R688st frame cut

[Voltronics]

Hey y’all,

 

just bought a 1985 r688st and wondering why someone would cut the rear of the frame. And wondering what can I do to get the slope back so I can get mud flaps and a pintle hitch.

 

thanks 

[Joey Mack]

Was it a dump truck at one time?

[Geoff Weeks]

My guess is the owner had a short-neck drop-deck that was made for a single screw and the frame hit when towed by a tandem drive tractor.

[mechohaulic]

technically that is an easier repair. depends on your future use and access to parts and supplies, good with a welder ??  since it's not in a very critical location such as midframe/ behind cab etc; number of ways. purchase channel steel same size as rails or a scrap yard near by have HD truck parts / ; find a rear section frame set up and splice it into yours. will have two rails/ one or two crossmembers -easy breezy place for lights/flaps  too late to ask why it was done , just forge onward and make it classy.not good with a welder ; what better job to learn on. remember to use old mud flaps to cover the air bags ; welder sparks can ruin an air bag !!(so I.ve been told )

[Geoff Weeks]

The use to pull with a pintle hitch makes it a little more critical, it has to be strong enough for the loaded trailer.

[Mark T]

8 hours ago, mechohaulic said:

technically that is an easier repair. depends on your future use and access to parts and supplies, good with a welder ??  since it's not in a very critical location such as midframe/ behind cab etc; number of ways. purchase channel steel same size as rails or a scrap yard near by have HD truck parts / ; find a rear section frame set up and splice it into yours. will have two rails/ one or two crossmembers -easy breezy place for lights/flaps  too late to ask why it was done , just forge onward and make it classy.not good with a welder ; what better job to learn on. remember to use old mud flaps to cover the air bags ; welder sparks can ruin an air bag !!(so I.ve been told )

IDK Mech, get'n a pintle hook on that one is gonna be a challenge.   🤔now about those sparks and air bags.....

[mechohaulic]

5 hours ago, Geoff Weeks said:

The use to pull with a pintle hitch makes it a little more critical, it has to be strong enough for the loaded trailer.

I totally agree with you;  rear chassis welding is very important , my statement referred to it not being as sophisticated as a mid chassis weld.  welding a piece of channel for a taillight is important . once again BMT is being given bare minimum of details on a question involving many particulars. not knowing experience/shop set up/ availability of parts. etc. reason for reply to a straight square cut=off might be an option. plate the section properly COULD be same as frame it self.

[Voltronics]

16 hours ago, Joey Mack said:

Was it a dump truck at one time?

That’s I can not tell you, I don’t know the full history on it.

[Voltronics]

10 hours ago, mechohaulic said:

technically that is an easier repair. depends on your future use and access to parts and supplies, good with a welder ??  since it's not in a very critical location such as midframe/ behind cab etc; number of ways. purchase channel steel same size as rails or a scrap yard near by have HD truck parts / ; find a rear section frame set up and splice it into yours. will have two rails/ one or two crossmembers -easy breezy place for lights/flaps  too late to ask why it was done , just forge onward and make it classy.not good with a welder ; what better job to learn on. remember to use old mud flaps to cover the air bags ; welder sparks can ruin an air bag !!(so I.ve been told )

Sorry very new to semi trucks as thid is my first one and using to haul grain and we have pintle hitch trailers for moving tractors and would like to put a pintle on the semi to haul them around. I have very little experience with this and may take it to a welder and see what he can do. Thanks for the reply was just asking why someone would cut this and possibly cost of repair for a welder to basically make the “ramp” you see on every semi snd put a heavy plate on back with a pintle hitch holes or hook up

[mechohaulic]

2 hours ago, Mark T said:

IDK Mech, get'n a pintle hook on that one is gonna be a challenge.   🤔now about those sparks and air bags.....

all depends on the situation and experience OR $$$$ behind the project. not knowing complete details or history of the truck . ponder the seller did a half/ ass job cutting the rear off to keep a pintle hook  frame set up ??? with ALL PROPER safety equipment used .good cut-off saw to straighten the taper on frame rails , mate a matching rear section ;; weld in and plate . will be done strong enough to hold a pintle. using a truck cut off section with crossmembers will be square/ straight/ strong >with help of a miracle , locate a rear double frame section and stagger the rails allowing the inner rail to over lap existing truck frame inside. bolts /weld better than new. too many possibilities not knowing the project.

[mechohaulic]

4 minutes ago, Voltronics said:

Sorry very new to semi trucks as thid is my first one and using to haul grain and we have pintle hitch trailers for moving tractors and would like to put a pintle on the semi to haul them around. I have very little experience with this and may take it to a welder and see what he can do. Thanks for the reply was just asking why someone would cut this and possibly cost of repair for a welder to basically make the “ramp” you see on every semi snd put a heavy plate on back with a pintle hitch holes or hook up

NO reason for "sorry" ; without asking knowledge is never learned. in time the statement "have very little experience "will be old news!!! speaking for the BMT crew ; up dates are always appreciated. to be 40 or so yrs younger and bit closer this would be a fun/ challenging easy project to tackle.