Geoff Weeks

I don't know if you can still get them, but before I spent a lot of money on that system, I would look into a 24 volt Maxwell ESM. Keeps the 24 volt cranking and cables, allows you to use the two best 6 volts for the rest of the 12 volt system, and Maxwell will recharge off the 12 volts. Not cheap, but if you are planning to change to 12 volt, you have to change the starter and cables, plus a set of 12 volt batteries, that makes the Maxwell more competitive.

Gone the other way on a few axles. I look at seal and bearing numbers and then compare with what you can find in the junkyard. Converted both IHC (Spicer) and Eaton to spokes using this method. If the bearing numbers match, the thing to double check is the bearing spacing on the spindle. Otherwise take your axle model and look for Hub pilot hubs on the same axle model. That is 100% to fit, but cuts your choices by a whole lot.

1st check the power and ground for good connection, 2nd check the sensor wires they should be a twisted pair and/or shielded. If not they may be picking up stray signals from something else. Also there are different impedance pick-ups, the wrong one usually just doesn't work. Sometimes swapping wires on the sensor circuit helps if one side of the sensor is grounded. If all else fails, run a twisted pair in a shielded cable to the back of the trans to keep out stray signals.

When I see an air problem 1st thing I check is how well the truck holds air going down the road. Take it out on the expressway with a trailer (if it is a tractor) in light traffic and see how long it runs between gov cycles (blow off if it has an air drier) On the highway without using brakes, it should go a MINIMUM of 15 minutes between cycles, if it can't do that, all other "fixes" will fall short. I realize a truck in town is going to use more air than a truck on the highway, but if the system leaks going down the road, then it will use more in town. Most trucks I see fail this test if they are a few years old or older. I had mine, at one point, air ride truck and trailer, air start, go 45 minutes between cycles, that was one tight truck! 30 min is about the best I can keep mine to.

I put AD-4's on my stuff, and never had a problem. Ran air start, If I got anything out of the wet tank, it meant I needed to look into what was causing it. Most often it was air leaks. I would go 30 min between compressor cycles running down the highway. If it cycled in less than 15 min I had work to do. Air drier alone isn't much good if the air system leaks like a sieve. Air drier can't do its job if it is constantly cycling.

For what it is worth, address the heat issue, start with the radiator, if you can find a good shop anymore. I put a new rad in my truck that I always had to watch the temp on. Shortly there after I was pulling a full load over the Big Horn mts. 45 min at full throttle and 25 MPH! That will test any radiator! Anytime you can't run full power for extended period of time, you have a problem, and it will only get worse. The radiator only has to drop the coolant temp 10 deg from inlet to outlet to keep the engine cool. If it can't do that, it is telling you where the problem is.

I see the rectifier was replaced with modern diode unit. That is good. I would leave it alone, if it is working for you. Only draw back is the space it takes up. To switch to a "modern" one wire, it would either have to be case neutral or positive ground unit. OR you have switch the polarity to neg ground, which would open up the opportunity for more accessories that are neg ground only.

I doubt that would work. My dog will not react to a dog or even a wolf on the TV but will to 'yoty's in the distance. There must be frequencies that we can't hear and don't reproduce in recordings.

Hear "yoties" at night, but they will not come anywhere there is a barking dog, they have learned a barking dog brings a farmer with a gun. Not the dog they are afraid of.

I'd say if the seal came with one, yes. Stemco seals had a "wedding band" ring that gets pressed on the spindle that looked something like that. Unitized seals are one piece. You wouldn't re-use a a grit guard with a seal that didn't come with one. That is why I said, it depends on what seal you get. If the seal comes with a metal guard like that one has, you should install it. If on the other hand you get a unitized seal, you should not re-use the old grit guard. The tool to install that ring looks like a fence post driver, a piece of pipe with two handles and an adapter that fits on the tube and the ring, you hammer it home by grabbing the handles and swing along the spindle. In all cases the wear surface is replace every time the seal is changed. Unitized seals are all one piece, Stemco type are two piece, one get pressed into the hub the other pressed onto spindle.

Not exactly sure what I am looking at. However I think what you are referring to is a "grit guard" to keep the bigger dirt out of the seal. That seal is toast, and need to be replaced, regardless if it is going to seal oil or grease. So it will come down to what you can get to replace it, not what was there in the beginning. There is a lot to be said for grease bearings, esp on something not in everyday service. As far as spoke vs, disk wheel hubs, the bearing and seal is the same. I'd go to SKF's seal finder app and see what you can find that matches the bore and shaft size. If you any numbers off the old seal, that might help also.

Most have already made most of the important points. To outfit a truck to do 40% grade with that load, would make it useless for other tasks. Meritor planitary hub rear axles with a deep primary reduction at the differential and then calculate the needed transmission reduction. Torque hubs put the final reduction at the hubs, the axle shafts will not see the full torque required, as would be with any conventional diff, of either single or double reduction.

Mack was indeed the 1st air to air charge cooler with the Tip turbine set-up. Front mounts required a re design of the engine bay/front of the truck, which is why engine mfg resisted it for as long as they did, it would limit what engine could be placed in a truck already on the market. It is why Cummins went to"low flow" cooling, to allow better charge cooling without changing the front end of the truck. You could get a high HP Cummins in a truck that couldn't take a high HP Cat, because the Cat required an air to air over 400hp. When the truck models got re-designed, the new designs all allowed room for air to air, and the "work arounds" like tip turbine and low flow cooling were quickly dropped in favor of the air to air in front of the radiator. Front mounts allow large surface area and are simple to cool, using the radiator fan, so when room was allotted for them in truck design, that is what everyone switched to. The Mack tip turbine was a very clever answer to the problem and compact. As an engine mfg it is hard to sell an engine to a truck that would require special front end designs to take it, so work arounds were used. It was clear that front mount air to air was the future of all engines and when truck models were updated, room was allotted for the air to air.

Depends, on type and which adjustment you are talking about. If you are adjusting for wear at the ball socket, then no. If you are adjusting for length then it depends on how the drag link is made. Some like my Marmon use a mini tie rod with left and right threaded ends, and that can be adjusted for length without removing an end, others like my IHC's and I think yours (hard to tell from the picture, but it looks to have only one thread) you have to remove one end to thread it in or out.

It varies by state, some do not allow you to keep a CDL at all if no med card (I think it is either AZ or NM) but under the Fed rules that most states use, you can run personal stuff and some excepted vocations, like here Propane del and AG chemicals are on the list. either intra or interstate excepted. A state can have stricter rules than the Feds but not more lax. The above states (and I can't remember which one) went stricter and you can't hold a Class A or B without a med card. So to be sure, you have to check with your state on what is allowed. When I retired, I change to interstate excepted and have my "CDL" or class A without a med card. If I were to go back in the seat, I would have to get a med card and go file it at the courthouse. Here, anyway it is called self certification, and you have to file it where you get your CDL lic or renewal. In Iowa it is at the county courthouse.

Rockwell made their own "top losding double reduction rears, are you sure they were not those models?

I think it comes down to the vendor that made them. I know that is the way it is on other makes. Being Mack rears are Mack only, I can't be sure. I've had IHC's with both types, and in the book, it stated it was who supplied the housing to IHC, other than that there is no difference

If there is a RPC in BOTH the outlet of the hydrovac and the outlet of the master, the brakes will drag esp after a bit of use. Some Hydrovac don't have a RPC in them and need one in the master. Other do have the RPC in the hydro vac and need a master without the check. The RPC keeps a little pressure in the system to keep the wheel pistons from being pushed back all the way in from the brake return springs. The hydrovac works by sensing input pressure and adding boost based on the input pressure. If the hydrovac is set up with a RPC in the outlet, and a Master Cyl is used with an RPC, there will always be a little inlet pressure and this will cause the brakes not to release properly. If you seam to have dragging brakes or brakes that will not fully release, with the 661 master, then take it a part and remove the metal disk thing at the very back of the master, behind the big return spring, that will "convert" the 661 to a 2657. The castings, bore and stroke are all the same.

The Master cyl pictured is a very common type, BUT there are different bore (may be stroke) and very important, with and without RPC (residual pressure check). If the truck doesn't have a frame mounted hydrovac booster, you need a master with the RPC, if it does have a hydrovac, it may or may not (depending on the booster) need a RPC in the master. The K-7's tha Jojo and I have are a 1 1/2" bore and do not have a RPC in the outlet. It is MC 2657. the same master with the valve is different, I want to say, MC662 but that is just from memory, so could be wrong. edit: I was wrong MC 661 is the number 1 1/2" bore with Rpc. You MUST use the correct configuration for your application and can not use "looks" alone to select.

coupla ways to determine what the truck is now. Some are not 100% fool proof, but will give a good indication. 1) 1st and foremost, look to see if it has an alternator. If so, which polarity is connected to the frame. If it does, it doesn't matter what the truck was originally, but does matter now. Hook the battery up backwards and you'll destroy any diodes. 2) assuming it has a generator, install a battery (it will not hurt a generator if the battery is "backwards) and turn on every load you can think of and look at the ammeter. If it points toward discharge, then you have it correct, if it points toward charge then it is backward. Be sure to disconnect any radio or other complex electrical component before connecting the battery. 3) often times generator voltage regulators are marked as to polarity. Whether the marking are still readable after all these years, is another matter. 4) some electric gauges for temp, fuel etc, will try and read backwards, go below the low stop when hooked to reverse polarity If it has a generator, and no indication above helps, it doesn't matter other than "looks" for period correctness, it can run either polarity (have to repolarize the generator for the polarity you choose) but neg ground affords much more options in today's world than positive ground.

Most common failure is leaking out the exhaust, either with the valve open or closed, next common failure is leaks to the trailer side with the valve closed. Whether a rebuild kit will solve the problem depends on the state of the casting. Sometimes where the valves seat get worn/corroded and a "kit" will not solve that.

HOLD on, what year truck are you working on? Is it pre -121? It could be a TP-1 (not sure, never seen one, as they were out of production long before anything I had). TP-1's and TP-2's are out of production and even rebuilds are NLA as far as I know except for N.O.S. There is a TP that does look similar but is newer and has a double check function built into it. TP-3's and later (post -121) valves all function different than the pre-121 and are not directly compatible. If your supplier went off looks alone, it is very doubtful he will get the right part. It is VERY important to get the right valve TP-1 and -2 have the trip function (air pressure trip to close the valve) in the TP valve itself. The supply side is ALWAYS connected to tractor air at all times. The later TP-3's and up the trip function is in the dash button, and supply air goes through the dash button to the TP, which then opens, anytime it see's air pressure on the supply line. A TP-3 has four connections a TP-1 or 2 has five. There is a later TP that also has five, but has two supply lines, and a double check in it. That valve looks similar to a TP-1,or-2 but functions different. We need to know what you are working on and preferably numbers off the valve to be sure. edit: Whoops, I missed the title (I'm going to blame on the time change!) and see it is post -121! I found some pictures on line that look like it. It is a Midland TP valve. The top connection threw me because Bendix early valves are like that. I didn't see many Midland valves in my work. More info and pictures would help. The above mention of TP-1's got me on the wrong track. PS early (pre -121) are sometimes called "3 line system" and later (post -121) are called "2 line".

I know how you feel, I have a drag link socket in my tool kit somewhere. However, the O/Per is working on a 1996 model, and I have never seen a adjustable link that late. even by 1969 they were not seen on most new equipment. The British buses I worked on were the newest thing I saw with adjustable ends, and they were in the 70's vintage and older.

I haven't seen an adjustable drag link on anything modern, they were more common in the 50's. Goggle "drag link socket" to see the correct tool to adjust them.

Took mine to town with a load of brush the other day. Ran sweet. I'll need to go again soon and get some lengths of conduit.