Floor pan replacement

[Elwiscon]

I removed the old vinyl flooring, the passenger floor pan is rusted beyond simple repair (it’s a Comanche after all), the driver side i should be able to fix with a wire brush and JB weld for the small holes unless someone knows of a better alternative. I will check to find the water leak source, likely from the rear glass. I already ordered the passenger side floor pan, bracket and center support from Keyparts. Since I don’t have a welder and the skills to use one I’m looking for a safe alternative, i’ve seen some YouTube videos of some guys using 3M Panel Bond to replace floor pans, has anyone replaced floor pans successfully with this product? Does it hold up long-term? Once repaired I will be prepping the whole floor and coating it with POR15, then adhesive promoter and 2 coats of raptorliner, same from the underside, then I will line the floor with dynamat before installing padding and carpet. If I have to learn how to weld or hire someone to do it for me I don’t mind as long as the repair is safe and I only do it once. 

[pizzaman09]

I work for a company that makes automotive panel bonding adhesives for OEMs, though not 3M.  Structure adhesives absolutely can work.  I helped a good friend glue new rocker panels on his XJ after he did and excellent job cleaning up and cutting out the old metal.  I've also done a bed side to an 86 F150 using the same method, it was much less stressful than welding.  

 

My key advice is make sure it fits right before spreading the adhesive and have a way to clamp it well while it dries.  My favorite method is to drill holes and use self tapping screws to hold the joint together every few inches.  Once the adhesive has dried, take the self tapping screws out and fill each of the holes with a little bit more adhesive.

 

This method can be extremely strong and is far less likely to result in you blowing a hole in the floor with a MiG welder, which takes practice before being good enough to tackle something like a floor pan in a rusty vehicle.

[Pete M]

these are all the leaks I found on the 88 I'm fixing up.  well, the ones on the pass side firewall at least.  there were more elsewhere in the truck.  

 

I could see myself grinding/sanding/wiring all that down pretty good and then POR-15ing everything and calling it a day.  after the leaks are addressed of course.

 

if you want to replace it all, Key Parts is now making replacement floorpans for the MJs.   you can find their stuff on ebay.

 

 

[ghetdjc320]

For pinholes in floor boards, once you get rid of any loose rust and scale, clean it up thoroughly and degrease. Place some masking tape on the back side of the pinholes (tape will go underneath the truck on the floor board), then apply por15 black and, if you have larger pin holes or pitted metal and want a nice finish, apply por15 silver which has lead filler in it. 
 

I’ve used plenty of 3m panel bond. For the most part all I use are 3m, Evercoat and Akzo Nobel products. 3m for all the sealants, adhesives and pillar foams. The absolute best thing you can do for your floor pans is use 3m panel bond AND spot weld in strategic areas. As with anything proper prep is key. Read the TDS and follow it to the letter. I would recommend panel bonding the whole perimeter (overlap the existing floor by 3/4” all the way around) and the subframe making sure every area is clamped as mentioned above. I’d also panel bond the floor bracing in the cab but I’d also spot weld the subframe inner cab floor bracing. The adhesive is top notch but the spot welds will increase the rigidity of the seams since a single spot weld will essentially fuse layers of metal together and has more shear straight compared to just panel bonding. Many cars today use panel bonding and it works excellent but they typically will bead roll their seems for rigidity before applying the adhesive if spot welds are not involved. Panel bond is a great way to create water tight structural bonds, spot welding makes it even better 

[Elwiscon]

48 minutes ago, pizzaman09 said:

I work for a company that makes automotive panel bonding adhesives for OEMs, though not 3M.  Structure adhesives absolutely can work.  I helped a good friend glue new rocker panels on his XJ after he did and excellent job cleaning up and cutting out the old metal.  I've also done a bed side to an 86 F150 using the same method, it was much less stressful than welding.  

 

My key advice is make sure it fits right before spreading the adhesive and have a way to clamp it well while it dries.  My favorite method is to drill holes and use self tapping screws to hold the joint together every few inches.  Once the adhesive has dried, take the self tapping screws out and fill each of the holes with a little bit more adhesive.

 

This method can be extremely strong and is far less likely to result in you blowing a hole in the floor with a MiG welder, which takes practice before being good enough to tackle something like a floor pan in a rusty vehicle.

Thanks, I will definitely check/test everything before applying the adhesive. I'm thinking about using rivets or bolts/nuts to provide additional clamping. Definitely don't want to ruin the floor plan or the Comanche's structure with a welder, I don't have one or the skills to use one, I would practice before tackling something like this.

[Elwiscon]

14 minutes ago, ghetdjc320 said:

For pinholes in floor boards, once you get rid of any loose rust and scale, clean it up thoroughly and degrease. Place some masking tape on the back side of the pinholes (tape will go underneath the truck on the floor board), then apply por15 black and, if you have larger pin holes or pitted metal and want a nice finish, apply por15 silver which has lead filler in it. 
 

I’ve used plenty of 3m panel bond. For the most part all I use are 3m, Evercoat and Akzo Nobel products. 3m for all the sealants, adhesives and pillar foams. The absolute best thing you can do for your floor pans is use 3m panel bond AND spot weld in strategic areas. As with anything proper prep is key. Read the TDS and follow it to the letter. I would recommend panel bonding the whole perimeter (overlap the existing floor by 3/4” all the way around) and the subframe making sure every area is clamped as mentioned above. I’d also panel bond the floor bracing in the cab but I’d also spot weld the subframe inner cab floor bracing. The adhesive is top notch but the spot welds will increase the rigidity of the seams since a single spot weld will essentially fuse layers of metal together and has more shear straight compared to just panel bonding. Many cars today use panel bonding and it works excellent but they typically will bead roll their seems for rigidity before applying the adhesive if spot welds are not involved. Panel bond is a great way to create water tight structural bonds, spot welding makes it even better 

Thank you, I may use just panel bond, but spot welding makes sense,

[pizzaman09]

Just now, Elwiscon said:

Thanks, I will definitely check/test everything before applying the adhesive. I'm thinking about using rivets or bolts/nuts to provide additional clamping. Definitely don't want to ruin the floor plan or the Comanche's structure with a welder, I don't have one or the skills to use one, I would practice before tackling something like this.

Yep, I've definitely utilized rivets too, if you want to keep them in, they are nice but if you plan to remove them, the self tapers or bolts are much easier.  

 

I'm not familiar with the 3M products, but a lot of the Lord Fusor panel bonding products can be had with glass beads in them that hold the bond line thickness to the perfect thickness so that you don't squeeze it all out.  

[Elwiscon]

40 minutes ago, Pete M said:

these are all the leaks I found on the 88 I'm fixing up.  well, the ones on the pass side firewall at least.  there were more elsewhere in the truck.  

 

I could see myself grinding/sanding/wiring all that down pretty good and then POR-15ing everything and calling it a day.  after the leaks are addressed of course.

 

if you want to replace it all, Key Parts is now making replacement floorpans for the MJs.   you can find their stuff on ebay.

 

 

Thanks, found those parts on eBay, already ordered them. I will be removing the dash and HVAC box next week, I'll check those areas for water intrusion, may apply some sealant and/or double-sided heavy duty tape before I re-install the blower and other firewall penetrations. I'll roll POR15 on the floor and raptoline it, I may do the fire wall as well and cover it all with dynamat or other sound deadener.

[Elwiscon]

11 minutes ago, pizzaman09 said:

Yep, I've definitely utilized rivets too, if you want to keep them in, they are nice but if you plan to remove them, the self tapers or bolts are much easier.  

 

I'm not familiar with the 3M products, but a lot of the Lord Fusor panel bonding products can be had with glass beads in them that hold the bond line thickness to the perfect thickness so that you don't squeeze it all out.  

I'll check out Lord Fusor, a good panel adhesive, rivets, POR15 and raptorliner should prevent or at least reduce rust on the floorpans..

, I was very lucky not to find any rust on the wheel wells when I bedlined the underside.

[ghetdjc320]

3 hours ago, Elwiscon said:

Thanks, found those parts on eBay, already ordered them. I will be removing the dash and HVAC box next week, I'll check those areas for water intrusion, may apply some sealant and/or double-sided heavy duty tape before I re-install the blower and other firewall penetrations. I'll roll POR15 on the floor and raptoline it, I may do the fire wall as well and cover it all with dynamat or other sound deadener.

Por15 and raptor liner are good combos. Some brishable seam sealer is also your friend on the joints. Just triple check for any possible water leaks before dynamatting. Otherwise the butyl traps the water onto the metal and it’s not a pretty sight

[ThatJeepGuy]

Please don't be like too many others and just plop down your new metal over top the unibody cap and call it good. Atleast drill out the rozet welds and remove the unibody cap - then address replacing sheet metal. 

 

Seems far too often folks will utilize that little 1.25" lip of material for their new sheet metal and call it a day. The problem is with how the unibody layers stack up, from the inside sure it looks good to go. But after doing that - now from the underside there develops a slot where the original sheet metal continues to rust away and eventually dissapears leaving a gap for all the elements to make there way between the "repair" and into the unibody rail

[Elwiscon]

12 hours ago, ghetdjc320 said:

Por15 and raptor liner are good combos. Some brishable seam sealer is also your friend on the joints. Just triple check for any possible water leaks before dynamatting. Otherwise the butyl traps the water onto the metal and it’s not a pretty sight

Yes, I will definitely make sure there’s no water leaks before I dynamat it. I will take my time and make it right.

 

[Elwiscon]

8 hours ago, ThatJeepGuy said:

Please don't be like too many others and just plop down your new metal over top the unibody cap and call it good. Atleast drill out the rozet welds and remove the unibody cap - then address replacing sheet metal. 

 

Seems far too often folks will utilize that little 1.25" lip of material for their new sheet metal and call it a day. The problem is with how the unibody layers stack up, from the inside sure it looks good to go. But after doing that - now from the underside there develops a slot where the original sheet metal continues to rust away and eventually dissapears leaving a gap for all the elements to make there way between the "repair" and into the unibody rail

Thanks, I’m planning to have my welder friend spot weld those areas and somehow seal it with a quality seam sealer, POR15 and a couple layers of raptorliner. I’m planning to restore this truck and drive it for many years. I already lined the underside of the bed and X-Frame, it came out great