Geoff Weeks

The 1/2" measurement is so the linkage has enough travel before it squeezes the clutch brake. Since you don't have a clutch brake installed you can ignore this measurement and just set the ~9/16" measurement between the T/O bearing and the clutch cover with the pedal pressed Why you don't have a clutch brake is anyone's guess. The 9/16" will put the throw-out in the area where it should be. You can check the free play when it is set there. With a properly set-up clutch and linkage, you want free play at the top, the arm set to where it has the most mechanical advantage when pulling in the angle spring, and enough travel before the clutch brake is squeezed against the bearing retainer to full release the clutch. It is all in the manual I posted a link too. Without a clutch brake installed, setting the T/O where it is at the best mechanical advantage on the lever and still maintains the correct free play is all you need to worry about. If the trans is ever pulled, I would install a torque limiting clutch brake, I wouldn't bother installing a 2 piece brake (just me, you do what you want) and just wait a bit for the gears to stop spinning before putting in low or reverse.

Ok, since nobody wants to read the link, here are some screenshots that explain adjusting. 9/16 between bearing and cover with pedal depressed, 1/2 between back of bearing and clutch brake or bearing retainer with clutch pedal released. If you don't have a clutch brake installed the 1/2"measurement means nothing. Angle spring clutches maintain clamp pressure through out the life of the clutch, which is why they are internally adjusted.

fjh, did you look at the manual and the pages I referenced? You don't have to remove the plate, only loosen the left bolt and remove the right, then the plate and "lock" pivots out of the way allowing for manual adjustment, then pivot it back to lock in place.

Look at the manual link I posted, the adjuster plate pivots to allow for manual adjustment. I doubt a newer set-up would bolt in place and work. It might, but you gain nothing. This clutch can be adjusted. Clutch brakes are optional. Push type often don't have them. JoJo your K-7 doesn't come with one. Clutch brake only speeds up how quickly the input stops.

Reading through, it has a "pin" that has to go into the bearing retainer sleeve for the self adjusting mechanism to work. Having said that, I too have not run across this type. The manual is dated 1981. It must have been an early design before the "Solo" self adjusters. I would try adjusting before giving up on it. From what little is shown, a pin that wore or broke would disable the self adjusting feature.

Clutch manual Page 25 seams to have that style. Supposed to be self adjusting.

I was surprised to learn my local "HyVee" grocery store sold it. I had seen it at WalMart's out in Wy where some people come a long way to get groceries, but was surprised in Iowa that it was that accessible.

I take this to mean he has had the thing all the way down. It is a known wear point on the Shepard box. I could re-seal once, and get some life out of the box (many years) but after that the shaft needs machine work. Any of the two digit boxes and the 392 series/type are old enough that shaft wear is likely.

dry ice works wonders

Here is a better explanation as to why speedi seal will not work in this application. Any oil seal, be it a rear main or a wheel seal, is vented to case pressure on the oil side. In a gear box or a rear axle that will be atmospheric, in a crankcase, it may be a few inches of Hg above atmospheric. Take the vent out of a trans or rear axle and put an air fitting in there and connect to 100 psi, would you expect no oil leak? most would say no, it would leak, now raise that pressure 20 fold! That is what the high pressure shaft seal on a Shepard box has to hold back. Stretching the seal a few thousandths over a speedi sleeve will damage it.

Speedi sleeves increase the diameter of the shaft by a few thousandths, not an issue for wheel seals and the like but a big issue for seals that have to hold back 2000 psi. It has been a long time since I did a Shepard box, so I don't remember exactly how the seal is. Last box I had to send off for a input shaft repair IIRC it was $1200. Input shaft seal area and pitman shaft bushings are really the only thing that goes wrong on those boxes. There is a fitting on the side that you can pump grease in between the high pressure and dirt seal, to keep grit out of the high pressure seal area, if this is done regularly it helps keep the high pressure seal in good shape. The grease forces any dirt up and out. Just one pump every oil change is all it takes.

With the Shepard box the input seal is a high pressure seal, a speedy sleeve will not work at those pressures, as you found.

If it is a Shepard gear, I think the correct repair is to cut the shaft to a smaller OD and shrink a sleeve on where the seal rides. You could possibly have the sleeve made from hard chrome stock, making the repair better than the original. These repairs need a qualified machine shop that can do the work. It would take tooling that can cut the hard shaft and sleeve. I was working on a car that had some brake parts that are NLA anywhere, my machine shop made a repair like the above and was surprisingly reasonable. You just have to think "outside the box" and remember anything made by man can be re-made by man.

Generally, here if the rear mounts are on the engine 1/2 of the bell, a rear transmission "leaf spring" type or rubber bisket mount is used. On set-up's where the rear mount is on the transmission 1/2 of the bell (thinking Volvo/White) then there is nothing at the rear of the transmission. It may have something to do with how much weight is cantilevered off the back of the bell housing, esp when aluminum housing are used. Just an observation

Not trying to say it will not work, just wanted to point out somewhere to check. The new mount is in a "different area code" as you put it, so needs checking, which it sounds like you have done. New things in different real estate is always a concern.

Yes, but what I see of the nodel mount is above the transmission.

clutch shaft higher also. will the added height clear the body/cab?

Ok that make sense. If the main air is lost, the spring brakes will apply regardless of what position the control is in.

Bendix pressure regulating valves Here is what I think you have. No pressure regulation, just adjustable hold off until the pressure is reached.

It looks like a pressure protection valve. It will hold off pressure until its setting is reached, then pass system pressure after that. In N-A they are used for air ride and such so a loss in the suspension will not drain the brake tanks below the setting of the valve. Yes, they are known to plug and stick. I have had several and sometimes if a truck or trailer sits for a long time they stick. Good find. Not knowing your system, I wonder if it has a separate tank for parking release and stuff like air ride? The weird thing would be that a loss of pressure in the main (before the valve) would still keep the spring brakes off as the tank after the valve would be isolated.

It was the "mechanical" aspect that makes me say no.

Oh, Jojo, you led me wrong LOL. I don't know all the Mack engines like you. I still say 500hp out of a mechanical inline six below 14L is going to take some compromise in the lifespan. Even at 14L it is going to be a stretch. Electronic sure changed that equation.

Then drop the "mechanical" ( and 11L ) requirement and choose one of the fine electronics already made at that power and drop (stuff?) it in. As I stated any two are possible, not all three.

They do!

early days of the Big Cams and 3406 A and B sure, they need bearing rolls. later they were good for 1m or more if cared for. I have a 3406B in my Marmon with over 750K on the bottom end. Overhauled a NT88 at 1.4m and 750K on the bottom end which could have gone much longer on the bearings. Oils have got much better. Big Cam 3 oiling made a huge difference over that of the 1 and 2.