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How do YOU measure rear end suspension travel?

Discussion in 'The Garage' started by BorregoK5, Nov 11, 2002.

  1. BorregoK5

    BorregoK5 1/2 ton status

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    The way I see it, there are two different aproaches to this ... articulated travel and equal wheel travel. Equal wheel travel could be measured by jacking the back of the truck up off the ground and measuring from the axle to the bump stop, but this assumes that your axle can reach the bump stop (rear springs fully compressed).. and if your not running bump stops then you magicly gain 4"? Articulated travel on the other hand could be measeured on an RTI ramp from the ground to the inside bottom of the tire on the ramp while the opposite tire is still on the ground, but has no relevance to equal tire travel due to the "Jacking" effect under articualtion. I've measured 36" of articualted travel, now how do I get a sane measurement on equal travel?
     
  2. Shaggy

    Shaggy 3/4 ton status

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    <font color="green"> I would measure from the bumpstop to the leaf spring at full stuff and full droop during articulated travel. This should give you a good measure of how far the springs *can* flex, and should give you a pretty close approximation of the actual travel at the spring, hence, equal travel.</font color>
     
  3. BorregoK5

    BorregoK5 1/2 ton status

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    Hence my issue, I dont run bump stops and the axle doesn't make contact with the mount. You also don't get as much articulated travel as you do equal travel because the twisting motion causes bind at the spring bushings and will restrict the drop out / stuff. In a link setup, you can remove the coil over and drop the suspension then jack it and measure the gain. Not the same for a leaf spring truck.
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Run zip ties on the shock rod and jump the truck...see how far the shocks compressed and either calculate or use a come a long to pull the rear of the truck down until the max stuff is equal to the zip ties...

    Rene
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    I know this probably ain't what you want to hear, this is what I did. I utilized a hi-lift and lifted up the rear, shocks were not attached, nor where the tires. I lifted the rear up until the axle quit moving, then stuck the tape measure up there measuring from the axle to bumpstop and came up with 14" of travel. Pretty impressive for a stock rig, but of course due to some idiot engineers at GM, I'm using a 10" shock, which takes out 4 inches of travel and leads to busted shock mounts. At least that's the way I remember doing it.
     
  6. Triaged

    Triaged 1/2 ton status

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    Just start loading stuff (like some sand...or a bunch of drunk guys at a offroad event) till the tires stuff into the wheel wells.
     
  7. zakk

    zakk 1/2 ton status

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    that is what i did after installing the Springer suspension. took 1/2 ton of guys to get the rear down to attach a busted shock.

    damn i need new shocks.... /forums/images/graemlins/mad.gif
     
  8. COCHEV

    COCHEV 1/2 ton status

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    well, you wouldn't want to run your springs into a negative arch so you could transfur a straight line from the front spring eye to the rear shackle at the maximum spring length. this would be where you would want to set your bump stops. droop would be the matter of lifting the truck and letting the axle hang as low as it could- assuming shocks and brakelines where not limiting travel.
     
  9. BorregoK5

    BorregoK5 1/2 ton status

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    Well, running the Ford 57's, the spring sits nearly flat at rest. Setting the bump stops there would be counter productive. I could see how this would be good on a lift spring in the rear.

    Rene... I think I follow the zip tie idea, but that just sounds like an excuse to get me out jumping the truck again... I dont think I wanna try and bottom it out like that! LOL

    I'm not sure I can wait to gather up a bunch of drunk friends... at least not enough to make the back end drop substantially.

    Maybe running a chain to the frame and attatching it to the bottom of a floor jack, then jacking up the axle can provide some results. I'll give it a shot tomorrow and see what I come up with. Thanks for all your help, everyone, theres always good ideas flowing around here.
     
  10. COCHEV

    COCHEV 1/2 ton status

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    so you must regularly go into negative arch. doesn't this fry your springs prematurely? could always strip the pack down to the main leaf making it easier to cycle the suspension. also, maybe some type of ratchet strap or come-a-long could be used to get full compresssion. not really real world accurate though.
     
  11. BorregoK5

    BorregoK5 1/2 ton status

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    The 57's have an extremely soft spring rate and yes they do go into negative arch at full stuff, especially with the overload flipped ( http://www.echobit.com/featured/ford-57inch-spring-swap/images/borrego-stuffed-rear-3.jpg ). I run my overload in the stock position now to prevent rubbing the rear seat but it still gets real close. This is how flat they are ( http://www.echobit.com/product-images/57s-flat-at-rest.jpg )
    They have been really resilliant to damage from the negative arch, the only problem I had with them was axle wrap warping the front half of the main leafs before adding a bar to control it. Now I'm just trying to document the flex as best I can before removing the springs and linking up the back end.
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    [​IMG]

    It's not the best picture but you can see the massive negative arch on the passenger side if you look closely. The axle tube was 2 3/4" from the stock bumpstop in that pic with the tire rubbing the inner fender and the shock bottomed...

    They do sit nearly flat at rest...

    Rene
     
  13. zakk

    zakk 1/2 ton status

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    so at what point is negitive arch a bad thing?

    By the looks of Rene's pic, there isn't a whole lotta room left before the spring looks like it is mounted upside down /forums/images/graemlins/laugh.gif

    Does anyone have expereince running these at SEVERE negitive arch? is there a breaking point anyone has found?
     
  14. COCHEV

    COCHEV 1/2 ton status

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    Nice chrome tips, Rene /forums/images/graemlins/pimp1.gif
    my old 52s would go negative also with a shackle flip and did start to sag after a while. i would imagine jumping or at least repetative cycling of the suspension at a faster speed (like woops at speed) would fry the springs faster then flexing on the trail.
     
  15. marv_springer

    marv_springer 1/2 ton status

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    Wow... 36"... /forums/images/graemlins/eek.gif! That's way more than mine will do.

    I think there's 2 meaningful measurements you can get... and you're right.... they're 1) straight up and down travel, and 2) articulated travel.

    I've always measured #2 by just using the edge of the fender as a reference and measuring stuff at the outer edge of the tire and adding this to droop to the outer edge of the tire on the other side when fully twisted.

    #1 is more meaningful for higher speed wheeling and jumping. I've estimated my rear to travel about 14-15 inches in this direction. How? Startin from level, I jacked up the rear of the truck till the rear tires came off the ground. Again using the fenderwell as a reference, I measured "straight down" droop to be right at 8". Then I measured from rest at the axle straight up to the bumpstop (BTW, I have the large 5" stops in there), This is about another 6". Now when I've been in the dunes, I've hopped it over a couple of jumps and seen the marks of that bumpstop on the axle - again this is an oversize bumpstop!...

    As far as negative arch, yes the F-150 springs do it a lot. Does it shorten their life? Yup... I'm sure it does. The best thing about running F-150 springs is that they're everywhere and they're cheap /forums/images/graemlins/smile.gif!... I've had mine in there since '98... and they're pretty much shot /forums/images/graemlins/tongue.gif.. Will they break? I'm sure they'll sag quite noticeably before they reach that point.

    Marv
     
  16. BorregoK5

    BorregoK5 1/2 ton status

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    Marv, I've been looking at our setups and we should be very close to the same flex, articulated and straight up and down. Take a look at the shackle hanger bolt as a reference point to the spring eye shown here:
    [​IMG]

    I measuered from the axle to the bump stop mount today and came up with 20". Your running a 5" bump stop so that puts me at 15", same as yours.

    With the overlaod flipped, you can easily get 36" of articulated travel (super wheel stuff image below), overload stock and it reduces it to about 27" (other less stuffed pic below). The dop out is huge on these 57's. The rock slider runs 20" below the top edge of the fender and you can see how far below the rock slider the edge of the tire reaches.
    [​IMG]

    By the way, I want to thank you again for introducing me to those 57" springs. I think I've got the measurements I need so I can compare the 57's to a full link setup after the links are completed. Thanks for all your help, everyone!
     

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