Towing heavy with auto/3.54

[Steve M]

I'll be picking up our '99 Jayco 293RKS this Thursday. The dealer let us take it out for a tow to see how our truck handles it before we got too serious about it. It tows pretty easy and up a 3% grade of . 5 mile it easily maintained 65mph in 3rd with power to accelerate. 70mph on the interstate was not a problem. I have a picture of the rig at the Sunshine Skyway bridge but don't know how to post it.

The book says it weighs 7600 lbs. The sticker in the cabinet says the UVW is 8600~ lbs. By the time we load up we'll be close to the 9700 lb tow rating or maybe even a few over.

What are you auto/3. 54 owners towing and how have things held up? I'm running totally stock with gauges and have no desire to drag race the clock or the other trucks on the road. I'm more interested in how the stock truck and transmission will hold up with stock power and an easy foot for the long haul. The Sunshine Skyway bridge is the tallest mountain we have around here. We'll likely go to Cherokee NC with this setup but will not be towing through the mountains with it. There's one short 6% grade between here and Cherokee.

I'm mostly curious of what others are towing with auto/3. 54s.

 

[Fireman Dave]

Steve,



I have the same truck as you except 4x4. My TT is around 7,000 lbs as I tow it. I've towed it to both the west and east coasts the past two summers. I'd say over 10,000 miles of the 38,000 that I have on the truck are towing that trailer. I'm also bone stock except for gauges and exhaust. I've been real pleased with mine. I towed up some good sized mountains on our trip west with no troubles. The only concern I've had is the transmission getting a little hot when stuck behind slower traffic on two lane mountain roads, but as long as I can keep it locked up, it's fine. I change the transmission fluid and filter each spring. I believe towing with OD locked out is best for the transmission, but I have been towing in OD recently a little more on flat grades. As long as the RPMs stay up, you should be fine. Good luck.

 

[tgrfan2]

I had my TT on a trip behind a Y2K 2500 with the 3. 55 gears. The combined weight was 16,400 with no passengers. The truck did fine and I drove it just like I drive my 12V's. That is overdrive only on rolling hills and I manually downshift and upshift as needed to keep the truck from "hunting" gears. I only use the cruise control on relatively flat terrain and no traffic. If the cruise is on and I see the truck is likely to shift out of OD, I back off slightly and manually downshift it. This has worked for me for a combined 160,000 miles on these two trucks probably 20K towing. I also shift off overdrive when in city traffic.

 

[MPatrick]

Towing heavy

Steve,



When my trailer is loaded, (see sig) I'm at about 7500 lbs and the trailer is very tall. I put a wing on so I could tow at around 67 to 70 mph on the fast roads with OD, otherwise without the wing, I tow the trailer at around 62 to 65 mph without OD. I have not hit a hill yet that I can not maintain speed. The nearest mountain to me is the Dames Point bridge (also 6%) and I can maintain 65 without OD. If I could stop spending money on other things, I would get some 275 injectors. Fireman Dave has allot of towing miles on his, I have about 4,000 towing. Remember, Do not tow under 1700 rpm's when in OD and change the trans filter and trans fluid at least once a year. I have changed mine twice and it has 34,000 on it.

 

[Fireman]

I never was happy with the auto/3. 55 combo when towing. I was towing 17,700. GCWR the only difference between me and M Patrick was the wing. I traded for a 6spd. and 3. 73 gear.



Just my two cents

Fireman

 

[WMeyers]

My fifth wheel is 7265 pounds and I've got a combined weight of 13, 925 pounds and have the auto and 3. 55. I'm very happy with it but unlike MPatrick, I've met many a hill where it won't maintain speed.

 

[RichB59]

JMHO

Upgrade the auto . It's well worth the $$$. It will give you much better performance and some peace of mind. I'll never regret doing it. LOL



RichB59

 

[DBF]

Steve, our Jayco 5er weighs 7380 loaded for the road, gcw = 13,540.



I can run up a 4-5% hill in OD with the upgraded transmission, but the trans temp gets too high fairly soon. I drop to 3rd to get better fluid flow and continue. In the hills, I drive by the trans temp gage, not the speedometer.



You really, really, should put a trans temp gage in. Then you can climb hills in the summer in Arizona or wherever with confidence that you're not killing the trans.



That stock torque converter is so slushy it puts out a lot of heat when loaded. Heat kills transmissions.



Regards, DBF

 

[Steve M]

I brought the big guy home today! I even backed it up beside the house without tearing down the fence or eve of the house!

I have a VDO transmission temp gauge (from my '95 auto) waiting for me to install it. Right now I think the worst thing I can do to my transmission is backing it into the yard. I back up for about ten seconds and let it idle in neutral for a minute while I got out to check for clearances and repeated that three times before I was ready to drop the jacks. It's pretty heavy in the thick grass and the fan was roaring to let me know it. I still prefer the auto over my '98 5spd for slow maneuvering. I've all but forgotten about spring wrapup!

 

[plntmgr]

I tow a 14K Alpenlite with a stock 98. 5 2500 with 3:54 gears. transmission was modified with a locking TC and a shift kit. Pulled a 6% to the top. (slowed to 32MPH). Also came down a 6% for 5 miles and it slowed me down. Totally satisfied. Have a good time traveling.

 

[Ramboy]

My trailer has a GVWR of 18K and I tow it all day long at 70 mph in OD with no problems. Flat country I average 11 - 12 mpg. Truck is slightly modified, though.

 

[WMeyers]

Ramboy - and what would be your definition of moderately to heavily modified ?

 

[Steve M]

Ramboy, Wow, can I assume you have a 4. 10 ratio in that puppy?

 

[Chipstien]

I am barely modified. Moderately modified involves twins and nitrous. Heavily modified would be a 2000 HP Cummins V16 in the bed for the powerplant.

 

[Steve M]

Just returned from an interstate trip though some rolling hills and headwinds. I had my foot to the floor quite a bit. EGT was 750* most of the way for just over 200 miles at 68-70mph/1800-1900rpm. I got 10. 5mpg. After a conversation with my father in law, I decided to try his method of locking out O/D and running 58-60mph at 2250-2400rpm. I didn't fair any better in the mpg but EGT was 450-650*. I don't really have the patience to run along at 58-60mph. But I can say I tried it for 200miles! It'll run 68mph in 3rd at 2700rpm. I don't know if that's bad for it or not? I used to run 2500rpm all day with my '98 5spd/4. 10. Boy was it noisy.

I stopped and weighed our truck and 5th wheel. It weighs 16,940 lbs. I'm over my GCWR rating. I could swap to a 4. 10 ratio and increase my tow rating to within the weight of our 5'er but then I'd lose the use of 3rd. That's a tough choice to make. I'd like to lower my EGT a little and run a little higher rpm but not at the expense of losing the use of 3rd for the steep hills.

I thought about removing the tailgate for better airflow under the 5'er. Does this make a noticeable difference? It also has high covers on the air vents on top. I can't imagine that they would make any difference but I'm sure it all adds up.

 

[GLASMITHS]

High GCVW

Ramboy is almost as heavy as mine. Dry, no fuel, empty 22,440.

Full of fuel (135G) lots of goodies, port gen, air compressor... . plus 5X8 Wells Cargo about 26K...



A note about transmission cooling. There is very little cooler flow at slow speed, that is why the transmission will heat up in traffic, mostly. Take you a Kleenex and move it over the trans cooler and on over towards the center of radiator. You will see what I mean. Maybe move the cooler over or put a small fan on it, would help.

 

[Gary - K7GLD]

I must be missing something here - or my Alzheimers has kicked in again...



HOW can you be over your GCWR at less than 17,000 lbs? And unless your EGT probe is post-turbo, they are quite low - and STILL low even if it IS post turbo!



What IS the GCWR spec for your rig, and where IS your EGT probe?



*I* certainly wouldn't call a GCWR of 17,000 lbs "heavy" - up there perhaps, but still well under what I *think* your maximum should be... We pull about the same weightas you - tho' we have an HO/6-speed - and I pull in OD up to about 4-5% grades as long as I can keep speed up 60 mph or better - depends on road and traffic - and EGT is no problem - all around towing mileage is around 16. 5 mpg - I hardly EVER am below 60 mph, even when roads or traffic force me down to 5th gear... Last time I weighed, my GCW was about 16,000, fully loaded...



YUP - I musta missed something somewhere...

 

[Steve M]

Mornin' Gary, My Pyro is post turbo in the elbow since I'm running stock. I use it for shutdown temps. The highest I've seen it get was 850* on a climb with foot to the floor in 3rd. That's why I thought running 750* for an hour or more at a time might be a little much. The motor actually smooths out and runs quieter at 2700rpm/68mph/3rd gear and EGT is low. Since that's the rated rpm of the motor I have to assume it's ok to run it there all day under load but I'm not sure of it. The hills don't even begin to slow us down when we're running at peak hp. But rolling hills and a slight head wind bog us down in O/D at 65-70mph/1750-1900rpm. If 750* isn't high for extended periods of time then I won't worry about that.

GCWR for my truck is 16000 lbs. If I had a 4. 10 ratio it would be 18000 lbs. It accelerates fine and we have no trouble stopping the rig. The tall O/D ratio is the problem when we're running against a headwind in the hills. I'm thinking a 4. 10 ratio would fix the 65-70mph bog but then I wouldn't have 3rd to downshift to on the steep hills. Or would I need 3rd anymore with a 4. 10 ratio?

I'm giving myself a headache.

Alzheimers ain't that bad. I wish I could forget a lot of stuff!

 

[Gary - K7GLD]

HMMmmm - I didn't realize any of the later trucks were rated that low a GCWR - that's what my old '91 with A/T and 3. 07 differential was rated at... Yeah, I know, apples/oranges...



As far as EGT, the most common estimate I'm familiar with is that you lose about 300 degrees in readings taken after the turbo, and that the redline for EGT pre-turbo is 1300 degrees - so you should be OK up to around 1000 degrees where your probe is mounted - of course, less is always better...

 

[Steve M]

Ahh, how I would love to have a 3. 07 ratio for towing in direct and cruising empty at a low lumbering rpm. The 3. 07 was right in the power band on the highway in 3rd. I like apples and oranges!