doubleclutchinweasel

Hopefully, you will find a "direct in 4th" setup, which gives you double-overdrive. Makes for a very long-legged puppy. I'll be watching this one closely! You've got me interested!

Is the shift plate still in the cab?

IF that's the original transmission and IF that's the original plate, and IF the plate is correct, and IF there was an overdrive in there, the plate would lead one to believe the overdrive was in the main box and the auxiliary was direct. Of course, I would still spin the main box to be sure. That's really the only way to tell for sure. See if the output shaft turns the same as the input in 4th or 5th. Anyway, I hope you get it sorted out. It's a real pain to give up highway speed. By the way, I have a friend who, years ago, swapped out a 9-speed Unishift for a "split 5" Fuller in a B61. He thought it was a 10-speed with overdrive, but it did not have a hi and lo range...just a lo and dir splitter on a 5-speed box. Wanted more speed. I tried to tell him his 9-speed was an overdrive box, and his Fuller was either a direct or would have roughly the same overdrive as what he had. He was convinced the Unishift was a direct. He was very unhappy after he went to all the trouble to put the Fuller in, only to find out it was a direct model...just like it said on the splitter (lo & dir)! Lost at least 5 MPH. Could have saved all that hassle just by shifting it and spinning the shafts, all while it was laying on the ground! What he ended up with was essentially the same thing as his Unishift, without the overdrive. Sorry. Kinda went off on a tangent there! That's neither here nor there. Just kind of a humorous story. Anyway, good luck getting it sorted out, and let us know what you figure out.

My RT-915 had the same problem. I usually had to flip it lo-hi several times before it would work the first time. After that, it was fine for the rest of the day. I think mine ended up being a combination of an air compressor bypassing a little oil and the "slave valve" on the transmission. Of course, the old model had been discontinued, and I had to adapt the newer model to it. Looked something like this.

Seems like I have seen the "reverse the arm" thing done before. If you can work in a cable setup, like 63BMack is talking about, I think you'll be very happy with the results. My '70 R had the cable setup on the pull clutch, and it was the easiest clutch I ever drove or adjusted. Be interested to see what you come up with.

Welcome to the Dog Pound, John. I think you'll enjoy it here.

Yeah, a TRT-7220 or TRQ-7220 should hold up fine. Learn to split all the gears, and that DD would sound great going up through the cogs! Only about 300 RPM drop if you hit all of them.

I'm kind of a Quad-freak! I grew up on the 18-speed double-overdrive Quadruplex. Have driven the 13-speed Triplex version. Same, without the LO-LO gears. Love those 2 boxes. Once you learn them, there truly is a gear for all occasions. Had 2-3 different shifting sequences, depending on the load and grade. Even developed a couple of different split-shifting styles. Again, depended on how big of a hurry you were in. To me, a Mack needs 2 sticks. The 15 RoadRanger I had in my '70 was a much more user-friendly box. But, I always felt a little bad that it didn't have the Quad in it. I hope to have another one someday.

Here was that engine... http://www.tyldenheritage.com.au/uploads/9/3/0/6/9306704/endt673c.pdf

Certain models of Triplexes and Quadruplexes (and there ARE different models...check your model number) were routinely used behind the ENDT-673C, which was rated at 250HP and 701 ft-lbs of torque. I have hauled 111,000# with that setup many, many times. So...

What kind of torque is that Detroit rated at? I see info suggesting 650-666. I think the n-plex boxes were used with engines rated up to 650 ft-lbs or so. If that's the case, it should be fine. Like with a Maxi, maybe keep the revs up...which shouldn't be an issue with the DD.

Sexy as socks on a rooster...

Here is some info about the later models, with REV on the compound stick. But, I can't find anything on the OD versions (1070). So, I don't know if they ever did one with OD AND REV both in the compound case. But, it seems possible. Again, the shift map plate would probably tell if it was a lo-hole or and OD setup. Here is the plate (off eBay) for a lo-hole model.

Here is some interesting info. Apparently, there WAS a setup with OD in the rear box. If this is the trans you have, then the OD on the compound stick can only be engaged when the main is in 5th. But, I don't know if these had REV on the compound. Doesn't sound like it. I am going to dig more into the "late" production boxes, and see what they have. Learn something new every day...

I love the look of that setup. Gotta have the Mack caps on them!

Couldn't zoom in far enough. Are those wheels stud- or hub-piloted? It's looking great!

Checking the front box in/out ratio would still be helpful. This would tell for sure if the front box had an overdrive gear in it. Some of these guys know a lot more than I do, but all the 2-stick Maxitorque auxiliary boxes I (personally) ever saw had a "lo" and a "dir". Never saw one with an OD in the auxiliary. I would suspect that there is only one set of reduction gears in the auxiliary (for lo), and the "dir" is just locked shaft-to-shaft. And, of course, the reverse set would be in there. If the aux is "dir", the sliding dog clutches would just key the shafts together. If there is an OD in there, then I would suspect the "lo" would be locked shaft-to-shaft, and the "od" would engage the overdrive gears. What did it say on the shift plate? LO and DIR? Or DIR and OD?

EB is what I was thinking. Here's a pic of a Jacobs piece.

Some tire manufacturers recommend a little less air pressure when running duals. This is because, due to uneven wear or the shape of the road, one tire can wind up with more weight on it than the other. Having a little less air pressure in them allows for some natural compensation between the two tires. This is also why the weight rating on a set of duals is sometimes (always?) a little less than double that of a single. At least that is how one of the big tire manufacturer's engineers explained it to me. Even the original door stickers on the older trucks called for a little less air in the duals than in the steers. You made get varying opinions on this.

Nice pair.

"Alaska Passage" - 1959. B-models.

Then I would definitely see if I could use the "new" rear box on the "old" front box. Since reverse is in the rear box, the front box is probably fine. Of course, I would like to hear from JoJo or one of the other pros about any issues one might encounter first.

I, too, thought the auxiliary was just low and direct. I always thought the OD was in the main box. In the "old" days, a "0" on the end of the model number indicated that 5th was overdrive. I don''t know how the later stuff was numbered. But, a TRXL-107 would have been direct, and a TRXL-1070 would have been overdrive, for example. Don't pay any attention to the exact numbers, as I may have them wrong. But, the "0" was the key...at least, it was at one time in history. Was yours a two-stick 6-speed? Or did it use air on the auxiliary? If it is the 2-stick, and the reverse is on the compound stick, I wonder if the "new" auxiliary would mate to the "old" main. Just thinking out loud.

That's what she said...

I have had the interior of hydraulic brake lines come apart myself, and they tended to act like a check valve in the line. You could apply the brakes, but they would not release. This is not unique to antique stuff. Had to replace both lines on the front of the wife's '05 Chrysler 300C for the same problem. Those were easy to diagnose, as it used twin-piston calipers on the front. Could push EITHER piston in easily, but it was almost impossible to push BOTH of them in. So, that narrowed it down pretty quickly. Really does sound like a rubber line issue.