Dave Kishpaugh's (Jeep West) geometry correction brackets are now available

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jjvw said:
I've done a couple short arm outboards with 12s split in half. We have not seen the suspension bind on the trail. On jack stands, yes. But not with the weight of the Jeep acting on the axles.
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Exactly my point (wait, are you agreeing or disputing?)... At 10" stock location and 12" outboard, you reach the max that the short arm system can articulate. Want 14" out there? Need mid arm or long arm to facilitate the travel. The geo correction does absolutely help reduce rear steer and can align to tuck the tire perfectly as well. :) I think my lowers are about 1/4" shorter than stock right now. Not perfect, but there was a change to the drill location instructions that Chris and I didn't get from Dave until after we were drilled.
 
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Pressurized said:
Exactly my point (wait, are you agreeing or disputing?)... At 10" stock location and 12" outboard, you reach the max that the short arm system can articulate. Want 14" out there? Need mid arm or long arm to facilitate the travel. The geo correction does absolutely help reduce rear steer and can align to tuck the tire perfectly as well. :) I think my lowers are about 1/4" shorter than stock right now. Not perfect, but there was a change to the drill location instructions that Chris and I didn't get from Dave until after we were drilled.
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I'm saying that with a 12" shock split 50/50, the short arm bind is a non issue when the weight of the Jeep is acting on the suspension. I'll go further and say that I see no reason why a longer shock couldn't be used. The arms aren't the issue. After 12s on factory width axles, the inner side wall is mashing increasingly hard into the outboarded shock body that the endeavor of adding more travel begins to not be worth the effort. Plus the jacking on a short arm becomes a real problem where the tire drives under the rig and tears stuff apart. Additionally, I know first and second hand that a Rubicon rear driveshaft on 4" spring lift and a Savvy skid will start to bind and quickly lock just after 5" of down. For some reason this isn't pointed out as often as it ought to be. This is why I put a center limit strap on mine.

And while I know what rear steer is, I have never been in situation where I recognized it as something to concern myself with.
 
jjvw said:
Plus the jacking on a short arm becomes a real problem where the tire drives under the rig and tears stuff apart.

And while I know what rear steer is, I have never been in situation where I recognized it as something to concern myself with.
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That's literally a by product of the rear steer... Do you not concern yourself at all with the instant center being up near 200% anti squat?
 
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toximus said:
Why is 200% a concern? What is ideal? And how do I calculate what my instant center is?
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I think there will be varying opinion on what is ideal, and I'm fine with that. 100% anti squat means that when you accelerate, the rear will neither squat nor rise under acceleration based on geometry. You may still squat based on weight transfer. When you are too high, your rear wants to rise when you apply throttle and that can cause the rear end to hop and lose traction when climbing an obstacle. Some people experience it a lot and others not as much.

Here are some images that should help with my explanation.

Anti squat.jpg


anti_squat 100.jpg


anti_squat_below.jpg



There are a number of calculators out there, but for a quick and dirty measurement, this one works well. With a tape measure and a few minutes you can see what you have.

https://www.baselinesuspensions.com/instant-center_general.php
Here was my result after install.

Instant Center.jpg


For reference, I put in the data for a stock TJ (close as I could get) and this was the result.

instant center stock TJ.jpg


Hope that helps.

And I'm open to criticism if someone is feeling it. ;)
 
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toximus said:
Why is 200% a concern? What is ideal? And how do I calculate what my instant center is?
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Instant center is fairly easy. It's the antisquat that very few, of any, here has actually figured out. And beyond that, the number we get from the calculator is irrelevant.
 
Pressurized said:
I think there will be varying opinion on what is ideal, and I'm fine with that. 100% anti squat means that when you accelerate, the rear will neither squat nor rise under acceleration based on geometry. You may still squat based on weight transfer. When you are too high, your rear wants to rise when you apply throttle and that can cause the rear end to hop and lose traction when climbing an obstacle. Some people experience it a lot and others not as much.

Here are some images that should help with my explanation.

View attachment 250374

View attachment 250375

View attachment 250376


There are a number of calculators out there, but for a quick and dirty measurement, this one works well. With a tape measure and a few minutes you can see what you have.

https://www.baselinesuspensions.com/instant-center_general.php
Here was my result after install.

View attachment 250377

For reference, I put in the data for a stock TJ (close as I could get) and this was the result.

View attachment 250378

Hope that helps.

And I'm open to criticism if someone is feeling it. ;)
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Mine doesn't climb stuff on flat ground. 😉
 
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Pressurized said:
Related yes, fix one and you fix the other...

...
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Or be mindful of the practical limits of shock travel on stock axles. 12" rears on lifted short arms is common. How often did we hear people complain about rear steer in the past? How did rear steer effect you?

Pressurized said:
...
Very high anti squat is a contributor to wheel hop and loss of traction.
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I'm familiar with the phenomenon. I've even seen the geo correction kit hop, skip, and jump it's way up a couple climbs. How did having a high AS effect yours?
 
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jjvw said:
Instant center is fairly easy. It's the antisquat that very few, of any, here has actually figured out. And beyond that, the number we get from the calculator is irrelevant.
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While it's true that unless you have calculated the actual COG of any specific Jeep, the actual anti squat number accuracy is questionable. But that's just being disingenuous to the data. Because the delta between the 2 calculations is still the same. So whether I was at 200% and now I'm at 130% or whether I was at 180% and now I'm at 110%, the change in instant center is the same. And if you want it lower, this is how you get it... FWIW, Garrett and I have both noted significant changes in handling, albeit different from each other a bit.

So, I'd be interested in hearing from someone that did the geometry correction and didn't get positive results... Does that person exist?
 
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I really don't understand the questioning about improving geometry? I did mine for one reason, wheel hop. In the process of eliminating wheel hop I also reduced rear steer. Reducing jacking is also reduced quite a bit too. I have not heard any downside of this mod.

I would be interested in the Geo Correction details that hop, skipped and jumped. Was it Dave's, home made or Nth brackets? Both frame and axle LCA mounts moved? What advantage does more rear steer give?
 
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The higher roll center and better clearance with the gas tank intrigue me. Wish my lower control arm mounts on the frame weren't beat up.
 
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rasband said:
Does Dave still offer the midarm? If so, why choose these vs the midarm?
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Pressurized said:
Dave has said that if you aren't going over a 10" travel shock in stock mounts or 12" if mounted outboard, there is little or nothing to gain with either a mid arm or long arm setup over the geo correction... I'm at 10's in the stock location and plan for 12's outboarded in a future mod.
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🤷‍♂️
 
rasband said:
What about the front? Does nothing need to be done there?

🤷🤷‍♂️🤷‍♀️
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Apparently if you cut mustard, a mid-arm is needed in the front.
David Kishpaugh said:
I do not make any front brackets. Any way you cut the mustard, the front end needs a mid arm even if they are only 24" links.
I have messed around with 2" taller axle mounts, 15" front upper and 26" lower arms with great success. It just doesn't compare to having a 3link mid arm.
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But why is still unanswered since November of last year.

Brianj5600 said:
What bad characteristics do longer front arms address?
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toximus said:
Apparently if you cut mustard, a mid-arm is needed in the front.


But why is still unanswered since November of last year.
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🧐 Call me a skeptic. I crawled lines in my SA that others with various kits didn’t easily. That’s not to say I don’t find something to possibly be valuable here, I’m just not sure what it is yet.
 
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