ruralandalone Posted July 26, 2017 Author Share Posted July 26, 2017 Many thanks for posting these pics. 1st pic -old spring, no load, rear shackle and mount. Rear mounts are original and untouched as far as I can tell. Spring hangs correctly 2nd pic - old spring (NOT OEM) 3rd pic - front mount old spring, passenger side 4th pic - front mount drivers side 5th pic - new spring, rear, no load. Obviously not aceptable 6th pic - new spring under load. NOT GOOD. Without the correct distance measure from the front mount bolt to the rear shackle mount bolt I can't verify that the new spring pack is correct, but the pack does match the dimensions given earlier (thanks again for that). I'll check to see if that is a weld or a crack in the 3rd picture. (I think it is a joint in the reinforcement/patch) I understand that the new spring does not hang correctly. That is what started the discussion. IF the front mounts are original, were they moved to accommodate that ridiculous spring pack? At a gut level I'm not happy about the amount of metal left on the front mounts. There is a lot of rust, and I suspect that they are weaker than they should be. My inclination at the moment is to remove what is there, purchase a 3 in spring hanger from 4wd or ruffstuff and weld them in the correct position (after suitable reinforcement/repair). Of course I am happy to hear suggestions from those with more experience.... Link to comment Share on other sites More sharing options...
Pete M Posted July 26, 2017 Share Posted July 26, 2017 I might be a bit off since I was being attacked by the entire 76th squadron of georgia mosquitoes, but I get 55" from mounting hole to mounting hole. Link to comment Share on other sites More sharing options...
ruralandalone Posted July 26, 2017 Author Share Posted July 26, 2017 Pete - that is above the call of duty! And thanks to you,, (and others) I think we have cracked it! I now know: 1) the spacing between the mounting bolts is roughly correct (give or take a mosquito) 2) the spring LENGTH is roughly correct. 3) this only leave the ARC of the spring, which, according to my supplier, is way off. I take them back tomorrow to get them corrected. I'll let you all know how I work out. I might have figured this out if any of the suppliers listed this dimension on their drawings.... Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 26, 2017 Share Posted July 26, 2017 Who's the supplier? Local? Did he have a blueprint like the below to build from? This is for the 3 + 2 MJ metric ton leaf spring. Link to comment Share on other sites More sharing options...
ruralandalone Posted July 26, 2017 Author Share Posted July 26, 2017 They were made by stanley spring and sold by a local dealer. Thanks for the schematic. That gives me something to take to them. I must say that 57 inches overall length seems a bit long. Doesn't that put the rear eye 2 inches (roughly) behind the top shackle bolt, if the front bolt to shackle bolt distance is 55 inches? Link to comment Share on other sites More sharing options...
Pete M Posted July 26, 2017 Share Posted July 26, 2017 57 inches is the distance along the leafs. once arch is taken into account, the distance between the eyes will be much closer to the distance between the mounting holes. :thumbsup: Link to comment Share on other sites More sharing options...
ruralandalone Posted July 26, 2017 Author Share Posted July 26, 2017 You are correct, Pete. 57 inches is the distance along the length, but that is not the way it is shown on the diagram - at least not the way I was taught to do it. The actual distance required to have the the rear eye directly below the shackle bolt, with no load, is 54 - 1/4 inch (+-) Assuming that is where it should be with no load, that is what I am going to be looking for after they get straightened. (a pain in the @$$, but likely the simplest and easiest solution to my problem) Next install the new floors! Again my thanks to all who helped out. Seriously. Never would have got it otherwise. Should have, but likely would not have. Ain't this stuff fun? Link to comment Share on other sites More sharing options...
Pete M Posted July 27, 2017 Share Posted July 27, 2017 lots of fun :D Link to comment Share on other sites More sharing options...
ruralandalone Posted July 27, 2017 Author Share Posted July 27, 2017 Well, the dealer did his magic, and I now have a reasonable arc in them, and they should work. They certainly look better! The dealer said that having incorrect arcs in the springs is not common. I guess I'm just lucky. First one goes on tomorrow Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 27, 2017 Share Posted July 27, 2017 Well, the dealer did his magic, and I now have a reasonable arc in them, and they should work. They certainly look better! The dealer said that having incorrect arcs in the springs is not common. I guess I'm just lucky. First one goes on tomorrow That's called free arch; it's 9.5" + or - .12" on the 3+2 MT spring. Every leaf spring has this spec, and it's critical for the flex vs. load characteristics of the spring. Manufacturing a spring with an incorrect free arch is not common if that's what you are saying. Did your dealer tell you how he corrected the free arch? Link to comment Share on other sites More sharing options...
ruralandalone Posted July 27, 2017 Author Share Posted July 27, 2017 No, he did not. But he has the equipment to make springs, so I figure he knows his stuff. (I'm a trusting soul) He did assure me that making the change would not affect performance. (I at least had the wit to ask that much) Link to comment Share on other sites More sharing options...
Rockfrog Posted July 28, 2017 Share Posted July 28, 2017 This is what it (shackle angle) should look like. This is on my XJ though, but the concept is the same. The rear spring eye should be behind the point of the top shackle bolt, with a roughly 45 degree lay back. This will give the best ride quality and spring travel overall. Sent from my SM-G930W8 using Tapatalk Link to comment Share on other sites More sharing options...
Eagle Posted July 28, 2017 Share Posted July 28, 2017 This is what it (shackle angle) should look like. This is on my XJ though, but the concept is the same. The rear spring eye should be behind the point of the top shackle bolt, with a roughly 45 degree lay back. This will give the best ride quality and spring travel overall. I respectfully disagree. The XJ is a spring over, with the springs set up to have essentially no arch when sitting at curb weight. That means whether the spring takes on more load or is unloaded, the rear shackle is always going to more forward Because either way the spring is bending/arching more, thus getting shorter). The MJ starts at curb weight with significant arch, and as the bed gets loaded the spring flattens and gets longer. For an MJ, the basic curb weight orientation should have the shackle closer to vertical, to allow the spring to work properly as the load is increased. Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 28, 2017 Share Posted July 28, 2017 Like so: Link to comment Share on other sites More sharing options...
Rockfrog Posted July 28, 2017 Share Posted July 28, 2017 Either way the shackle should lean back, not forward like the OP's picture. How much really comes down to preference in the end. More angle means softer ride (due to greater degree of leverage), less means more room for travel (due to more swing), but stand it too tall and it can roll over center and net a bent main leaf. Regardless of axle position (SOA/SUA) the spring will pull the shackle forward under droop. Sent from my SM-G930W8 using Tapatalk Link to comment Share on other sites More sharing options...
ruralandalone Posted July 28, 2017 Author Share Posted July 28, 2017 I set mine to sit pretty much vertical with no load (and no box) on my hoist. It leans slightly backwards when on the ground. I think that is close enough to correct to be ok. Link to comment Share on other sites More sharing options...
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