Almost killed myself. Time to Diagnose!

[Pznivy]

^^ Excellent Post. excellent info. Im on the sidelines for this one, but its info every lifted truck will need.

My question is, how do you know when its right? Is it some crazy geometric equation? Or is it right or wrong. Meaning, is the install fool proof?

Or do i need a shop to measure down to the millimeter and then do alignment afterwords?

I'd like to do this and install myself, but need it to be completely correct. Need the keep my passengers in good shape.

[Timmy]

My question is, how do you know when its right? Is it some crazy geometric equation? Or is it right or wrong. Meaning, is the install fool proof?

I'm assuming you are referring to the track bar and the drag link being parallel to each other? Just for reference for everyone, a non-parallel solution creates "bump steer" not "death wobble." They are two different issues entirely. To your question, I don't think it needs to be that accurate, it just needs to be close. Obviously, the closer it is, the better the ride, but it's not like if you are off 1/2" that you will have a bad ride and bump steer all over the place. I think with most Jeeps, we are so used to a little play in the steering that if you came to a stop and the wheel moves say 1 degree left, it's not going to drive you that bonkers. The bump steer that drives you nuts is when you are going over speed bumps and the wheel whips hard to the left say 5 degrees even though the Jeep tracks straight.

Also, the fix is easy, I don't personally think you need an alignment afterwards. I replaced my own tie rod end on my tie rod bar, which certainly impacts the toe in/out of the wheels (that was to fix death wobble, not bump steer.) I then went for a drive and checked out how the vehicle drove, decided if I liked it or not, and came back and re-adjusted as needed. I noticed how my tires were wearing prior to this change and I noticed that the inside of my tires were wearing much faster than the outside. I realized this was because of too much toe-in from the shop that put the lift on, so I took some of that toe-in out and now my tires are wearing nice and even and the Jeep drives great! I just keep an eye on my tires on a regular basis to see how they are wearing. As for the drag link and alignment. Jeep and Syngergy has made this stupid simple to adjust. Basically, if you drive down the road and your steering wheel is not center, just shorten the drag link if the steering wheel is left of center while going straight, and extend the drag link if your steering wheel is right of center while going straight. Probably three or four trips up and down the road and you can pretty well get your steering wheel dead center while driving dead straight down a road.

When I bought my Jeep and started to learn about the lift on it, bump steer, death wobble, and the dynamics of a solid axle under a body, that's when it all started to click with me. I never really realized that your front axle actually shifts left and right under the body depending on if the axle drops (say catchin' a little air, grin) or compresses under the Jeep (think speed bump.) Engineer Johnny had to find a way to prevent the steering wheel from moving/rotating as the drag link moved up and down, which obviously either shortened or elongated the distance from the wheel to the pitman arm of the steering. That is ultimately the purpose of the track bar, and why it is crucial that it is parallel with the drag link. When the suspension compresses, the track bar forces the axle to the passenger side every so slight, say 1" depending on how much it compresses, or pulls it to the drivers side if it drops. It needs to move the axle to the passenger side because as the axle comes up into the Jeep, the drag link comes up as well, and since the drag link comes up, one of two things must happen. Either A) the steering arm (pitman arm) needs to move to the drivers side since the distance itself is shortened, thereby creating "bump steer" or B) the axle must move to the passenger side, thereby keeping the distance from the pitman arm to the wheel the same, ala, no bump steer.

So, long story short, it doesn't have to be exact, but obviously the closer the better. If you don't flip your drag link from the bottom to the top of the knuckle, then you really shouldn't need to relocate the track bar because Engineer Johnny at Chrysler already put those two in parallel with each other. The problem with not relocating though is that the angle for normal driving is now steeper, which naturally shifts the axle to the drivers side so they are not running in-line with the rear wheels. You can elongate the track bar and draglink to fix this, but the angle is still steep which means any compression will really move the axle to the drivers side a lot. To fix that, you ultimately want the drag link and the track bar as horizontal as possible, and they only way to make that happen is to flip the drag link to the top of the knuckle. Well, once you flip it, you track bar is no longer in parallel, so you now have to relocate that up by the same distance.

Hope this helps anyone struggling with bump steer. Feel free to ask more questions, or there are already gobs of posts on this all over the web.

A picture is worth a 1000 words on this subject, so here's a few that I found that help describe the situation better.





PS... All this does make you wonder... Why hasn't Engineer Johnny found a way to locate the steering box directly on the axle so the distance of the drag link NEVER changes to begin with?

[JeepLab]

Whoa Timmy!

You are killing it with the pics!

This is great info. Im going to start tearing Betty's steering apart. If im gonna get in there, im going to strip it down completely and figure out whats going on.

I will not just blame the stabilizer, (even though the stabilizer is definatly getting changed.)

[Snarf77]

Whoa Timmy!

You are killing it with the pics!

This is great info. Im going to start tearing Betty's steering apart. If im gonna get in there, im going to strip it down completely and figure out whats going on.

I will not just blame the stabilizer, (even though the stabilizer is definatly getting changed.)

I'd like to see some pics if you find anything suspect.