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
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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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
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MTBob
Montana
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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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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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bigfootford
Fair Oaks, California
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This is a great conclusion to the HJ lubrication!!!
What I did with mine, the first time, I had my camera there as a witness....Hee hee.
One thing everyone should notice is the mounting of the jacks.
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
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MTBob
Montana
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tr3rt wrote:how can I get this write up?
As said in another post, the only way to get a "write up" is to printout this post. Happijac supplies a limited amount of (and somewhat misleading) lubrication instruction (the screw cannot be lubricated unless the jack leg is disassembled). They do not provide any detailed information about how to take a jack apart, nor do they provide parts lists or assembly diagrams. If you have troubles with a jack, they recommend that you send the jack back to them for maintenance. I forgotten the exact cost but it's not much... around $50 / jack if I recall. But, you also have to pay the shipping cost and it's fairly high.
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.
* This post was
edited 08/15/10 08:43am by MTBob *
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MTBob
Montana
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KKELLER14K: You've done a great job in documenting the jack tear down and maintenance. Similar to you, I've done the same job and took photos of all the steps. Since your post is so well done I've not added anything here except recent posts about the gear box and motor maintenance.
Like you said taking care not to lose parts or get them back in the wrong order is critical. It is a good idea to get the bearings (particularly the trust roller bearings) back in the same orientation that they came out. Bearing can have a tendency to "set in" to a given track or grove and changing that orientation can lead to accelerated wearing after reassembly. To make sure I got them back in the same order I placed the bearings and shims on a small piece of wire, made a loop and secured it. I then cleaned the shims and bearings while on that loop and reinstalled them in the same sequence and orientation that I removed them. Depending on shop layout and bench space it may also be handy to get several zip lock bags to keep parts and pieces from "walking off".
On my 10-2000 2002, Nothernlite I have 4100 and 4600 series jacks. If I recall correctly its the 4600's that use a ball screw and are on the front. The jack components are similar to the 4100, but there is a ball nut on the jack leg with matching ball type screw. The gear box and motor drive appeared to be the same on both models.
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KKELLER14K
BEAVERTON OREGON
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Thanks Jim, I do sign on to that account to keep it current on a regular basis...I heard the same rumor and I have a lot of my pics of projects there, would hate to let you all down. I had the fear that some jacks would be differant....but it does give some idea of how it works. jjinatx, your so very right in the mentioning of attention to detail as to how it comes apart...can't stress that enough. I have two separate pairs on mine and have yet to tear another one down yet so more info to come if it is differant...thanks all!
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jjinatx
Austin, TX, USA
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Just finished jack #2. Jack#2 has only a touch of rust on the upper part of the acme rod. Not much of any residual lube though - it would come pretty close to passing a "white glove test." Interesting that the 2 jacks I've worked on are slightly different from each other and from the one in Keller's pictures. I would caution anyone attempting this operation to pay REAL CLOSE attention to how things come apart and in what order. You can't depend 100% on the pictures shown in this thread. Either HJ has multiple suppliers or each build lot is different. Wondering if jacks #3& #4 are going be different in some way.
-jj
* This post was
edited 08/30/10 07:02pm by jjinatx *
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bigfootford
Fair Oaks, California
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I think everyone that has HJ's should print the whole procedure, pix's and all.
The pictures may disappear and then the article/thread will be worthless....
The pictures are on Photo Bucket so if KKeller14K does not keep his account up we will loose these valuable pictures.
Jim
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