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Discussion Starter #1 (Edited)
I've posted this comparison before but not in its own thread. The results are pretty interesting. From my experience, the high roll center works much better in all conditions. I haven't noticed any jacking. This comparison helps show how it effects axle location during articulation:

Front - 13.3" from ground to roll center


Front - ~30" (actually a trackbar)


Rear - 19.75"


Rear - ~30"
 

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roll center is what ???

the point on the where the axle is held stable from side to side movement ???

so now what about with a traditional panhard setup??
the axle movement isnt nearly the same.
my cruzah is pretty low and i have a short panhard up front. maybe 28"......with the setup i am using my rig is really stable on sidehills.....no roll at all from the coilovers. it handles good on the road too
:D

i guess with the 4 link , depending on where you mount the arms you can decide where you want the axle to swing for clearance etc. then on the chassis side you can make it more stable on sidehills etc etc..... but then you still have to worry about as and all that. this is cool lots to think about:D
 

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Discussion Starter #3
The roll center is where the roll axis crosses the axle centerline.

The simplest(not 100% accurate)way to figure out the roll center height with a trackbar is to measure to the centerline of the bolt on the axle mount. The 2nd front pic is a trackbar setup.
 

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what about unwanted flex due to side force. the higher it goes the easier it will be to shift the axle. so there has to be a point where it would start hindering. have you experienced anything like that.
 

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Discussion Starter #5
TINY said:
what about unwanted flex due to side force. the higher it goes the easier it will be to shift the axle. so there has to be a point where it would start hindering. have you experienced anything like that.
I haven't noticed any jacking from my setup(and I have been looking). Even with the rear tires turned it isn't an issue. I think the long control arms really help.

CJ
 

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glad to see you post this up, I was very curious what the actuall measurements were.

Thanks
 

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Great pics. They show the differences very well. :)

Hard to tell from the pics, but how was the suspension set up before and after to put the RC where it was each time?

Looks like the rear went from reverse-triangulated uppers with parallel lowers to a more standard dual-triangulated setup?

Kinda hard to tell on the front, but it looks like the lowers were triangulated to a point at the axle and maybe parallel uppers. Not sure about the after pic, but you say there is a track bar somewhere...


No offese, but both of your "before" setups seem kinda back-asswards from the norm. But maybe that's why you made changes. :)
 

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His first set ups were built a few years ago when there was no "norm" and link suspensions were pretty much a black art amongst rockcrawlers...
 

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CJ Lagos said:
The roll center is where the roll axis crosses the axle centerline.

The simplest(not 100% accurate)way to figure out the roll center height with a trackbar is to measure to the centerline of the bolt on the axle mount. The 2nd front pic is a trackbar setup.
roll center pivots off the axle mount on a track bar? i thought it was midpoint on the track bar centerline from bolt to bolt(axle/frame)? maybe thats what your saying and i cant read it right, or maybe im wrong?:D
 

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Discussion Starter #10
Booger Weldz said:


roll center pivots off the axle mount on a track bar? i thought it was midpoint on the track bar centerline from bolt to bolt(axle/frame)? maybe thats what your saying and i cant read it right, or maybe im wrong?:D
I've seen a few different ways to do it, your way is probably more accurate than mine.

CJ
 

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Booger Weldz said:


roll center pivots off the axle mount on a track bar? i thought it was midpoint on the track bar centerline from bolt to bolt(axle/frame)? maybe thats what your saying and i cant read it right, or maybe im wrong?:D
I believe you are correct sir!

Jack
 

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There is no jacking based on roll center height with a solid axle. That is probably why you havent noticed any :D You will get some jacking from a panhard bar if/when it is not perfectly level. If you had an independent suspension with a 30 inch roll center height, you would have a death trap. With a solid axle it is great.
 
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