hiwy50 Posted October 27, 2015 Share Posted October 27, 2015 Is there rear end for a B67 Mack I can interchange to run 65 MPH at 1700 RPM, or does the truck have the power to do it ?? Thanks Richard Quote Link to comment https://www.bigmacktrucks.com/topic/42368-b-mack-gearing/ Share on other sites More sharing options...
The Fireman Posted October 27, 2015 Share Posted October 27, 2015 I just finished swaping the rear in my B42 this week, I went from a 7.85 (35mph) to 4.60 I've only had her out once since the swap but I pushed to 61-62 and still had a lot of room to climb before reaching the govener. I had the good fortune to find a mack rear end out of a B67 here on the forum and after a little research here we were able to determain that my axle housing would hold the hogshead from the other axle so I just swaped that and had the drive shaft shortened to fit. Your top speed will also depend on whether you have an overdrive transmission or not. I've got a 10 speed duplex with over drive when I'm in 4 hi which is direct I top out at 55 on 22" rubber. My posts from this whole swap are here in the antique section and are with in the last 2 months. Quote Link to comment https://www.bigmacktrucks.com/topic/42368-b-mack-gearing/#findComment-308983 Share on other sites More sharing options...
Freightrain Posted October 27, 2015 Share Posted October 27, 2015 It will take a 4.10 gear and a single overdrive transmission. My B will do it pulling my trailer(14K lbs) on relatively level ground. Any kind of grade and it will loose steam. Around 65 mph at 1800 rpm.The truck alone will run speed without too much effort. I have a 4spd aux and it gives me 85 mph at 2100 rpm. Only on level ground though without trailer...........um, well, as far as I figure. I've NEVER had the truck that fast...................(well about 80 once). 2 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/42368-b-mack-gearing/#findComment-308985 Share on other sites More sharing options...
Popular Post thomastractorsvc Posted October 27, 2015 Popular Post Share Posted October 27, 2015 In July I had a couple B30s up to 70 but had to slow down because I kept losing tires. 3 Quote Robert"I reject your reality and substitute my own." Link to comment https://www.bigmacktrucks.com/topic/42368-b-mack-gearing/#findComment-308993 Share on other sites More sharing options...
Hobert62 Posted October 27, 2015 Share Posted October 27, 2015 You forgot to say it was 70 in reverse. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/42368-b-mack-gearing/#findComment-308999 Share on other sites More sharing options...
Maddog13407 Posted October 28, 2015 Share Posted October 28, 2015 my 613t will do 75 on 11R24.5's a single over triplex and 4.00 rears just bobtailing but try to pull anything with it and it falls on its face with a 711. it was originally specked with a 673t, a single over triplex and 4.66 gears on 22'' rubber and in the spec sheet it said must go 65mph. like they said it all depends what you wanna do with it and what tire size and if you have an overdrive trans. you can get higher speed out of on but don't expect to pull much weight with it. I believe my B613 was specked to go 65mph with 22 inch rubber and a single overdrive but I bet the overdrive in 5th was ''go home empty gear' only Quote Link to comment https://www.bigmacktrucks.com/topic/42368-b-mack-gearing/#findComment-309018 Share on other sites More sharing options...
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