Tire change jack for lifted PUP?

Discussion in 'Taking Your Camper Off Road' started by BamaCamper, Nov 7, 2016.

  1. BamaCamper

    BamaCamper New Member

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    I have a Starcraft Comet 10RT. If I ever need to change a tire, I'll need a pretty tall jack. The manual says not to lift by the axle, but use the side frame. The low point on that frame is 22 inches from the ground. I suppose I could put several blocks of wood under my Grand Cherokee jack, but I wondered what you all use? Will a 30" scissor stabilizer jack work for tire changes?
     
  2. tombiasi

    tombiasi Well-Known Member

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    You need a jack that is capable of handling the weight. Stab jacks usually are not for lifting. (some are)
    You nee to make sure you can change a tire before you go out with it.
    I use my Trailblazer, it works fine.
     
  3. yetavon

    yetavon everything is better around a campfire.

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    Never could understand this....the axle supports the P'ups weight, plus the added jolt transfer of weight while driving....
    Why cant it support the pressure of being jacked up?
    Every trailer I have ever had gets lifted at the spring mount on the axle.
     
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  4. xxxapache

    xxxapache Well-Known Member

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    I also use the spring plate on my trailers with leaf springs.
     
  5. 94-D2

    94-D2 Happy Campin'

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    An engineer could answer this better but if you think how the springs and axle are arranged it will allow you to see how the components work together to do the job. Each side of the leaf spring shackles support weight at each end. The middle of the spring is bolted to the axle tube at its strongest point. And the weight is pulling down on the axle not up, which is how the jack applies force...upward. So now, all the weight is being pushed up on the axle tube and not down which is not how the axle manufacturer designed it. Same holds true for those with an axle flip. The weight is still a downward force, it's just at the top of the tube pushing down. The jack does the opposite. Another factor is you are now lifting the weight of half of the axle and tire, rim and lug nuts. This is called unsprung weight. Weight which is not supported by suspension. So now you have the unsprung weight and the weight of the trailer above the axle pushing up, and the weight of the trailer and the unsprung weight pushing down effectively doubling the force when you leverage it against the ground. That could break/damage or deform an axle.


    That is why your manual says to use the side frame to lift.
     
  6. ByramTra

    ByramTra Member

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    Really? Sounds like snake oil to me...

    I assume this is all related to leaf spring suspension? (Wasn't stated by the original poster.)

    The only way that makes sense is if you are lifting the axle in the center, which would be unstable on a trailer, and even then I doubt the axle would be compromised. On a leaf spring axle there should be no risk jacking it up next to or under the spring plate. I have been doing that all my life on trailers and TVs and never had a problem. My Grandfather, who was a bus mechanic, taught me to do that. As I recall on my Dodge Dakota the manufacture specified to lift it under the spring plates on the rear solid axle.
     
  7. 94-D2

    94-D2 Happy Campin'

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    Well, that is an answer. I don't see how lifting a bus or Dodge Dekota has anything to do with 2-3,500 lbs axle but ok....If lifting it your way works for you then you are successful. No one can argue how and why if that is the case. Not a problem. But, I have seen axles bend that way. Ever see how they align a trailer axle? Anyway, glad your successful with your method. Good for you.........
     
  8. 1380ken

    1380ken Well-Known Member

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    Obviously it is okay to lift anything under a solid mount like the leaf spring mount, that is just common sense. The reason they recommend not lifting from the axle is that some people don't have common sense and will somehow damage the axle. The frame is much harder to mess up.
     
  9. f5moab

    f5moab Retired from the Federal Government

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    I was told not to jack on the axle for two reasons. One, most axles have a pre-determined bend for camber that allows for driving under load and a jack might cause more of a bend or cause one side to straighten out, depending on the jack used and placement of the jack.

    Two, many people will use a bottle jack that has a very small contact to the axle due to the smaller head. This causes more pressure to one small part of the axle and since the axle on trailers is hollow and not very thick walled, it could cause a dimple or worse. A floor jack has a larger contact area thus less chance of damage. Placing a piece of wood will spread out the pressure from the contact, but this could cause a bottle jack to become more unstable.

    But, this is what I do with my trailer, someone wants to lift on the axle, it's their trailer, not mine so I could care less. I just personally don't want to take a change of dimpling or bending my axle when there are other ways to lift the trailer.

    I lift my trailer with a distance of more than 24" from the ground to the bottom of the frame with either a floor jack with wood on the pads or a bottle jack with wood underneath and located the jacks in front of the wheels. And placement of a bottle jack along the side frame is a lot easier to reach and pump, then it would be to place it under and axle. Never tried it, but I can guess I would have one heck of a long reach to pump it under the axle vs. the side.
     
  10. BamaCamper

    BamaCamper New Member

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    Thanks for the replies. So sounds like I just need to use multiple blocks of lumber. I was making sure there wasn't an offroad jack I was missing. The closest thing I found was a combo bottle jack and jack stand all-in-one PowerBuilt makes that lifts to 21 inches for $39. If I can find that one in a case I may go with that and attach it to the bumper, along with some wood blocks.

    My Jeep jack would require emptying the cargo area to remove, so I would prefer to have a dedicated jack if it doesn't break the bank. I agree about the axle; I'm sure there is a safe way to do it without damage or slipping off the jack, but the manual has to cover all bases. We need "Certified Non-idiot" decoder rings so manuals can put encoded instructions for those of us who can follow explicit instructions and safety guidelines.
     
  11. rabird

    rabird Howdy!

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    Main frame is where I jack, it would take a more agile person than I to get a jack & boards behind the wheel.

    At home with the tongue near the ground there is some good access from the rear for a jack stand and my jack, to the main frame beam!
     
  12. xxxapache

    xxxapache Well-Known Member

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    Jacking from the frame is not without damage potential, either. You can bend the frame from jacking in the wrong spot....The warning not to try and level with the stabilizers is repeated here often.
     
  13. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

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    I use my TV jack.

    1)I drive the flat up on blocks to reduce the jacking for putting the inflated tire on.
    2)Losing lug nut before jacking.
    3)Once the trailer is up, I put down the stab as a safety step before removing the wheel.
     
  14. ByramTra

    ByramTra Member

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    In order to mess up the camber you would need to be jacking it up in the center of the axle. You really feel like crawling under the trailer to place the jack there? and then have a "teeter-Totter" trailer due to lifting both wheels? OK...
    Lifting it by the frame there is more risk of damage if it comes off of the jack.
    I can understand some Not wanting to contort themselves to get the jack under the axle. That's understandable. Jacking the frame requires a lot more lift height due to unloading the suspension, unlike jacking under the axle, so you would need to make sure you have blocking with you. Fortunately the trailers I own, and especially the ones I've built, are stout so I am not worried about their frame integrity; but some trailers that I have seen I would be concerned about jacking under the frame.
     
  15. adrianpglover

    adrianpglover Well-Known Member

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    At home I use a bottle Jack without blocks and lift at the base of the forward spring hanger. On my model it's pretty heavily reinforced. My frame is in the same height range as the OP.
     
  16. adrianpglover

    adrianpglover Well-Known Member

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    I just found this in my bookmarks. I had forgotten about this company. Instead of needing blocks you can get one of these extensions and put it over the ram on your bottle jack. Don't know how well they fit as I don't own one...

    https://safejacks.com/collections/bottle-jack-accessories
     
  17. BamaCamper

    BamaCamper New Member

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    An update: I purchased the Powerbuilt #640912 bottle jack and jack stand all-in-one unit because it has a 21" reach. With two 2x8 boards underneath it is able to lift the tire off the ground. I'll probably also cut some 3/4" plywood for the top to avoid scratching and to give it just a little more reach. I bought it for $40 at tractor supply and it works great. Ignore the scrap wood I used in the pic; I've cut the 2x8 board to travel sized blocks since I tested it out.
     

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  18. tombiasi

    tombiasi Well-Known Member

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    Do I understand correctly that that jack is also a safety stand? If the hydraulics fail the stand will still hold up the load?
     
  19. f5moab

    f5moab Retired from the Federal Government

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  20. tombiasi

    tombiasi Well-Known Member

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    Thanks, I have a use for that.
     

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