Alignment ?

Brian H · Oct 2, 2006

64FJ40 said:
No.

Bump steer refers to the phenomenon wherein (as Crusty described) movement of the axle (such as hitting a bump) causes a movement of the steering linkages (steer) that is independent of the driver's input.

Death wobble results from poor caster (and sometimes other things). If you've ever had death wobble, you understand precisely why it is thusly named.

In my 99 chevy truck with a 6 inch suspension lift I had the death wobble. There was no stopping it at 35 to 65 when i started. The only way that it went away was to come to a complete stop. So how was that caused when its an ifs truck? What my truck did is different from what that guys jeep did. The guys jeep is that way because he pointed the pinion at the transfercase and had tons of negitive caster which causes him to turn uncontrolably left or right to even a an unlevel spot in the road. As for my truck it would do it and shake the shat out of you and still b driving straight down the road.But you say that what the jeep and the truck do are the same thing.

Knok2222 · Oct 2, 2006

64FJ40 said:
No.

Bump steer refers to the phenomenon wherein (as Crusty described) movement of the axle (such as hitting a bump) causes a movement of the steering linkages (steer) that is independent of the driver's input.

Death wobble results from poor caster (and sometimes other things). If you've ever had death wobble, you understand precisely why it is thusly named.

Every cherokee ive been in has that problem....

64FJ40 · Oct 2, 2006

Knok2222 said:
Every cherokee ive been in has that problem....

I owned a cherokee once. It had a death wobble that was caused by bad/worn balljoints. Well, new ones made the problem go away anyway. Then I got rid of it.

Brian H said:
In my 99 chevy truck with a 6 inch suspension lift I had the death wobble. There was no stopping it at 35 to 65 when i started. The only way that it went away was to come to a complete stop. So how was that caused when its an ifs truck? What my truck did is different from what that guys jeep did. The guys jeep is that way because he pointed the pinion at the transfercase and had tons of negitive caster which causes him to turn uncontrolably left or right to even a an unlevel spot in the road. As for my truck it would do it and shake the shat out of you and still b driving straight down the road.But you say that what the jeep and the truck do are the same thing.

What you experienced in your truck is death wobble. Could be from bad balljoints, poor caster angle, etc. I don't know if anyone can precisely explain why death wobble happens sometimes and why it doesn't others.

The problem on the jeep usually manifests itself as really bad steering wander. Like it's nearly impossible to steer out of ruts in the road. If it's as bad as you're making it sound, it's pretty unsafe and there probably isn't an established name for the phenomenon since anyone who tried to drive it at highway speeds doesn't live long enough to tell the tale.

Clear as mud?

Brian H · Oct 2, 2006

64FJ40 said:
I owned a cherokee once. It had a death wobble that was caused by bad/worn balljoints. Well, new ones made the problem go away anyway. Then I got rid of it.

What you experienced in your truck is death wobble. Could be from bad balljoints, poor caster angle, etc. I don't know if anyone can precisely explain why death wobble happens sometimes and why it doesn't others.

The problem on the jeep usually manifests itself as really bad steering wander. Like it's nearly impossible to steer out of ruts in the road. If it's as bad as you're making it sound, it's pretty unsafe and there probably isn't an established name for the phenomenon since anyone who tried to drive it at highway speeds doesn't live long enough to tell the tale.

Clear as mud?

Well as for the truck i had all the joints replaced and les scrubs align it but it still had the problem. I guess it is a ifs chevy lift kit thing. As for the jeep it is a lack of fabrication skills on the owners part. It drives like that because he did a spring over a decided to get a better drive line angle at the same time(Big no no). I am going to fix that by cutting off the old perches and putting new ones on and setting the caster at positive 4 to 6 degrees and call it good.

CrustyJeep · Oct 2, 2006

What sort of tires did the chevy have on it?

TreeClimber · Oct 2, 2006

Brian H said:
I am going to fix that by cutting off the old perches and putting new ones on and setting the caster at positive 4 to 6 degrees and call it good.

And what then happens to the front drive shaft angularity? Cutting the (poorly designed) springover axle perches off, rolling the pinion back down to get the desired caster will give a large lifted rig a horrible front drive shaft angles. The possible cure is a CV front shaft, but the correct cure is to cut the (C) off the housing and rewelding them back onto the tubes in the correct location.

Crusty said:
Caster is important. It helps with your return-to-center and if it's negative I think it can cause, or at least accentuate death wobble. Don't fawk with it. If you want better pinion angle, great, but don't get it at the cost of camber. Cut and rotate your C's. Nobody wants to see you dead in a ditch because your rig got too squirrely at 32 MPH between trails.

Camber I would say is effectively irrelevant for this sport, for a couple reasons. First off, anything even remotely close to zero will work fine. Where as on a street or race car, where a degree can make a huge difference, a degree won't do diddly when your flexed up on a rock at .005 MPH. Uneven tire wear isn't even a consideration on a pure trail rig. Second, you can't change it much anyway on a straight axle. Forget about it :flipoff:

Jason C · Oct 2, 2006

if the rig has a poor draglink angle with poor castor it will make the bumpsteer more aparent. if the drivier has the wheel in a death grip the tires will turn. with his castor rolled forward his tires are turning at the ground making the rig feel twitchy since it will grab ruts and whatever bumps in the road. too much Castor and poor tire scrub (other that worn parts) are primary causes of death wobble. the more wheelbase the less castor the rig will need. After all this work is done to correct the castor the rig will still have bunpsteer. it will just not be as obvious since it will soak up bumps and ruts and "try" to return to center making the rig "feel" more driveable.

jeeptech 1 · Oct 2, 2006

TreeClimber said:
And what then happens to the front drive shaft angularity? Cutting the (poorly designed) springover axle perches off, rolling the pinion back down to get the desired caster will give a large lifted rig a horrible front drive shaft angles. The possible cure is a CV front shaft, but the correct cure is to cut the (C) off the housing and rewelding them back onto the tubes in the correct location.

Yes Treeclimber u r right but he should allso run jeep wagoneer knuckles (flat tops ) and convert to a high steer system like I run . I have no death steer or bump steer , pm me for setup setting.

Brian H · Oct 3, 2006

CrustyJeep said:
What sort of tires did the chevy have on it?

35 12.50 r 15 mud terrains

Brian H · Oct 3, 2006

TreeClimber said:
And what then happens to the front drive shaft angularity? Cutting the (poorly designed) springover axle perches off, rolling the pinion back down to get the desired caster will give a large lifted rig a horrible front drive shaft angles. The possible cure is a CV front shaft, but the correct cure is to cut the (C) off the housing and rewelding them back onto the tubes in the correct location.

A spring over on stock springs isnt a HUGE lift. It will be fine once its done.