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bump steer ?
January 12, 2009
9:22 pm
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Fred
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While working on other things on the Jeep this weekend, I took the time to compare the draglink and trackbar angles. I've got about a 2" difference in angle at the frame/pitman arm end of the trackbar & draglink. I know that in a perfect configuration they would be perfectly parallel. Does anyone have any idea how far off they can be without having bumpsteer?

I've got the RE 1610 trackbar with 1611 trackbar bracket with the stock pitman arm. I'm wondering if I could further improve my steering and handling by removing the 1610/1611 combo and going with a different trackbar mounted to the factory mount or maybe switch to a drop pitman arm.

January 12, 2009
11:02 pm
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I'm no expert in front ends, but everything I've read says not to drop the pitman arm unless your lifting 6" or more.

I've read using a dropped pitman arm on a 4 or 5" lift increases the bump steer.

anybody else?

January 12, 2009
11:12 pm
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JohnDF
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Rob and Justin run a dropped pitman arm. I don't think they get bump steer. But they are lifted over 5 inches. I still run the stock pitman arm, no bump steer, and over 5 inches. Also, my angles don't match exactly, and no bump steer. Just get them close and it should be fine. It's a Jeep, not a Lexus.

I used to wheel a lot. . .

January 12, 2009
11:21 pm
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Fred
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"gamfam" wrote: I've read using a dropped pitman arm on a 4 or 5" lift increases the bump stear.

That's what I've always heard too. But I've also heard you need to keep the trackbar and draglink parallel. Before switching to the RE1610 trackbar with RE1611 bracket my steering would have been parallel.

Generally speaking, the RE1611 bracket isn't recommended for a 3.5" lift either. I installed it with my 4.5" lift and retained it when I went back down to 3.5". I had to clearance the spring perch a bit to make it work. I also had to shorten the threaded shank of the RE joint on the trackbar so I could adjust it to work with the smaller lift.

At this point the trackbar mount at the frame end is a couple inches lower than the draglink/pitman arm TRE. To get things parallel I either need to raise the trackbar mount or lower the draglink TRE. RE's installation instructions note that a DPA should be installed when using the RE1611 bracket.

http://www.rubiconexpress.com/Img/Produ ... ions/0.pdf

Or, I can just leave well enough alone, but since when did that start?!?!?

January 12, 2009
11:26 pm
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Fred
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"JohnDF" wrote: ... my angles don't match exactly, and no bump steer. Just get them close and it should be fine.

I can't really say that I feel like the Jeep has bumpsteer. I'm probably just dreaming if I get the front end as perfect as possible I wouldn't have to replace the Detroit locker. embarassed

edit) I've been trying to think back to when I first started noticing the locker issues. It was about the time I went from 3.5" springs to 4.5", installed the front anti-rock, Currie steering, and RE1610 trackbar and 1611 mount. Since then I've gone back to 3.5" springs and replaced the anti-rock with a sway-lock.

January 13, 2009
1:54 am
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RobD
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"JohnDF" wrote: Rob and Justin run a dropped pitman arm. I don't think they get bump steer. But they are lifted over 5 inches. I still run the stock pitman arm, no bump steer, and over 5 inches. Also, my angles don't match exactly, and no bump steer. Just get them close and it should be fine. It's a Jeep, not a Lexus.

Wrong, I run a CJ pitman arm that is flat.....

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January 13, 2009
2:02 am
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I have spent stupid amounts of time and money trying to sort out the same thing. (Perfect handling Jeep)
Shocks have played a huge role. I have the other Rubicon Express track bar if you would like to give it a try?

Do you also have the 1/2" bolt in the bushing end of the track bar?

January 13, 2009
2:06 am
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BKGM Jeepers
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I run a stock pitman arm and have no problems. I think Rob's (the CJ style) is truely flat.

I believe it comes down to the how parallel your drag link and track bar are (and how good a shape your bushings are in).

January 13, 2009
2:38 am
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Fred
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"jsmorrow" wrote: I have spent stupid amounts of time and money trying to sort out the same thing. (Perfect handling Jeep)
Shocks have played a huge role. I have the other Rubicon Express track bar if you would like to give it a try?

Do you also have the 1/2" bolt in the bushing end of the track bar?

Yes, I've drilled out the axle end of the trackbar mount for a standard size bolt. I don't recall if it's 1/2" or something a little smaller. And the trackbar mount at the frame end is drilled out for 9/16" or whatever it is for the RE1600 trackbar. I've got a brand new JKS trackbar that mounts like the RE1600 I could try, but I'd have to drill out the axle-end bushing to fit the standard size bolt.

January 13, 2009
2:47 am
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Fred
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"BKGM Jeepers" wrote: I believe it comes down to the how parallel your drag link and track bar are (and how good a shape your bushings are in).

I pulled a string from the axle end of the trackbar bolt up to the frame end of the trackbar bolt. Looking at it from the front, the axle end of the trackbar lines up perfectly with the draglink. The frame end of the trackbar is about 2" below the draglink. So it's not too far off, but it is off. All the steering joints and trackbar bushings are in good shape.

A drop pitman arm isn't that expensive or difficult to replace, I may just get one to try it out. I could modify the JKS trackbar I have and try it, but if it doesn't work out I've pretty much ruined the resale value.

January 13, 2009
2:56 am
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Fred
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Assuming a drop pitman arm would get my draglink and trackbar parallel, are there any drawbacks to using a drop pitman arm?

January 13, 2009
3:18 am
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RobD
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"BKGM Jeepers" wrote: I run a stock pitman arm and have no problems. I think Rob's (the CJ style) is truely flat.

I believe it comes down to the how parallel your drag link and track bar are (and how good a shape your bushings are in).

It is almost flat, I think there is like a 3/4 inch drop in it.

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January 13, 2009
4:25 am
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BKGM Jeepers
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"RobD" wrote: [quote="BKGM Jeepers"]I run a stock pitman arm and have no problems. I think Rob's (the CJ style) is truely flat.

I believe it comes down to the how parallel your drag link and track bar are (and how good a shape your bushings are in).

It is almost flat, I think there is like a 3/4 inch drop in it.

I think the TJ pitman arm provides about 2" of drop.

January 13, 2009
2:35 pm
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Justin
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Here is my set up when it was all shiny and new. You can see that the dropped pitman arm lined everything up about perfect. 8)
The second pic is the drawback of a dropped pitman arm. Tom and I have both broke them. 😯 We can only guess it was from the added side torque it takes when steering.
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January 13, 2009
4:30 pm
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Fred
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"Justin" wrote: The second pic is the drawback of a dropped pitman arm. Tom and I have both broke them. 😯 We can only guess it was from the added side torque it takes when steering.

Thanks Justin, it makes sense that the DPA has additional leverage and would be more prone to breaking. I think I'll give my other trackbar a try.

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