How to replace the floor pans (?)

[joel323]

I would recommend going to the gas set up, the Bmw medal is 18 and 20 gauge and Flux core will work but is tougher for a new welder on thin gauge metal. And if you buy wire get the .23. Other than that just practice and get your settings right and you should have no trouble.

A few things that will really help your finished product.

Make sure everything you weld is extremely clean and rust free
If you overlap metal to weld it together use a weld through primer like U-POL
Never Weld very long in one area , it will burn through and warp the metal and will also cause heat stress.

[Jester323]

Eric, I don't know what your welding capabilities are, but I may have been in your same spot a few years ago, learning to wire feed on an e21, prolly the same welder too. Go buy yourself a gas bottle & the smallest non-flux core wire your welder will handle. Welding thin sheet metal with flux core is an artform in disaster. You'll burn fewer holes and make more production in your learning curve, and less buble gum welds too.

[82eye]

+ 1 on the above two posts

[pommeree]

I would recommend going to the gas set up, the Bmw medal is 18 and 20 gauge and Flux core will work but is tougher for a new welder on thin gauge metal. And if you buy wire get the .23. Other than that just practice and get your settings right and you should have no trouble.

A few things that will really help your finished product.

Make sure everything you weld is extremely clean and rust free
If you overlap metal to weld it together use a weld through primer like U-POL
Never Weld very long in one area , it will burn through and warp the metal and will also cause heat stress.

Weld-through primer! Hadn't thought of that. I was wondering how best to protect seams when doing a lap weld.
I googled "weld-through-primer" and stumbled on this set of videos pretty much explaining the "how to replace a trunk floor" from start to end.

http://www.ehow.com/video_2326975_we...unk-floor.html

They emphasized the welding technique like you recommended which I'd describe as a "succession of tacks" to prevent heat build up and warping.

[Jester323]

friendly words of advice. I had a couple of replacement panels that were unavailable at the time when I was rebuilding mine and so I did the best I could to form & patch some sheet steel in to place. Maybe others with more metal fab skills than mine wouldn't have such an issue with it, but it was a LOT easier and saved me tons of time when I had pre-formed patch panels... and ultimately I feel better about the repairs that I made with these panels.

[pommeree]

Nothwithstanding Jesse's advice and common sense, I started shopping sheetmetal yesterday.
First I called T-Hoff, my favorite euro-parts supplier and machine shop.
The kind old Gent I spoke to recommended I call Durham Brazing and Welding.
The kind old Gent I spoke to at DB&W said the thinnest sheet they carry is 16Ga. at $65 for a 4x8' sheet. I explained I was shopping for 18Ga. to do a floor pan in an old car. He got excited and started telling me his favorite "Knew-a-guy-once who was fixin' a car" story. He told me I needed to call Young Roofing because they carried everything.

I called Young Roofing and the kind, old Gent I spoke to (are you sensing a theme, yet) got his list and gave me some pricing.
(all 4x10' sheet: 18G. $80, 20G. $70, 22G. $60)
I explained I was looking to replace the floor pan in an old car. He wanted to know what Make/Model and got pretty excited when I told him "An '82 320i" He started tellin me a story about a guy he knew years ago who had restored a Bimmer though he couldn't remember what model and suggested I look the guy up "in case you need some parts" which I thought was pretty funny.
He also told me that 18Ga. was what floor pans were made of but (echoing Jesse's advice) I was going to have a hard time "puttin' stiffeners in 'em" (I had him explain and that meant putting a bead in it)
So I'm still mulling over my options:
~$300 for floorpans shipped from W&N vs. $80 worth of "educational opportunity" in the form of an 4x10' sheet of 18Ga. cold-rolled.

Next stop: National Welders Supply, Durham.

[Jester323]

Yeah, rolling beads in them to stiffen the panels will be a challenge, but perhaps even more so will be sealing the edges when you are all done. Even with correct pressed floor panels, you'll still want seam sealer and filler to smooth the edges, without them, you may literally have filler 1" thick in places.

I know the $300 + shipping is a hard pill to swallow, but it's worth it. This will be the last time I pester/harass you on this topic, and either way you go, it will be a learning experience and I can't wait to see the progress & results.

[tomscat1]

Hi Eric,

As an ardent Energy Conservationist----- MY energy! ---- I am with Jesse on this one. I have a feeling that welding in the pre-formed panels will provide you with plenty of educational opportunity--- I know it would for me! Not to mention the aggravation/frustration factor.

There is plenty of time for you to learn how to form the panels on your NEXT E21 restoration project!
The 'educational opportunity' all too often turns out to be something along the lines of... if I only knew THEN, what I know NOW.... .... or... wtf was I thinking???

Either way, good luck and we look forward to watching your progress. I admire your ambition and initiative in taking this on! Damn the torpedoes!

[pommeree]

I went to Eastwood's site to see if they sell denial in a gallon can.
Denial had been working really well for me until I took a flap-disk to the rear clip.
"It's just an 1/8" of bondo with primer over top applied maybe 12 years ago. How bad could it be, right?!"



Under 1/8" of bondo, there was more bondo!


"Always work in a well ventilated area."


This is interesting. There were barely visible signs of rusting around the neck-hole. Maybe a bubble or two. But when I poked it, my finger went straight through ... even before I removed the neck.
My advice: If you see a bubble, walk away.


This is the crap that collects on top of the fill neck where it's sandwiched against the inner wheel well. Just FYI.

[joel323]

I just finished my rear panel install brace the quarters good they will move around with no tail panel. They are around 400 shipped for a the whole thing

[Hibbard]

in for this thread! good luck and i like the optimistic attitude

[MrGumby]

This thread helps confirm why I put up with the 110+ temps here in the summer!

[pommeree]

This thread helps confirm why I put up with the 110+ temps here in the summer!

That reminds me.
The greatest irony I find about all the rust on this car is that it HAPPENED FROM THE INSIDE-OUT.
The towers, wheel wells, fenders, doors, rockers and spare tire well are all rust free. Inside *and out*

The floor pans rotted out because once there was so much as a pinhole in the front wheel well, the water got in and started eating it's way back out under the carpet.
And with the trunk, once a pinhole was established under the rear lights, the water would sit in the trunk all along the rear clip, slowly eating it's way out again.

[E21fun]

SMH! To get the sound deadening up you use dry ice not a heat gun lol... if its winter time you could prolly get away with just a hammer tho.

[tyson 323]

i have been in your same boat with my 320. the previous owner had a master cylinder leak and never did any clean up on the brake fluid. it ate the metal from the inside out. i had about all of the area where the drivers feet go gone. i decided to go the make my own panel route. used 16 gauge cold rolled and it worked fine. the key is the bends in the steel, they give it an amazing increase in strength. you car is looking good from what ive seen. and i would defo go with the advice about using non flux welding wire. its a pain in the ass for me and i do alot of welding for work

[E21Adam]

SMH! To get the sound deadening up you use dry ice not a heat gun lol... if its winter time you could prolly get away with just a hammer tho.

still sucks -ing for forever

Also remember: never touch the dry ice directly...especially with your penis. You can try to give your friends a dollar to do it though, if you have a lulz craving.

[pommeree]

SMH! To get the sound deadening up you use dry ice not a heat gun lol... if its winter time you could prolly get away with just a hammer tho.

Charbel told me that technique, too.
He said in the Michigan winters that foil-backed crap will peel right off the floor.

UPDATE:
My friend Phil wrecked his E21 race car and is transplanting everything into a new chassis.
I'm going to check out the wrecked car this weekend as he thinks the sheet-metal I need is salvageable off his car.
Knock wood and I'll have two replacement floor pans and a rear valence to start welding onto my car.
Keep your fingers crossed!

I decided to go the make my own panel route. used 16 gauge cold rolled and it worked fine. the key is the bends in the steel, they give it an amazing increase in strength

How did you make the bends/beads in the steel? Do you have a bead roller?

[tyson 323]

How did you make the bends/beads in the steel? Do you have a bead roller?

i did it the old fashioned way- hammer and an immovable object. its not the easiest way to do it but it works. wear ear plugs though. it takes some time to perfect but it becomes easier to do after a few pieces. the only drawback to doing it that way is there is no way to do compound bends, i.e. from horizontal to vertical in a corner

[E21fun]

still sucks -ing for forever

Also remember: never touch the dry ice directly...especially with your penis. You can try to give your friends a dollar to do it though, if you have a lulz craving.

[ToddK]

Just went thru replacing rusty floors on a Triumph Stag. Pans were unavailable, so I went with the Harbor Freight bead roller. Used trunk lids for the sheetmetal.

[pommeree]

His name is "40Cf Ar/CO2 tank"
$94 at the local welding supply.
$27 for the fill
$4 for a 2Lb spool of .023 wire.
$29 Flow regulator from Harbor Freight.

[mwilderl]

I have a friend that put 18 gauge sheet metal in a 240z that had a similar looking floor pan. He picked up all the metal and then some from a remnants yard for just over 20 bucks. If the floor pans off the wrecked e21 don't work out, you might search around for one. You can find a lot of decent metal for very cheap.

[jmitro]

Eric P - I love welding. But welding sheetmetal has got to be one of the more difficult tasks I've learned. thin gauge metal burns through so easily. How comfortable are you with welding?

tips I would take to heart from above when welding sheetmetal.....

-do not use flux core. It's a mess as Jester323 stated. Looks like you've got that covered with your new friend
-Weld in a series of quick tack welds to avoid warpage and burn-through.
-use 0.024" gauge MIG wire with relatively lower heat and medium wire speed. You'll have to play with it for awhile.
-Make sure your metal is very very clean, and the surfaces are touching each other. Even a gap of 1mm will make it easy to burn through.

[bmac320i]

Eric P - I love welding. But welding sheetmetal has got to be one of the more difficult tasks I've learned. thin gauge metal burns through so easily. How comfortable are you with welding?

tips I would take to heart from above when welding sheetmetal.....

-do not use flux core. It's a mess as Jester323 stated. Looks like you've got that covered with your new friend
-Weld in a series of quick tack welds to avoid warpage and burn-through.
-use 0.024" gauge MIG wire with relatively lower heat and medium wire speed. You'll have to play with it for awhile.
-Make sure your metal is very very clean, and the surfaces are touching each other. Even a gap of 1mm will make it easy to burn through.

+1 Each weld should a 1/4" or smaller

[jjgbmw323]

CLASSIC:

still sucks -ing for forever

Also remember: never touch the dry ice directly...especially with your penis. You can try to give your friends a dollar to do it though, if you have a lulz craving.

I had lots and lots of rust. It seems like they always rust in the same areas, where the water will pool up. Now that I have restored and garaged my car, I am hoping that my days of rust are over.....