Ok guys here is the deal. After reading some posts on 0-60 times I though I would go out and see how much the new 315/70r17 slowed me down. My truck with juice/attitude has never ran faster than 6.5sec in 2wd.


First couple of attempts produced 8+secs with t/h, level 5, 1800rpm launch, no defuel 4-5. I was like damn, the tire size jump from 285's could not have made that big of difference. right? so i tried no defuel all lock shifts. ran 7.9 secs, but the shift between 1st and 2nd sent my copilot (dog in the passenger seat) kissing the dash. The tires will spin in 1st, 2nd and 3rd, but not between shifts. so I checked the attitude records and it showed a 79% backdown. Am I missing something or isn't the transmission settings suppose to limit, adjust... this. The tranny is stock with 65,000 miles and i have never limped it in 20,000 mile with the juice or sent a code. As some of you have posted some truck are just faster than others, but i have lost just under 2 secs


Any ideas?


Thanks TomEdited by: Gray Gmax

I had also never zinged or limped the Allison, and never set a code, but when I opened it up and looked at the clutches, the C3 steels were burnt. I would bet that with as many miles as you have with the juice, that it has been wearing down on the Allison clutches. With the extra leverage of a 35" tire, it will slip even more, and the stock ECM will defuel. Regardless of how you set the attitude, the stock ECM can still defuel on its own.

By putting on larger tires, you increased the leverage the tires have against the trans, possibly creating more slip esp during WOT shifts. The trans might have been fine with the HP/smaller tire combo, but now the increased leverage is pushing it perhaps past it's limits based on it's current amount of wear, etc. I seem to recall this being the reason GM was so dead-set against the larger tires.


I'm not supporting GM here, I think they were silly to assume that bigger tires would not go on these trucks, but the trans calibrations don't seem to support bigger donuts.........

You can tell the Attitude not to defuel between shifts. And it won't as long as there is no slip detected, however if there is slippage detected, the truck will still defuel between shifts to try and save the Allison. IMHO


At least mine did. After the ATS trans upgrade.... there is no defuel between shifts.

Thanks guys!


I thought as much. Just wanted to hear i didn't have to throw a code when slipping that much.


I could swear I noticed it with the reg juice. Just seemed to me that level 3 pulled harder than level 4.


Guess i have to upgrade the tranny to keep the dog slobber off the front windshield...shouldnt' be too hard to convince the wife either. (really hard to see though all those nose prints.)http://www.dieselplace.com/forum/smileys/Big Smile.gif

Guess i have to upgrade the tranny to keep the dog slobber off the front windshield...shouldnt' be too hard to convince the wife either. (really hard to see though all those nose prints.)http://www.dieselplace.com/forum/smileys/Big Smile.gif


ROTFLMAO http://www.dieselplace.com/forum/smileys/Cool.gif


I think that's as good a reason as any to upgrade the Trans.

How do you check Attitude records?

After I installed the attitude, I also noticed that the truck was much slower than before with just the hot oj. It couldn't have been the tranny slipping, because I had tranny and converter upgrades done by Mike Lovrich, so this was a mystery.


In studying the manual (!!), I noticed that the Attitude defuels up to 100% when it sees EGT's over the preset limit. In addition, you can overide the defueling by either (1) setting the setpoint higher than the factory 1350, or (2) press the "enter" button twice quickly and the defuel overide timed screen comes up. Set how many minutes you want and press enter once more. In addition, when you do that the Attitude defaults to the #5 setting. Great for racing on short notice.


My 0-60 times dropped from 6.5sec to 6.2 seconds by using the overide. The highest egt I momentarily have seen was 1470F.


Try it, you'll like it. Great for smoking (literally) kids in their blat-blat beener cars.

HEy, don't make fun of the little import cars. I'm kinda fond of them my self. I like my truck more but still. some of those little ricer rockets out there will bite ya in the but as they go by. so don't get to big headed. I'm gonna build me another little honda this winter that will beat up on any stock trannied Dmax. I make sure my tranny is on roids before I build the honda though. I can't have my honda faster then my truck. just wouldn't be right.