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Death shake straight axle. Why?

Discussion in 'The Hokey Ass Message Board' started by merctruck, Mar 15, 2012.

  1. I bought this truck with a shake in the front end at times. You will be driving down the road at 25 or 30 and hit a bump and the front end was getting this horrible death shake. If you slow way down it would stop. Someone told me it was bad heim joints on the pan hard bar so I replaced them and went for a test cruise. Once I got up to about 25 to 30 again and hit a bump it started the shake again. Can't figure this one out. Yes I did a search before I posted and did not see a problem like mine or a answer that would fix my problem. Sorry if it has been posted before and did not find it but please help.
     
  2. sounds like the ideler arm is gone
     
  3. It has do do with caster angle. Most straight axels like around 6 to 8 dergees negitive. Which means the axel leans back. And they like a bit of toe in, adound 1/8th of an inch.
    If you have check all the components in the system and can find no bad components then check the caster. The also like about 1/2 of a degree negitive camber.
     
  4. what kind of truck are we talking about hear ??? maybe we can get some alignment info for you and then you could have it checked out. or jack up the front end and grab hold the front tire and shake it boath up and down and side to side .This could tell you a lot without costing you anything ..do it just to see .....
     
    Last edited: Mar 15, 2012
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  5. deto
    Joined: Jun 26, 2010
    Posts: 2,621

    deto
    Member

    my buddy spent a month and plenty of dough fixing a front axle death wobble. It was bad tires...
     
  6. brianj
    Joined: Jan 1, 2012
    Posts: 93

    brianj
    Member

    What do you have for a steering set up? You might want to do a search on "death wobble" or "Ackerman angle". Check this out well- it is called the death wobble for a good reason.
     
  7. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    Member
    from florida

    Do a search of death wobble. You will see that there are 100 things that can cause it and sometimes the reasons are elusive. So many factors that contribute. Most of us have had DW at some point and we didn't all have one single thing that we could put our fingers on, it usually is a combination.

    Not that this is a cure all, but put a So Cal stabilizer on the front end, but first do everything possible that you read about to solve the problem. I don't want the stabilizer to mask your problems, but just enhance the road feel once you get things corrected.


    Don
     
  8. BobF
    Joined: Dec 30, 2004
    Posts: 230

    BobF
    Member
    from Poway, CA

    Ahh the death wobble. Wheels start oscillating, steering wheel going back and forth like crazy.
    I had this problem once on a Model A with tiny skinny front tires, only happened when hitting a imperfection in the road surface, but I could never figure exactly WHAT kind of imperfection caused it. I almost eliminated it by going to slight toe out vs toe in. It didn't seem to be caused by worn out parts, as I replace a bunch, with no help. Eventually I changed the front wheels and went to a slightly larger wider tire, never had the problem again.

    I've seen Top Fuelers have the same problem after a burnout, Larry Dixon in particular a few years ago.
     
  9. Roadsterpu
    Joined: Nov 10, 2008
    Posts: 895

    Roadsterpu
    Member

    I chased a death wobble in my RPU that woudl only show up when I hit a bump. As soon as I fixed it, it would start again. I tried caster changes, new kingpins, new axle, New tie rod, tire rod ends, noone of it worked. My first fix was to adjust toe-in. Once I got it set at 1/16" it would start again. I changed the rear tires and it went away again. It came back and I tried changing the toe-in from 0 to 1/8" and no help. I raised the front tire pressure and it went away. I was running 15-17 PSI on a 2100 pound car. at 22 PSI there is no issue. Hopefully it will not come back.

    Tell us a little more about what kind of suspensiona nd steering you have on your truck and what you have tried.
     
  10. the lights
    Joined: Apr 23, 2009
    Posts: 113

    the lights
    Member

    I had this problem as well, someone told me to replace my shocks so that's what I did.
    It actually worked so try the cheap and easy things first.
     
  11. F&J
    Joined: Apr 5, 2007
    Posts: 13,217

    F&J
    Member

    My take is that it is more common on cars with heavy caster (7) AND the wrong wheel offset on the fronts....like your mags...they will shove the scrub radius way off. Also more common on side steer vs. cross steer.
     
  12. I had the same thing. I do have weak shocks. It is almost gone with increased air pressure. I have no loose front end parts and my alignment was good. The above posts that talk about many factors are true. Make sure nothing is loose. Then check alignment and pressures
     
  13. pasadenahotrod
    Joined: Feb 13, 2007
    Posts: 11,776

    pasadenahotrod
    Member
    from Texas

    The most common cause of this situation in an old worn-out car is bad kingpins/bushings and a worn-out or poorly adjusted steering box.
    This really never happens on a correctly built hot rod because we replace worn out parts before we go riding and we adjust things like steering and suspension and wheel alignment too.
    There are a myriad of things like bad tires that can cause the rpoblem too but that is the most likely to start with.
     
  14. designs that work
    Joined: Aug 29, 2005
    Posts: 411

    designs that work
    Member

    I had a shake at a specific speed with my modified. Everything in the front end and steering was brand new except the wheels and tires. The tires and wheels were my friends, tires were old but in good condition. Finally bought new tires, same shake at same speed. Tires and wheels were balanced off the car. Took the wheels and rotated or clocked them two studs. Apparently the brake drum was enough out of balance to cause the shake and rotating the wheel two studs was the solution.
     
  15. 500LBGorilla
    Joined: Jul 30, 2003
    Posts: 402

    500LBGorilla
    Member
    from Austin Tx

    had the same thing, old tires..
     
  16. All of them I've chased down have been worn or loose parts, King pins, tie rod ends ect.
     
  17. Separated belts in the tires would definatly give you a shake. Try another set of tires from a buddy and eliminate that variable. Doesn't cost nothing and easy. Got fooled a few times in the past.
     
  18. SKULL ORCHARD
    Joined: Jul 22, 2009
    Posts: 432

    SKULL ORCHARD
    Member
    from KS
    1. The Gas House Gang

    put a steering stabalizer on it, fixed there less than 25$
     
  19. Rookie1
    Joined: Apr 5, 2009
    Posts: 63

    Rookie1
    Member

    Agree with all of it ! A tire worn a little more on the inside or outside (conical) will cause this, pulled my hair out on a 4x4 and it was uneven tires.
     
  20. coolbreeze1340
    Joined: Aug 18, 2009
    Posts: 1,342

    coolbreeze1340
    Member
    from Indiana

    I have been there and I got all the same answers you did. It sounds like you have the same issue I had which is different than "death wobble". Check the back connection on your hairpins (I can't tell from your pics but I think you have hairpins on that front-end). I had one that had loosened up in the past so I tightened it down. When I started chasing the problem I couldn't get it fixed. Tried differnet tires, re-aligning everything, checked everything twice. Then I pulled the rear connection of the hairpins and removed the bolts completely. One of the connection points had worn in a egg-shaped! (The rear connection went to a sleeve that went thru the 32' frame) I got a new sleeve, cut out the old, welded in the new! No more death hop going down the road. I drove the car lots after that fix and it never came back. Good luck and if my post was confusing PM me.
     
    Last edited: Mar 15, 2012
  21. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,243

    Mr48chev
    ALLIANCE MEMBER

    Leaning the axle back creates "positive" caster. Also

    Unless you are doing some sort of corner cutting racing the norm for the street is to run "positive" camber rather than negative camber. The piece of misinformation comes about due to the fact that magazine articles about setting up cars for autocross racing where going around corners fast tops having the car track down the road in a straight line. By the way Negative is leaning in at the top while positive is leaning out at the top.

    Going back to the original subject of the thread. I fought the dreadetird death shake on my T bucket when I had it and attribute a lot of it to the tire/wheel combination that I was running, balance or lack there of on the tires and the just right looking lever shocks that I ran on the front.

    Thees first thing I'd do is jack the car up and check the front tires for runout. Make sure that they are actually round . Then if they pass that test find a shop with an on the car spin balancer that can spin the tires on the car and dial the whole tire/wheel/hub assembly as far as balance goes.

    Then it's check the shocks to see if they are actually doing their job and check each and every piece in the front end for wear.

    The wrong amount of toe in may cause the vibration problem or allow something to cause it and not dampen it.
    too little or excessive caster could be an issue as I now believe I had seriously excessive caster on my T. That was bad when I worked as a front end man and did wheel alignments daily along with spending about 50 percent of my time chasing down vibrations for the extremely picky and spoiled customers of Frank Weaver Pontiac in Waco, Tx.

    I don't think camber excessive or not would weigh into this problem one way or another. Proper camber keeps your tire tread in good contact with road and usually on American roads having 1/4 degree more positive camber in the left wheel than the right wheel will help the car/truck track down the cambered roads we have and drive straight. Too much positive camber in towards the drivers side might cause the car to drift to the left and too little difference between the wheels may allow the car to drift to the right. Roads in areas with more rain that have more camber built into the road to allow rain to run off need more positive left wheel camber bias than roads in Arizona would.
     
  22. fiftee6effie
    Joined: Oct 23, 2011
    Posts: 124

    fiftee6effie
    Member

    With no specifics on year make or model I agree mostly that loose components are the problem and an often overlooked pieces are the adjustable drag link ends which have springs inside holding the ball sockets. The adjusters have to be adjusted good and tight to eliminate deflection of the spring and causing a shake or wobble . An old front end guy I know who worked on cars and trucks from the fifties told me this problem was very common. Good luck!
     
  23. I had this problem on a non-Hamb car. It turned out to be a tie rod stabilizer that evidently got air in it. Instead of dampening the movement of the tierod it pushed back, causing the oscillation. Replacing the damper cured the problem.

    Alden
     
  24. austinhunt
    Joined: Nov 26, 2011
    Posts: 533

    austinhunt
    Member

    All good info here and it may be too late to post, but RESONANCE is a major problem in a light vehicle.

    Try changing to a different shock with a different damper rate. You could have all the right set up and just have a resonance between some of the parts (tires, spring, chassis) that amplify eachother.This is a problem for newer mustangs and often on race cars.
     
  25. Had the same thing with new bias tires. Never used that of type of tire since and no issue's since.
     
  26. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,284

    Kerrynzl
    Member

    The most difficult one I had to cure was on a Mitsy Pajero [ Montero ] with 31 x 10.5 x 15 tires.
    Everthing was new in the suspension, front wheels alligned correctly, balanced etc.

    In the end I discovered it while driving really slow on smooth hotmix asphalt.
    The R/R tyre was out of round ,creating a temporary Wedge in the ride heights [ the caster was trying to correct this by steering left and right as the wheel went round and round ]
    There are many crazy causes of "death wobble" [ too much caster is one ] but make sure everything is mechanically healthy first!
     
  27. John 79
    Joined: Aug 13, 2006
    Posts: 922

    John 79
    Member
    from Sweden

    Had this problem on my bucket at high speeds.
    Had to do with the offset of the front rims.
     
  28. langy
    Joined: Apr 27, 2006
    Posts: 5,735

    langy
    Member Emeritus

    Post some pictures of your setup would be the first step, you may have something obvious that is wrong, As Donshotrod said there can be many contributing factors to this problem.
     
  29. TheTrailerGuy
    Joined: Jun 18, 2011
    Posts: 392

    TheTrailerGuy
    Member

    How about an all brand new system? I don't know if I would call mine a death shake but she starts a really annoying shimmy right where you hate it... 55-60mph. Brand new everything, 6 degrees of caster. I have tightened up the friction shocks, set the air pressure on the tires over and over and it still shows up. I am sure it is something easy and I will figure it out and post here when i get mine fixed.
     
  30. langy
    Joined: Apr 27, 2006
    Posts: 5,735

    langy
    Member Emeritus

    Do you have a 7/8" OD tierod ???
     

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