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Cj5 With Bad Wheel Bounce / Axle Wrap?

Discussion in 'Early CJ5 and CJ6 Tech' started by Costjohj, Nov 24, 2018.

  1. Nov 24, 2018
    Costjohj

    Costjohj New Member

    Massachusetts
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    I'm new to the site. I've been working on my first jeep (56 cj5) for several years. I've done numerous muscle cars, trucks and car flips. I finally got the CJ on the road this fall, only to (occasionally) be experiencing a violent bouncing of the rear. So bad, i need to pull over, coast to a stop. I can get right rolling smooth again right after, like nothing happened, until it will occur again. I have done an SOA, with longer Cherokee springs in the rear, stock CJ, 7 leaf,up front. stock axles. I had pulled two leaves out of the rear springs, was running fine. Then one day, I hit a series if bumps in the road when i first noticed the bouncing. Thinking axle wrap may be the culprit (but i have never experienced it in an y other vehicle before) I added one of the leaves back, but now it occurs more frequent.

    I know there can be many issues with the SOA, I've tried to address all, but fear I missed something.

    Reading thru many posts on the subject, pros and cons on SOA, I'm seeking advise direction.

    I did a lot or research and took my time, but obviously missed/overlook something. Any help advise would be greatly appreciated

    Is this an axle wrap, wheel hop issue? Will a ladder bar help to eliminate? Are these other areas I should be considering. I've never experienced this issue before on any of my other cars or trucks.

    I appreciate any and all advice one can offer. I love to put the wrench time into my projects, i just want to be certain as i can that I take the right course of action.
     
  2. Nov 24, 2018
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
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    Welcome to the site.

    This sounds like a shock issue. What kind of condition are the shocks in, and are they the proper length for the modifications you did?

    Jump on your rear bumper/bed. There should be no bounce, and you should should hear an audible "ffffft" upon its upward travel.
     
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  3. Nov 24, 2018
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
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    Also, are your tires balanced?
     
  4. Nov 24, 2018
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

    Hills of NH
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    Are you certain it's the rear? This sounds exactly like Death Wobble in the front end, which is a well known Jeep phenomenon.

    I never heard of such a thing in the rear, unless it was shocks or tires as suggested.
     
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  5. Nov 24, 2018
    Sierra Bum

    Sierra Bum Member

    The High Sierra
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    Welcome from the High Sierra.
    My first thought was also shocks. I've done a spring over with shackle reversal on these jeeps with good success. I used early CJ rear springs front and rear (the rears are longer on early/intermediates). I'd suggest a stiff gas shock like a Bilstein or an RS9000 adjustable.

    Not knowing what your goals and experience are, SPOA is often seen as a cheap way to get lift. It's not. If done properly, there are steering issues, and drive line angles and lengths to deal with. Also there is typically increased wheel travel, which is good, but requires re-engineering the shock mounts, and length and axle location in the front.

    IMO, SPOA is great for more clearance and more wheel travel with the right spring configuration and proper engineering, and its usually not a cheaper shortcut to that end. If I was to do it again I'd definitely look at over-the-top steering knuckles for a dana 30 or 44, just for starters. FWIW, I'm not a fan of ladder bars. But I digress.....

    Other thoughts related to your problem.....

    How much lift did you end up with?
    Condition of springs?
    What are your tires?....size, age, radial or bias ply.....
    Tires out of round?
    Tires out of balance?
     
  6. Nov 24, 2018
    colojeepguy

    colojeepguy Colorado Springs 2019 Sponsor

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    Exactly what I was thinking as I read the description of the problem.
     
  7. Nov 25, 2018
    Jrobz23

    Jrobz23 Member

    Northern, WI
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    Me too. Never had DW in the rear.
     
  8. Nov 25, 2018
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2020 Sponsor 2019 Sponsor

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    interesting problem and welcome.
     
  9. Nov 25, 2018
    Rick Whitson

    Rick Whitson Detroit Area 2020 Sponsor 2019 Sponsor

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    Welcome for Michigan, I agree with all the above, Good luck.
     
  10. Nov 25, 2018
    70cj5134f

    70cj5134f Member

    East Tn
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    Have u checked your rear driveshaft angles?
    I had a similar problem until I phased the rear shaft.
     
  11. Nov 25, 2018
    Costjohj

    Costjohj New Member

    Massachusetts
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    Thanks to all, you have given me several things to consider. I can respond to some of the above.
    Yes tires are balanced. Front shocks were new, rears were initially for mock up. I just jumped on the rear bumper to bounce the jeep as ITLKSEZ suggested. Slight bounce, perhaps more important, only heard then "fffff' from one side. Honestly, when planning out the build, the shocks got the least attention. My shock angle is a lot more vertical than the original shock geometry in the rear, could that play a factor?

    The drive shaft angle is steeper with the SOA, I installed a slightly longer drive shaft, and massaged the yokes to insure no binding. My hopes are that the F134 will not produce enough torque to grenade the u-joints, time will tell.

    I'm gonna get out in the garage today to dig deeper, one comment/question about possible Death Wobble. The issue only appeared after several weeks of around town driving, it appeared right after running over a very bumpy section of the road. I coasted to a stop, resumed driving, and did not return for the remaining ride home. I went back over the same stretch, and same thing happened. I then added a leaf to the rear springs. I was on my way to return to same bumpy road, when it occurred on a relatively flat section of road, never got to the bumpy section. Why would essentially stiffening the springs promote the issue?.

    I will take some pics of the front and rear setups, and upload later.
    Again, I really appreciate the input!
     
  12. Nov 25, 2018
    ITLKSEZ

    ITLKSEZ Volvophilic

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    Thanks for the follow up. This helps. First things first, go out to that same spot and get it to do it again. Stick your head out the door and confirm if it is the front or rear. If it is the rear hopping, get new, quality shocks, then go from there. And to answer your question, going more vertical with the shock placement will actually give you better dampening resistance over the stock angled position. The ride may be a little more harsh than stock, because your shocks are now working at a 1:1 ratio to your axle movement.

    If you look out and see the front tire shaking left/right violently, that's death wobble. It's usually the culmination of several problems working together at once. Side play in your spring bushings, slop in your steering components, tires that are statically balanced as opposed to dynamically balanced... any or all of these can add up to death wobble.

    Your tires, due to inertia, want to spin straight if they are equally and evenly balanced. When you hit a bump, it knocks the tire out of its plane and inertia forces it back straight again, like a gyroscope. If your springs or steering components have too much play in them, the action of the tire trying to straighten itself will swing your springs under your frame like a pendulum. Your steering is connected to your frame, which is not moving, so as your axle moves sideways, your steering doesn't, and it turns the tires. Repeat in the opposite direction, repeat.... A violent wobble follows.

    If the wobble happens when you hit a bump, it's more likely loose components causing it. If it happens out of the blue at a certain speed, it's more likely your tires diagonally out of balance.

    Try swapping your tires front to rear and see if it makes a difference.
     
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  13. Nov 25, 2018
    Focker

    Focker That's what I do, I know things and I fix stuff. Staff Member 2019 Sponsor

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  14. Nov 25, 2018
    ITLKSEZ

    ITLKSEZ Volvophilic

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    That falls under "suspension components." Sloppy shackle and spring bushings, non-tight ubolts, cracked spring and shackle frame mounts... anything that could allow sideways movement.
     
  15. Nov 25, 2018
    Focker

    Focker That's what I do, I know things and I fix stuff. Staff Member 2019 Sponsor

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    One more question...

    Wouldn't "axle wrap" happen at low speeds and take off (torque) too?
     
  16. Nov 25, 2018
    47v6

    47v6 junk wrecker! 2020 Sponsor

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    If the rear tire is bouncing, its NOT death wobble. Its a shock thats blown out allowing the spring to bounce uncontrolled. When you experience "death wobble" you don't have time to look at your rear tire. You're trying to not die or kill someone else. BTDT

    Buy new shocks. The end.
     
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  17. Nov 25, 2018
    ITLKSEZ

    ITLKSEZ Volvophilic

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    Yup, axle wrap is basically the axle trying to drive out from under the vehicle under power. On a spring-over setup, the axle can do that. The further the axle is from the main leaf (i.e., lift blocks) or the softer the springs, the worse it is. The chatter you can experience with this is caused by the pendulum effect that it can cause. Spring-under setups are less prone to axle wrap because the axle is sitting on the main leaf, and the axle being above the spring counteracts a lot of the negative effects for reasons I don't have time to get into at the moment.


    Here it is in action on a SOA.
     
  18. Nov 25, 2018
    47v6

    47v6 junk wrecker! 2020 Sponsor

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    What an awesome video!
     
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  19. Nov 25, 2018
    heavychevy

    heavychevy Sponsor

    Danielsville georgia
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    Welcome from northeast georgia. Agree the shocks may be to blame. The angle the shocks are may contribute some too.
     
  20. Nov 25, 2018
    PeteL

    PeteL Member 2020 Sponsor 2019 Sponsor

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    Death wobble can be any one or a combination of a dozen factors. Steering geometry is a big one, and springs affect that. Loose or worn components are the other major source.
     

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