doubleclutchinweasel

I have posted a couple of different Quad shifting patterns on here before. That box can intimidate some people, but it really is not that complicated. Whether using the clutch or not, getting the RPM right between shifts is key. Once you learn how big the drops are between gears, you can hear it easier than you can watch the tach. DON'T RUSH IT! DON'T FORCE IT! WAIT FOR IT! I don't want to sound insulting, so please don't take this next part that way. But, remember to let the RPM FALL when upshifting and RISE when downshifting. I was trying to teach a guy about double-clutching and "floating" gears, and he kept trying to RAISE the RPM between upshifts. I don't remember if you had the 18 or 20 speed. But, in either case, there's not much need to shift the compound until you have the main in 4th gear. At least if empty of lightly loaded. Oh, and the LO-LO isn't really much use on the road. Use LO-SPLIT to start off. Shifting the main with the compound in LO-LO can be a little tricky, since the road speed is kinda low. Try this (for the 18-speed version). LO-SPLIT 1st LO-SPLIT 2nd LO-SPLIT 3rd LO-SPLIT 4th DIRECT 4th HI-SPLIT 4th HI-SPLIT 5th If it is the 20-speed version, try using LO-SPLIT all the way into 5th, then DIRECT and HI-SPLIT 5th. Oh, and another mistake I have seen a lot of folks make is letting the RPM drop TOO much during upshifts. If you try to engage the next gear too soon, it will grind. But, in that case, the grinding will get slower and slower until the gear drops in. If you wait TOO long to try to engage the next gear, it will grind...but the grinding will get worse (faster) the longer you wait. In that case, release the clutch and bump the RPM back up a tick and try again. You'll get it. It just takes a little practice. And, once you master the Quad, you'll be able to claim something that not a lot of us can!

Old belts can definitely cause "flutter". So can off-center, bent or unevenly-worn pulleys (sheaves).

Looks like the 15-speed "Direct in 5th" Triplex. Love your truck, man.

"V", correct me if I am wrong, but aren't the primary and secondary needles connected to 2 different tanks? If so, that might make it easier to isolate the system with the leak.

I completely understand! Maybe nobody else would have known it was there, but it would have driven me crazy too!

I think they are super cool. Used to be a guy on here with one. Like the man said, "PICTURES"! We like pictures.

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!