doubleclutchinweasel

The double reduction rear uses 2 sets of reduction gears. This eliminates common issues found with deep reductions through only one set of gears, namely the huge difference is size between the 2 gears. The smaller gear is always weaker. By using 2 sets of reduction gears in series, you get 2 stronger pairs of gears. in a typical 4:1 pair, for instance, you might have 10 teeth on the input and 40 on the output (just easy numbers, not real numbers). The 10-tooth will be weaker then the 40. But, if you do a 2:1 and then feed that output into another 2:1, you have 2 sets of gears that are closer in size to each other, and therefore stronger. Most of the S/A units I have seen have the first reduction set in front of the axle. But, I have seen a few with it on top, like the tandem versions. You can see the cross shaft cover on the side. Here is a little graphic for reference. The first reduction is similar to a regular spiral/bevel setup, and the second is more like a helical spur gear setup.

That Joseph outfit always has some interesting old stuff. Not sure how or why they end up with so much of it. But, like Vlad said, they never post any prices. So, you can't tell if they have any good deals or not.

Yep. Pretty good info there.

A lot of life left in that Dawg.

Lord Love a Duck, this thing looks nice! Listed on TruckPaper. I have no connection to it whatsoever (unfortunately). If one of ya'll will buy it, I will be glad to keep it for you! https://www.truckpaper.com/listings/trucks/for-sale/212525513/1988-mack-r

Maybe Check with Jeff Lakaszyck or Jim Hancock over at justoldtrucks.com. Those 2 have some of the biggest collections of pictures in the truckin' world.

Shoot, I'd LOVE to have a kit. Better still, I would have LOVED to had one before I sold my truck! LOL!!!

I wish Mack had stumbled onto the idea of the galvanized cabs sooner. Imagine how may more "steel dash" cabs we might have to work with if they had been galvanized. I see quite a few of the later cabs, still with no rust on them. Oh, well...

Yep. "Ferrules". Not to be confused with "feral", as in wild pig, wild dog, etc. Never heard them called olives. But, I like it! Some of the manufacturers call them "sleeves". But, could a "feral" pig eating "olives", wearing long "sleeves" have a "ferrule" on his tail? How much wood could a woodchuck chuck...

Anybody remember this ad?

On that R I had, it seems like I replaced practically every single part in the air brake system. It was a pretty good education. Got to be real familiar with the Bendix catalog. Most of the parts are incredibly simple. The last thing I replaced before I sold the truck was the treadle valve. I used the one with the 2-stage spring, so the initial application was easier and got harder after that. One of my earliest memories of a Mack truck was being at the shop with my dad, waiting for them to put a treadle valve in a B model so he could get on the road with it. I was no more than 4 at the time. I literally grew up in the cab of one Mack or another!

That's how I learned pretty much everything I know. Take it apart and look. But, you are right on the money with the safety aspect. Always be wary of springs and things.

Can't remember the part number for the kit on mine. It was the 9K axle.

I actually pulled the hubs off to get in there. Looked like it might have been possible to do them without it, though. Easier than most light-duty pins I ever did back in my youth. Shame more designers don't understand the basic principle of the taper!

Dude! You continually amaze me with your knowledge of these things and your ability to help people work on them!

That's what mine had. I replaced them myself and they were very easy. That nut to adjust the thrust bearing was a really good idea. And, the tapered shanks made for easy removal of the pins.

You know, I've seen those models before, but never knew any of them tilted. I'll have to pay more attention now, for sure. Thanks for the education, High Binder.

That'd be okay too. I've been told worse by better!

Curiosity got the better of me. I emailed the seller and asked for more information about it. And, asked them for the VIN. Have not heard anything yet. Just want to know what that thing REALLY is. I get the feeling it's a compilation of parts. Not a bad-looking pile of parts, mind you. And, I'm with you guys. An R needs 1 big, round headlight.

Yes. Thanks for the follow up. Too many people use these guys’ advice and never follow up with the final solution. Glad you got it sorted out.

Thanks, 'Train. I learned something else today!

I guess what threw me on the engine is the lack of an oil cooler. I'm not used to seeing them like that. I think every one I was around had one.

I gave away almost all the ones I built through the years.