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B61 Conversion from Tandem to Single Axle

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Ok folks - newbie first post.

I am looking for a B61 to have a bit of fun with and to pull our vintage JD tractors to the local pulls. I have been looking at a number of trucks and think I may have found one that would suit my needs but....its a twin screw. I would rather have a single axel and have googled the conversions of a twin to single but nothing related to the B61.

I would like to ask the experts here the complexity of this type of mod. I would think most if not all (maybe a new driveshaft) of the pieces and parts are already there and my simplistic brain is telling me remove both axles and take the back and move it to the front - done! But I know there is brake and suspension considerations as well.

Can you let me know your thoughts on this if it is feasible and what I am missing.

Any and all comments, recommendations and concerns are very very appreciated.

Thank you all in advance!


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Welcome, Jim. I spent last winter doing a tandem to single axle conversion of my B61. The job itself is pretty straight forward . Assuming that the tandem you are talking about is a camelback suspension with top load rears, You probably won't be able to reuse them as a single axle. You will need  to find a single axle rear, springs and spring hangers. Then you just basically drill for the hangers, mount the rear, make a new driveshaft, and re plumb the brakes. There are some options to consider, like what gear ratio would suit you best, or do you want to install a modern rear and air ride. Also keep in mind that your DOT may complicate matters if you try to reduce the truck's GVW. You don't have to change the GVW, and maybe it doesn't matter if you tag the truck as an antique. Just another consideration. There are plenty of single axle trucks around.

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Easiest way is pull all the Mack stuff out and find a single axle air ride and slip it in and bolt it up.  Might take some spacers to get to fit the narrower frame of the B.

Pretty sure you can't do much with a camelback and making it a single axle.  Air ride will ride nicer too.

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1959 B61 Liv'n Large......................

Charter member of the "MACK PACK"


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another thing to consider is most all camelback tandems are double frame and the frame is doubled on the inside. this may not be an issue but youd have to use the 1/2 narrower crossmembers from the tandem unless of course your going to air ride. myself I would keep it a tandem cause there are a ton more single axles out there than B61 tandems. tandem axle b61's are kinda scarce. would be unethical to shorten one up in my eyes unless the frame had issues


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image.jpg.326cad073eb9da8ebc019664febad9e5.jpgimage.jpg.dd730fe02e7ac0f4401b953a0a924037.jpgI do the same thing.  Mine started out as a b-67 short wheelbase single axle.  I cut everything off the back and left about 4' of bare frame.  Then slid a set of freightliner frame rails with a single axle air ride setup right over it.   I drilled and bolted through 3cross members,   fuel tank brackets, and a toolbox mount.    The truck drives and rides very nice.   It handles the weight much better then my pickup, but in all reality my gass job pickup will out pull it on a hill load for load hands down.  Our one show is basically all flat but everywhere else I go is hills and it does slow down and I get a lot of shifting practice.  Mine still has the original non turbo 673 a 237 upgrade with the extra hp and torque would be a big plus!   

The end result is, if possible for me (i have 2 kids) the mack goes over the pickup  just for the "cool factor".   Lots of heads turning, thumbs up, & cell phone pictures as we drive by.  Way cooler then my 2004 chevy! 

There is a post on here of what I did.  I think it's called "finally time to assemble".   Or some thing close to that.      Good luck

Edited by Hobert62
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