8.1/Allison question

ctryboy60 · May 8, 2006

Pulled the camper this weekend for the first time. The motor and tranny were all I thought they would be as far as performance, ect. Just a couple of questions. The trans wnted to stay in 4th most of the time unless I let off on a downhill. It did cycle into and out of 5th afew times. Is this operating properly? Im just used to my old truck where this was bad if you let it happen alot. In 4th I'm running about 3100 rpm at 65 mph which I feel is fine. The trans temp was around 225-230. Is this acceptable/normal? Just wanted a few opinions to ease my mind that everything is working OK.

PS the trailer weighs approx 7000Lbs

the Tow/Haul was also on

Trouttrooper · May 9, 2006

Pulled the camper this weekend for the first time. The motor and tranny were all I thought they would be as far as performance, ect. Just a couple of questions. The trans wnted to stay in 4th most of the time unless I let off on a downhill. It did cycle into and out of 5th afew times. Is this operating properly? Im just used to my old truck where this was bad if you let it happen alot. In 4th I'm running about 3100 rpm at 65 mph which I feel is fine. The trans temp was around 225-230. Is this acceptable/normal? Just wanted a few opinions to ease my mind that everything is working OK.

PS the trailer weighs approx 7000Lbs

the Tow/Haul was also on

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In tow/haul the tranny won't even begin to think about shifting into 5th until around 65mph. If it senses too much of a load it won't shift at all. Don't worry about the Allison, that thing is smart enough to prevent anything bad happening to itself.

Sounds to me like everything was working just like it was suppose to.

Shooter_va · May 9, 2006

I second ctryboy60.

My tranny shifts into 5th on long straight hauls at about 55-60mph but stays mostly in 4th at around 2200rpm. Tranny temps run about the same as coolant, maybe 10°F more.

rlarson · May 11, 2006

I pulled a full load finally a few days ago with my 8.1/aly and it stayed in fourth most of the time going 65-69 at 3000 RPM which drove me nuts seeing the 8.1 at that RPM for 150 miles but thats what it wanted to run

Bart2500HD · May 11, 2006

I pulled a full load finally a few days ago with my 8.1/aly and it stayed in fourth most of the time going 65-69 at 3000 RPM which drove me nuts seeing the 8.1 at that RPM for 150 miles but thats what it wanted to run

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3000 RPM is nothing to worry about. Wait until you come down a good hill and step on the brake and it downshifts with RPMs zooming up to 4000! Scary, but she can handle it!

ctryboy60 · May 12, 2006

Thanks for the replies. The other thing I noticed was my trans temp seemed a little high by the time I got back home. The truck has a Lund chrome grille insert that was there wen I bought it and it looks to me like it really restricts my airflow. No problems empty but pullimg it gets warm

lord-dogbert · May 13, 2006

Hello,

I have an 03 with the same setup. I have the stock grill as I found that the b illet grills block too much air flow for my liking. My 5th wheel is about 12,000 pounds and I do hang out in 4th gear most of the time at a good freeway clip. Introduce a 30 mph headwind and you're down to third gear at high revs. I found that less speed and safe semi drafting will bring you back to 4th.

Your tranny temp bothers me as I have never passed 200 except for the time I forgot to turn on race/tow mode on a trip to vegas with the 5'er. I was reminded about tow mode when the tranny started making a weird whine. The tranny was up to about 220 but when I turned on tow mode and dropped to normal after about 10 miles.

Try taking the grill off and see if that makes a difference.

Have fun with the truck, I wouldn't own another HD truck without an Allison