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Has anyone every replaced the rear cross sill on a TJ?

Claybrick5

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Has anyone every replaced the rear cross sill for TJ?

My rear most body mounts (Position 6) have rusted through the underside of the tub and are no longer doing anything besides rattling like crazy. Looking for suggestions on fixes besides trying to figure out installation of this new rear cross sill.

04-body-mount-locations-jpg.jpg


 

Fouledplugs

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Has anyone every replaced the rear cross sill for TJ?

My rear most body mounts (Position 6) have rusted through the underside of the tub and are no longer doing anything besides rattling like crazy. Looking for suggestions on fixes besides trying to figure out installation of this new rear cross sill.

View attachment 158414

Why are you wanting to not replace the cross sill?
 

PJOJeep

2000 TJ Since New
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Northern Illinois
I’m confused, if the rear body mounts have rusted through the tub, then replacing the cross sill will not fix your problem. The cross sill is part of the frame and if I recall, has a 7/16” body mount bolt into the nutsert in the tub. I know they make repair sections for the (3) locations on each side, but I have not seen any for the rear (4) locations or the front one.

Since it is right on the rear corners, I’d try and loosen all (3) of the center section mounts on each side, remove the (2) over the gas tank (yes that means removing the fuel tank), and lift the rear of the tub up off the mounts and inch or so to gain access. You might be able to fabricate a replacement section from some 14 gauge sheet metal with a heavy 7/16” nut and washer welded to the back side and then weld the patch panel to the tub. If the tub is rusted out real bad.... this may not work.
 
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Claybrick5

Claybrick5

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Houston TX
I’m confused, if the rear body mounts have rusted through the tub, then replacing the cross sill will not fix your problem. The cross sill is part of the frame and if I recall, has a 7/16” body mount bolt into the nutsert in the tub. I know they make repair sections for the (3) locations on each side, but I have not seen any for the rear (4) locations or the front one.

Since it is right on the rear corners, I’d try and loosen all (3) of the center section mounts on each side, remove the (2) over the gas tank (yes that means removing the fuel tank), and lift the rear of the tub up off the mounts and inch or so to gain access. You might be able to fabricate a replacement section from some 14 gauge sheet metal with a heavy 7/16” nut and washer welded to the back side and then weld the patch panel to the tub. If the tub is rusted out real bad.... this may not work.
If I’m not mistaken, the cross sill and the cross member are different. Cross sill being part of the tub, the most rear portion to which the body mounts screw into.

The 2nd photo of this cross sill looks to me like it has the nurserts and everything on the far ends of the piece. Just not sure how difficult of a task this is


 

PJOJeep

2000 TJ Since New
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Jan 31, 2019
Messages
207
Location
Northern Illinois
If I’m not mistaken, the cross sill and the cross member are different. Cross sill being part of the tub, the most rear portion to which the body mounts screw into.

The 2nd photo of this cross sill looks to me like it has the nurserts and everything on the far ends of the piece. Just not sure how difficult of a task this is


My mistake, I didn’t open the link...just looked at the diagram. I replaced 3 of my center body mounts, welding them in was a pain in the ass, but once in, they function pretty well.
 

someguysjeep

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that's a fun 1. looks like the piece.

gonna be a fun location to work in, need to remove the tank.
if your going in there inspect the cross member above the tank, the shocks fit into. now is the perfect time to address it as well if needed.
 
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Claybrick5

Claybrick5

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Update: Local shop only charging roughly $550 for the labor and I decided to pull the trigger instead of doing myself due to in-experience with spot welding body metal.

I acquired both the inner and outer Rear Cross Sill and will bring to the shop here shortly. (cheaper for me to get parts instead of body shop ordering). Both parts fit together perfectly and match stock parts on Jeep.


 
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someguysjeep

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I’d like an update on this. My body shop wants to charge me 1800 to do this
then get a quote from your cousins favorite body shop too.
1800 seem high but really depends on what they are gonna do and how it's gonna finish out, some shops do top notch work and charge for it.. some shops hack and patch and can pass the savings cause they spent no time on it.
550 seems like the deal of a lifetime, and you've seen no pics of 550$ worth of results. i'd not be surprised to see quotes from 1200^ for a reputable shop to restore the vehicle. 400$ of any estimate is parts and paint.
 
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Claybrick5

Claybrick5

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The rear cross sill is 2 parts that form a closed box of sorts. I can post some pictures later today of what i had done and how it’s holding up.
 
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Claybrick5

Claybrick5

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May 3, 2020
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Houston TX
then get a quote from your cousins favorite body shop too.
1800 seem high but really depends on what they are gonna do and how it's gonna finish out, some shops do top notch work and charge for it.. some shops hack and patch and can pass the savings cause they spent no time on it.
550 seems like the deal of a lifetime, and you've seen no pics of 550$ worth of results. i'd not be surprised to see quotes from 1200^ for a reputable shop to restore the vehicle. 400$ of any estimate is parts and paint.


The rear cross sill is 2 parts that form a closed box of sorts. I can post some pictures later today of what i had done and how it’s holding up.
 

Deadhorse

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Mar 30, 2022
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13471
Guys, this is the most information I've been able to find about this allusive rear sill, just acquired a 2005 that's in need of a new one, would appreciate anymore information anyone could provide?
 

Rdsharb

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Jul 17, 2022
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15001
The rear cross sill is 2 parts that form a closed box of sorts. I can post some pictures later today of what i had done and how it’s holding up.

I can't seem to find the replacement inner part of the box anywhere online. I ordered the outer part from Summit. It really isn't that hard of a job. A few spot weld the drill out, put new one in and paint. If they guys on here have bad rust here I'm willing to bet they need to replace the 2 rear quarters too. Might as well do it all at once.

https://www.summitracing.com/parts/...8kV2w73yWnfP37bAAK1029QjxN4Rd5WhoC9LYQAvD_BwE
 
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Rdsharb

New Member
Joined
Jul 17, 2022
Messages
3
Location
15001
The rear cross sill is 2 parts that form a closed box of sorts. I can post some pictures later today of what i had done and how it’s holding up.

I can't seem to find the replacement inner part of the box anywhere online. I ordered the outer part from Summit. It really isn't that hard of a job. A few spot weld the drill out, put new one in and paint. If they guys on here have bad rust here I'm willing to bet they need to replace the 2 rear quarters too. Might as well do it all at once.

https://www.summitracing.com/parts/...8kV2w73yWnfP37bAAK1029QjxN4Rd5WhoC9LYQAvD_BwE