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Montana_2203
10-27-2004, 03:04 PM
Just curious if I should always keep the 'tow' button in when towing my camper... I am pretty sure you should but sometimes on level, long stretches of highway... as in I-95 southbound to Florida.... when you are up around 65mph.... it seems that it might be ok to engage the cruise.... however, I do not want to do anything that would mess up my truck... so, what's the consensus here?

2002 2500HD Duramax/Allison: 2005-3400RL

thanks,

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Montana Sky
10-27-2004, 03:16 PM
I use the tow mode when towing in city traffic or bumper to bumper traffic on the freeways during rush hour. Once the I reach my cruising speed of 65 - 68mph I turn the tow mode off. If the transmission starts the game of searching for the right gear or hunting to find the gear I turn it back on. I also tow with the cruise on as well. You are correct, the long level stretches of highways are the perfect place to run in fifth gear. Just listen to your engine and it will tell you if you need to have it on or off. Also keep an eye on the trans temp.

Glenn and Lorraine
10-27-2004, 03:37 PM
quote:what's the consensus here?
I concur with Montana Sky. With my 2500HD D/A I am in overdrive and on cruise control anytime I am on the open road such as I-95. I only kick it out of OD and cruise when in traffic or on a grade.

Montana_2203
10-27-2004, 03:41 PM
[quote]Originally posted by Montana Sky

I use the tow mode when towing in city traffic or bumper to bumper traffic on the freeways during rush hour. Once the I reach my cruising speed of 65 - 68mph I turn the tow mode off.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Ok, great... one other question.... this camper is heavy and although I think the truck is plenty for the unit.... does the 2500HD Duramax/Allison (mine is a '02 and has the tow package) generally come with all the stuff needed to do the towing... like trans cooler, oil cooler, heavy duty fan and all that stuff.... and although this is not a 'dullie' I have the proper tires and know about the proper inflation....I will check but I get the impression that you know your stuff so I thought I would ask here...:)
thanks......
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Bill Hill
10-27-2004, 04:10 PM
You're really talking about 3 different things here: 1) use of the tow/haul mode, and 2) use of the cruise control, and the OD lock-out feature. Since you have the D/A, do you have boost & egt gauges? You really need both to tell you what your engine is doing.

First my thoughts on tow/haul mode. Use it whenever you're towing or hauling. It is designed to change the way the transmission shifts based on the additional weight, etc. It also engages the automatic downshifting mode, so that as the vehicle slows down, the transmission downshifts to act both as a brake (as much as an un-braked diesel will do) and to keep the rpms at the optimum level.

Use of the cruise control is something else. If you are on relatively flat terrain, it works fine, but you still need to be ready to kick out of it at any time, especially if you want to pick up a little speed to climb a hill.

The Over-drive lockout is the third component. This is where the pyrometer (exhaust gas temp gauge) really comes in handy. You can be in OD at 59 mph and 1850 rpm where the peak torque is, but you may be running much hotter than you want, like 1050-1150 deg F. If you kick it down to 4th you increase the rpm to about 2250, but your e.g.t. will go down about 200 degrees. This is a good thing.

I don't mean to sound like a lecture here, but this is something I struggled with for months after getting my '04 D/A. My first e.g.t. gauge seemed a little off, so I took it back to the installer. Turns out it wasn't right, but the new one read much higher temps. Took it back again, but it was right. The D/A does run a bit hot, so that's why you should have the gauge to help you adjust the throttle, tranny, etc. to get the maximum work with the least temperature.

Hope this helps, and I'm really not a hopeless pedant!

sreigle
10-27-2004, 04:38 PM
Are the GM's different than the Fords? I use tow/haul all the time when towing, without exception (well, occasionally I forget to turn it on) but also use cruise and keep it in overdrive all the time except when it shifts out on its own. I was under the impression the GM's could be done the same way. Tow/haul does not lockout the overdrive on mine. I've seen it running the same rpm at a given speed as when not in tow/haul. That's on level ground.

I figure if the tow/haul makes it easier on the engine and/or transmission then I'll keep it turned on.

Montana_2205
10-27-2004, 04:58 PM
Unless I forget, I always use the tow/haul mode. From everything my son and I have read, the transmission was designed specifically for the purpose of towing. The first time it was in tow/haul we were pulling the camper home from the dealer. As I was getting off the Interstate, it started downshifting as I let off the accelerator and pressed the brake pedal. It startled me at first, then I realized what it was doing. There is a short, but very steep hill about a mile from our house. The first time we went down the hill, it shifted down a couple of gears and the RPMs went up very high and I was a little worried, but I guess it was doing what it was suppose to do.

On our first trip, I used cruise control, but I soon learned that I could keep it from shifting as much if I was in control. It may be different on very flat roads, but I think I'll keep it off cruise control.

Scott

OntMont
10-27-2004, 05:02 PM
quote:Originally posted by sreigle

Are the GM's different than the Fords? I use tow/haul all the time when towing, without exception (well, occasionally I forget to turn it on) but also use cruise and keep it in overdrive all the time except when it shifts out on its own. I was under the impression the GM's could be done the same way. Tow/haul does not lockout the overdrive on mine. I've seen it running the same rpm at a given speed as when not in tow/haul. That's on level ground.

I figure if the tow/haul makes it easier on the engine and/or transmission then I'll keep it turned on.

I do the same as you with my Chev. Someone once wrote "the Allison transmission is smarter than the average driver", so I let it do its thing. On those occasions when I forget to engage T/H mode, the truck still seems to perform OK, but I think I would rather have it T/H.

DHenry
10-27-2004, 05:47 PM
I only use the T/H in town or the hills, the rest of the time it is off. My Duramax tows my 3670 with ease. I do have the air shocks to level out the load though.

Montana Sky
10-27-2004, 09:49 PM
Steve,
The Duramax with the tow mode will also allow you to use 5th gear while engaged as does your Ford. I will clarify how I use the tow mode. When on flat highway roads I usually turn the tow mode off once the trans has shifted into 3rd gear. The only reason I do this is so that it will shift out of fourth gear sooner into 5th (O/D). I had found that if I left the tow mode engaged it will not kick into O/D until I reach 60-64mph bringing the rpm's into the high 2's. I dont feel it needs to hold the shift that long and that is why I turn it off to allow the 5th gear as soon as possible. I have never found a need to lock out the O/D yet. Another thought, the boost and EGT guages that were mentioned above, I am getting mixed stories on. Most of the dealerships I have talked with about these guages tell me I dont need them. As long as I keep my eyes on the tranny temp and engine temp that is all I need to know and worry about. Some say with the Allison transmission and all the computers onboard, they will set off a warning light long before any damage can be done. I am still considering having these two mounted on the pillar of the truck. Need to get more info before I do anything yet.

Montana Sky
10-27-2004, 10:01 PM
Speezack,
I have the 2005, 2004, and 2003 brochure here in front of me and this is what they say for the Chevy Silverado. If your truck has the Heavy Duty Trailering Package then you have the following, trailer hitch platform, seven pin wiring connector, auxiliary transmission oil cooler, trailer brake control harness and seven-way to four way adapter. I can tell you that I have the same truck and coach as you and have not had any trouble towing this coach. Been up and down a few mountain passes in Northern Idaho, Montana and Wyoming and the truck walked up and crawled down just fine without a hitch. In my opinion you have all the truck you need to tow the 3400RL.

tnorfitz
10-28-2004, 04:59 AM
I don't know about the D/A combo, but I have a 2002 GMC Sierra 6.0L that we are ready to trade in for a 2005 GMC Sierra CC 4X4 D/A. On the 2002, the tow / haul just adjusts the shift pattern. It hold each gear until higher RPM's are met. This makes it easier on the tranny by keeping the RPM's up. It will go into overdrive on straight stretches, but it likes to jump out of overdrive easier with a load being carried, or the slightest incline in the road. When we pulled our 19' Wildwood TT, we found it easier not to use the Cruise, but just monitor the speed manually. In certain cases, we even dropped it into '3' and travelled down the road at 65 - 70. I am looking forward to seeing how the new truck will work. I was told the Allison tranny in tow / haul also adjusts the shift pattern for higher RPM shifts, but also helps brake when you let up on the gas, which helps in downhill coasting. Can't wait. The truck comes off the production line this week.

padredw
10-28-2004, 09:13 AM
quote:Originally posted by tnorfitz

I was told the Allison tranny in tow / haul also adjusts the shift pattern for higher RPM shifts, but also helps brake when you let up on the gas, which helps in downhill coasting.


I can testify from experience that what you have heard about the downhill is absolutely true. It is one of the best features of this engine/transmission team. In fact, I never use the tow/haul except in the mountains (or steep hills), but then we are towing a Montana 2955RL which is not one of the heavyer trailers. I also do not use cruise while towing. I tow in overdrive at about 65 MPH on level, faster downhill where legal and slower uphill.

Karl
10-28-2004, 11:53 AM
We have a GMC 2500 Duramax/Allison also. I do use the Tow mode when towing, however, I often will hit the button briefly to go out of tow mode to allow the tranny to shift into 5th just a bit sooner than it would in tow, then I go back to tow mode. I do this especially on two-lane roads where I will be driving at a speed just a bit below the "sweetspot" which seems to be 63 mph/1800 rpm on my unit.

There have been a few times in mountain driving, and more times driving against a severe headwind that I have used the "lockout" of 5th to keep the tranny from doing the seek and shift.

I did ask my dealer about my habit of undoing "tow" to allow the upshift, and he/they did not feel that that would be any problem.

I applaud GM/Chev for arranging the marriage of Duramax/Allison and hope they have many offspring!

sreigle
10-28-2004, 01:58 PM
Thanks everyone. I hope noone objected to a Ford guy asking a question in a GM thread. It was a legit question and I like to understand these things. Thanks for the replies.

Montana Sky, your GM gauges may be better than the Ford gauge. The boost gauge on mine works well so I'll just use the one on the dash. On the prior Ford I had pillar pod gauges for water temp, EGT, and trans temp. The dash on the Ford has water and trans gauges but they're glorified idiot lights. They work as gauges until reaching the normal range. They then sit in one spot until the temp goes above or below some preset threshhold. I want to know when it is starting to heat. The gauge moving to Hot is too late. Picked up the new truck this past Monday and have an appt this next MOnday to have the gauges installed. After watching those gauges on the traded truck I'm a believer. If your dash gauges work as real gauges then you probably don't need the aftermarket gauges.

Montana Sky
10-28-2004, 10:22 PM
Steve,
Thanks for the info. I think I will be checking into getting the EGT, boost, water temp gauges installed this coming spring. No need to spend the money now since the coach is in storage until spring.

tnorfitz
10-29-2004, 02:44 PM
Haven't gotten my 2500HD in yet. How do you lock the tranny out of 5th gear with the D/A combo? Is there a special button, or do you move the shift lever to a lower position. On my 2002 GMC 1500HD, there is no way to lock out overdrive, unless you shift it into '3'.[?]

Karl
10-29-2004, 03:35 PM
All you do is hold the "Tow/haul" button till the little idiot light tells you it is locked out. Hopefully your dealer will take a drive with you to show you all the options. If he/she doesn't offer, insist upon it, and be sure to ask as many questions as possible. Remember, she is YOUR servant till the deal is complete---that means when the vehicle is in your hands and you are completely satisfied!

sreigle
10-29-2004, 06:12 PM
Tnorfitz, I meant to congratulate you on your new soon-to-be-delivered truck but got carried away and forgot. I think you'll like the engine/transmission combination. Although mine's a different brand, the help slowing down the vehicle on a downgrade is fantastic as I'm sure it is in the GM's. There have been times on twisty mountain downhills whre a line of vehicles ahead of us constantly are on and off the brakes that I've actually stepped on the brake just to let the cars behind us know that, yes, our brake lights do work. I know I don't like being in a tight downhill situation thinking the guy ahead of me has no brakelights and you just know a FW going downhill has to be using the brakes frequently. Enjoy the new truck.

tnorfitz
10-29-2004, 06:50 PM
Thanks for the info on how to lock out 5th gear. Now I am wondering if that works the same way on the GMC Sierra that I have now. Maybe it is just a function of the Allison tranny.

tnorfitz
10-30-2004, 02:53 PM
Went to the truck dealer today and he showed me the tow/haul/overdrive lockout button. That should really come in handy in certain situations. I found out that this was not an option in the 2001 D/A models. The owners son, nor my salesman, knew that was a function on the new trucks. Thanks for the info, again.
Wish that would have been an option on my 2002 GMC 1500HD 4X4 Sierra CC. We pulled a 19' Wildwood TT to Phoenix and back and wished we could keep the tranny from trying to get into overdrive. We drove some of the trip in '3' just to keep it from shifting so much.
From what I have heard from all you great people out there, it sounds like our combo should pull fairly well down the road, even in overdrive. Never had a diesel before:)

Montana_2203
10-31-2004, 12:29 PM
[quote]Originally posted by Montana Sky

In my opinion you have all the truck you need to tow the 3400RL.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

I think you know what you are talking about..... I went to the dealer, ran my VIN #... got a print out on the options.... and you were exactly right.... My buddies are telling me I need a dullie but I have already convinced myself that 28 yrs. in the drivers seat of a tractor trailer pulling doubles in all types of weather and running 48 states should give me enough experience in the pickup... the only reason I was researching all this stuff is cause all my experience was in a "big truck" and this is the first 'diesel' pickup and the first 5th. wheel camper and I was just pickin' peoples brains..... you get an "A"
thanks Montana Sky......... see ya around the campgrounds.... if ya ever see my rig... my license plate on the truck is "CRAZYDOG" and when you see "Zack" in the front seat you will understand why...

[^][:X] :D

Karl
10-31-2004, 01:40 PM
I certainly agree with those who say there is not a need for a dually. When I was looking, my truck dealer said that in his opinion, the reason he would get a dually would be if he were hauling something like a stock trailer where the load would be somewhat "liquid" in his vernacular. I went for the single wheel 2500 GMC duramax/allison, and have not been sorry at all. I have had no feeling of instability in my 15,000 miles of pulling, often in quite windy conditions.

Not that the dually wouldn't do the job, but why have the extra wheels/tires and the extra "turning" wear if you didn't really need it.

c5racer
10-31-2004, 06:54 PM
Not many dealers know a lot about towing. Was told a dually was required to deliver new 5vers. Factories might know more about towing.

Montana Sky
10-31-2004, 08:27 PM
Speezack,
I am glad to hear you are happy with your truck decision. I know I could not be happier with my 2500HD. I will keep my eyes open for ya on the open roads. Let us know how things are going.

Karl
11-01-2004, 01:01 AM
Since my truck dealer also is the largest dealer for large Pace Trailers (cargo, racing, and livestock) in the midwest as well as one of the major installers of gooseneck and fifth wheel "hitches", I decided to trust him on his recommendation, and I have found no reason since to feel the subsequent decision was inappropriate.

sreigle
11-01-2004, 03:59 AM
C5racer, near Goshen, IN, we saw a billboard advertising for delivery drivers. It said "Must have one ton truck" but said nothing about duallies. Maybe that's assumed and answering the ad would result in them saying it must be a dually. But we saw a lot of delivery trucks towing away from the area that were not duallies. They had the business name on the side of the truck so I'm sure they were deliveries. I could see where a dually would be required for the heavier rigs where more pinweight would put a SRW over it's GAWR or GVWR.

Montana_1683
11-01-2004, 09:30 AM
I always pull my 3295RK in overdrive. Never pull using cruise control. Trailer Life magazine had a response to a letter regarding this. I have found that fuel mileage is much better without using the tow/haul portion of the Allison tranny. We have made only 3 long trips since we bought our Monty. First to Oklahoma City, did fine through the flint hills on I-35, only jumped down below 3rd gear 2 times. I didn't anticipate the long climbs quick enough on the way to OK City. Did better comming home. The 2nd was to Bella Vista, Ark; never kicked out of overdrive during the time we were on on the road. 3rd time went to Nashville, Ten; only time came out of overdrive was going up the climb after crossing the Mississippi river.

This was traveling 65 - 70 mph, with rpms around 2000 according to the Tachometer.


Gary

Jeff Heiser
11-02-2004, 03:49 AM
I drive a dually crew cab. My reasons are that I like to carry alot in the bed of the truck - sometimes an ATV, sometimes my motorcycle, other times my generator and a whole lot of other stuff. With the dually, pulling a 327RKS (and a Mallard 30E in the past) I have always been able to load up with out worrying about being too heavy. At the time I purchased my truck the only 1 tons that were avalible from Chevy were the duallies. I understand you can now get a 1 ton crew cab thats not a dually from Chevy. I might consider it next time. I have 108000 on the truck now. At 65 - 70 I turn around 2100 rpms get between 7 and 9 gpm and drive in overdrive all the time with no problems. I figure maybe another 100,000 miles and it will be time to get another. Unless of course I find something I really like better then all bets are off. As for listening and believing what your truck dealer tells you beware. Some of them have a hard enough time telling the difference between a SUV and Truck let alone knowing anything about tow vehicles.

Jeff Heiser
Merritt Island Florida
1999 Chevy 454 Vortec Crew Cab Dually Long Bed
2005 327RKS TT

tnorfitz
11-03-2004, 04:57 AM
Jeff,
Just a wise guy response here!!!
If I was only getting 7 - 9 gallons per mile, I would look to trade it in for something that got at least 7 - 9 miles per gallon.;)
Sorry for the input, but I just couldn't resist.

Montana_2213
11-03-2004, 05:34 AM
The main point to remember is that part of the formula for the towing capacity of your truck is in the braking capability and the DuraMax/Allison combo gives you some important engine-braking. If you do not have your DuraMax in Tow/Haul mode, and you need to brake suddenly, it could create a problem.

Please be careful shifting out of Tow/Haul while cruising. My "policy" is to keep my truck in Tow/Haul at all times when pulling a load. You never know when you might need the extra engine-braking capability.

Phil

Jeff Heiser
11-03-2004, 06:40 AM
quote:Originally posted by tnorfitz

Jeff,
Just a wise guy response here!!!
If I was only getting 7 - 9 gallons per mile, I would look to trade it in for something that got at least 7 - 9 miles per gallon.;)
Sorry for the input, but I just couldn't resist.


OH MAN! You got me. These past two weeks have been...well lets just say challenging. So do I really have to tell m wife its really 7 - 9 miles to the gallon and not 7 to 9 gallons per mile. Man if she finds out I will never be able to trade the truck in for something new.:D

Jeff Heiser
Merritt Island Florida