Cat3406 Posted April 11, 2017 Share Posted April 11, 2017 Hello everyone. I'm new to the forum I have been reading through and I'm amazed how much information is been shared here. You guys are great. I have been trying to buy a Mack truck for a while but I didn't have the chance until now. I came across a 2007 Mack Vision conventional sleeper truck with an AC 350 (cxn613) engine setup that really caught my attention until I found out that it has a 7 speed (no splitter, straight 7) transmission. I have never seen this set up before on a road tractor. My concern is whether this truck will be able to pull 80k down the road and especially on hills. Is this engine and 7 speed transmission a good set up? Does it have enough horsepower to pull 80k without issues? Thanks in advance. Truck's info: 2007 Mack Vision Engine: AC350 Tranny: 7 Speed Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/ Share on other sites More sharing options...
alex g Posted April 11, 2017 Share Posted April 11, 2017 In my opinion I would like more gears. I think your gonna be busy shifting that thing a lot. It must have pulled real light loads.Sent from my SM-J320W8 using Tapatalk Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367035 Share on other sites More sharing options...
TeamsterGrrrl Posted April 11, 2017 Share Posted April 11, 2017 Is this the Maxitorque 7 speed or an Eaton or Spicer 7 speed? Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367044 Share on other sites More sharing options...
Cat3406 Posted April 11, 2017 Author Share Posted April 11, 2017 Thanks, AlexG. Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367047 Share on other sites More sharing options...
Cat3406 Posted April 11, 2017 Author Share Posted April 11, 2017 52 minutes ago, TeamsterGrrrl said: Is this the Maxitorque 7 speed or an Eaton or Spicer 7 speed? It is Maxitorque 7 speed. Thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367048 Share on other sites More sharing options...
TeamsterGrrrl Posted April 11, 2017 Share Posted April 11, 2017 It's probably a Maxidyne engine then, and the transmission would be a 5 or 6 speed wide ratio Maxitorque with one or two low holes. Should work fine, the Maxidyne engine has a 1200-2100 RPM power band so it should work fine with the 7 speed Maxitorque. Might want to check the truck's history though, they switched over from Mack to Volvo engines late in 2006, but a Mack engine could have still found it's way into a 2007 built in late 2006. Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367058 Share on other sites More sharing options...
tjc transport Posted April 11, 2017 Share Posted April 11, 2017 350 7 speed is going to be a dog with 80k lbs and hills. i ran a 400 8 speed for a while and it was a lot of down shifting when hills were seen. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367062 Share on other sites More sharing options...
TeamsterGrrrl Posted April 11, 2017 Share Posted April 11, 2017 Several big fleets ran the 7 speed Eaton and Spicer transmissions at 80k pounds and more with no problems, and that was with a conventional torque rise diesel. With a Maxitorque who can have huge gear splits like the Mack 5, 6, 7, and 8 speeds have because the engines power band is so broad. Sure, you could use a 10, 13, or 18 speed behind a Maxidyne, but it won't deliver the freight any faster. The only major advantage to more gears with a maxitorque is actually fuel economy, as with tighter splits the engine can be kept in it's fuel economy "sweet spot" more of the time. But with the 300 series Maxitorque wide ration transmissions the split between top and the next gear down is only 40%, the same as on the conventional split 9 and 10 speed transmissions. For on highway use you spend most of your time in those top two gears anyway, so there's no advantage to putting a transmission with more gears behind a Maxidyne. Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367072 Share on other sites More sharing options...
Cat3406 Posted April 11, 2017 Author Share Posted April 11, 2017 3 hours ago, tjc transport said: 350 7 speed is going to be a dog with 80k lbs and hills. i ran a 400 8 speed for a while and it was a lot of down shifting when hills were seen. Thanks for the feedback, TCJ. Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367077 Share on other sites More sharing options...
Cat3406 Posted April 11, 2017 Author Share Posted April 11, 2017 40 minutes ago, TeamsterGrrrl said: Several big fleets ran the 7 speed Eaton and Spicer transmissions at 80k pounds and more with no problems, and that was with a conventional torque rise diesel. With a Maxitorque who can have huge gear splits like the Mack 5, 6, 7, and 8 speeds have because the engines power band is so broad. Sure, you could use a 10, 13, or 18 speed behind a Maxidyne, but it won't deliver the freight any faster. The only major advantage to more gears with a maxitorque is actually fuel economy, as with tighter splits the engine can be kept in it's fuel economy "sweet spot" more of the time. But with the 300 series Maxitorque wide ration transmissions the split between top and the next gear down is only 40%, the same as on the conventional split 9 and 10 speed transmissions. For on highway use you spend most of your time in those top two gears anyway, so there's no advantage to putting a transmission with more gears behind a Maxidyne. I stopped by the local Mack dealer today and I had a chance to talk the shop manager. He gave a similar explanation about those engines and transmissions wich it makes a lot of sense. I'll be running in Texas 99% of the time so big hills are not much of a concern. Another interesting point about this truck is that it does have two rear axles but only one differential. Should this be a concern? Thank you. Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367080 Share on other sites More sharing options...
TeamsterGrrrl Posted April 12, 2017 Share Posted April 12, 2017 Sounds like a single drive with an unpowered tag or pusher axle. Good for places like Texas that seldom see snow, gets better fuel economy due to less friction from a 2nd differential. If the undriven axle can be lifted under light loads, that'll improve the fuel economy even more and reduce tire wear. On the other hand, with only one driven axle this truck may have problems if it has to go off road or on snowy/icy roads. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367095 Share on other sites More sharing options...
mackey58 Posted April 14, 2017 Share Posted April 14, 2017 I drive a 90 RD690 with a 300 and 7 speed hook it to the lowboy when the lowboy truck is down move a jd200 at over 85 k it ain't fast but gets it done Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367323 Share on other sites More sharing options...
mackey58 Posted April 14, 2017 Share Posted April 14, 2017 300 em6 300 L seven speed camelback 5 :73 rears Quote Link to comment https://www.bigmacktrucks.com/topic/49498-7-speed-mack-transmission/#findComment-367324 Share on other sites More sharing options...
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