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Compiled coil, shock & suspension spec thread for 80 series

Discussion in '80-Series Tech' started by GW Nugget, Dec 1, 2017.

  1. Corbet

    Corbet Speski OffRoad LTD. Supporting Vendor

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    Comparison picture of 3 rear springs. Slee 4” heavy, Ironman TOY025C "medium", and OEM.

    Kind of cool to see the material difference between them. I wish I would have weighed them all at the time. The Slee easily felt twice as heavy as the Ironman.

    72FA213A-B874-4890-805F-A6BFB6267DC7.jpeg
     
    Last edited: Dec 7, 2017
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  2. Box Rocket

    Box Rocket

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    Here's a couple similar pics of 75mm Slinky HD coils next to OME J coils. Same lift height, but much different free height.
    [​IMG]

    [​IMG]
     
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  3. Box Rocket

    Box Rocket

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    The Slinky kits don't need a bumpstop extension in the front. In the rear it's a 1" taller frame mounted bumpstop you can see in this photo. If you want to run 37's with the Slinkys its recommended to add 1 more inch of bumpstop via spacer.
    [​IMG]
     
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  4. Dragos80

    Dragos80

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    I'm still not clear on the bump stop idea.
    If one is looking for increased flex from any given suspension setup, why would you limit that travel with a bump stop?
     
  5. chap79

    chap79 SILVER Star

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    The bump stop is to keep your suspension from bottoming out and/or from keeping your tires from contacting the fender well. Whichever occurs first. This is why you see people cutting their fenders and/or reshaping the inner fender, to gain more up travel with a taller tire while maximizing the up travel of the shock.
     
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  6. Box Rocket

    Box Rocket

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    It's a matter of matching the bumpstop to the suspension. With the slinky kit for instance, since the shocks are different lengths than a factory shock the original bumpstop would not be in the correct location to keep from bottoming out the shocks. In this case the bumpstop isn't limiting the travel of the suspension at all. It's putting it in the correct location to use all available travel but not damage the shock.

    in the case of running 37's with the Slinky kit the extra 1" of bumpstop recommended would be to help keep the larger tires from rubbing.
     
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  7. Dragos80

    Dragos80

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    So is it a bad idea to use the entire up travel and have it limited be the shocks? (given the tires don't rub)

    I've seen some Land Rovers with a huge suspension droop to the point where the coils were maybe 1/5ft to 1ft from the axle. They might not even use shocks in that case.
    Not sure if they limit the up travel either with that setup.
     
  8. Box Rocket

    Box Rocket

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    yes. You never want to have the shocks be the limiter in droop or compression if you can help it. Either situation can damage the shock. Bottoming out the shock is generally more risky because of the forces involved.

    Also having the coils drop free of the coil buckets with tons of droop might look cool for photos and for a ramp queen but in the real world it's not ideal. When the coil drops free of the bucket there is now no pressure to push the tire to the ground (other than the weight of the tire) and traction is dramatically reduced. With the dual rate coils where the upper section of the coil compresses almost completely at ride height, this is how you fit a longer coil without increasing lift. So when the axle/tire droops the coil is still long enough to not drop free of the coil bucket and still provides some downward pressure to maintain better traction at the limit of the suspension.
     
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  9. chap79

    chap79 SILVER Star

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    DSC_0481-1.jpg

    Looking at this picture one can see that the body of the Fox shock is much longer than that of the OME it will be replacing. To keep from over compressing and bottoming out the piston in the longer shock the bump stops would be to be extended so that the bump stop makes contact with the axle BEFORE the shock is fully compressed. Due to the design of the bump stops and the force being applied against them they will compress some, so don't set your bump stops at the exact full compression of your shocks.
     
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  10. Dragos80

    Dragos80

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    deleted.
     
    Last edited: Dec 7, 2017
  11. LFD2037

    LFD2037 TEXAS LEXUS!

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    Those tires that are hanging free are doing nothing for forward progress. The lockers are their saving grace. They need limiting straps or will soon need new shocks!
     
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  12. GW Nugget

    GW Nugget I need to stop messing with it & just drive it!

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    So I'm going to repeat what most of wrote already above but I'm going to approach it at a different way.
    As far as bump stops you should be able to clear the tire of choice without any coils sitting on the bump stops. So before you install your lift kit pull out your old coils, set your rig on the bumps with tires of choice, install bump spacing or cut as needed.

    From reading probably hundreds of threads here on on mud & my experience I've come across this general theory... 33s do not need any bump stops 35s will require 1.5" bump stops and 37s will require 2.5" bump stops without cutting. Cutting up fenders will allow less bump stop spacing for more uptravel... for instance I'm running 37's with 2" cut front fenders a 1" body lift plus .5" bumps up front plus 1.5" rear bumps stops. (That is equivalent to 1.5" front & 2.5" rear if one does not have a body lift.)

    (Here is my rig without coils on .5" front bumps, 2" cut fenders & 1" body lift.)
    20160521_145436.jpg 20160521_145526.jpg

    Ha, I just derailed my own thread...
     
  13. DylanICON

    DylanICON

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    Yes. You never want the shock to bottom on compression. However the shock is almost always the droop limiter in most vehicles. This is ok, there is a full extension damper inside the shock. if you look at an IFS coil over like a Tacoma or Tundra there is a TON of residual spring pressure at droop that the internal extension damper must control. On an 80 the top out force is no problem for the shock.

    I agree. Ramp queens with a ton of droop are not great in the real world. That's why I set up our system for equal up and down travel. When you have more droop than compression and encounter an obstacle that requires a lot of articulation, one wheel begins to compress and the other droop. When the compressed wheel hits the bump stop you can still articulate more but only by drooping. This doesn't mean the other wheel continues to stop going up, it is now lifting the chassis. This means you are now RAISING you CG to get over the obstacle! With these rigs that is not something we want. Prime example: Climbing a ledge at an angle. This is already going to lean the vehicle over. Having less compression distance on the climbing tire is not only going to make it harder to let that tire climb, but it is also going to make the vehicle lean over more.

    Safety at speed on big terrain:
    Distance to bump, especially in the rear, is very important for safety and stability over rough terrain. We have all seen the videos of the prerunner trucks with the back end "Donkey kicking" 3-5ft off the ground. this is from all the mods being put in the front end not addressing the rear. On our RXT rear system for the Raptor we went to great lengths to actually move the bump position HIGHER in the frame to increase distance to bump and prevent Donkey Kick
     
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  14. DylanICON

    DylanICON

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    This is shocks installed no coils:
    Stock bump stops
    35" (315/75R16)

    IMG_6440.JPG IMG_6439.JPG IMG_6441.JPG
     
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  15. DylanICON

    DylanICON

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    The importance of bump travel

     
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  16. GW Nugget

    GW Nugget I need to stop messing with it & just drive it!

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    Has anyone installed a full Dobinson 2" & 3" Tapered lift kit front & rear coils plus the yellow shocks?
    Pictures & specs would be awesome.

    Thank you for your time
     
    Last edited: Dec 7, 2017
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  17. Shoredreamer

    Shoredreamer

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    GW you da man! This is a great thread. Tire rub on bottom out specs in this post assumes tire sizes with the stock 16x8 zero offset FZJ alloy rims? I know with wheel spacers and different rim spacing, tire rub varies.
     
  18. GW Nugget

    GW Nugget I need to stop messing with it & just drive it!

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    I have the FJC wheels which come out like approx 5" (actual is 125mm) with a 1.25" they come out just over 3.5" BS.

    Do you remember the specs on your front TJM 50mm fronts?
     
  19. Shoredreamer

    Shoredreamer

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    Yeah:
    TJM Front 50mm- 770FR80C: 21.2”/20.8” free ht. 17mm coil, 10.2 winds
    TJM Rear 50mm - 770RR80C: 20.2”/19.8” free ht. 17.4mm coil, 8.8 winds
    They are a taller coil with more winds vs. OME medium/heavy which likely means a more supple ride and lower spring rate. Very good on an unladen 80.
    Is there an equation to take coil dimensions and determine spring rate? Wish I knew.

    TJM Tiger 9 way adj shocks- Front 14.6”/24” 9.4” stroke
    Rear 15.15”/24.25” 9.1” stroke
    FC487C44-8CF0-420B-A6CD-DEC75286B497.jpeg
    I also have specs on Slee 4” heavy Progressive rears: 20.4”/20.1” free ht. 21.5mm coil, 10.2 winds
    (SOFR4HP)
    D0E76219-F42D-4702-B359-D6C57C43CFEA.jpeg
    863>770RR80C>864
     
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  20. Shoredreamer

    Shoredreamer

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    Also here’s the rear axle sitting on bumpstops +30mm (1.2”). Notice the coil bucket cushion touching at the same time. Take what you will from it. 0E16C118-3512-4FFF-BB18-CEAFDB23CD67.jpeg
     
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