Towing: When to use "3" and not "D"

[Spong]

I was thinking last night as I was buzzing down the interstate at 75 mph with my trailer in tow, at what point do I need to use "3" when towing?

I'm guessing once the weight gets to a certain level? Last night my trailer was empty so the weight was only 1100lbs and I towed in "D". I might be pulling it out to WI in August. I'm guessing the weight total will be about 2000-2300lbs. Would I need to tow in 3 the whole way?

Thanks,
Steve

[Aerostud1026]

I was thinking last night as I was buzzing down the interstate at 75 mph with my trailer in tow, at what point do I need to use "3" when towing?

I'm guessing once the weight gets to a certain level? Last night my trailer was empty so the weight was only 1100lbs and I towed in "D". I might be pulling it out to WI in August. I'm guessing the weight total will be about 2000-2300lbs. Would I need to tow in 3 the whole way?

Thanks,
Steve

I've done some research on the subject and I believe that people prefer to use 3 over D when towing most of the time in any scenario b/c it creates less heat and eliminates D from trying to search for a gear while towing. I've read posts that people use 3 the whole trip regardless of weight.

[Frostee]

I was thinking the same thing since at the end of July, my camping trip involves a lot (meaning all) highway driving. The parts where it gets hilly, I was going to go to 3, but the flat sections, about half or more of the trip, was going to leave it in D.

I wasnt sure what this (if anything) it would do...

[coolcloo1019]

Im going to be towing an enclosed 8x12 trailer with some furniture in it up to Tennessee from Florida this weekend. I would think driving at 75mph in "3" would make the RPMs wayyyy too high. Am I wrong?

[Aerostud1026]

Im going to be towing an enclosed 8x12 trailer with some furniture in it up to Tennessee from Florida this weekend. I would think driving at 75mph in "3" would make the RPMs wayyyy too high. Am I wrong?

It might, however any speed up to 65MPH would be absolutely fine in 3rd.

[Spong]

I think drag is also a big consideration. The trailer could only weigh 1000lbs but if it's tall and boxy, it would feel like 4000lbs when towing.

My trailer is a utility trailer that's lower than the TB's roof and about the same width so drag really isn't an issue. If it was an enclosed trailer then I wouldn't even consider towing in D.

Here's my trailer:

http://images24.fotki.com/v872/photos/4/41590/3295654/DSC05971-vi.jpg

http://images23.fotki.com/v869/photos/4/41590/3295654/DSC05978-vi.jpg

[Envoy Fan]

Well, if you had a Dashhawk, you could monitor your transmission and coolant temps and know if it was ok to be in "D" ;)

[coolcloo1019]

I think drag is also a big consideration. The trailer could only weigh 1000lbs but if it's tall and boxy, it would feel like 4000lbs when towing.

My trailer is a utility trailer that's lower than the TB's roof and about the same width so drag really isn't an issue. If it was an enclosed trailer then I wouldn't even consider towing in D.



So my whole drive to TN should be in "3"? I think my rpms will be too high. I think if I start to notice it searching for gears, I'll switch it to 3 but otherwise D. The trailer I am towing is taller than the TB but it's about the same width.

[LineNoise]

I tow in D on the highway on long flat stretches.

If I have to pass I put it in 3rd and around town I put it in 3rd. It wastes too much fuel to leave it in 3rd all the time.


I mainly heard that you want to prevent the trans from popping in and out of overdrive that why you stay in third, but on long flat roads with the cruise on you don't have to worry about popping in and out of OD or in our case 4th.

I guess what I tow would be helpful :-) I tow a small popup usually and when I brought my mom's car back about 80 miles, I used 3rd the whole way cuz that bish was heavy.

[Spong]

I totally agree that driving in 3rd will use a ton more gas which is why I wanted to know if I need to or not! I guess the question is, which is cheaper, Gas or a new tranny?

I don't want to tow in 3 unless I have to hence the whole reason for this post. There has to be a point where 3 is required. You can't expect people to tow any load small or large in 3 only.

I already use 3 around town, towing or not. Simply because the OD likes to kick in at too low of speed IMO.

[blueblazer5_3]

I have towed many times before. I have towed with my 07 Tb with the 5.3 also with 6000 lbs behind it. If you are only towing 1000 lbs, "D" is no problem. The whole towing in "D" thing is due to the excessive heat on the torque convertor and fluid because the trans in trying to multiply the force. The engine with 3.73's and 5.3 V-8 will have no problem in overdrive. With over 2000lbs, I would only do "D" when going on level ground. Over 2500, tow in 3rd.

This is just easier on the trans and keeps the trans from shifting from OD to 3rd all the time.

Don

[coolcloo1019]

Cool, seems like for my trip I will be able to travel all of Florida and Georgia in D (pretty much flat and level) and when I start getting into the mountains in Tenn. I'll put it in 3. Thanks guys.

And sorry for hi-jacking your thread Steve! :D

[Spong]

Cool, seems like for my trip I will be able to travel all of Florida and Georgia in D (pretty much flat and level) and when I start getting into the mountains in Tenn. I'll put it in 3. Thanks guys.

And sorry for hi-jacking your thread Steve! :D

What's your trailer weight? A 8x12 enclosed trailer is going to wind drag pretty hard. Is it a single or double axle?

Also, what rear end do you have? If 3.42 (GU6) then I would stick with 3 because your tranny might hunt a lot in D.

I wouldn't just assume D is ok because the terrain is flat.

[Doc Brown]

I totally agree that driving in 3rd will use a ton more gas which is why I wanted to know if I need to or not! I guess the question is, which is cheaper, Gas or a new tranny?

I don't want to tow in 3 unless I have to hence the whole reason for this post. There has to be a point where 3 is required. You can't expect people to tow any load small or large in 3 only.

I already use 3 around town, towing or not. Simply because the OD likes to kick in at too low of speed IMO.

Well thats the real question isn't it, whether to spend it on gas or the trans. The weight isn't going to get you as much as wind resistance. If your load isn't outside the profile of the truck I see no reason you can't tow in "D" for most of your trip. I sometimes tow my TT in WI while in "D". Its pretty flat here except in the western part of the state. Once it starts shifting, up hills or in the wind, I switch to "3". That may be a good way for you to approach it. Just watch the shifting. If you are dropping into "3" a lot, just shift into that gear and leave it for a while. You'll get as much benefit from OD as possible then.

Consider slowing down a little too. Running at 60-65 is going to be a whole lot cheaper than 70-75. And less RPMs to boot. Not to mention safety issues. A trailer is a lot easier to control at 65 than 75 when you have to slam on the brakes. If you are going to run those speeds, I hope you have electric brakes on the trailer. I've seen trailers "wag the dog" so to speak. Its not a pretty site. 2300# of out of control trailer and cargo can easily flip the TB over on the highway. I'd hate to see you end up in a ditch (or worse) just to save a few minutes.

Oh, and you need to get a little dirt on that thing too! :p

[coolcloo1019]

What's your trailer weight? A 8x12 enclosed trailer is going to wind drag pretty hard. Is it a single or double axle?

Also, what rear end do you have? If 3.42 (GU6) then I would stick with 3 because your tranny might hunt a lot in D.

I wouldn't just assume D is ok because the terrain is flat.

To be honest I don't know what the trailer weight is right now. I am towing it for my father-in-law. It is a single axle. Also, I have the 3.42 gears.

[Spong]

Well thats the real question isn't it, whether to spend it on gas or the trans. The weight isn't going to get you as much as wind resistance. If your load isn't outside the profile of the truck I see no reason you can't tow in "D" for most of your trip. I sometimes tow my TT in WI while in "D". Its pretty flat here except in the western part of the state. Once it starts shifting, up hills or in the wind, I switch to "3". That may be a good way for you to approach it. Just watch the shifting. If you are dropping into "3" a lot, just shift into that gear and leave it for a while. You'll get as much benefit from OD as possible then.

Consider slowing down a little too. Running at 60-65 is going to be a whole lot cheaper than 70-75. And less RPMs to boot. Not to mention safety issues. A trailer is a lot easier to control at 65 than 75 when you have to slam on the brakes. If you are going to run those speeds, I hope you have electric brakes on the trailer. I've seen trailers "wag the dog" so to speak. Its not a pretty site. 2300# of out of control trailer and cargo can easily flip the TB over on the highway. I'd hate to see you end up in a ditch (or worse) just to save a few minutes.

Oh, and you need to get a little dirt on that thing too! :p

Yeah, if you tow north up 41 hwy then that is a VERY flat route!! We always come into the state from the west (usually enter at Dubuque on 151 hwy) and 151 is a hilly mofo all the way to Madison. I wouldn't even consider D on that part of the trip.

I do have electric brakes on the trailer. :yes:

To be honest I don't know what the trailer weight is right now. I am towing it for my father-in-law. It is a single axle. Also, I have the 3.42 gears.

Well my trailer pictured above is 5x12 and weighs 1100lbs empty so I'm sure your's is heavier. I think drag is going to be your biggest factor. Can you take a picture of the trailer hooked to your TB?

Since you have 3.42 gears, towing in 3 might not be that bad. You'll be running in the heart of the 4.2's powerband.

[coolcloo1019]

Yeah, if you tow north up 41 hwy then that is a VERY flat route!! We always come into the state from the west (usually enter at Dubuque on 151 hwy) and 151 is a hilly mofo all the way to Madison. I wouldn't even consider D on that part of the trip.

I do have electric brakes on the trailer. :yes:



Well my trailer pictured above is 5x12 and weighs 1100lbs empty so I'm sure your's is heavier. I think drag is going to be your biggest factor. Can you take a picture of the trailer hooked to your TB?

Since you have 3.42 gears, towing in 3 might not be that bad. You'll be running in the heart of the 4.2's powerband.

I'll see what I can do about a picture. I think it's going to be more of a trial process. See what its doing when I start pulling it. Im not even sure how much furniture we're going to be putting in it yet. I don't think it's going to be jam packed, just a few things. I'll check to see if I can find out what the weight of it is also.

[muddy tires]

I tow my boat and covered snowmobile trailers (about 2,500 lbs) in "D" most of the time unless I feel the engine lugging then I'll drop it down into "3". Your axle ratio and terrain will determine the correct choice. The key is to not let too much heat build in the transmission and hunting for gears will kill it. When towing my camper (~5,000 lbs guesstimate) I always run in "3". I've tried "D" but the truck ususally stays in "3" anyways and who am I to argue.

Does somebody have a link to the 5.3 torque/power curves. Running at higher RPM will likely get you closer to the sweet spot anyways. Other than the kick to the wallet at the pumps, the truck seems to like it better when it starts to spin. And the pumps won't be your friends no matter what you do.

Steve, learn to love to hear those 8 little guys sing!

[Spong]

I agree that trial and error will be a big thing. No two towing situations are the same, too many variables.

Here's some power charts I've had for a few years. They may be different now

http://images16.fotki.com/v3/photos/4/41590/90193/4200curve-vi.jpg

http://images16.fotki.com/v3/photos/4/41590/90193/5300curve-vi.jpg

[muddy tires]

Wow! Look at how flat the I6 torque curve is! :eek:

But higher RPM's with the 5.3 will get you more torque. I think that the biggest mileage killer for me isn't the higher RPM's but rather that it never kicks into DOD mode and keeps all cylinders firing.

[Spong]

Wow! Look at how flat the I6 torque curve is! :eek:

But higher RPM's with the 5.3 will get you more torque. I think that the biggest mileage killer for me isn't the higher RPM's but rather that it never kicks into DOD mode and keeps all cylinders firing.

I actually like driving around town in 3rd. I will often times run up over 60 mph for short periods and I love the power in those rpms!

As for the DOD, it does almost ZERO for mileage anyway. I'm turning mine off and I know others that have as well with no drop in MPG. I'm sure towing plus the higher RPMs is for sure what drops the mpg! :yes: I could just drive on the interstate in 3rd gear and see a big mpg drop.

[muddy tires]

I'm turning mine off and I know others that have as well with no drop in MPG.

Could you calculate mileage before and after under similar driving conditions? I agree around town there would be little difference but should see improvement on the highway.

[Spong]

Could you calculate mileage before and after under similar driving conditions? I agree around town there would be little difference but should see improvement on the highway.

Send a PM to "nukedog" he just shut his off and posted results in my thread about real world gas mileage.

If you have a tune like myself and others then you really hate the DOD!!

I suppose it would help if you drove flat roads all the time because it would stay engaged longer but most of what I drive isn't flat so the DOD is constantly going on and off.

http://forums.trailvoy.com/showpost.php?p=369001&postcount=68

[muddy tires]

I stand corrected. Pretty hard to argue with real world data by quoting GM marketing. I guess I missed the end of that thread the first time around.

Sorry for the hijack.

[Spong]

No problem!

That's what makes this board interesting! People can start talking about a topic and then branch off to other topics related to the main topic.

[Nukedog]

Anything about 2200rpm and the 5.3 starts to suck the gas. I pull my 2500lb motorcycle trailer at 62mph in "D" because pulling at 62mph in "3" with 3.42 gears is a bout 2600rpm and it only gets like 10mpg doing that...

[Spong]

Eric, How was the mileage driving back to FL from MO? Did you see any drop in MPG with the DOD disengaged?

[turbomike]

I tow about 5300lbs. with car and trailer. Running around 70mph in OD mileage is 14-15 on fairly level terrain.

[Spong]

I tow about 5300lbs. with car and trailer. Running around 70mph in OD mileage is 14-15 on fairly level terrain.

Dang!! Does the tranny get hot towing that much weight in OD?

[turbomike]

If torque conveter stays locked no additional heat will be generated. If pulling up hill when torque converter unlocks I just drop down into 3rd.

[muddy tires]

If torque conveter stays locked no additional heat will be generated. If pulling up hill when torque converter unlocks I just drop down into 3rd.

How can one tell when the torque converter locks or unlocks? Can you tell by sound or by watching RPM's?


Dang!! Does the tranny get hot towing that much weight in OD?

Your comment raises a good point. Since heat is public enemy # 1 in a transmission to the point that many of us have installed auxilliary coolers, how can we monitor that heat to know when to take a little break? I've seen a few threads about installing temperature guages but none have seemed easy. Is there a plug and play installation or inexpensive scan tool available to monitor transmission temperatures?

[Envoy Fan]

Is there a plug and play installation or inexpensive scan tool available to monitor transmission temperatures?

The Dashhawk (sold by Vector Motorsports) can monitor the transmission temp, coolant temp, and a lot of other parameters. It works on any CAN bus compatable (05 5.3L is) vehicle.

[nowgrn4]

I go to ohio in a couple weeks to take delivery of a new 21 ft,TT,weight about 4000 lb.I just instsalled B@M cooler and temp guage(how to info on guage install@ electronic add on sub forum).I hope to have tranny temp info in different gears at various speeds,and gas mileage info when I get back.

[addicted4life]

If torque conveter stays locked no additional heat will be generated. If pulling up hill when torque converter unlocks I just drop down into 3rd.

You make a good point. I was reading through this and wondering if anyone was going to talk about the torque converter. You can essentially tow any size trailer in D as long as the converter stays locked. When it unlocks that is when extra heat is generated. It's easy to tell when it unlocks by watching your RPMs. When it is locked and you give it gas the RPMs will climb as speed climbs (just like in a manual transmission). If it unlocks when you give it gas the RPMs will jump around 300-500 immediately and will float around as you speed up/change throttle position. When it re-locks you can usually see the RPMs drop a couple hundred.

[ScarabEpic22]

Ive always towed in D, but lately Ive been experimenting with D b/c I have EFILive and can watch the trans and engine temps. My tests are done with ~4100lbs boat trailer, dual axle at ~60-65mph. On essentially any hills, the I6 loves to kick down to 3, or at least unlock the TC, but on the flats its fine. I cant tell much difference towing in 3 or D except it never kicks down in 3 but does quite often in D. I have the 3.73s and a trans cooler, and at 65mph in D Im at about 1800-1900rpm (if memory serves properly) and in 3 Im at about 2900-3100rpm. My test terrain is hilly, so Im pretty sure thats what kills any positive effect D might have, and the fact I sometimes push 70 with the boat. Its a pretty big load, but my TB tows it way better than our old Jimmy with the 4.3 did. I really want to get an SS and see how much better it is, but who knows when that will happen (notice I said when, not if b/c I will have an SS eventually. Maybe not a new one, or for a few years, but I will have one).

[jaylind]

I towed just over 4000lbs (2001 s10 loaded down on a dolly) from Charleston SC. to Denver Co. 1889 miles. I was doing d and then 3 in the hill/mountains but 3 was way to high rpms. I just left it in d the rest of the trip and let it downshift when it needed it. My speeds where mostly 70-84mph. I was scared at first thinking the steering would be "loose" but the TB ran/handled like a champ.

http://i127.photobucket.com/albums/p156/jaylind/sc2co.jpg

[coolcloo1019]

Good to know jaylind. Makes me feel a little better about my trip this weekend.

And btw Steve...nice avatar! :eek:

[Spong]

Just out of curiosity I checked my RPMs tonight running 70 mph in 3 and D. In 3, I'm running about 3050 rpms @ 70mph. In D, I'm running about 2150 rpms at 70mph. I'm sure a difference of 900 rpms would be noticable on the gas gauge.

[jaylind]

Just out of curiosity I checked my RPMs tonight running 70 mph in 3 and D. In 3, I'm running about 3050 rpms @ 70mph. In D, I'm running about 2150 rpms at 70mph. I'm sure a difference of 900 rpms would be noticable on the gas gauge.

I forgot the MPG part... My trip I would avg only 9MPG... Gas up often...

JAy

[Nukedog]

Eric, How was the mileage driving back to FL from MO? Did you see any drop in MPG with the DOD disengaged?

My last leg of Journey at 72mph @ 2000rpm i went 380 miles and it was 19.8 gallons.

That isa 19.09 MPG so i averaged about 18mpg overall for my trip...

[confusedsoul]

Towed my parent's boat to the lake for them this weekend. Its about a 100 mile one way trip up there. I6 w/ 3.73 with Tune & KN Drop-in filter and we averaged 16-18mpg driving 60mph in 3rd gear. Was running pretty much at 2500 RPM the whole way. Tried it in D for a little ways but it shifted into 3rd three times while trying it so I just dropped it back to 3rd. Really wasn't any wind on the way up there, and we might have had a tail wind on the way back, but it wasn't much of one if we did. We didn't tow the boat on the way back home btw. They'll bring that back behind the 3/4 ton GMC and 24' 5th wheel LOL. Just figured it'd be safer to tow the boat for them on the way up.

The boats not huge, its a Lund Tyee 1750 Deep V w/115hp motor, but the cover was on and you could tell it was back there. Here is a pic of an older one to give you an idea:

http://i14.ebayimg.com/05/i/000/a8/1c/5925_3.JPG

According to the DIC, we averaged 19mpg for the whole 200 mile trip Very happy with that! I do wish there was even less torque management taken off from the Tune, its still definately noticeable!

[coolcloo1019]

Well I made the trip safely. I got some pics that I will put up later. It looked like I had a 4" drop in the rear lol. Tires were near tucking. The trailer was 3200lbs empty, probably another 800-1000 lbs of stuff. It was HEAVY. I averaged 11mpg the whole trip to Tennessee. Had to keep it in 3rd and the rpms were around 3100 at 70mph. On some of the mountains I had to even put it in 2nd because it just wouldn't go, felt like a dog. I will say, even though she did me good, I won't do that again unless I have no other choice.

[coolcloo1019]

http://gallery.trailvoy.com/data//506/medium/trailer_1.jpg

http://gallery.trailvoy.com/data//506/medium/trailer_2.jpg

[ScarabEpic22]

Towing a boat + cover= bad, way more wind resistance (even if its a "trailering cover"). I suggest pulling it all the time, I pull mine off both our boats even if its raining out and going to be more than just a 15min jaunt.

[jacobrb]

I couldn't help notice that your TB is the same color as mine but without the two-tone. How in the world did you get a 5.3V8 in yours with the short wheel base?:confused: Did it come from the factory like that?
I have a utility trailer similar to yours for pullin' a couple of Honda 4-wheelers.
I figure I'm pulling about 2250lbs. with the I6. Mine seems to do ok when the a/c is on but it constantly wants to go stay at the spot betwwen OD and third. I guess thats when the torque converter is not locked in. Any thoughts:undecided

This Message is intended for Spong with the Little Red Jewel.

[Spong]

http://gallery.trailvoy.com/data//506/medium/trailer_1.jpg

http://gallery.trailvoy.com/data//506/medium/trailer_2.jpg

Oh yeah, bigtime wind drag on that baby!!

Towing a boat + cover= bad, way more wind resistance (even if its a "trailering cover"). I suggest pulling it all the time, I pull mine off both our boats even if its raining out and going to be more than just a 15min jaunt.

I never untarp the boat for towing. Seems to me with the cover on the drag would be less since it's a smoother surface. :undecided

I couldn't help notice that your TB is the same color as mine but without the two-tone. How in the world did you get a 5.3V8 in yours with the short wheel base?:confused: Did it come from the factory like that?
I have a utility trailer similar to yours for pullin' a couple of Honda 4-wheelers.
I figure I'm pulling about 2250lbs. with the I6. Mine seems to do ok when the a/c is on but it constantly wants to go stay at the spot betwwen OD and third. I guess thats when the torque converter is not locked in. Any thoughts:undecided

This Message is intended for Spong with the Little Red Jewel.

Mine's a 2006. They started (finally) putting the 5.3 in the SWB models in 2006. Red Jewel is also a new color for 06. I wish the bright red was still available like in earlier years.

What rear end do you have?

[jacobrb]

i'm not sure....haven't been able to get under there and look yet but there is a way to look it up from the vin or the options sticker in the glove comp. right??

[ScarabEpic22]

Covers billow up and air flows under them, making them more like a sail than anything. Why do you see covers on the side of the road sitting there ripped up or on a boat flapping around madly on the freeway? Its because they billow like heck b/c there is a TON of surface area. Now, this is my personal opinion and like I said before I do break it from time to time for short trips, but it if Im going on the freeway there is no way Im going to stress my $900 boat cover for 6 hours between Seattle and the cabin, its just not worth it IMO.


i'm not sure....haven't been able to get under there and look yet but there is a way to look it up from the vin or the options sticker in the glove comp. right??

Yep there is, open the glovebox and look at the white sticker in there. Look for one of these codes:
GU6- 3.42
GT4- 3.73
GT5- 4.10

G80- locking rear (available with any of the above)

And nice to have another WA member, I always comment on that b/c I see about 5-10 TVs a day on average and NONE are members!!!

[Chickenhawk]

When towing trailers over 1000 pounds, I always use a rule of thumb that says one must use the appropriate RPM range for minimum strain on the drivetrain and just live with the mileage that one gets. It would seem silly to try to extract 1 or 2 more miles per gallon and suffer much shorter transmission life in exchange.

Heat is the killer of transmissions. For every 20 to 25 degrees increase in temps, transmission life is cut in half. If a transmission can last over 100,000 miles at 175 degrees, it will last less than 25,000 miles at 220 degrees (which is easily reached when towing heavy loads in "D") and it can last only HOURS if the temp ever reaches 300 degrees.

To decide which gear results in the least strain on the drivetrain at any given time while towing, don't look at the RPMs; look at the throttle position. (High RPMs are not inherently harmful when the engines are designed for it; low RPMs and straining transmissions resulting in high trans temps ARE harmful.)

Find a level stretch of road and travel at a steady speed in "D." Feel for the position of the gas pedal. Now shift to "3." If you need less pedal to hold the same speed, travel in "3." If you used more pedal in "3" then you can travel in "D."

[Mijeeper]

Chickenhawk gives very good rules of thumb. Only point of difference is itds not the life of the transmission -- its life of the transmission oil. I have seen products where lube temps are over 300F. Not a good practice but as long as lube is changed frequently the product will live.

I flat tow a almost 4000lb Wrangler with the Envoy and usually leave transmission in D. I usually keep speed under 65mph and use cruise. When I notice transmission shifting frequently I will drop to 3. The first big trip with the Envoy was from Detroit to Colorado. It has since made several trips to northern Michigan, Tennessee and Kentucky pulling the Jeep.

At 50k miles I changed transmission filter and fluid - swirtched to Mobil 1 synthetic. Envoy now has 70K and still going!

[nowgrn4]

I'm pulling a 21' TT that goes around 4350 lb. loaded(my GVWR is 6200 lbs).With the 3.42/LH6 pulling in OD the revs are way to low and out of the torque curve. In 3ed gear I'm getting at 55MPH, 12.5 MPG @ 2400 RPM, 60 MPH, 11.5 MPG @ 2500 RPM and at 65(all trailer tires are rated for 65 MPH max!) MPH, 10 MPG @ 2600 RPM.Tranny temps when pulling at Hwy. speeds are 160-170,stop and go/around town temps,180-190 degrees.I could see pulling a lower weight/less wind resistance load in OD with the 3.73 rear gears.An easy way to monitor tranny temps is with a handheld laser thermometer.My Raytek MT6 consistently reads within 5 degrees of my temp gauge.

[ssilicon]

How can one tell when the torque converter locks or unlocks? Can you tell by sound or by watching RPM's?




Your comment raises a good point. Since heat is public enemy # 1 in a transmission to the point that many of us have installed auxilliary coolers, how can we monitor that heat to know when to take a little break? I've seen a few threads about installing temperature guages but none have seemed easy. Is there a plug and play installation or inexpensive scan tool available to monitor transmission temperatures?

Also, if you prefer a round gauge, the Aeroforce Interceptor works good too. I have one and put it in the hole that would otherwise be used by the 4x4 selector switch.

[Bithead]

I'm pulling a 21' TT that goes around 4350 lb. loaded(my GVWR is 6200 lbs).With the 3.42/LH6 pulling in OD the revs are way to low and out of the torque curve. In 3ed gear I'm getting at 55MPH, 12.5 MPG @ 2400 RPM, 60 MPH, 11.5 MPG @ 2500 RPM and at 65(all trailer tires are rated for 65 MPH max!) MPH, 10 MPG @ 2600 RPM.Tranny temps when pulling at Hwy. speeds are 160-170,stop and go/around town temps,180-190 degrees.I could see pulling a lower weight/less wind resistance load in OD with the 3.73 rear gears.An easy way to monitor tranny temps is with a handheld laser thermometer.My Raytek MT6 consistently reads within 5 degrees of my temp gauge.

:iagree:Pretty much my own situation. I'm towing a 21ft Kiwi, GW=4550. I find that the real deal, here is wind resistance, and how badly you need the torque, depends totally on how much hill and headwind you're dealing with. My trailer is terrible for wind... it's like towing a bloody brick.

As a result, my MPG ends up around the same as yours is, at all points. I find I do better at 55 towing than 60 or 65, though without the trailer, there's not enough difference to worry about. There again, the wind is the primary factor. I've found for that reason that I like twoing on two lanes better than freeways, unless the traffic is really light; I find I set myself up at around 55-60 and let the world go by if they want. Hard to do in a corwd, but in some of the outbakcs, not so much.

I'm kind of wondering what a tuner would bring to my particular party.

[jay boy]

Can anyone with a dic and a3000lb boat give me some gas mileage readings at different speeds when towing? Maybe even different gears? what is the difference in mpg between 3 and D ? Thanks Jay:thx