- Reply to Topic
Thread: Welding in new floor pans Reply to Thread
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
09-17-2019 08:53 PM
BagusJeep Whilst structural adhesives are used in modern cars 3m say "Only bond to clean, rust-free, bare metal" which makes them unsuitable for many repairs to rusty floor pans. Prep is vital to get the bond.

If you are going to use it, you should also mechanically fasten the parts together. When Lotus first came out with the adhesive bonded aluminium chassis 25 years ago, they found in crash testing that the adhesives could peel and that fasteners reduced this substantially. Still a great product to use but the limitations need to be understood before making such repairs.
09-17-2019 10:58 AM
2oldjeeps you can stop the leaks, its not ez but worth it...
09-17-2019 04:02 AM
Originally Posted by dented View Post
I'm sure some cringe at the sound of self tapping screws, but they are such a simple way to hold the pan in place while the adhesive hardens.
I used them on an 87' Cherokee I posted here years ago. Worked well with adhesive, then if you want cut the tappers from the bottom.

I would also suggest bedlining every Cherokee floor. These things all leak water, which rusts after sitting under carpet.
09-15-2019 07:25 PM
Originally Posted by CJ7-Tim View Post
When I installed a complete floor pan, I used uni-body adhesive, and a few self drilling sheet metal screws where the pan wanted to pull away. The prep took much longer than the repair.

I'm sure some cringe at the sound of self tapping screws, but they are such a simple way to hold the pan in place while the adhesive hardens.
09-15-2019 07:23 PM
dented Drivers side before. And Driver's side almost done.
09-15-2019 07:19 PM
dented I have an IronRock 3 Link. All the control arms bolt to their cross member. Bolting all that to the pseudo frame is just not strong. I cut from in the cabin and added 1/4 plate like a giant washer with nuts welded to it. It is much stronger. Next I will put in frame stiffeners. It will make it all VERY strong. The third picture is it welded back up. 4th pic is the pan cut to size. I made holes for spot welds to hold it while the adhesive hardens. 5th pic is everything buttoned up with a rust encapsulator over everything. I painted all the way to back seat.
09-15-2019 01:35 PM
CJ7-Tim When I installed a complete floor pan, I used uni-body adhesive, and a few self drilling sheet metal screws where the pan wanted to pull away. The prep took much longer than the repair.
09-15-2019 01:29 PM
dented So far I've done the passenger side. I cut out all rust, ground down to bare metal in other places. I then coated the whole thing with a rust encapsulator. I fitted the pan and marked where I would use the adhesive and ground it down to bare metal again. You can weld through the adhesive when it is wet. Just remember it is very flammable so your weld will keep burning. I made holes around the metal pan and along the frame rail. I plugged welded it to hold it in place. Adhesive is stable in 4 hours and solid in 24. It is very simple, but dirty and labor intensive. I'll post some pics later.
09-14-2019 09:01 PM
Originally Posted by dented View Post
2001 XJ. Drivers side has a big hole. Passenger side has a small hole.

I was going to cut out the size of the pan then weld in the new metal, but I'm thinking why lose the integrity of what is still good.

Can I grind out the rust, use something like POR15 on the rest then weld the new pan on top? I'm thinking of using a plasma cutter to make holes in the pans where the jeep metal is the thickest, spot weld it and then weld the edges in. I could deal with the rest from the bottom with all metal to seal everything up.

Anyone with experience?

I replace and welded in new pans on my 2000 last year. Was not hard just time consuming and rust was worst than what I thought. I welded my pans in with my mig welder using .021 wire, low heat and gas.

I drilled holes on the new pans about 1/2 inch apart and plug welded them in. I used good weld thru primer along edges where i was going to weld and coated with rust bullet (same as por15 but can be painted over) then used oil base primer, good brush able seamsealer and paint on the inside. Underneath same thing. Main thing is don't cut corners and cut out all bad rust and grind away and seal the minor ones.
09-12-2019 06:00 PM
kadetklapp Following.
09-12-2019 03:25 PM
2oldjeeps i cot out all rust and left a one inch band where new pan fit with seam sealer.
not the least worried about the small area of floor affecting structure. it had been gone for years b4 i fixed it!!
used bolts/nuts on frame thru pan and big self threaders. pans sat in a bed of sealer
09-12-2019 02:51 PM
dented I feel I need to weld the pan to the frame rail. Unibody is all structural. The self tappers would work. I think I will use a combination of adhesive (mostly) with some strategic welds. I'll take some picks.
09-12-2019 12:55 PM
dented Wow you may have just saved me a ton of work. I definitely plan to grind down rust.

I think I can weld to the unibody frame rails with MIG. 3M says you can weld through uncured adhesive. The metal is thicker there. I will definitely coat everything after.
09-12-2019 12:19 PM
2oldjeeps i put in good size pans bolted to frame rails,heavy self tappers thru to good existing metal
and good body sealer to avoid voids to reduce future water leaks. i think welding causes more rust.
EVERY factory WELD spot on a new hummer in 2010 showed early rust. it weakens the metal..

btw guys on another jeep forum expressed hysteria about using self tappers! it was really fun!.
09-12-2019 11:19 AM
CJ7-Tim 1) Small to moderate size holes in the floor are not significantly detrimental to the structural integrity.

2) Hole repair or an entire floor pan replacement, you should use unibody structural adhesive instead of welding. Unless you have TIG welder you will just blow holes in everything. Remove all rust from repair areas. Rough grind the glue joint areas. Overlap any hole repairs by about 1 inch all around, and POR-15 over the repairs, the patch edges, and any bare metal.
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

For the best viewing experience please update your browser to Google Chrome