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Unread 12-20-2011, 09:45 PM   #61
jermeyg
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Originally Posted by Imped View Post
Jermey, unless I'm going crazy the horizontal separation for the uppers is way off.

Idaho, download the calc and find out for yourself. Raising the lower mount at the axle = less separation = less angle = IC further out = less AS
Yep I think you are right. I need to get some actual measurements from a stock suspension of the frame ends for the uppers and lowers. I tried to base some of the number of Ragged's setup but there is a lot of estimation to get it back to stock suspension.

Maybe if we can have someone with a stock TJ give us some dimensions we can plot out a more accurate TJ suspension.

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Unread 12-20-2011, 09:48 PM   #62
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Originally Posted by RaggedOleMan View Post
So what your saying is that a tj, with a short arm lift, installed in the factory locations essentially ruins the geometry...I think I'll start by pulling the 1-1/4" pucks.

So, what/where should the numbers be, in your opinion, Imped?
That's an open-ended question. Here's what I shot for:

60-90% AS
High roll center
Roll axis as close to zero as I could get it.
Clearance everywhere possible.

My goals were to take my rig, which is no longer at stock height, and get it to the point of performing better than a stock height rig, all while improving on clearance in front of the rear tires, under the frame, and under the axle. Nothing hangs below the axle tube, it climbs like a billy goat, and the lower arms never touch a thing.

Become a google-research freak of nature and you'll find more information than you can believe. You won't learn everything just from this thread.

Jermey--I have a stock TJ plotted but I can't open any of the calc files. This is pissing me off because it's a ton of valuable data from a bunch of different setups (Hendrix being one) that I can't reference to show you guys.
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Unread 12-20-2011, 10:02 PM   #63
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Originally Posted by jermeyg View Post
Imped if you find it let us know. I will try and plot my setup to see how it looks.
You have some manner of goofiness present in your dimensions. Visualize the frame just above the frame side LCA mount. A short distance directly above it just on the inside the frame is the UCA mount. I'd guess the distance of horizontal separation to be roughly 2" or less center to center given that the lower is kicked inward slightly and the upper is set off the frame slightly for the flag nut.

The is also a fair bit of triangulation in the uppers if you look at how far inboard the uppers are due to them being inside the axle spring perches.
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Unread 12-20-2011, 10:06 PM   #64
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Jermey, you've also got some really funky numbers going on at the roll center height and roll axis angle. The roll axis should come down once you plot the uppers correctly but the roll center height is way excessive and I can't figure out why by looking at your other numbers.
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Unread 12-20-2011, 10:11 PM   #65
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Originally Posted by mrblaine View Post
You have some manner of goofiness present in your dimensions. Visualize the frame just above the frame side LCA mount. A short distance directly above it just on the inside the frame is the UCA mount. I'd guess the distance of horizontal separation to be roughly 2" or less center to center given that the lower is kicked inward slightly and the upper is set off the frame slightly for the flag nut.

The is also a fair bit of triangulation in the uppers if you look at how far inboard the uppers are due to them being inside the axle spring perches.
True statement. I didn't mess with the horizontal separation. I agree with you that it should be adjusted and triangulated.
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Unread 12-20-2011, 10:16 PM   #66
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Originally Posted by Imped View Post
Jermey, you've also got some really funky numbers going on at the roll center height and roll axis angle. The roll axis should come down once you plot the uppers correctly but the roll center height is way excessive and I can't figure out why by looking at your other numbers.
Okay I think this is getting closer. Sorry I should have worked the horizontal separation a bit more.
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Unread 12-20-2011, 10:17 PM   #67
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I would love to see numbers on say a 4 inch as lift and 4 inch long arm ....
Most off-the-shelf long arm kits don't improve much over stock mounts. Part of that is due to the fact that unless you replace the axle side lower mounts, you've still got a fairly steep arm. Getting proper frame separation requires exhaust modifications and tub clearancing, which most don't want to do--so you end up with improper separation. Too much separation at the axle and not enough at the frame won't give you much of an improvement in behavior.

So if you're gonna put in some time and money, either stick with stock mounts and good components or cut it all off and start with a bare slate. I chose to keep my arms shorter in order to keep them tucked in behind the tire. You can go as long as you want but you'll sacrifice clearance and won't necessarily gain anything unless you run CO's and can actually use the extra potential travel.



Jermey, see what that did to the numbers? Now angle those lowers out a couple ticks. Are you trying to plot stock suspension at stock height or lifted some amount?
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Unread 12-20-2011, 10:20 PM   #68
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Originally Posted by RaggedOleMan View Post
So what your saying is that a tj, with a short arm lift, installed in the factory locations essentially ruins the geometry...I think I'll start by pulling the 1-1/4" pucks.

So, what/where should the numbers be, in your opinion, Imped?

EDIT; Here's the current image with dims;
RaggedOleMan, sorry for confusion with the horizontal separation... I tried to correct it but not sure I know enough to be more effective
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Unread 12-20-2011, 10:22 PM   #69
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Originally Posted by jermeyg View Post
Okay I think this is getting closer. Sorry I should have worked the horizontal separation a bit more.
Check your rolling radius on the tire size. I suspect it's closer to 13.75 than 14.5.
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Unread 12-20-2011, 10:28 PM   #70
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Originally Posted by Imped View Post
Most off-the-shelf long arm kits don't improve much over stock mounts. Part of that is due to the fact that unless you replace the axle side lower mounts, you've still got a fairly steep arm. Getting proper frame separation requires exhaust modifications and tub clearancing, which most don't want to do--so you end up with improper separation. Too much separation at the axle and not enough at the frame won't give you much of an improvement in behavior.

So if you're gonna put in some time and money, either stick with stock mounts and good components or cut it all off and start with a bare slate. I chose to keep my arms shorter in order to keep them tucked in behind the tire. You can go as long as you want but you'll sacrifice clearance and won't necessarily gain anything unless you run CO's and can actually use the extra potential travel.



Jermey, see what that did to the numbers? Now angle those lowers out a couple ticks.
Once again Y spend money on good components with crap geometry for short arms ??? CO's are my plan So long arms now make sense ?????


Why dosent any major manufacturers post up real world numbers?
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Unread 12-20-2011, 10:34 PM   #71
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Once again Y spend money on good components with crap geometry for short arms ??? CO's are my plan So long arms now make sense ?????


Why dosent any major manufacturers post up real world numbers?
Read what I've said a little closer. Stock mounts do not provide crappy geometry if you stay low. Short arms do not automatically denote crappy geometry. I run short arms, just in a somewhat unique application and it happens to work unbelievably well. As for long arms making sense, you're assuming that's what I meant. Get to the point of understanding everything in this thread and maybe you'll be able to make some informed decisions on where you go with your suspension instead of relying on manufacturers to post up numbers that they themselves don't know or care to know. Remember? Their goals are packaging, not overall performance.


Tip: THINK past the tip of the iceburg and the standard blanket statements ("short arms are crap", "long arms are better", etc). Ftgiles said it perfectly a while back: "It's not the length of the arms that matters so much as the mounts at either end" or something along those lines. The relationship between the mounts (pivot points) determines the behavior of the suspension.
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Unread 12-20-2011, 10:41 PM   #72
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Check your rolling radius on the tire size. I suspect it's closer to 13.75 than 14.5.
Yeah, well it looks like I need to get some solid measurements to get things closer.
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Unread 12-20-2011, 10:43 PM   #73
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Originally Posted by Imped View Post
Read what I've said a little closer. Stock mounts do not provide crappy geometry if you stay low. Short arms do not automatically denote crappy geometry. I run short arms, just in a somewhat unique application and it happens to work unbelievably well. As for long arms making sense, you're assuming that's what I meant. Get to the point of understanding everything in this thread and maybe you'll be able to make some informed decisions on where you go with your suspension instead of relying on manufacturers to post up numbers that they themselves don't know or care to know. Remember? Their goals are packaging, not overall performance.


Tip: THINK past the tip of the iceburg and the standard blanket statements ("short arms are crap", "long arms are better", etc).
Lets see some numbers........ and its just your opinion that what you run works unbelievably well..


as for your TIP I do think past that but Im yet to see REAL facts (meaning numbers )
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Unread 12-20-2011, 10:47 PM   #74
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Originally Posted by jermeyg View Post
Yeah, well it looks like I need to get some solid measurements to get things closer.
[IMG][/IMG]

Jermeyg, these have been slightly revised, based in part on your discovery's. If they're not solid enough, tell me exactly where they seem incorrect and I'll confirm them, and/or what else you need so I can get them.
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Unread 12-20-2011, 11:14 PM   #75
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Originally Posted by flip2spin View Post
Lets see some numbers........ and its just your opinion that what you run works unbelievably well..


as for your TIP I do think past that but Im yet to see REAL facts (meaning numbers )
The numbers are nice to know and it is beneficial to understand the relationships, the bottom line is how it performs. Since Imp has run his suspension in different configurations and he understands how "the numbers" influence the performance, I would trust him when he says it works well now. That said, his final configuration would be based loosely on a target number and final adjustments would be based on how it performs - the final numbers fall where they do.
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