bigfootford
Fair Oaks, California
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MTBob wrote:tr3rt wrote:how can I get this write up?
Because these jacks are such a critical part of owning a TC, I made the decision to dig into the jacks and figure out how they work myself. They are not terribly complicated, but they do require some level of mechanical skills to work on the jacks. Failure to disassemble, lubricate and reassemble them correctly could lead to jack failure.
Excellent statement!!!!
A failing stabilizer jack, due to lack of lubrication killed over 200 passengers on a Douglas DC9 (I think). Our 4500 Heavy duty jacks are made the same way.
If our jacks seize at an in-oportune time it sure will ruin your day!!!! I can not think of another thing on our campers that will create such havoc as a seized jack....You can't crank it, you are completely stuck....
Jim
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2000 2500 9.6 Bigfoot,94 F250, Vision 19.5, Mich 245/70XDS2's, Bilstein shocks, air bags/pump, EU2000, PD 9260,Lifeline 100ah, 200W. solar, Morningstar Sunsaver 15A/ display panel, Trimetric, Delorme/laptop, Holux gps rec,led lights, Wave-3 heat.
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MTBob
Montana
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Joined: 07/17/2008
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bigfootford wrote:I had a couple of degree outward tilt to the passenger front jack....and about a 1 deg on the front drivers....
Think about this....If you raise the camper way up you will begin to notice a bit of binding of the jacks....and if you lower the camper all the way down It will really bind. This is really a serious issue, especially if you have more than 1 deg tilt in any direction. You will not notice any issue if you never lower the camper way down....
Jim
I'm glad you brought this subject up. After watching how the jacks work during raising and lower, it's obvious that there is considerable stress on the legs, unless the legs are extended and retracted at exactly the same rate. From my experience that never happens, they always travel at different rates. So, what you've got are four (mostly) perpendicular posts attached to a "box". When the legs travel at different speeds, or have different extension lengths in relation to the "box", they will "crab". For instance, if you raise only the front two legs, the feet of these two legs will try to move forward since the front of the "box" is rising and moving the vertical plane to the rear at the top, and to the front at the bottom. If you notice that when you position the "box" on the truck bed and lower it, the legs will often shift and relax into an unrestrained position, indicating that there was stress on the legs. Conclusion: have any significant difference in uniformity of leg extension will cause stress on the legs and that stress will be transferred to the "box". I always try (usually unsuccessfully) to raise / lower the legs at the same rate and same amount.
Bob
2002 10-2000RR Northern Lite
2008 Chevy 3500 DMAX, SRW,
2001 Lund 1700 Fisherman
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jjinatx
Austin, TX, USA
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MTBob wrote:I always try (usually unsuccessfully) to raise / lower the legs at the same rate and same amount.
Actually, if you stop and think about it, if you have manual jacks, it is impossible to even come close to raise/lower the jacks at an even rate - maybe if you hired 4 burly quadruplets, but probably not even then. One or two are essentially always at different heights than the others by the very nature of the operation. The rule for manual jacks is to never, ever let the front get lower than the back and that works for electric jacks too.
I use a bullseye level on the floor of the camper near the door and keep a close eye on it while I'm raising/lowering using the controller. I also keep an eye on the rear jack feet when lowering because my RR has a tendency to lift before the LR. I make paired or individual adjustments with the controller accordingly.
-jj
Current Rig: 2017 F350 Crew Cab Short Bed 4X4 Powerstroke, 2018 Grand Design Reflection 29RS. Dearly Departed: 2003 GMC Sierra 3500 Dually, 2002 Bigfoot 25C10.6.
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jjinatx
Austin, TX, USA
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Update on my jack saga. It turns out my rear jacks are 4100 models, not 4500 models like the fronts. The 4100 is quite a bit different internally and I'll post some pics soon of the insides of them to add to this great thread. I also see evidence of lubrication on the 4100's and in fact did not seem like they needed re-lubing at all.
Bad news. The 4500 that had been given me problems and had frozen up appears to need replacing. Even after I re-lubed it and can turn it with my fingers on the bench, when it under load coming down it binds up occasionally. When it does, I have to unload some of the weight by lifting a bit on the opposite side. My best guess is that the mechanism that is preened into the top of the lower leg that the acme screw threads through is worn and binding under load. But before I order a new one, I'll take it apart once more for closer inspection and maybe replace the thrust bearing in case that is the problem.
I have a bit of a dilemma when it comes to replacing it. I can get one 4500 for about $350, or a pair of 4600 jacks for about $550 (the place only sells them in pairs). Is the 4600 worth upgrading to from the 4500? Is the only difference between them the quick released? Or is the mechanism stronger/better? Do I want to spend $200 extra now to save $150 just in case the other one goes out too?
If I do have to replace the jack, I'll cut it open and post some pics of the innards of the lower leg to this thread.
-jj
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jjinatx
Austin, TX, USA
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MTBob,
I took apart the clutch in the motor that was popping and could see that it had indeed been recently slipping. Mine is a bit different than yours. It has 6 ball bearings that are smaller than yours. Also, I tested the torque on the clutch nut of a different motor and it looked to be about 30 - 35 inch-pounds, so that's what I set the one I took apart to.
-jj
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bigfootford
Fair Oaks, California
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When I lubed my 4500 for the first time they were really rough. I used my 1/2 inch drill attached to the end of the screw and ran it back and forth the whole length about 20 times adding grease and wiping off the excess at the end of the full in and full out runs. They freed up and were slick as could be.
When I found a rough spot I would run it back and forth right there, adding wd40 and then grease. I inspected the area of the screw but found no damage. I think old dry grease/ shavings/rust was caked in the screw threads.
Jim
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edited 08/26/10 07:42am by bigfootford *
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wnjj
Cornelius, Oregon
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RichieC wrote:I bought some used happijacs from a dealer that have the quick release.
These jacks are so well lubricated that the extension would start to extend on it's own from gravity when the quick release lever was activated.
IMHO, that's the way they should work.
Don't assume too much from the way it moves. Only one of my four jacks moves that easily right now. It's the only original one (now almost 4 years old). The other three I sent back to Happijac when they were 2 years old for a paint issue and they retubed them (free re-build for me ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile") ). When they came back they move much harder manually. My theory is there is more grease in the rebuilt ones than the original one. I'd be willing to bet the used jacks you got will need refreshing sooner than you think.
A couple of years ago my brother rebuilt his and had the same thing happen. More grease meant harder to move when released. I don't think that's a bad thing.
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stevenal
Newport, OR, USA
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The hanger trick didn't work for me. Anyone know of a two jaw long narrow gear puller that would fit in the tube?
'18 Bigfoot 1500
Torklifts and Fastguns
'17 F350 Powerstroke Supercab SRW LB 4X4
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Super_Dave
Harrisville, UT
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Maybe I haven't ever looked close enough but is there anywhere on the jack that tells you what model # it is?
Truck: 2006 Dodge 3500 Dually
Rig: 2018 Big Country 3155 RLK
Boat: 21' North River Seahawk
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wnjj
Cornelius, Oregon
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stevenal wrote:The hanger trick didn't work for me. Anyone know of a two jaw long narrow gear puller that would fit in the tube?
Have you tried holding constant pressure up on the hanger hook then tapping down on the shaft? Otherwise find something a little stiffer like bucket handle maybe?
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