R Model on EquipmentFacts

[Toller]

I saw this 1966 R609 up for auction next Saturday. Probably a bit too far for me to be interested in adding it to my own pile of iron, but I was hoping someone smarter than me could answer a question about the back of the frame. I don't recall having seen a frame behind the fifth wheel like this one, and I can't figure out whether it was made this way for a particular application -- maybe to hook onto a trailer than was too low for the frame? I'm stumped, but I'm sure somebody can help me.

Otherwise, not a bad looking rig for its age.

https://www.equipmentfacts.com/listings/trucks/auctions/229286393/1966-mack-r609

[Vladislav]

Nice looking old R-model indeed. Would be a nice addition to someone's stable if the bid doesn't go sky high.

As of the chassis the story was (as I can see) the truck had shorter wheelbase in its younger times. Than somebody moved the bogie to get more of WB. You can see a set of holes from the original location of the trunnion bracket (the elephant ears) in the green circle. Also four old holes for attaching the trunnion between the "ears" are seen to the left of the circle. When the bogie was moved the guy added the rear portion using just what he found in a corner of his yard I guess. 

[Toller]

That explains it, thank you! I'm guessing the hydraulic tank and diamond plate behind the cab were later add-ons, so they need to push back the rear end to make room. Mystery solved.

[Vladislav]

If using for hobby the bogie could be moved into its original location with not much labour and the look of the truck would be even more attractive. But definitely more shaky, especially with those heavy rears. Just my thoughts or maybe my general approach 

[JoeH]

I was more so thinking that they hacked the rear frame down at an angle because they have some steep jumps to drive over, and the trailer would otherwise interfere with the rear of the frame. 

It certainly does look like the trunnion may have been slid back, there is some weird metalwork involved on the rear of that frame.

[Toller]

It sold for $5,085, so I guess somebody wasn't worried about the frame.

[66dc75]

Looks like it was converted from single axle to tandem 

[terry]

49 minutes ago, 66dc75 said:

Looks like it was converted from single axle to tandem 

Data plate says ST, six wheel, tractor.  Terry

[Brian L Blaylock]

It looks to me like the only thing that the extra frame does is provide a place for the ramps behind the fifth wheel and to mount the tail lights and mud flaps the boogie is all still bolted to the original frame 

[mechohaulic]

On 12/4/2023 at 1:00 PM, Vladislav said:

Nice looking old R-model indeed. Would be a nice addition to someone's stable if the bid doesn't go sky high.

As of the chassis the story was (as I can see) the truck had shorter wheelbase in its younger times. Than somebody moved the bogie to get more of WB. You can see a set of holes from the original location of the trunnion bracket (the elephant ears) in the green circle. Also four old holes for attaching the trunnion between the "ears" are seen to the left of the circle. When the bogie was moved the guy added the rear portion using just what he found in a corner of his yard I guess. 

excellent observation on the original bolt holes.  it had to be one rough riding tractor being such a short wheelbase twin screw. 

[mechohaulic]

6 hours ago, 66dc75 said:

Looks like it was converted from single axle to tandem 

original single axle would have had different bolt pattern on spring hanger mounts . looks as it was slid back enough for front hanger to be bolted to rear bolt holes. requiring new holes  for two rear hangers L/R side only.