death wobble

[liftedhorse]

First let me say hello to all im new here.I recently purchased a 1985 CJ7 ,told it was a daily driver and let me tell you it wasnt.I have replaced all tie rods,drag link,shocks,tires and brakes.It does have a three inch shackle which is my question.Can it cause a wicked speed wobble ? Thanks for any help.

 

[CJ]

Hello liftedhorse and welcome!

The shackles can easily be the problem. They change the castor angle of the front end.

 

[Old Dog]

A 3" lift shackel. That will cause all kinds of problems.

 

[BajaEdition]

Most death wobble is caused by bad joints and incorrect geometry on the drag link, caster being wrong could complicate things but the first thing is to find what is causing the wobble.
is there certain speeds, or when accelerating or decelerating?

 

[liftedhorse]

So i was told my axle angle is -1 should be between +3-5 they said its cause the shackles so today i will go buy new stock shackles and try that.

 

[TDHofstetter]

That's always a very good move. That'll also bring your driveshaft u-joints back into agreement with each other.

 

[liftedhorse]

Well i replaced the shackles with stock ones today and wow its like new again.The wobble is gone and all is tight on the road.Now on to the next project.

 

[Kane]

Good job buddy. It is nice to know that when you go out for a drive your Jeep will actually drive straight and not kill you.

 

[CJ]

Well i replaced the shackles with stock ones today and wow its like new again.The wobble is gone and all is tight on the road.Now on to the next project.

Glad to hear that. It's amazing what a poorly executed lift will do...

 

[liftedhorse]

You know what amazes me more is that they even sell something like that.I see jeeps all the time with the shackle kit.Worst invention ever.It makes me wonder if when i see jeeps slowing crusing the freeway its cause they start to wobbling if going to quick.

 

[CJ]

If you cut and reweld your spring perches, longer shackles can work. I believe Longhorn has longer then stock shackles.

 

[BajaEdition]

I have run longer lift shackles on many jeeps.
and you can set it up quite simply
here is what you do,
buy a set of new spring pads(perches) and u bolts
lift jeep and place on jacks to body so wheels are just off the ground, lock hubs in 4x4
take off the tie rod and drag link, and u bolts and push the axle to the side still cradled by the springs (keep an eye on the drive shaft, it should be no problem
mark on top of the axles exactly where the u bolts are so we can use this again to weld new pads exactly here again
cut off the old perches and grind the excess metal off axles
using the bolts on the diff cover as a place to set level, rotate the axle till these are 90 degrees to the ground, now chock the wheels to keep it there (remember we locked the hub)
So now we trust our leveling or get a hanging protractor to make fine tune adjustments till we get 90 degrees.
ok now to weld, first we want to make sure we do not weld the bearing surfaces together by just placing the ground anywhere, so we get a tab of metal and tack weld it about 1 inch from where the new spring pads will go. this is done on both sides.
A word of caution here, we do not want the path to ground to pass any bearing surface as this will heat the bearing, warping or welding it to another surface, we need the ground to be very close to our weld area so this does not happen.
ok, slide the axle back over till centered on the springs and set up the slide the pads where they need to be, bolt on the old u bolts set the jeep off the jacks and unlock hubs. Now we need to make sure we have retained the level angle at the diff bolts. If all is correct, tack weld the pads and lift the jeep again, unbolt and push the axle off the springs and weld those puppies on.
Paint
set back on springs using 3 degree shims to maintain 3 degree positive caster. or that the top of the axle is 3 degrees toward the cab, from strait up and down.
Ok that was not hard at all, the only specialty tool besides a welder and grinder needed is a hanging protractor and you can get those at sears for less than 20 clams.

Just remember. when ever you are taking the jeep off the jacks the springs must be bolted to the axles. I have actually seen someone forget this, not good.

 

[coldwater]

Worse death wobble I have ever seen.....just horrible...

YouTube - Anchor laughs at model falling down twice

 

[LongHorn]

Worse death wobble I have ever seen.....just horrible...

YouTube - Anchor laughs at model falling down twice

Most death wobble cases I've seen occur at speed over 40 mph.
That's got to be the slowest DW I've ever seen.

 

[liftedhorse]

With all the work of cut, weld, grind and hope your there with proper degree why not just but a lift kit involving new springs.I have lifted alot of trucks and assume that shackles are not the best way.I will stick with traditional spring lift and probablly use national springs and bilstein or fox which is what i have used in the past on my other toys.

 

[BajaEdition]

good question, but not everyone wants the same thing.
spring rate, expense,and other things get involved
Ordering off the shelf is like going to mcdonalds, you get what is offered, a lot of guys want to set up a jeep this way or that and then tune it in.
I run 2 1/2 inch springs with 1 1/2 shackle lift so that I have a softer spring rate and more articulation, the down side is I have to tune in the steering geometry. OK, I know where things need to be and will do the work to get them there. I just showed how.
Most guys will just buy an off the shelf spring kit and never question how things turn out, and later sell the jeep until someone who cares, and is looking to get the Jeep right shows up and ask questions. I answered that question.

 

[LongHorn]

With all the work of cut, weld, grind and hope your there with proper degree why not just but a lift kit involving new springs.I have lifted alot of trucks and assume that shackles are not the best way.I will stick with traditional spring lift and probablly use national springs and bilstein or fox which is what i have used in the past on my other toys.

Your right about "National Springs".
They make a great product, but you'll pay for it.
I've been running a set of their springs on my 1 ton Ford for about 12 yrs.
Before that I had another 1 ton with a set of their springs for near the same amount of time. They don't sag at all & I've used those trucks to haul heavy loads, skid logs, pull heavy trailers. They don't come cheap though.

 

[Crjcw]

My 68 does this from time to time, always around 35 or 40 mph. I have noticed a lot of play in my front shackles, you think that could be it? It hadn't done it a while, and then I had a slight load in the back, and bam! 4 Times on that 30 mile trip.

 

[LongHorn]

My 68 does this from time to time, always around 35 or 40 mph. I have noticed a lot of play in my front shackles, you think that could be it? It hadn't done it a while, and then I had a slight load in the back, and bam! 4 Times on that 30 mile trip.

Sounds like a great Jeep, "Con-Fer" use to make great products.
When you load up the back of the Jeep, you take weight off the front suspension. This let's the slack out of your worn parts including your shackles.
That slack moving around causes DW. The shackles are part of it, but I'd bet theres more.

 

[LongHorn]

My 68 does this from time to time, always around 35 or 40 mph. I have noticed a lot of play in my front shackles, you think that could be it? It hadn't done it a while, and then I had a slight load in the back, and bam! 4 Times on that 30 mile trip.

Shackles, Ball joints, tie rod ends, wheel bearings, there are many contributing issues that can causes DW.