doubleclutchinweasel

A good place to start MIGHT be to see if there is a number on the RH end of the axle beam (FA534, FA535, FA536, etc.). This should tell what series the axle is. From there, there are lots of places to look up the ends. Mack has done some strange things through the years on tie rods and ends. But, knowing what axle you have to start with might be a good place to start, at least.

I can't help but remember this one whenever I hear about a bandsaw incident. Sorry, no pictures. Well, maybe NOT that sorry. Anyway, we had an operator running an automated vertical bandsaw, slotting tapered mounting bushings. These bushings sat on a locating fixture, and the operator presses the Cycle Start button. The saw table would rapid advance to the point where the OD of the bushing would almost touch the saw blade. Then, it would feed slowly through the wall of the bushing. The saw would then rapid across the bore of the bushing, and approach the other side. This wall would then be cut partially through. The table would then retract and the operator could swap out the part for a new one. Repeat ad nauseum. On one cycle, as the blade emerged from the first wall, he stuck his finger in the bore of the bushing and tried to remove it...before it was finished. With the finger securely in the hole in the bushing, the saw rapid advanced to the other side. The blade split his index finger from the tip to the first joint. We called the ambulance. They came and got him. It was several days before he came back. Once back, our safety committee asked him to explain exactly what happened, so they could try to improve the situation. He did a fantastic job of explaining exactly what he did, even pointing out what he did wrong. Problem is, when he demonstrated what he did wrong, he took it a little too far. Using the index finger on the OTHER hand...yep, you guessed it...he actually DID IT AGAIN! We called the ambulance...again. When he returned this time, we kept him far away from things that cut. To this day, that guy has 2 perfectly matched, longitudinally-split forefingers. I'm sure the joints are not perfect either. LTK, glad you are on the way back. And kudos for having the guts to tell what really happened. Best of luck in the recovery.

I think it sucks. And the only way I can think of to fix its suckiness is to park it in my driveway. Then it would be cool.

Waiting...waiting...waiting...!

The '67 I used to drive had a through-the-floor clutch pedal like a B, and a mechanical linkage. The '70 I had used a hanging pedal and a cable. Lots of variations out there.

Those First Gear Diecast trucks are pretty cool. I have several of them.

Here are a couple of pictures from 2 different pages in a service manual. I think one is for air operated and one is for electric. See if any of the notes help with anything. I think B1 and B2 are from the same page, and B3 and B4 are from the other page.

Here is some other discussion from another forum. https://www.smokstak.com/forum/threads/1957-mack-b61-tt-in-tennessee.164568/page-3

Sounds like there have been issues with these before. One post at the bottom of this thread (below) had some interesting comments about the clutch linkage.

There have been several things posted on here with dimensions on them. B-Model_Cabs.pdf

Let me look tonight. There might be some Unishift info in a service manual I have at home.

Sitting here watching “Towing” (1978). Mack C model tow truck. Don’t know if anybody listed this one yet.

It's like I said before. Once you go through that engine, it will be as good as the rest of that ride. I'm glad it wasn't worse. I look forward to seeing it back together.

Different people have different things which are important to them. Me, I don't like to do body work. So, I would pay extra for good sheet metal. Some of these (like Matt) are absolute artists with sheet metal. So, sheet metal work doesn't bother them. If you feel good after buying it, then you got a good deal.

Glad to hear you found the switch and got it sorted out. Plus, you were able to keep it original. Thanks for posting the follow-up. Follow-ups are very helpful for the next guy with a similar issue.

Sounds backward. Red line (IIRC) should pressurize when trailer air system is charged. Blue line should be "service" brakes, pressurized when service brakes are applied (foot valve or hand valve). I'm sure the brain trust will chime in here before long.

Did I ever mention that these guys are amazing?!

The 1750 engine (I think) were referred to as "limited" or "governed" engines. But, yes, the PERCENTAGE drop or rise would be the same. So, if you can go to 2100, then you would drop to about 1200 instead of 1000. And, you could downshift at 1200, double-clutching up to 2100 to catch the next lower gear. Sounds a lot like your "1200-2100 operating range", doesn't it?!

Actually, it looks like the ratios in that box ARE pretty widely spaced, requiring lots of "drop" while upshifting and lots of "rise" while downshifting. The MPH on this chart will vary with rear gears and tire sizes. But, the top and bottom of the RPM changes should be constant. Looks like shifting around 1750 will drop you to about 1000 on most shifts (43% RPM drop). Conversely, you would have to pull down to about 1000 before downshifting, double-clutching up to about 1750 to match the gears and let them slide in (75% RPM rise).

Welcome aboard. Shifting a non-synchro box (up or down) is a matter of matching the speed of the engine/input shaft to the rest of the transmission. "Double-Clutching" takes just a little practice to master. You have to listen to and feel of the beast to know what it wants. As far as smooth engagement of the gears, there is no magic RPM. If it matches, it goes in. If it doesn't match, it grinds. That simple. Now, some engines do have a preferred RPM range to work within. So, for any combination, there will be a sweet spot where the power delivery is optimized. But, work out you shifting to get it smooth first. You may be correct on those downshifts. That may be the speed you have to be at before you have enough RPM available to make the downshift smoothly. Or, it may need a different RPM before going into the lower gear. Each box (and each shift, for that matter) has a specific RPM percentage change. For instance, your comment about coming out at 1800 and going in at 1200 represents a 33% drop in RPM for that shift. I don't know the ratios for that box, but that may be a little too much RPM drop. If, for instance, the drop is really 25%, then it might go in better at 1350 instead. Your 2000-1600 is a 20% drop, so that might be the percentage you need right there. And, remember that downshifting is the inverse of the upshift. That is, if the RPM after an upshift is 3/4 of what it was before the shift, then downshifting that same gear change will give RPM that is 4/3 of what it was before the downshift. It just takes a little time to get used to it. And, each transmission will have its own drops. Obviously, a 5-speed will have far greater drops between gears than an 18-speed. Pretty soon, you will learn how to unload the drivetrain with careful throttle work, and you will be shifting without even using the clutch..."floating" the gears. When floating, the correctness or incorrectness of the RPM matching is even more evident! Just be patient and give yourself time to learn it.

Way back when, Mack sold a conversion kit. Had one on the truck I drove in ‘80. Still had the oil bath bottom on the can. But, when you dropped it, there was a dry filter up in the main body. I couldn’t find anything like that for my later truck. I’ve seen a lot with the Donaldson can swapped onto them.

Yep. It loaded. That's what I thought...or was afraid of! LMAO!

I couldn't get it to load right now. Is that Raymond J. Johnson, Junior?

By the way, we also called the forward/reverse lever in a direct-drive Caterpillar tractor the "Johnson Bar". I think the steam locomotive engineers used that term for other things, too. EDIT: A quick search shows that steam locomotives' "reversing bar" was sometimes called the Johnson Bar. I guess that's where the Cat guys got it.

"Missed it by thaat much."