Driving Old Mack

Moonlite37 · Dec 30, 2015

A friend I sometimes help during harvest has an old Mack B61 with a 600 bushel grain bed. He only hauls about two miles from field to bin. and about half the distance is on paved road with little traffic. I have never driven this truck but have driven 5 speed with a 2 speed and I have driven his GMC with a five speed with a 4 speed auxiliary. On the Five with a four speed aux I drove using only the five speed and the aux in third while loaded and the aux in four when empty. Could I also do something like this with the Mack and just use one lever, like low when loaded and high when empty?

John T · Dec 30, 2015

Best I recall maybe 40 years ago SO NO WARRANTY. If its a Mack DUPLEX twin stick 10 speed tranny, if you need all gears and are heavy loaded and cant skip a shift,,,,,,,,,,, First gear Low then shift Low/High to high,,,,,,,,Second gear low then second gear high,,,,,,,,,,,,third gear low then third gear high etc etc etc. If not so heavy loaded or no hills ect you could get by with just the 5 gears leaving low/high in high.

Later Macks just used a 5 or 6 speed single stick tranny since the Mack engine could be lugged down before you need to shift UNLIKE A DETROIT that needed a 10 or 13 speed Fuller Road Ranger etc as you cant lug it or it overheats

THATS BEST OF MY RECOLLECTION IT MAY OR MAY NOT BE RIGHT............

John T

L.Fure · Dec 30, 2015

(quoted from post at 14:48:34 12/30/15) A friend I sometimes help during harvest has an old Mack B61 with a 600 bushel grain bed. He only hauls about two miles from field to bin. and about half the distance is on paved road with little traffic. I have never driven this truck but have driven 5 speed with a 2 speed and I have driven his GMC with a five speed with a 4 speed auxiliary. On the Five with a four speed aux I drove using only the five speed and the aux in third while loaded and the aux in four when empty. Could I also do something like this with the Mack and just use one lever, like low when loaded and high when empty?

I think there is several ways to drive a twin stick. The way I remember it when starting out with a load you put both sticks in low. Once you got underway you shift the first stick to second. Then you shifted the second stick through all the gears. Then shift the first stick to third and down shift the second stick to low and shift through the gears with second stick again. Remember, when shifting the first stick to a higher gear you let the rpms drop, then when you bring the second stick back to low you are actually down shift it and need to bump the rpms up before you can get it in gear. I doubt that you will get the truck all the way up to road gear with the short distances you need to go. You'll just have to gauge your speed with how far up in gears you need to go.

JOCCO · Dec 30, 2015

One caveat first identify it!!! Is it a 9/10 speed or 15 or 18 quad There are some gears in the 18 you cannot use (it is basically a 5+4 it has 20 gears 18 are somewhat usable. We always said with the GMC type you mentioned you can atleaset get it in something the mack may be a little more difficult!!! All were kind of unique but glad there in the past today 8ll is all the rage!!!

VicS · Dec 30, 2015

The Mack I drove had 2 sticks. One with high low and reverse. The other was a five speed. They called it a 6 speed. The lowest gear was low and 1st. Then was high and 1st. The neat thing was could run winch forward or reverse and had 5 speeds. On the road just used high and the 5 speed.

Kent Petersen · Dec 31, 2015

You want some real fun try a Mack quad plex 24 with 2 sticks

Driving Old Mack

Moonlite37

Well-known Member

John T

Well-known Member

L.Fure

Well-known Member

JOCCO

Well-known Member

VicS

Well-known Member

Kent Petersen

Well-known Member

Similar threads