TJ Draglink and Trackbar in same plane - why ?

[DippStick]

OK, I'm getting my hi-steer done as we speak and have always read that the angle of the draglink and trackbar should be approximately equal.

Why is this and what will result if they are not ?

Thanks

DS

[FNG]

Bumpsteer

[Dan-H]

Originally posted by FNG:
<STRONG>Bumpsteer</STRONG>

geez FNG, do ya have to drone on and on with the long explanations <IMG SRC="smilies/wink.gif" border="0">

[Jerry Bransford]

Heh heh, I'm incapable of short and to-the-point answers like "Bumpsteer".

Unless the draglink and trackbar (AKA Panhard) are parallel, the draglink's radius will change disproportionately to the trackbar as the suspension moves up and down. That causes the steering wheel to turn left and right as the front suspension travels up and down... which is known as 'bumpsteer'. So if you hit a bump, the steering wheel can be violently spun right or left out of your hands. Or as you crawl slowly over uneven terrain, you'll feel the steering wheel turning left and right in sync with the front axle's up and down movements.

So yep, it's important the steering geometry be considered to avoid such problems.

[DippStick]

The reason I asked this is I've always read this but it doesn't make a lot of sense.

I thought bumpsteer is caused by too high an angle in the draglink - it has nothing to do with the front trackbar. The purpose of the trackbar is to center the axle.

DS

[mike]

Originally posted by DippStick:
<STRONG>The reason I asked this is I've always read this but it doesn't make a lot of sense.

I thought bumpsteer is caused by too high an angle in the draglink - it has nothing to do with the front trackbar. The purpose of the trackbar is to center the axle.

DS</STRONG>

Well, this is true on a leaf sprung vehicle. Since the springs retain the axle in a fixed position the droplink has to be on the same plane as the tierod to keep it moving on the same arc as the suspension. On a linked suspension the springs do not provide this functionality, so the trackbar does. Since the trackbar is now doing the work the leaf springs do (and thus effecting the arc the axle travels in while cycling) the droplink has to move in the same arc as the trackbar.

[nasvik]

DS - where are you putting the tie rod? Or... how are you doing the hi steer? I'll be doing mine shortly too.

Paul

[DippStick]

I got a single hi-steer arm from Joel @ StageWest. The mounting lock cones and c-lock nuts are coming from Dynatrack. I believe they sell the arms also.

You can get D44 arms from www.samsoffroad.com which should help ya <IMG SRC="smilies/wink.gif" border="0">
They have pics of the shape.

I'm drilling the cast knuckles out to 3/4" and using heims from MORE on the tierod.

On the draglink I'm drilling out the hi-steer arm and using a 3/4" heim there with a 1/2" spacer to allow flex and mounting underneath.

On the PA side I'm drilling through a stock PA @ 5/8" and mounting the RockRam above and a 5/8" heim below.

I was asking about the trackbar because Troy doesn't believe me on the dragling and trackbar having to be @ the same angle. I wanted clarification since I've seen it written on various boards so often - I just wanted to know why.

I guess we may need to lift the trackbar mount slightly (although CJ Lagos thinks its pretty good if you go under the hi-steer arm).

DS

[nasvik]

Sounds similar to my plan. I'll do a Heim ended trackbar like you describe. Will put it under the hi steer arm. The ram will attach to the pitman arm like yours.

I think the tie rod will go knuckle to knuckle on top of the stock location. TREs though. They'll be one ton stuff. I'd like to put it higher, but I think it'll interfere with the springs on full turn.

Paul

[Dan-H]

<STRONG>I think the tie rod will go knuckle to knuckle on top of the stock location.</STRONG>

I looked at doing an over-the nuckle TR but it looks like the sway bar mounts would need to move, the steering stabilizer mount would have to move or be trimmed and the leading edge of the spring cup mounts would need to be trimmed.

are your knuckles different than mine?

- Dan

[nasvik]

Dan - yes my knuckles are different. The whole front axle is a lot bigger. <IMG SRC="smilies/biggrin.gif" border="0">

I'll be removing the stabilizer, and moving the link brackets is no problem.

Paul

[ChinLei]

One thing I haven't seen mentioned on this thread is that the drag link and the track bar should not only be parallel, but equal length also. Just my 2 cents.

[DippStick]

Why equal length ?

DS

[nasvik]

DS. Take two toothpicks and hold them parallel between your fingers. Move one side up and down. The fingers stay parallel. Now, cut 1/2" off of a toothpic and to it again. Each toothpick will travel in a different arc. Same is true if the ends are different differences apart, but the toothpicks are the same length.

That's bumpsteer. <IMG SRC="smilies/biggrin.gif" border="0">

Paul

[DippStick]

Hmmm, OK, that makes sense.
Something else to consider I guess.

Thanks

DS

[Brad Kilby]

My track toothpick is 3" shorter than my steering tooth pick and I don't have bumpsteer. I guess I should go fix it, huh? <IMG SRC="smilies/biggrin.gif" border="0">

[M/C MAN]

I like the idea of using a light weight material for parts, but what do you guys weld the toothpicks with? Matches? I can't get them to hold very well. <IMG SRC="smilies/rolleyes.gif" border="0">

[Grandpa Jeep]

Originally posted by M/C MAN:
<STRONG>I like the idea of using a light weight material for parts, but what do you guys weld the toothpicks with? Matches? I can't get them to hold very well. <IMG SRC="smilies/rolleyes.gif" border="0"></STRONG>

They take that special Wood rod. <IMG SRC="smilies/biggrin.gif" border="0"> Expensive and hard to get though.

[mike]

Originally posted by Brad Kilby:
<STRONG>My track toothpick is 3" shorter than my steering tooth pick and I don't have bumpsteer. I guess I should go fix it, huh? <IMG SRC="smilies/biggrin.gif" border="0"></STRONG>

betcha it all moves in the same arc dont it <IMG SRC="smilies/wink.gif" border="0">

[nasvik]

Originally posted by Brad Kilby:
<STRONG>My track toothpick is 3" shorter than my steering tooth pick and I don't have bumpsteer. I guess I should go fix it, huh? <IMG SRC="smilies/biggrin.gif" border="0"></STRONG>

Yeah!! There's no way you can't have bumpsteer!! <IMG SRC="smilies/wink.gif" border="0"> <IMG SRC="smilies/thefinger.gif" border="0">

Paul

[P&T Jeeps]

Dan, I have already done a setup similar to what you are describing on my TJ. I could not use a solid tie rod from knuckle to knuckle is b/c I have 30 knuckles on a 44 and the tie rod would not clear the diff cover. So I ran a solid draglink to the top of the knuckle then welded a bracket at about a 45 degree forward/down to connect the tie rod to. This was very effictive in eliminating any play you might have in you steering wheel. I did learn not to drill out your knuckles to 3/4", rather drill to 5/8" and use a reducer in the heim. This will allow you to use the tapered spacers from RE to get more movment out of the heims. The swaybar mounts do have to be moved and the spring perches cut as you said. So far I have been nothing but satisfied with the setup. I do have some pics if interested.

[nasvik]

Originally posted by P&T jeeps:
<STRONG>I do have some pics if interested.</STRONG>

Yes please!!!

[DippStick]

P&T,

My axle has D60 knuckles so it's slightly different to your setup. This is how I can drill to 3/4".

I'm getting 1/2" tapered spacers made for all the heims to allow them to flex properly.

Things nearly done if Sams Offroad could feed their monkeys now and again and get them to do some work <IMG SRC="smilies/wink.gif" border="0">

DS

[P&T Jeeps]

dipp, where are you getting the spacers from? I couldn't find any with a 3/4" ID...

[DippStick]

A friend in San Jose is machining them for me <IMG SRC="smilies/smile.gif" border="0">

DS