Stretched TJK (bigger rubber & extra inches)

sierradmax said:
It's been a while since I posted an update on the TJ Build. July was spent working on getting a turbo out and back into my truck while most of August, I shifted efforts to get the Buggy trail worthy.

I did get the Genright comp tank "mocked up" for install and didn't like the way its forward mounting tabs hit the center crossmember/tank support. Since this support will no longer serve as upper shock mounts or gas tank support, it's only function is to support two body mounts. I knew it needed to be modified anyways as normally, 4-link mounts will interfere @ full stuff. I cut the crossmember out in prep for a small piece of steel C-channel.

Currently, the only support for the frame rails, from the skid back, is now the rear frame crossmember/bumper support. I've debated a back-half kit but I want to retain stock frame width. Measuring where the frame arch is in relation to the center of the fender, It's exactly what I've been planning.. 5.5"

Who here has stretched a TJ frame? What's the correct way to shift the arch back to match the opening?

A. four large fishplates on each frame rail with a 5.5" piece of box tubing?
B. 2nd clean frame cut 5.5" longer then fishplate both together?

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I haven't done it, but if I were to do so, I'd cut it near the last mid tub mount (the ones outside the frame) and weld in the extension there. I'd plug weld some plate on the inside of the tubing, to make a tab if you will, on each of the 4 sides and slide my extension over top. Then weld the seam and plug weld the extension. Finally, I'd fish plate the frame toward the center of the vehicle.

That moves the whole arch back and you trim 5.5 inches off the rear of the frame and re-attach the cross-member.
 
where to cut will depend on if you're extending the links or taking the upper link brackets back with the rest. fish plates and chunks of tube will do fine.

i have lots of 3/16"material that could be fish plates if you need. might even have some tube layin around i'll look this wkend.
 
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The frame is cut behind the center skid where the rails become parallel. That's where the extension piece goes to move the arch backwards.
 
Mike_H said:
I haven't done it, but if I were to do so, I'd cut it near the last mid tub mount (the ones outside the frame) and weld in the extension there. I'd plug weld some plate on the inside of the tubing, to make a tab if you will, on each of the 4 sides and slide my extension over top. Then weld the seam and plug weld the extension. Finally, I'd fish plate the frame toward the center of the vehicle.

That moves the whole arch back and you trim 5.5 inches off the rear of the frame and re-attach the cross-member.
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Yep that is pretty much what I did on mine. If you look where I'd marked it at for the cut it's right where the rear body mount is. And then I cut off the 4.5" of stretch off the back and did the butt-crack tuck at the same time.
 
With lasers, a careful eye (after several beers), measuring, marking frame dimensions off the tub, and taking a bunch of notes, I made the cuts and the back half is free.

20220902_211612.jpg
 
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sierradmax said:
I wheeled it last weekend. incredible difference from a bodied-rig. point and go. Very stable and I'd have to guess less than 3,000 lbs. but I need to weigh it. You wouldn't even notice the tires aired down to 8psi.
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I can’t imagine, totally different experience I’m sure
 
@Wildman , I don't feel like combing through 295 pages to see what you did with your rear frame crossmember. I want to retain it to re-use a bumper and rear support for the tank. Did you cut the welds, chop the frame and shorten?
 
sierradmax said:
@Wildman , I don't feel like combing through 295 pages to see what you did with your rear frame crossmember. I want to retain it to re-use a bumper and rear support for the tank. Did you cut the welds, chop the frame and shorten?
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I cut the rear frame and did the butt crack elimination. It starts on page 136 on my build. And yes, I retained mine for a rear bumper and mount for the fuel tank also. I hope this will help some. If you have questions, I'll try to answer them.
 
I didn’t do a frame cut, but I stretched my rear 5”. I had to modify the rear crossmember for both the relocated spring mounts and for the axle side upper CAs. For the upper CAs I cut the crossmember, then boxed it with 1/8”. My build doesn’t have a picture of that, but I can get one easy enough if you’re interested.
 
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sjalkian said:
I didn’t do a frame cut, but I stretched my rear 5”. I had to modify the rear crossmember for both the relocated spring mounts and for the axle side upper CAs. For the upper CAs I cut the crossmember, then boxed it with 1/8”. My build doesn’t have a picture of that, but I can get one easy enough if you’re interested.
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I can picture it. I've researched a ton of these builds. I also know that my full up travel might be limited by my upper axle control arm mounts or the upper control arms, both hitting the tub..
 
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sierradmax said:
I can picture it. I've researched a ton of these builds. I also know that my full up travel might be limited by my upper axle control arm mounts or the upper control arms, both hitting the tub..
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my upper link mounts can get up within 1/8" of the tub...........i don't consider that a bad thing, i about used every bit possible (on a truss).
if they didn't contact the tub b4 why would they now? are you changing the compressed shock limit?
 
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Original suspension was stock geometry. I've followed a couple "Jeeps with JK axles" builds. Most triangulated builds had limited up travel with either the upper control arm mount hitting the crossmember (which I will replace) or upper links coming close to the bottom of the tub (depending on link placement).
 
sierradmax said:
Original suspension was stock geometry. I've followed a couple "Jeeps with JK axles" builds. Most triangulated builds had limited up travel with either the upper control arm mount hitting the crossmember (which I will replace) or upper links coming close to the bottom of the tub (depending on link placement).
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Here’s a pic of my crossmember cutout. I’ve got 6” of up travel and I have about a 1/2” of clearance to the tub:
BEB0FFC5-DD85-4E5D-A99C-D24047521DC8.jpeg


29137D5B-4927-49C7-AEFC-E732A8BEF289.jpeg

My build has the pics of the rest of the stretch. Hope this helps.
 
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A little more progress. I had to wait a week for the 2.5"x 4" piece of box tube to come in.

Two questions.
1. Since the rear section of the frame is now pushed back 6", it places the arch in line with where the forward tank/body mount support goes. And, the bottom of the arch is almost parallel with the tub support. What are some ideas here?
2. After I relocate the rear crossmember/bumper support, I think the front mounting location for the GenRight comp20 will be "floating in air", somewhere beneath the arch of the frame. Further ideas here?

frame.jpg


rear bumper.jpg
 
i'd move the back in and mock in the tank see what the options are with the pieces up in there.

i got all kinds of stuff to make brackets and tabs if you need it.
 
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sierradmax said:
A little more progress. I had to wait a week for the 2.5"x 4" piece of box tube to come in.

Two questions.
1. Since the rear section of the frame is now pushed back 6", it places the arch in line with where the forward tank/body mount support goes. And, the bottom of the arch is almost parallel with the tub support. What are some ideas here?
Click to expand...

I moved the shock crossmember by cutting it loose and then bolting it to the body and tacking it to the frame. Then pulled it back out and welded it in place. Others have made their own crossmember for the body mounts with either round or square tube and then made mounts for the body pucks.

sierradmax said:
2. After I relocate the rear crossmember/bumper support, I think the front mounting location for the GenRight comp20 will be "floating in air", somewhere beneath the arch of the frame. Further ideas here?
Click to expand...

I did the butt crack elimination which I really didn't need since the tire is pushed back so much and yes there is then a gap as the tank is up against the body and there is about a 1" gap between the rear crossmember and the tank mounts. I'm going to use some aluminum pieces to made spacers. I'll show you what I'm talking about here soon I hope. But here is the gap.

20211217_130513.jpg
 
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