Specs for Bolts Connecting Rear Bumper to Frame

SSTJ

SSTJ

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I noticed that this bolt (red circle) is missing on both sides of my bumper. FSM doesn't say what size or thread they are. Anyone know what I should buy?

I'm also missing one of the flanged nuts on the gas tank skid (green circle), if anyone knows those specs too. Of course I can remove one and match if not.

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Solution: My 97 (and maybe some other years?) takes a 7/16" x 1.75" bolt with a thread pitch of 14. Most other years call for a M12 bolt at 30 to 45 mm long, with a thread pitch of 1.75. Diagram provided here. Note that if your TJ takes the SAE bolt, then the metric won't go in at all. But if your TJ takes the metric bolt, the SAE will screw in easily by hand, but will feel a bit loose.

Solution: The tank skid nuts are M10 x 1.5 flanged locking nuts.
  • Update: No they aren't. Maybe on other models, but on my 97 they are 5/16"–18 thread with a 1/2" hex head.

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On my '05, the bumper-to-crossmember bolts are M12 x 1.75 and about 30 to 45mm long, class 8.8. The PO had UNC 7/16-14 bolts in there, which have a close enough thread to go in a little loosely. I fixed that.

But I think those bolts changed at some point, so your '97 may use something different. Can't remember where I may have read that.
 
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If it is metric use grade 8.8, if it is sae use grade 8. If the wreck breaks those bolts, your family will be planning a funeral.
 
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OldBuzzard said:
On my '05, the bumper-to-crossmember bolts are M12 x 1.75 and about 30 to 45mm long, class 8.8. The PO had UNC 7/16-14 bolts in there, which have a close enough thread to go in a little loosely. I fixed that.

But I think those bolts changed at some point, so your '97 may use something different. Can't remember where I may have read that.
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Thanks again. From the Curt diagram above, it looks like this should work on my 97. But of course we'll see ...
 
JKP said:
Well it's either number 2 or number 3 on the Curt chart. I'm pretty sure my YJ is SAE. Your 97 could go either way.
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Thanks. By the diagram, it's number 3 I'm looking for. Will find out today if this is another quirk of the 97s.
 
JKP said:
Number 2 is the SAE version.

Number 3 is the metric version.
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Got it, thanks. I should have read that small print, which explains why #2 is just floating around out there.

I suppose that is what @OldBuzzard was describing above also.
 
If your '97 wants SAE, the metric bolts probably won't go in at all. Good. But if it wants metric, the SAE bolts will screw in pretty easily, by hand, but will feel a little loose, and won't hold well. If you can check both at the hardware store, you'll be sure.
 
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jonny jeep said:
Those bolts going into the bottom of the chassis in the rear are UNC on my 97. Can't remember the size though.
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Thanks. I had to Google that one, but it sounds like UNC is the new term for SAE?

Also, check out the "quirks of 97s" thread in my signature, and let us know if you have anything to add.
 
SSTJ said:
Thanks. I had to Google that one, but it sounds like UNC is the new term for SAE?

Also, check out the "quirks of 97s" thread in my signature, and let us know if you have anything to add.
Click to expand...

Don't get @jonny jeep started on 97' quirks or specs. He knows all. ;) He's the @Rubi4MyMrs , but British.
 
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