M54A1 Posted September 7, 2007 Share Posted September 7, 2007 Is it possible to convert a single axle B model to tandem axle if you have a good cut off set of tandems, and how would you go about doing it? Thanks. Quote Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/ Share on other sites More sharing options...
theakerstwo Posted September 7, 2007 Share Posted September 7, 2007 Is it possible to convert a single axle B model to tandem axle if you have a good cut off set of tandems, and how would you go about doing it? Thanks.Yes you can do that first strech your frame the wheel base you want and if useing a mack set up then slide your tandem in the frame and bolt it down. glenn Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-13813 Share on other sites More sharing options...
ThaddeusW Posted September 7, 2007 Share Posted September 7, 2007 One piece of advice don't weld a section between the existing frame rails and the cut off frame rails, even if the rail sizes match. Depending on the frame material welding it will make it soft and prone to failure. Better get smaller length of "C" channel and butt the two frame sections together and then bolt the smaller inner C rail across the two to make a strong joint. If you can weld cut both frames at an angle so the weld goes at a 45 degree angle instead of up and down. this gives a stronger weld as there is a longer weld and will help prevent stress cracking. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-13815 Share on other sites More sharing options...
Maxville Truck Posted September 7, 2007 Share Posted September 7, 2007 I disagree about not welding....... I stretch frames all the time in my shop and we weld everything.... We grind all the frame sections to a 45 then weld both sides, then we install a piece of channel usually at least 3 feet long centered on the welded section then weld and bolt that piece in. The trucks we send out are hauling usualy way over loaded, no failures yet..... we make sure everythng is extra heavy!!! (but im not a frame expert!!) Quote Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-13816 Share on other sites More sharing options...
M54A1 Posted September 22, 2007 Author Share Posted September 22, 2007 Well I just bought a single axle B-model, and would still like to have a tandem set up, my frame is 10' 2'' long measured from the back of the cab, is this long enough to slide in a camelback tandem and bolt down, with out doing any frame cutting or welding. Quote Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-14098 Share on other sites More sharing options...
b61mack Posted September 23, 2007 Share Posted September 23, 2007 Well I just bought a single axle B-model, and would still like to have a tandem set up, my frame is 10' 2'' long measured from the back of the cab, is this long enough to slide in a camelback tandem and bolt down, with out doing any frame cutting or welding.I have slid the tandems to the rear of the frame bolted it and welded a frame behind the tandems where there is no stress on it. Ron Quote Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-14112 Share on other sites More sharing options...
HK Trucking Posted September 23, 2007 Share Posted September 23, 2007 I have slid the tandems to the rear of the frame bolted it and welded a frame behind the tandems where there is no stress on it. RonThat would be my suggestion too.He should choose a wheelbase dimension short enough to allow all of the bolts in the trunnion stand to be located in the original frame, then add frame rails rearward from there to the desired length. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-14115 Share on other sites More sharing options...
theakerstwo Posted September 23, 2007 Share Posted September 23, 2007 That would be my suggestion too.He should choose a wheelbase dimension short enough to allow all of the bolts in the trunnion stand to be located in the original frame, then add frame rails rearward from there to the desired length.That is the best way then you have no stress on the splice.There is no stress behind the trunnion stand on a mack except the weight of the tail lights.I have did this before and end up using mild stell to roll the frame reils and works good. glenn Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-14116 Share on other sites More sharing options...
HK Trucking Posted September 23, 2007 Share Posted September 23, 2007 That is the best way then you have no stress on the splice.There is no stress behind the trunnion stand on a mack except the weight of the tail lights.I have did this before and end up using mild stell to roll the frame reils and works good. glennExactly.Unless he's going to put a dump body on it, in that case I would recommend a reinforcement either inside or outside of the splice, extending at least a foot in each direction from the splice, bolted and welded, just as Maxville said earlier.About 15 years ago I changed over an R685T from single axle to a 34K Mack tandem rear suspension, and mounted a dump body on it.The trunnion was in the original frame, then I added to the rear of the frame and reinforced it inside and out.The truck's owner proceeded to beat the livin' sh*t out of that poor truck for the next 11 years before selling it to some guy up north.He went thru 2 engines, 2 transmissions, several clutches, and several rear ends during those 11 years.The frame held together just fine. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-14118 Share on other sites More sharing options...
terry Posted September 23, 2007 Share Posted September 23, 2007 The way i have always done it is to have the splice right in the middle of trunnion bolts, then there is no joint on either side of the trunnion, no flexing on the welds that way. Terry Quote Link to comment https://www.bigmacktrucks.com/topic/2834-single-to-tandem/#findComment-14121 Share on other sites More sharing options...
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