Driving the Mack I Grew Up In (Insight Appreciated)

[Treemover6]

My family has had a tree moving business for 40+ years now and one of the trucks we use is a 1984 (I believe) Mack Series R with an 80" Vermeer tree spade on it. Any insight into this truck would be appreciated as it appears Mack made every combination of truck they could lol. It's got a 5 speed with a standard/lo/reverse stick and I believe it's a straight 6 motor. (Will add more pictures when I can). One thing that is interesting about it is I've heard from many people that your not supposed to split gears with the right stick, but my family has been doing it for 40+ years on the original transmission so it must be pretty tough. Thank you.

[67RModel]

The antique B model twin stick transmissions were true 10, 14, 15, 18, and 20 speed transmissions meant to be split shifted because the engines of the time had a very narrow power band, had very little torque rise and were not designed to be lugged below 1500 rpm. A Mack of this vintage with an EM6 285 is a Maxidyne engine has a very wide operating rpm range like 1100 - 2100 rpm so only 5 gears are needed. The guidance is correct that your transmission isn't meant to be split. This is mainly because the sequential splits are not progressive shifts. There are probably combinations of the two boxes that will work in certain scenarios but they are not all numerically lower progressive shifts from 1 Lo. Technically that transmission is supposed to be used with the main box in 1st when the auxiliary is in Lo. Then once you get moving shit the auxiliary to direct. then the main to 2, 3, 4, and 5. Reverse has 5 speeds that can be shifted while moving. I doubt you would cause harm to it using the auxiliary Lo in gears other than 1st so long as your not grinding or jamming them in. 

[mowerman]

Explanation was excellent. Great job truck looks excellent. Good for you. Have a ball with it. Yes I used to run at Maxine and you can shift all five gears and reverse. I have done it. Thanks for the post.… bob