I'm considering buying a mack R model that a friend has one for sale. Its a mid 70's and he said it has a 5 speed and only runs about 55. Is there any other transmission that I can put in it to get it running about 65 without the engine being on the governor all the time?

 

You might want to look at the rearend gears. Even a tranny with a double overdrive can only accomplish so much. I'm wondering, is it a 2 stick tranny in the Mack now?

 

It's got a single stick in it now. I'm not sure if that transmission even has an overdrive in it. My friend also said that it pulls 80k with no problem so im afraid it could be geared really low.

 

I remember when those were being tried in the 70's. One of the guys who was driving one called it the "ruination of a good driver and a good truck." I would think you could swap it for something better.

 

Ive drove a two stick before and they are good trucks. Does anyone know the actual shift pattern for one of those?

 

Does it have the air shift on it? It should have more that a 5 spd. Probably 10? But the rear ratio is probably the best option for more speed.

 

It didn't get a good look at it because it was dark. All I saw was a single stick. Is it possible to have the hi/lo switch on the dash instead of on the shifter its self? I was also told that if it has a maxidyne engine i would have to stick with whats in it. Whats special about that particular engine? Sorry for all the questions, I'm not familiar with macks.

 

It's probably a 5 speed Maxitorque .
"The Maxidyne
In the early 1960s, Mack Truck's executive vice president of product and engineering, Walter May, developed the Maxidyne high-torque rise engine. The engine was first available in 1968 it is model year trucks. This was an industry-changing event. The Maxidyne allowed a heavy Class 8 truck it is to be operated with a 5 speed (Maxitorque) transmission. Previously, heavy trucks were typically equipped with 10 or more gears it is."
http://www.thetruckpeople.com/newsite/mack-trucks.htm
I have driven Macks with the Maxitorque at highway speeds . An axle ratio change might do the trick but think twice about it if you are going to be doing much off highway driving with heavy loads .

 

Gearjammer, im a 20 year old that first learned to drive truck in an old 2 stick mack! Don't want to get them both in neutral! I graduated high school with my class a's, and doubles, triples, and tanker endorsements. I can remember sitting in the old bench seat with grandpa as we hauled coal, watching for hours as he shifted both gear shifts for hours.

 

Most likely no O/D in that trans.

I drove an '85 RW613 Superliner with a Mack 8spd (don't recall model number), and it topped out at a whopping 52mph flat out on the interstate. Foot buried in the floor the whole time. LOL

Our '90 CH w/ EM6-300 had a T2050 5spd trans. 5th IS an O/D, but it is a HUGE jump from direct. Something like a .60 ratio. Takes up to 2 miles to hit 55 sometimes. LOL

The T2050 took a dump, and now we have a T2060. Basically a T2050 with a granny hole (via an air shifted splitter). Had to shorten the driveshaft.

 

learned to drive in a 5 speed maxidine go for changing rears but there may not b a large selection of different ratios good luck

 

That 5speed tranny is made for that engine. You could change the rear end gears or if it has ten twenty tires on it you could also maybe change to ten twenty two fives tires and wheels but eather way its going to cost more than you probably paid for the truck in the first place...best leave it and sit back and enjoy the scenery at 55mph....

 

Yes. It’s standard 5 speed pattern. Second stick is direct and overdrive. Shift 1-5 direct I think if I remember right no direct 5 Shift to overdrive in 4 then hit 5th. Really can’t say for sure. Last one I drove was 1985. The truck was a 1970 DM but really ran nice. 67-68 R tractors were 5 speed direct in 5 th