Can a DM-690S dbl frame chassis be used to rebuild an R-model w/a damaged fame?

[coastaldm611]

Can a DM 690S double chassis be used to rebuild an R-model truck w/a double frame chassis seriously compromised by rust?

[mowerman]

I am just guessing, but I would imagine they’re both the same frames. You might have to add on a piece or two. Good luck…. Bob

[67RModel]

Dont think so Bob. The DM frame has a much deeper web section of the channel and changes dimension significantly just ahead of the front drive axle. I'm not sure if the DM frames are splayed like the R model's are. So in short the frames themselves are very different. Could you make an R model cab, hood, and other components integrate onto a DM frame? Maybe. I think you will run into too many fitment issues. Practically my answer to the OP is "no". 

[doubleclutchinweasel]

An F chassis, yes.  A U chassis, probably.  A DM chassis, probably not without a great deal of work.  Would be a beast of an R if you did!

I think the R, U, and F all start with the same bare RAILS.  Of course, those common rails then get a variety of crossmembers and mounts attached to them, resulting in a considerably different assembly.

Of course, with enough work, pretty much anything can be mounted on anything else.  Like '67 said, it's probably not practical.  Definitely not a "bolt-on" project.

[67RModel]

Rather than do all that nonsense you could get brand new rails made. P.G. Adams in Maine or another outfit in Cleveland, Ohio I cant think of the name right now. Take your old rails there and get brand new ones with identical dimensions and hole locations. 

[67RModel]

Vicon Fabricating in Mentor, Ohio....a suburb of Cleveland.

[JoeH]

PG Adams can't do Mack frames, they can't do the splay around engine trans.

DM and R frames are different.

[doubleclutchinweasel]

I suspect the splayed shape of the rails would give most people fits.

[doubleclutchinweasel]

4 hours ago, 67RModel said:

Vicon Fabricating in Mentor, Ohio....a suburb of Cleveland.

I have a friend in Mentor.  Runs a tool and die shop.  He makes all of my custom cutting tools and bars.  Takes my mental nightmares and turns them into reality.

[67RModel]

1 hour ago, JoeH said:

PG Adams can't do Mack frames, they can't do the splay around engine trans.

Yes they can. They choose not to advertise it because it takes too long and ties up too much manufacturing space for other jobs I guess. They actually have a thread on the forum here of them doing it. Its several years old now.....

[67RModel]

 

 

[terry]

As far as putting a R Model cab on a DM frame, i bet it could be done, just move the cab back and fabricate front hood and radiator mounts. And on the earlier ones the hood was mounted to the radiator.  Lots of work though, i almost tried this some years ago on a perfect DM frame, but ended up buying a fully groomed cab from Manders in Lakeville minn.    terry

[MACKS]

We used to call the DM frames fish belly rails..

[JoeH]

6 hours ago, 67RModel said:

 

 

I stand corrected; I guess I should correct it to the won't?

[mowerman]

I was sure you fellas would have budded in I had a 83 cruise liner and the frame didn’t look any different than my U model … that’s what were here for … bob

[67RModel]

10 hours ago, JoeH said:

I stand corrected; I guess I should correct it to the won't?

I think if you give them enough $$ and enough time time they will do it. I think they have to have your old ones to work from though. They cant just make a set without a pattern.

[mowerman]

Seems like either way this guy has got a lot of work to do changing the rails. Seems like a big pain in the ass a lot easier just to find another frame that fits.Bob

[mechohaulic]

agree 100% ; alot of work tooo many differences.  depending on your maintenance  set up == time down ;; most important $$$$. look into making a RD  unit. R with double frame  must have been an RD from start???? is the DM that bad to use as donor ? rails are a challenge to change , .RD might have rails similar to DM , R  models will be different