doubleclutchinweasel

It amazes me the information guys like Jojo and vmac3 have stashed away in their heads. I always learn something new when I get on here. Freakin' encyclopedias!

You know, the front of that thing still reminds me of an Econoline van on steroids.

Not sure if the later models shared any of these part numbers. Cab Breakdown.pdf

I see one around here every now and then. Never can seem to get a picture. May have to chase it down next time I see it!

You know, I don't think I ever saw one of those in person before. Says here they only made 215 W71's from 1953-1958. I'd say that makes it pretty rare.

The Watts guys might be a good place to start. https://www.wattstruckcenter.com/store/

You said a mouthful! Double-clutching a gasser takes a little more practice than a diesel. I suspect it has to do with the rate at which the revs rise and fall. Passes by the sweet spot a little quicker.

Anybody got a picture of an "exhaust turbocharger conveyor" system in-use? That's a new one on me.

Just remembered something while reading all the Detroit comments... Once operated a small tug boat. Had a 6-71 Detroit in it. Was labeled as "Gray Marine". I can't remember if Gray actually built those engines based on Detroit's design, or if they started with the Jimmy and converted it to marine use. Whatever. It was definitely a 6-71 design. The guys I worked with bought me a cap with gold braids on the bill, and for a while I acquired the nickname "Cap'n". The superintendent told me they would provide a life jacket in case i fell off the boat, but would not supply a parachute if i jumped off. Luckily, never had to do either.

My '70 had the inverted camelback springs. Fairly light spec...34K I think. It always amazes me how the guys on here can spot so many details looking at a picture! Serious knowledge housed in the members of this forum!

I think you could safely say that!

Fractured rod joints are awesome. Perfect fit and incredible stability.

Sorry. Had to step out for a while. I was thinking it was sometime in the 80s when the 17 digit numbers came out, but wasn’t sure exactly when. On my ‘70, the title had the vin listed as R611ST5525. It had no 17 digit number. Maybe vmac can confirm this, but it looks like, on the truck in this discussion, they HAD the 17 digit number, but just listed the last 4 digits on the door plate.

Looks like the right info...

By the way, I don't know if the Mack museum is back to normal yet, but they are the best source for how the truck was originally built. Here is the front page off the build sheet they sent me for my old truck.

Don't anybody shoot me if I am wrong, but I THINK there was a tag on one of the valve covers. Or, maybe on the RH side of the head? Also, I think the engine model was stamped on the gear case near the front of the fuel pump. Here is a link to a post I put up years ago. This is where mine was marked "T-673-C". Oh, and VMAC has a good point. By 1985, the 686 probably moved beyond the 283 HP Maxi. He is way more up on that "later" stuff than I am! Most of my knowledge peters out by the early '70s. LOL! And, NO...there was NOT a 17-digit VIN back then. R686ST3147 WAS the number back then. Not sure where VMAC got his number, but he is usually correct on such things. Probably a cross-reference of some sort tha the has access to???

Maybe just a little unnerving working under the cab when it's up...

That "R686ST" on the sticker (if that's the original number) tells you a lot. Like Jojo said, check on the RH frame rail and see if the number matches. I think the 686 uses a 283 HP Maxidyne engine. That information is on here somewhere (wiki?). Normally, there is a plate on the engine that lists HP and valve clearances. Maybe it's 2 plates. The "ST" means it is a Six wheel ("tandem axle") Tractor. Or, at least that is what it started life as.

I assume that one uses the oil feed tube in the end of the compressor crank like all of the ones I have seen. DON'T FORGET THE TUBE!!! It'll make you feel silly if you do!

Did you ever figure out anything on your air compressor???

Look in the driver's side door jamb for something that resembles this...

I am a design and manufacturing engineer, so I tend to look at mechanisms in a slightly different (warped?) way. The twin-countershaft design of the Eaton-Fuller is actually a super good design. The load balances very naturally between those 2 shafts. These were some of the first high-torque capacity transmissions to be developed. And, only having 1 stick was far easier to master than 2. I figure Mack HAD to come up with something to compete with the Fullers on torque capacity. And the original Maxitorque was the result. They had this new Maxi engine, and the old Mack boxes were simply not up to the task of handling the torque. Sure, they could have used Fuller boxes, but...you know! I mean, a RoadRanger behind a 237 Maxidyne was and still is a really nice setup. The Mack triple-countershaft design, if I had to speculate, was probably done just to avoid the patents on the Fullers, or to "one-up" them. If 2 are good, 3 must be better...right? Like I said, I figure Mack HAD to come up with something to compete with the Fullers. And the Maxitorque was the result. The later 13- and 18-speed Mack boxes are a natural evolution of those old original Maxi boxes. Once emission regulations effectively killed off the original "high torque rise" Maxidyne engines, those 5- and 6-speed boxes were kinda short on gears again! So, they took the triple-countershaft design, added the rear section (kinda like Fuller did), and voila! Mack versions of the Fullers! The only "real" advantage I can see for 1 over the other is that the Eaton-Fuller boxes are cheaper to maintain/repair, which, ultimately, might make them more cost-effective (profitable?) to operate. But, that's about it. Like some have said, the gear ratios in the Mack box might suit your operation better. Or, the Eaton might. Depends. I don't think I would arbitrarily remove brand A to put in brand B unless there was some compelling reason. If I had a busted box, and had the other one on-hand, maybe it makes sense. I knew one guy who swapped all his Mack boxes over to RRs just so ALL his trucks would have the same exact box in them. He did it with the clutches, too. Made sense for him. But, if I was driving a Mack box, and was happy with it...damned if I'd pull it out just for the heck of it. On the other hand, if it was causing me grief, out she'd come. Dang! I guess I'm not all that brand-loyal after all! Sorry for the length. Was having a crummy day, and this helped take my mind of of it! Weasel out...

You definitely DON'T need to use every gear every time! In fact, it is extremely rare to need all of them. Just use whatever you need to keep the RPMs where you need them and keep the truck under control. On the old Quadruplex boxes, MOST of the time I only used 7 gears. Sometimes 8. The most I ever used in sequence was 13...or 14 if pulling out of a deep hole. Using too many gears on those 2-stickboxes was a sure way to miss a gear, let your road speed drop, and have to start hunting for a gear that would work! Drove lots of 13-speed RoadRangers, using them like an 8- or 9-speed, and only using the splitter in high gear as an overdrive.

What he said... "M" means Maxi-dog!