Rear suspension: Understanding the rear track bar arc and how it binds suspension

Just rethinking all of this, sitting having my morning coffee, I keep asking myself, 'What have I changed?' Yes, alot of crap I know nothing about. Starting out, since I have not yet destroyed the original mounts, I am going to reconnect everything as before, UCA in lower mounts, and see how everything plays out. Check flex, movement, etc. Sometimes you need to take a step back to step forward.
 
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Then that right there tells you there's bind at ride height. I would adjust that arm for the bolt to slide in (at ride height) and try flexing it again.

When I tacked everything in place yesterday, it was at ride height. When I tacked in the second UCA mount, I adjusted the UCA to the exact length of the first one, then tacked in.
 
When I tacked everything in place yesterday, it was at ride height. When I tacked in the second UCA mount, I adjusted the UCA to the exact length of the first one, then tacked in.
We set the axle at ride height. We center the axle at ride height. We check uptravel at full stuff to fix any interference issues. After that, it has to do what it has to do and you won't change much of that.
 
When I tacked everything in place yesterday, it was at ride height. When I tacked in the second UCA mount, I adjusted the UCA to the exact length of the first one, then tacked in.

So what happened between tacking it in and now? If it was set with no bind then but has bind now, something had to have moved, right?
 
Silly question, why not have track bar connect at center of axle?
Center horizontally would just make the track bar really short, exacerbating the inherent bind due to a reduced arc.

Centered vertically would either do the same due to an increased angle or require a really low frame end.

To minimize bind you want it as long and as level as possible.
 
To minimize bind you want it as long and as level as possible.


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That is exactly what I have rolling in my head, just wanted to verify. Thanks for leveling the rocks in my head
 
I know for my JT one of the best lifts I've seen pulls the upper links into a fully triangulated setup (UCA mounts on top of diff), and eliminates the TB altogether. Is the TJ too short a wheelbase and rear UCAs to move them into the center more, and eliminate the TB?
 
I know for my JT one of the best lifts I've seen pulls the upper links into a fully triangulated setup (UCA mounts on top of diff), and eliminates the TB altogether. Is the TJ too short a wheelbase and rear UCAs to move them into the center more, and eliminate the TB?
Yea the TJ links are too short to 4-link. Need to get the arms longer for it to work, such as a midarm setup. I would go that way, but 💰 💰 is short.
 
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So I am going to post an update on my progress, going to be long. I decided to raise the track bar the same amount it was over the original mounts, 2".

Made some extensions to go on top of old track bar bracket.

PXL_20210108_231544907.jpg


Raised mount -

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Of course many of you already know what is going to happen. At near full bump, the track bar this the gas tank mount/frame brace.

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Well, do not know if you try right? So the bar needs to move forward, hmmmm :unsure:

Lets flip it to the other side and see what happens.....

PXL_20210109_004858034.jpg


Got to full bump with a little more than an inch to spare. Lots more room to pass by the frame. I think this might work.

PXL_20210109_005006779.jpg


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Clearances are looking good on the drivers side. I reinstalled the passenger UCAM, and set everything up, pinion angle, centering axle. Up and down movement was good from bump to full extension. And flex is good side to side, did not break any mounts off flexing. :) I think I am getting there.

So time to reconstruct the track bar mount. I cut the back part off, and added a forward mount on top of UCAM.

PXL_20210109_184047157.jpg


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your piggyback should work, as long as it's not stopping the UCA joint from any motion. the other way would have worked also if you just angled the tabs forward.
 
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Lookin GREAT. Glad you got the bind issue figured out. Now just a little more tinkering and playing with it going up & down....


I'm waiting to mess with the front of mine until I get the stretch kit installed and then I can play with things more.
 
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So I am going to post an update on my progress, going to be long. I decided to raise the track bar the same amount it was over the original mounts, 2 3/4".

Made some extensions to go on top of old track bar bracket.

View attachment 216627

Raised mount -

View attachment 216628

Of course many of you already know what is going to happen. At near full bump, the track bar this the gas tank mount/frame brace.

View attachment 216630

View attachment 216629

View attachment 216631

Well, do not know if you try right? So the bar needs to move forward, hmmmm :unsure:

Lets flip it to the other side and see what happens.....

View attachment 216632

Got to full bump with a little more than an inch to spare. Lots more room to pass by the frame. I think this might work.

View attachment 216634

View attachment 216633

View attachment 216636

Clearances are looking good on the drivers side. I reinstalled the passenger UCAM, and set everything up, pinion angle, centering axle. Up and down movement was good from bump to full extension. And flex is good side to side, did not break any mounts off flexing. :) I think I am getting there.

So time to reconstruct the track bar mount. I cut the back part off, and added a forward mount on top of UCAM.

View attachment 216641

View attachment 216642

View attachment 216643

I can't wait to see that thing all welded up. Good work getting it all figured out.
 
Would a Watts link work on a TJ? Seems like it would be a perfect solution but I'm still new to all this

Packaging. The center hub of a Watts would need to be pretty large to accommodate the typical TJ suspension travels.
 
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How high are the UCA and TB mounts above the axle?

UCAM 8-1/4" up from center of axle, 1" forward from center of axle.

Trackbar 10-1/4" from center of axle.

These measurements are to center of axle to center of mount bolt.

I have no idea how this is going to affect how it drives, performs, etc. It could make it better, it could be the same. Probably have it all completed mid next week and report back how it performs on the street.
 
Look forward to hearing if this helps any or not. You've put a lot of work into this and I hope you can get Sarah handling how you want.
 
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