS all people and cargo in the truck.)
 

·
Registered
2002 gmc envoy_slt
Joined
·
101 Posts
Discussion Starter · #4 ·
Experienced tow'ers will tell you to ALWAYS tow in 3rd when pulling any load over about 1000-2000 pounds or so. You should always tow in a gear that gets you the best power band range of the engine for long engine and transmission life, and then simply live with whatever mileage you will get.

It is false economy to try to save a few dollars on gas and burn up your transmission.

To find out for SURE what gear to tow in, you just do this little test: with the load in place and on a level stretch of highway, get a feel for how far down your pedal is depressed in 3. Now shift to D, wait for the torque converter to lock up and see how far down the pedal goes. If you need more pedal, you are outside the best power band and you should go back to 3.

You should always tow in the gear that results in the least pedal depression. (Note, this is NOT the same as the gear that gives you the lowest RPM!) You will inevitably find anything over about 1000 pounds should be pulled in 3rd on level stretches and be prepared to downshift even lower if the engine starts lugging on upgrades.

Otherwise, it will be hard to offer advice on transmission coolers etc., without knowing the weight of your load, your style of hitch and what else will be loaded in your truck. (Don't forget that you need to keep your truck at or below the maximum gross combined weight rating as listed on your door sticker, and this includes the total of trailer PLUS all people and cargo in the truck.)

Thanks for the great reply.
Car weighs 2,322lbs--will probably have about 250-350 pounds of "stuff" in the car to free up a little interior room in the Envoy. Then with passengers, Gr'animals and misc--I'd say another 500lbs.
So total will be 3,000-3,100.
OH! And then the 2-wheel tow thing--umm 800-900 lbs?
So will be at least, I'm estimating, 3,900lbs. We'll just round it to 4,000.

I will use your little test.

My thing was the fact that since I have 4.10 gearing I will enter into the power band at a lower speed then a lot of folks with the GU6 and GT4s.

Going to go check out trans cooler tonight over at a couple local auto stores.
After seeing that we'll be at 2-ton, it can't hurt to have trans cooler--especially when we enter into the mountains.

Again thank you.
 

·
Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
Joined
·
3,700 Posts
If you're towing anything heavy, for trans life, just tow in 3rd... The weak part of any transmission that has one is the Forward Sprag... We have one... There is a clutch (over-run clutch) that locks up the forward sprag, and takes the load off of it... That clutch is not engaged in any gear, when the selector is in 4th (D)... It is engages in every gear when the selector is in 3rd... Keep the selector in 3rd when towing anything over ~3000# or so...

Mike
 

·
Registered
2003 chevy trailblazer_ls
Joined
·
1,236 Posts
I'm with the other guys... You WANT a cooler. Pulling those 10,000 foot mountain passes is a big deal while towing! I cooked one transmission running empty in OD just on the long drawn-out hills in Missouri. The mountain passes in Colorado were much worse!

Also, tow in 3, as others have said. Not much apply clutch in OD. Adding the RPM to the engine won't hurt anything, but, as others have already said, cooking the transmission sure will. I've towed as much as 8000# behind mine, and sometimes for distances of 600 miles or more -- all in 3. Engine runs about 500-600 RPM higher than OD -- gets it solidly into the power band -- just where you want to be with a load out back.
 

·
Registered
2003 gmc envoy_slt
Joined
·
270 Posts
+1 to what every one els has said.

And what ever you do, don't try to set any land speed records either. Take your time, drive at a speed that is comfortable, not at the speed of traffic. I was towing my boat (3000 Lbs loaded) to the lake the other day and I got it up to the speed I was used to driving and it started wagging like a dog. It took me almost a mile of coasting down to get it under control. ( the toung weight being off from the total weight was my biggest problem) Bottom line is take your time and I would avoid cruise control at all costs. More work for your legs but definatley gonna save the transmission in the long run.:m2:
 

·
Registered
2003 chevy trailblazer_ls
Joined
·
1,708 Posts
I agree with everyone about the cooler, but have you changed to Dex-VI ? Running a synthetic tranny fluid will also help Keep it cooler and help it to last longer.
 

·
Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
Joined
·
3,700 Posts
I agree with everyone about the cooler, but have you changed to Dex-VI ? Running a synthetic tranny fluid will also help Keep it cooler and help it to last longer.
Dex 6 also has a higher "overheat" temperature, so where Dex 3 fluid would start to oxidize at 250F, Dex 6 supposedly is OK at 280 or so, though I haven't seen any numbers put out by GM on that...

Mike
 

·
Registered
2004 chevy trailblazer_lt
Joined
·
997 Posts
All great suggestions, and I second the view that a good transmission cooler and a change to Dex VI will help.

Our trucks can easily pull the weight you are talking about, and as long as people are reasonable with their speed, understand the importance of tongue weight and keep within the factory GCWR limits, they are great trucks to tow with.

As one person said above, reasonable RPMs do not hurt these engines in any way. They are made to be worked hard and to be revved within their design limits. It does no good having a double-overhead-cam 4-valve-per-cylinder engine (that only a few short years ago was found only in Formula 1s and BMWs) and keeping it under 2000 RPM their whole lives.

Heat, on the other hand, KILLS transmissions. I once saw a chart of transmission life versus transmission fluid temperature, and it was quite eye-opening. At 175 degrees, the fluid could easily last 100,000 miles of driving.

At 275 degrees (the maximum it should reach for short uphill climbs,) fluid could fail at less than 4000 miles.

At 375 degrees, your transmission would fail in MINUTES, not hundreds of miles.

The one downside to auxiliary transmission coolers that no one has mentioned yet is that it is possible to overcool the fluid at low ambient temperatures. If this may be a concern for you in winter, you can find coolers with auxiliary thermostats.
 

·
Basic Vendor- Skid Plates
2007 chevy trailblazer_ls
Joined
·
3,700 Posts
The one downside to auxiliary transmission coolers that no one has mentioned yet is that it is possible to overcool the fluid at low ambient temperatures. If this may be a concern for you in winter, you can find coolers with auxiliary thermostats.
I usually mention it, but nobody mentioned it this time, because he's just making a trip north... he lives in NW FL..

Mike
 

·
Registered
2002 gmc envoy_slt
Joined
·
101 Posts
Discussion Starter · #12 ·
I usually mention it, but nobody mentioned it this time, because he's just making a trip north... he lives in NW FL..

Mike

Well actually we're moving to Idaho. The good ole' USAF has decided it's our new home for the next few years. So yes I guess I do need to be concerned with the winter temps.
I could make a cut/off to bypass the cooler in the winter months up there or as mentioned one with an auxiliary thermostat..:undecided

Everyone's comments have been great. I thank each of you.
Since I'm short on time, I'm going go change to Dex VI and drive smart with using 3rd gear and not breaking any land speed records. So will make it a 4-day trip instead of 3. Either way it's going to be 34 hours or more! :hopeless
I think with the 4.10 gearing and conservative driving I should be just fine after reading everyone's inputs.

So I'm going to head over to my fav auto parts store today and spend some more money. :D

TrailVoy rocks!
-Drew
 

·
Registered
2002 gmc envoy_slt
Joined
·
101 Posts
Discussion Starter · #14 ·
WE MADE It!

Well it ended up being 2,200 miles pulling the 2,300 lb car on a tow dolly with about 300lbs loaded into it. Plus 250-300 in the Envoy along with my wife and I.

The Voy did AMAZING! I could pull the hills with great ease and the few BIG climbs and down grades she held her own.
I did NOT put on a cooler or go with DEXIV.
We just did it smart using 3rd gear. Used "D" maybe 150-175 miles of the trip on the very flat areas.

Got To Love These vehicles!

Now she needs/deserves a good detailing! :cool:
 

·
Registered
2005 chevy trailblazer_ls
Joined
·
1,733 Posts
Well it ended up being 2,200 miles pulling the 2,300 lb car on a tow dolly with about 300lbs loaded into it. Plus 250-300 in the Envoy along with my wife and I.

The Voy did AMAZING! I could pull the hills with great ease and the few BIG climbs and down grades she held her own.
I did NOT put on a cooler or go with DEXIV.
We just did it smart using 3rd gear. Used "D" maybe 150-175 miles of the trip on the very flat areas.

Got To Love These vehicles!

Now she needs/deserves a good detailing! :cool:
We know you meant DEX-VI! Congrats on the safe (and I'm sure interesting trip!) and thanks for your service to our great nation!:thumbsup:
 
1 - 16 of 16 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top