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Mack 2004 cv713 falling rpm when shifting

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I just bought a 2004 Mack cv713 Granite, tandem axel dump truck, 370 hp with the mack 10 speed trans. 22.5 x 4.25 front and 24.5 rears. My issue is when loaded, when I shift I loose to many rpms and it takes me out of the power curve, it will pull out gradually but I know it's not good to lug the motor. The trans won't let me shift any faster like my eaton 8LL. I have to let rpms drop, I find myself sometimes in the 1200 rpms in the next up gear if pulling a slight grade. I can't stay in the power curve. As with my other trucks, 1450- 1500 rpms is where my power is. Suggestions?  I'm thinking transmission change? I'm not sure of the gear ratio in the rear but at 70 mph I'm at just over 1800 rpm, a friend has an 06 same setup and tells me he's 80-85 mph truck witch I don't doubt. I feel this could easily fixed with the wright combinations. Suggestions? Thanks, Lou     

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Sounds like you have a Maxidyne high torque rise engine with the proper wide ratio transmission, and yes, it's supposed to work that way. If your right arm is bored and you like your engines screaming, at great expense you can swap in a transmission with more ratios. Bit it won't go any faster. Just drive it like Mack and god intended, if the revs are at 2100 and you're going up hill and the truck isn't gaining speed, hold on to that gear until the road flattens out. Same with down shifts- Hold on to the gear unless the revs are dropping to 1200 and you're losing speed.

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It's not you, Lou, it's the Truck. It's very fixable. 370 is a perfect candidate.

I'm a little suspicious of your friend blowing your doors off with his 2006 CV713 w/same set up? Does he go by the handle Old Red Mack, Nelm, Mackncheese, Big John, Dcrow,  03 Big Red, Mackvette, Mudman, Byrohoe or R.E.D.? If yes, then he's keeping secrets so he can laugh at you when he flies past you coming out of the pit. 

 

 

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