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SR pondering

Discussion in '40- & 55-Series Tech' started by snailwagon, Jun 27, 2005.

  1. snailwagon

    snailwagon

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    Hopefully I'll get some time this week to tack in some new spring hangers and springs, and maybe even a front axle this weekend in the 40. I was planning on a shackle reversal due to a little issues with the frame and alignment. The frame is in plane, front to rear, but has a little twist to it where the military wrap would go in stock configuration. So I figured I could compensate for that by putting in a through frame hanger at the proper angle and height.

    Now reading in the tech links Jim C. has a real nice explanation of why shackle reversals may not be optimal. Now I don't know much about mini-trucks, but when helping a friend this weekend I noticed his hilux has a stock shackle reversal. Why was this used in this case, but not on a stock cruiser? Was it just due to more arc in hilux springs? How is brake dive adressed when doing an SR in a cruiser, or is it really not much of a big deal?

    Thanks, just pondering a little here before metal starts glowing.
     
  2. dgangle

    dgangle total rice SILVER Star

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    It is good to ponder before cutting. Opinions are like assholes...everybody's got one and they all stink. No seriously, some make a good point of either setup. Some use their name in the industry to make their point seem more meaningful. For me personally it is one of the first mods done, along with disk brakes. A SR can cause issues with driveshaft slip joint lengths, lower u-joint angles and/or caster angles. Both can be fixed and are not insurmountable.
     
  3. bustanutley

    bustanutley

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    Is there someone near by that has a cruiser near by that is SR that you can drive or at least get a ride in to help your decision? I personally like my SR for lots of reasons; mainly approach angle and my cruiser tracks way straighter now because the shackles aren’t on the front of the truck shifting around. Most vehicles that have leaf springs from the factory have the shackles located on the back of the spring, go look at fords a Chevy’s. I understand the added stress to the frame for the fixed mount to be up front, but I boxed all that in anyway so I don't think it is an issue.

    Hope that helps. :beer:
     
  4. fj40_rico

    fj40_rico

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    That's my new favorite quote. :D


    For what is worth though, I didn't do an SR in my truck and I wish I had. I have a friend that I wheel with a lot that has a minitruck and he can get up rocks a lot easier than I can even though I have more clearance.

    I have heard that with the shackles on the front, as you try to go over a rock, the tire actually pushes towards it. but with the shackle in the rear it pushes away from it making it easier to go over the rock. Another thing I heard is that it will help with your steering too becuase of having a fixed point on the front.

    my .02 cents.

    - Rico.
     
  5. texas77fj40

    texas77fj40

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    i got a sr question,

    if you do an sr should you flip the springs around? simple question i know but i was just wondering?
     
  6. Mark W

    Mark W

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    I just finished ripping an SR out from under my newest '40 and returning it to the original configuration. Along with the commonly mentioned shortcomings of an SR, unless you use one of the "kits" which drop the front of the spring back down to the same distance from the frame that it had with the shackle, you will have greatly reduced clearance for your steering linkage. With a Flexy SOA setup your steering linkage will wind up being your bumpstop. :(

    Mark...
     
  7. dgangle

    dgangle total rice SILVER Star

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    I was unaware that this could be possible but I understand and agree with your reasoning. I see your point. Would not a 4X4Labs high-steer solve this problem? Pictures?
     
  8. woody

    woody unhelpful spotter Staff Member Admin

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    I run a LOW SR setup, Luke's steering arms, and Scout PS....I do have to run a bumpstop ahead of the pitman to keep the springs out of the drag link, and it does contact the frame and rub on the passenger side too. The tie rod (behind axle) does not contact the frame at all. Mine is set for about 3" max up travel (including bumpstop compression) and it uses nearly the entire 14" shock stroke (LOTS of droop) (LOW = 23" at the bottom of the frame with 39.5" tires....)

    There are a lot of reasons I like the shackle reversal, but one critical for offroad...when you drive the spring pack into a rock, the front solid mount may bend, but it won't push the shacke back and invert/bend the springs. I watched it happen too many times to guys with the shackle in front, and it's a quick way to junk a spring set. I do not like the fact that the axle wants to "walk" forward/away from the t-case tho, but I run a center limit in front that controls the dropout (2" max center droop).
     
  9. mr_manny

    mr_manny

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    I performed a SR on my truck, and agree the benefits mentioned above.
    Another benefit is the opportunity to address our wonderful fj40 front shackle angle :D

    You will be amazed how nice a 40 can go down the road (on and off-road).

    55 springs is the rear will take care of the back...
    manny
     
  10. snailwagon

    snailwagon

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    The main reason I was going this route was because of the bent frame. With a new hanger on, it would be titlted maybe 15 degrees. Since this cruiser will be the beater of the family, I figured I could compensate for that frame bend by a through frame hanger/tube at the original zero degree/horizontal. Since it will be the beater, the clearance will be nice. Too many times I've had my tiny stock 55 shackles beat against rocks. I'm sure my springs love it. It looks like when turning left, the pitman may be a problem when in SOA configuration. After staring at it for 30 minutes yesterday, I'm still not too sure what to do about the frame, maybe weld a dog ear to the bend, attach that a very large boom truck and maybe attach the other side to the old 1-ton power wagon? More pondering.
     
  11. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    This is the only reason IMHO to do a SR.

    the misconception that a SR axle moves backwards during articulation is junk. with flat springs (more typical in a SO conversion) the front axle actually walks forward. The "it wanders less" typically is because people have solved either caster issues or replaced bushings.


    I would NOT however use a SR to equalize a bent frame. Spend a couple of hundred at a frame shop getting it straightened. What you are considering doing is a bandaid and will cause larger problems at a later time.