This was quite a bit to go through at one sitting, but I must say, what an absolutely great thread! Thanks to the OP and everyone else who contributed (and I am going to print out the whole thing and stick it in my camper binder).
Jack update: I installed the new 4600s and the camper raises and lowers like new, as you'd expect. The 4600 quick release seems to work OK, BTW. A couple of minor complaints though. First of all, the plastic plug/axle opposite the motor release handle on one of the jacks is defective - the head is missing and there is a gap there that will admit water. I'm hoping Happijac will just mail me a new one. Secondly, after I mounted the first jack, I couldn't get the motor to slide down inside the tube. Apparently they punch rather than drill the holes for the motor releases and the punching operation pinches the top of the tube so it is narrower than the motor housing. I had to remove the jack and use a hammer and wooden block to expand the pinch. The motor then fit fine. Also curious that the pair of jacks came with a crank and z brackets, etc, but no square plastic plug for the top of the tube in case you weren't going to motorize them.
As promised, I took apart the lower leg of the bad 4500 jack to get a closer look at the inside. At the top of the leg there is a re-circulating ball mechanism that is peened into the top of the lower leg. Instead of trying to reverse the peening to get the mechanism out, I decided to use a quicker, destructive method. I sawed into the square tubing just below the peening on all 4 sides. I used my horizontal bandsaw to cut it. The result is that the RB mechanism came out with about a 1/8" section of the leg attached. I have not removed the RB mechanism from the shaft as I suspect this would release all of the balls. In fact, I did back it off far enough to see the balls and managed to remove one of them. As I suspected, the ball is rusty and pitted from moisture intrusion.
The picture below shows the RB mechanism. In the background you can see where the bottom leg was cut.
The next picture shows what is at the bottom end of the acme rod. Note all of the rust on that end.
The next picture shows where the bottom end of the rod is when the jack is fully lowered. The tape measure shows the distance from the top of the foot pad. The only way to lube that plastic-to-metal friction point would be to drill a hole in the bottom leg at this point in order to be able to spray lube it. Note that you would still have to disassemble the jack in order to get to the hole.
The picture below shows what came out of the lower leg when I turned it upside down and tapped it on a shop rag on the floor.
From these pictures you can see that there has been a considerable amount of moisture in the lower leg over the years. Would a hole drilled into the bottom of the foot pad allow any accumulated moisture to run out?
Again, I would suggest when storing, or traveling, to keep the jacks fully retracted so the O ring at the top of the RB mechanism seals tightly. This keeps the acme rod all the way down inside the bottom leg and also keeps any intruding water from running down into the RB mechanism. One or both of these apparently caused the failure of my jack.
Current Rig: 2012 F150 Super Crew 4X4 5.0L 3.73 diff, 2013 Skyline Koala 23CS. Dearly Departed: 2003 GMC Sierra 3500 Dually, 2002 Bigfoot 25C10.6.
I followed the pictures today to take apart my left rear 4150 and want to say what a great series of photographs.
I didn't make the bent rod and was able to take off the circlip by putting one screwdriver in through a hole on the inside and bracing the clip, then prying with another screwdriver on the outside of the clip to just move it off enough to get it with a needlenose plier.
Then I used about a five inch spike to hook behind the gear. I gripped the spike in a pair of vice grips, put the head of the nail behind the gear, and tapped lightly to get the gear over the burr.
The long thread came out manually and carefully, and is now sporting a new layer of lube.
The worst thing I found was the little plastic box that holds the motor leads where they plug into the lead coming from the controller. The plastic is totally disintegrating, has leaked, the screws inside were rusty, and I am going to be coming up with something better... Maybe a tube of tygon tubing with the leads inside and filled with sealant? Tubing of some sort for sure to go over the connections.
Tomorrow I open the motor box and check out that part, then on to the next jack.
Hope there isn't anything too different with the 4500's on the front.
thank you, Mike
Mike and Carole
2009 Triple E F254SSXL Fifth Wheel
2005 16.6 Double Eagle
2000 F350 7.3 SC 4X4
previously Snowbird Campers
If you need a new trust needle bearings I found some replacements made by INA (made in USA) PN# TC1018. The races are also INA brand PN# TWA1018-HLA. These bearings worked for both my 4500 and 4150 model jacks.
Some threads never die and to see someone using the pics and info is what makes this a good source of knowledge for all of us...I'm not an expert, just someone who wants to know why and how stuff works. If it fails can you fix it? Someone out there has the same issues so share the experience.
Mine are the model 4500 and have been troublesome since day one they have been rebuilt at the factory once and one motor is bad now the other three operate poorly, and have blown fuses since day one the remote has been rebuilt once the controller has been replaced once they are four years old. when i called happijack i was told to send all four motor heads back that their was probably a problem and they needed to be checked and rebuilt, (wish I had atwood jacks) your post and pictures are excellent after I get the motor heads back again I am going to attempt to clean and relube the tubes again thank you for the post and information this is the best information relevant to happi jacks i have read i hope the 4500 come apart the same way
The 4500's come apart in exactly the same way. The only difference is the angle of the thread on the long threaded screw.
One thing I found was that when reassembling I had difficulty getting the pin back into the hole. What I discovered after several attempts was that the clamping spring needed to be set a tiny bit deeper into the hole where the bent let fits in. It's a big hole for a small leg, and has almost a 1/16 inch difference from top to bottom. Once I moved it to the "southernmost" position in the hole, I could put the pin in without difficulty.
The screw will not come completely out of the inner tube. It is built this way so you cannot overextend the jacks resulting in complete failure.
What I did with mine was I put my cordless drill onto the top end of the screw, and then grabbed handfulls of grease and held my hand with grease around the screw while I ran the screw back and forth into the inner tube and greased and greased and greased it.
If you are trying to remove the threaded rod top from the outer tube you have to remove the 3/16 by about 3/4 inch pin that is underneath the gear. It can sometimes be hard to see if there is grease there. Even a bit tricky to get it back into place upon attempting reassembly. Watch the instructions in great detail in the pictures.