1998 TJ frame swap for a 2005 frame

[98TJHP]

Hello,

I am currently in the process of a complete frame off restoration of a 1998 TJ 4.0L automatic and I am loving every step! I have gotten down to the point where the tub is off, frame is out and engine/trans are off the frame as well! I started working with the idea to do safety caps to fix the rusted frame but ended up finding out my frame was WAY to far gone to safely do this. So I jumped onto FB Marketplace and scored a ZERO RUST 2005 TJ frame as a complete roller. The seller included the 2005 steering box with the longer shaft so I can just connect my steering column right to it. He also left me the transmission skid plate. This is where I have a question! Since I have a 2005 skid plate for the transmission do I need to move anything over or do anything to make my 1998 transmission mount to the 2005 skid plate? I obviously have both the 1998 and the 2005 skid plate available but I'd really like to keep the 2005 one since it's cleaner. I do need to order new transmission and motor mounts and they look the same for both a 1998 and 2005 so I'm just slightly confused. I have seen people talk about the need to drill different holes but I wasn't sure if it was when they used the older one instead. Thank you for all of the help in advance!

 

[macleanflood]

Scroll down...just posted...

Thread 'Need Some Help With Skid Plate Recommendations'

Feb 28, 2025

I am doing a frame swap on a 2000 TJ. It is a 4.0 with an automatic trans. I am using a 2005 frame. I realize there are some compatibility challenges. I have the 2005 steering gear and I plan to reuse that. I have the 2005 skid plate as well. I believe I can use that skid plate but I will need to re-drill the holes for the trans mount. I have two questions:

1. Has anyone done this and if so can you share how you located the new holes that you needed to drill.
2. Is there a good option for a "universal" skid plate that comes predrilled with the required holes? I've looked at...

• olysan
• Replies: 3
• Forum: TJ General Discussion

-Mac

 

[98TJHP]

Thanks! But that seems like they are looking for a skid plate replacement and I have already taken the engine off my old frame…..

 

[macleanflood]

I did a frame swap on mine.

97 to 2000 for me so not many answers.

Sounds like your addressed the steering box issue.

-Mac

 

[98TJHP]

I did a frame swap on mine.

97 to 2000 for me so not many answers.

Sounds like your addressed the steering box issue.

-Mac

Yes! The steering box issue was addressed easy since he left the box and intermediate shaft for me. So that will just connect right to my steering column. I just want to make sure the transmission doesn’t need anything different (or move anything from the 98 skid plate) or do anything different on the skid plate since I’m using the 2005 skid plate.

 

[mrblaine]

Yes! The steering box issue was addressed easy since he left the box and intermediate shaft for me. So that will just connect right to my steering column. I just want to make sure the transmission doesn’t need anything different (or move anything from the 98 skid plate) or do anything different on the skid plate since I’m using the 2005 skid plate.

Not sure how this is being missed but if you lay the early and late skids side by side, they only have 2 things in common. They both use 3 bolts per side into the frame to hold them on and they hold up the transmission.
The holes are not the same, they are not in the same place, they don't use the same transmission mounting method, the trans mount holes are not in the same place, they are not the same shape, etc.

Your current skid uses an adapter to bolt to the holes in the skid to adapt the transmission mount. That adapter is not used on the 03 up belly skids.

 

[98TJHP]

Not sure how this is being missed but if you lay the early and late skids side by side, they only have 2 things in common. They both use 3 bolts per side into the frame to hold them on and they hold up the transmission.
The holes are not the same, they are not in the same place, they don't use the same transmission mounting method, the trans mount holes are not in the same place, they are not the same shape, etc.

Your current skid uses an adapter to bolt to the holes in the skid to adapt the transmission mount. That adapter is not used on the 03 up belly skids.

Okay yeah that’s what is having me confused! So when I put my engine and transmission from my 1998 onto this frame, what must be done to bolt it to the skid plate that came with the 2005 frame?

 

[mrblaine]

Okay yeah that’s what is having me confused! So when I put my engine and transmission from my 1998 onto this frame, what must be done to bolt it to the skid plate that came with the 2005 frame?

Bolt the trans mount to the trans, set the height the same as it is on the early skid and then see what it needs.

 

[98TJHP]

Bolt the trans mount to the trans, set the height the same as it is on the early skid and then see what it needs.

Sounds good! I was hoping someone has done this before to know exactly what was needed to be done. Thanks!

 

[98TJHP]

I guess the real question is do I need to take my automatic transmission wedge off of my old skid plate and put it on the 2005 skid plate.

 

[macleanflood]

Post a picture...I believe that's exactly what @mrblaine is saying.

Essentially that'll have four bolts...I think they're M8, just replaced my skid plate with a Under Cover Fab low profile skid...so you'd think I'd remember...

Basically you need to locate and cut holes/slots like the original skid in the 2005 skid.

-Mac

 

[mrblaine]

I guess the real question is do I need to take my automatic transmission wedge off of my old skid plate and put it on the 2005 skid plate.

That is what the "set it at the correct height" step is for. I suspect it will be needed but I've not laid the two side by side with the intent to make that determination.

 

[mrblaine]

Essentially that'll have four bolts...I think they're M8, just replaced my skid plate with a Under Cover Fab low profile skid...so you'd think I'd remember...



-Mac

Easy way is to remember that the gas tank uses SAE carriage bolts and the rest are not SAE. The adapter is held on with carriage bolts and they are metric.

 

[98TJHP]

That is what the "set it at the correct height" step is for. I suspect it will be needed but I've not laid the two side by side with the intent to make that determination.

Okay got it that makes sense! I’ll take pics of them both tomorrow and report back. Thanks again!!

 

[98TJHP]

Post a picture...I believe that's exactly what @mrblaine is saying.

Essentially that'll have four bolts...I think they're M8, just replaced my skid plate with a Under Cover Fab low profile skid...so you'd think I'd remember...

Basically you need to locate and cut holes/slots like the original skid in the 2005 skid.

-Mac

Here are the two skid plates! The one in the frame is the 2005 and the one out of the frame is the 1998.

 

[Dylan_See_TJ]

Those bolts for the mount are indeed M8s if I remember correctly.

 

[macleanflood]

Those rear slots for the transmission mount look dangerously close to the older skid... that from a look at two pictures and not standing there with a tape measure.

Is it me or does the earlier frame narrow more to the front and the newer frame is wider?

-Mac

 

[mrblaine]

Those rear slots for the transmission mount look dangerously close to the older skid... that from a look at two pictures and not standing there with a tape measure.

Is it me or does the earlier frame narrow more to the front and the newer frame is wider?

-Mac

The frames are the same.