how to pull in 5th gear! maybe

[fasterthanyou]

I think I may have found an inexpensive solution to the downshift from 5th to 4th while towing. Superlift suspensions has a product, that arrived on my door today, that re-calibrates your spedo. The new trucks are drive by wire, not good old adjustable kick-down linkage, and to stop the non-useful,over-reving, fuel consuming downsifts, we can fake out the tranny. I think- What this unit is designed for is over-sized tires and gear ration swap. It re-calibrates wheel speed and allows you to set two different wheel speed/size set-ups. At the flick of a switch you can go from 60 mph to 80 mph. This will cause the tranny to want 5th gear and should fake it enough to help this downshifting problem. Please understand this is not what I really wanted. I don't want to rack up extra miles on the odometer just to gain a few MPG, but I don't know any other way. Maybe the edge 'Juice" thing, will cause enough torque to keep 5th all day and night and this was a waste of $120. I'm going to instal it tomarow and head from northern Cal to Farmington, NM tomarow for a race. I'll let you know how it went when I get back. My trailer is weighing in at about 12k# so it should be a good test. The computer is fully adjustable so both switch setting can independently be controlled and my GPS will accuratly tell me how fast I'm really going. Hope it works and send me your comments asap.

[hoot]

I was hoping someone would try that thing. I suggested it a year or so ago but know one had any clue if it would work, even for tire recalibration. I called Superlift and they did confirm it works with the Allison.

Let us know as soon as you can!

Mike

[ 04-23-2002: Message edited by: hoot ]</p>

[Jake99Z71]

fasterthanyou,
Good luck on the install. I have been working with Superlift on the TruSpeed for over a month now with no luck on the install. If you read the installation instructions it calls out a pin 50 on the C2 connector in the PCM that is suppose to be Dark Green and White wire. This pin does not exist in the C2 connector on a Duramax. At this time they are not sure as to which wire to connect to. I'm on their contact list for when they figure it out. Later...

[D-max Man]

Wouldn't that thing cause your odometer to show more miles than you actually traveled if it thinks you are going 80 instead of 60?

Just a thought.

[hoot]

D-max man,

He said that in his post. You're gettin as bad as me.

[srubrn]

Try this. Get a ZF-6. Mine stays in overdrive until I pull it out. Not being deceitful, just love those manuals.

[fasterthanyou]

surbrn,
I would love to have a zf-6 after the problems I've had, but thought the Allison would solve all tranny woes in the world, I guess it's not a perfect world. I got the tru-speed installed today, and Yes there is a dark green and white wire in the position #50. I have lots of hands on experience with everything from fabing to maintence of off-road rigs. It is much more difficult than I first thought to install. Maybe your wire loom is different than mine, but I don't think the made 2 looms for 2001 duramax trucks, also note, it is the same as the 8.1. The computer is even hard to find and access. It is on the front driver fender and has a half-moon plastic cover. There are two rear facing wire looms that enter the cpu. Make sure you look at the cpu as the crappy picture does to decide c2 from c1. Then remove the hex screw and the stubborn plastic wire cover to expose the #'s of the wires. Mine was hard to read, but there. GOod luck, I can send pics if you really need them when I return. Alway there to help and maybe just lucky it went so well. I'll play with it, but the first test drive felt better, and tighter shifts. Maybe I just wanted it to feel that way- The real test will be tonight- see ya

[Kennedy]

The Allison reads trans output RPM, so near as I can tell, shifting will NOT be affected.

My suggestion is to adjust it so the speedo is calibrated correctly (dyno) and drive it!

[fasterthanyou]

Dam Kennedy,
You're right! I'm so bummed on the downshifting thing, and I thought I had it solved. I fiddled with that thing forever, still didn't change a thing. I was able to get the spedo exatly perfect to the GPS speed and that is nice. I think it was about 3mph off at 70 mph. Waste of money and waste of time- ONE MORE IDEA, can I use a controller like the motor homes with the Allison World tranny selector that holds any gear you select from the push pad? Does the Juice or any other hi-po device increase torque enought to hold 5th? I'm getting 8 mpg towing in a pretty loud cab. The motor is at 2900 rpms in 4th and the fan is turning the whole time. It's wearing on me guys!

[pullinpower]

fasterthanyou thats a great idea,let us know what you find out.

[CurtA]

With my truck, after it had the up date, pulling my 5th wheel doesn't shift back and forth anymore. What I have to do is take it up to speed, push the tow/haul button, set the cruise and it will not down shift, no matter how far down you push throttle. You can try it empty also.

[Alli-max]

srubrn...

Arent the easiest explainations sometimes overlooked? Funny reply... :D :D

[srubrn]

Alli-max,

It would seem so easy. I have never been a fan of auto's. When towing 10,000lbs running 70mph, my engine is running 2100rpm and the fan is not on. Very quiet in cab. Also software updates don't effect it much either. Saved $2200 too!! ;)