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Another quick shackle angle question

Discussion in 'The Garage' started by Can Can, Dec 10, 2006.

  1. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I was looking at the spring shackles on my V3500 today, and they appear to be oriented almost straight up and down, both front and back. I'm going to assume that is considered 0 degrees.

    Everything I've read claims that the "sweet spot" on a shackle is around 4 degrees. Would having a shackle at zero instead of 4 cause any ill effects?
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    My fronts are basically straight up and down , and I have no ill effects . When it compresses it goes to the back , and when it droops it goes to the front . All within what the designers had in mind for a stock truck .

    I wouldn't worry about it ( shackle angle itself ) if you plan on just driving it , and towing with it .
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I'm engaged in a showdown with some very minor DW right now, and I've just about got it licked. The problem is, the V3500 isn't gonna be driven until spring, so I figured I would take this time to edumacate myself on all things DW-related before I get her back on the road. Apparently shackle angle is one of the potential contributing factors.
     
  4. dremu

    dremu Officious Thread Derailer Premium Member

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    Oh oh oh.

    Castor angle is NOT shackle angle.

    Castor (caster, whatever) is the angle of an imagine straight line drawn through the knuckles, through the center of the ball joint or kingpin or whatever the knuckle turns on, from the vertical.

    Shackle angle will be determined by spring geometry and does not directly affect castor.

    Make sense?

    -- A
     
  5. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    I actually some minor death wobble after the front end rebuild after Moab . And the housing stayed on the truck the whole time . All I had done was removed the tie rod to get the carrier out . Never touched the springs or u-bolts .

    In my case it happened at certain speeds with light brake pressure . Turns out I had a bad rotor , and since I grabbed a whole hub rotor assembly from my garage , it wet away . It may or may not of been the main cause , but a bad rotor was the trigger . I am getting tw brand spanking new ones next brake job , and going to have my turned and set them on a shelf for ease of the time after that .
     
  6. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    :doah: :doah: :doah:

    I've been doing a little too much reading tonight, and managed to mix up my terms, which I'm sure provided for some head scratching for some of the guys, eh? :rotfl: :rotfl:

    This post is strictly about shackle angle, for now........
     
  7. dremu

    dremu Officious Thread Derailer Premium Member

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    Well, all that said, while the primary way to change castor would be shims between the leaf spring and the axle ... longer shackles would change the castor.

    Don't see why the shackle ANGLE would change anything, unless it was really close to horizontal or something ... :-?

    -- A
     
  8. Hossbaby50

    Hossbaby50 3/4 ton status

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    Shackle angle is more about ride quality then anything else. If you improve your shackle angle you improve the ride quality.

    Pauly, Death wobble can be cause by lots of stuff but if you took your tierod off the diff for the service & it got bumped out of adjustment the improper amount of toe can help cause death wobble. Rotor warp a very mild form of death wobble. If you have ever had true to life death wobble you know that rotor warp is a walk in the park. I remember the first time it happened to me was right after I did crossover steering & I thought the whole front of my truck was going to fly apart & after it was over I had to pick seat cushion out of my arse. :crazy:

    Harley
     
  9. blazinzuk

    blazinzuk Buzzbox voodoo Premium Member GMOTM Winner

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    This is just my opinion but I think a shackle laid back just a bit with a brace in the middle of it is the best for on road. I would probably leave well enough alone. I have messed around with shackle angles on a couple of Toyotas and it seems if they are laid back just a bit (like 5 degrees) they absorb hard hits on the road better. Same with my Blazer.

    Also I would think the sweet spot (if there is one) would be different on every vehicle. I just think about 5 degrees laid back rides nicer. Although I have not played around with a big v3500 before so it may be different
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'm about through fighting the death wobble now. Shackle angle was one thing that changed during the last build. Previously with the Rancho's my shackle angle was pretty much '0'...straight up and down. My current shackle angle is more like 15 degrees which makes it ride great. Did that contribute to my death wobble? I dunno to be honest. It certainly is one of the variables...and some change i made triggered the nightmare.

    My battle to date has gone something like this:

    Had death wobble on the second test drive (didn't go far or fast on the first drive)

    Checked caster angle...10 degrees positive which is too much from everything I read. Shimmed diff 4 degrees. Caster now at 6 degrees.

    Still had death wobble.

    Add one more fender washer to the stack already in there. Death wobble gone...but king pin springs bound and steering spooky.

    Order King pin rebuild kit. KP's good, no play in the bearings so I replaced the bushings and springs. Seemed fine, but steering felt 'light'. Drove for two days like that...got death wobble in traffic out of the blue. I'm thinking new springs and bushings settled just enough.

    Added a pair of fender washers. Death wobble gone...steering seemed a little weird, not terrible but enough that i wasn't not happy.

    Check toe-in (now that it has new bushings and springs) find it's toed in 9/16". Adjust it back to a hair under 1/4". Steering is almost 'there' now and still no wobble even when aiming for the stuff that used to set it off (potholes, manhole covers etc)

    In my case I think the longer shackles with somewhat aggressive angle, way softer springs being more apt to deflect laterally, way more suspension movement up front, and still unbalanced bias TSL's that I'm about as good as it's going to get for now. I'm very seriously thinking of adding track bars front and rear to remove the lateral flex from the equation.

    sooo Paul, my question to you is: have you added even a single shim washer to the top of your new king pin springs? Everything I've changed/experimented with or have been told is the magic cause hasn't done crap...except for adding a little pre-load to the king pin springs. About the only other sure fire 'cure' i know of is hydro assist steering (it's on my never ending list)

    Rene
     
  11. supersize75k5

    supersize75k5 OrganDonorRacing.com

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    :crazy:

    last two cases I had were completely resolved from adjusting the toe


    good god death wobble is nammed very well I will tell you that, hell that could be a nice prank if it did not have such ill effects..could cause an accident if it happen to the right person:eek1:

    good way to find loose bolts:D
     
  12. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Nope. That will be my very first project next spring. I'm gonna start with two per side and see if negatively affects my steering. If so, I'll go down to one and see if that adds enough preload to eliminate it.
     
  13. muddermilitia

    muddermilitia ThatTrazerGuy GMOTM Winner

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    Alright so you say that 5 degrees back would be good for the road, but what if the truck is only driven off-road.

    Would it be better to have more of an angle like +/-20 degrees? For more droop than compression
     
  14. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Mr. Canmore, it has come to my attention that since you bought this rig you have been frequenting the Garage more often.
    All the time you spend in here, Fumes and Boggerless are running riot in the Lounge while your back is turned....just thought you should know!:D
     
  15. beater_k20

    beater_k20 Banned

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    hush up foreigner! :wink1:
     

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