Not more speed. I actually have a 13 in my "old" truck and a 9LL in my "new" 2001 RD688 and I am thinking of swapping them before the International gets sold. The two trannys have the exact same ratios in the upper four gears (on the high side of the 13) and both are .73OD final drives. The beauty of the 13 is the RPMs can be kept in the fat part of the power curve, less lugging and less revving. Come to a hill, split the gear. The 13 can run in a 3-400 RPM range. I expect the Mack to have to be revved more before shifts and lugged more in the next higher gear and/or not be able to pull the next gear. Just for more versatility. Easier on the truck.
I have a 9 spd, just bought the kit to turn it into a 13. I like 13s for the same reason you stated above. My question is regarding MPG consumption, did you notice a difference after turned into 13 in mpg consumption compared to when it was a 9 spd?. I guess it would help having more range less lugging and maintaining momentum when going through hills but not sure. Just wondering
9 speed to 13?
in Driveline and Suspension
Posted
I have a 9 spd, just bought the kit to turn it into a 13. I like 13s for the same reason you stated above. My question is regarding MPG consumption, did you notice a difference after turned into 13 in mpg consumption compared to when it was a 9 spd?. I guess it would help having more range less lugging and maintaining momentum when going through hills but not sure. Just wondering