How Much Should I Remove

[Bristow911SC]

I'm getting ready to repair a rusted rocker panel, support panel and door jamb. Here are some pictures - just wondering if I should pull off the entire rocker panel or just the rusted part and butt/spot weld in a piece cut off from a rocker panel I got from Restoration Design? I've read several posts that stated that, in retrospect, they wouldn't have drilled through all of the spot welds or have done all the grinding. Would it be a mistake to just weld in a section of the replacement panel or should I just replace the entire piece?
I'm a beginner and I'm just learning how to weld - I'll be practicing for a couple of weeks before I start on the repair. All advice will be appreciated.

[dondarnell]

I would only remove what's bad. No reason to cut out good material just because they sold you a larger piece.

[sballard]

I had similar rust issues in the rockers. If I had it to do do over again, I would only remove the rusty sections. The Dansk replacement panels I used were not perfect fits and if you remove too much sheet metal, you can easily loose your perspective on where the lines are supposed to be.

[drcoastline]

Originally Posted by dondarnell

I would only remove what's bad. No reason to cut out good material just because they sold you a larger piece.

This is exactly right in my opinion. Cut back to clean metal. Trim the new piece to fit.

[Bristow911SC]

Thanks for the advice. I was leaning that way but it's good to get advice from those that have done it before. The rest of the outer rocker panel looks good, same with the door jamb but the support piece (kidney bowl) looks completely rusted.

[yel911]

If I may suggest, prep all your metal surfaces, fit check and before you weld, spray all bare metal with weld-thru primer, to protect the backside of your new/reworked parts. A lot of people/shops do metal work, few mention the ways to protect your work. It's not rocket science.... be patient.

[Bristow911SC]

Thanks and your suggestions are welcome. With respect to the Restoration Design parts should the prep include removing the paint that came on the parts or just putting primer on the cut areas? Will the weld through primer be enough on the parts that do not show or should that get epoxy primer as well?

[cary]

Weld thru primer is only for the metal to metal contact area.

You'll probably have to cut off the rear fender to get at the kidney bowl.
I'm in for the same repair when I restore my 911.

[962porsche]

Originally Posted by cary

Weld thru primer is only for the metal to metal contact area.

You'll probably have to cut off the rear fender to get at the kidney bowl.
I'm in for the same repair when I restore my 911.

your 100% correct !
that is the only place you would want to use a weld primer .
the name it's self tells you that WELD THRU PRIMER .

[Iciclehead]

Just be careful with weld through primers, I have tried several and settled on the Wurth version. The other two I tried, SEM and 3M gave heavy splatter and poor welding until they burned off in the welding process.

I got to the point of spraying on the weld through and then sanding it out of the way where I was going to place welds.

Dennis

[Bristow911SC]

Should I put epoxy primer or anything else over the panels/welds before they are covered up? The support panel/kidney bowl will be covered up - can I put POR 15 over the weld through primer to help prevent future rust? Now that I think about it I believe that's what DaddyGlen did when he fixed his 911. I assume there won't be a problem primering or PORing over weld through primer?

[yel911]

I didn't mean to open a can of worms, but, protecting the parts that can't be reached seems to go un-mentioned, or people assume everybody knows what to do. I found out the hard way and would hate to see someone skip this step.

[cary]

I'm doing this on my extensive 914 Rustoration.
914World.com - The fastest growing online 914 community!

You'll open a huge debate on what products to use.

POR15 is a vampire product. Only the be used out of direct light.

I wish I could find a Wurth dealer here in PDX. So I could buy it off the shelf.

On the inside stuff that has grown what I call condensation rust I'm just using 2 coats of Semi-Gloss Rustoleum. Better than nothing. And its survived 40 plus years so far without anything.

My paint store sells SEM, but I haven't been back to buy some chassis paint.

[962porsche]

Originally Posted by Iciclehead

Just be careful with weld through primers, I have tried several and settled on the Wurth version. The other two I tried, SEM and 3M gave heavy splatter and poor welding until they burned off in the welding process.

I got to the point of spraying on the weld through and then sanding it out of the way where I was going to place welds.

Dennis

the wurth weld primer IS made by SEM and put into the wurth can .
SEM makes many products for the WURTH CO.
wurth makes nothing of there own they buy other peoples products and are packaged in a wurth container .

[sballard]

I assume that cavity wax would be relatively effective for inhibiting rust in those difficult to paint interior spaces such as the rockers.

[962porsche]

the inner boxes areas of panels are not painted for the factory they are coated when the cars go thru there dipping proses of there undercoat . that is the only protection the inner panels would ever need as they last for years and years before the inner panels start to corrode . if the panel has a black or the gray e-coat primer on when you buy the panel that is all it needs to last just as long as it does from when the car was built it the factory . you have to remove the part of the e-coat when you weld the new panel on were it meets up to the joining panels . so all you have to do is spray or brush a weld primer on that area were you stripped off the e-coat to do your welding .
if you buy a panel that comes in just a galvanized coating on it take a red pad and scuff the inner part . then spray one to two coats of a e-primer (etch or epoxy ) . let the primer dry then remove the primer to bare metal were it meets up with the joining panels and coat what you strip the coating off with your weld primer in just the same way you do for a precoated replacement panel . from there once you do all your welding you could used a cavity wax .
what we would do quite often is use rust-shield with a the cavity wax gun and spray the rust-shield down the insides of the panels .
if you have no access to the inner panel once you have it welded and it's completely boxed in you will have to do all your inner coating before your welding is finished . that you would do in the same way as if your dealing with a pre e-coated replacement panel .

[Iciclehead]

Originally Posted by 962porsche

the wurth weld primer IS made by SEM and put into the wurth can .
SEM makes many products for the WURTH CO.
wurth makes nothing of there own they buy other peoples products and are packaged in a wurth container .

Very interesting......the can I have is labelled in German with an English/French sticky over top so perhaps the Wurth stuff in Canada is different? I'll check the other Wurth stuff to see if it lists country of manufacture.

Product wise there was a difference, I finally tossed the SEM stuff as I just could not get a weld bead to stick until I burned off the weld thru primer, made for a very splattery, messy weld.

The Wurth stuff appears to be quite a bit better (although not perfect) so I wonder if it is a different formulation or something.

IN any event, the processes listed here are definitely on the right track, I have a degree of paranoia about closed sections where I can't get to the inside, I have been doing everything listed here and was going to finish up with the Eastwood product for spraying insided chassis members (it has some sort of rust inhibitor as well), then do a spray wax as a final protection.

Dennis

[cary]

I'd like to learn more about DIY cavity waxing ................

Weld Thru .............. I'm using U-Pol sprayable. Then a diffrent can of brush on. I like the brush on best. Can't remember the name.

[yel911]

cary, that's a sick 914 link!!! Well done!!

[962porsche]

Originally Posted by cary

I'd like to learn more about DIY cavity waxing ................

Weld Thru .............. I'm using U-Pol sprayable. Then a diffrent can of brush on. I like the brush on best. Can't remember the name.

cavity wax is just another type of coating . it's very ez to use and does a ok (not great) job to seal seams . it has no chromates to stop rust that is not what the product is for . it's nothing more than a wax coating to help protect the inner panels from starting to rust .

in my shops we used more brush on weld primer than spray on weld primer .
the biggest reason is the over spray you get from a spray on type .

many people tend to over do it with weld thru primers . they use way to much !
I believe the thinking is the more the better . when that is not the case at all .
you only need one very thin coat for it to do it's job . if you apply to much you will get bad weld penetration and it will give you real bad weld splatter .

I had a guy working for me some years ago he said the same thing that only the 3m weld thru primer was any good . so for the fun of it we poured out the 3m and replaced it with the sem we were always buying . and put the sem into the 3m bottle . the kid was like see this 3m works much better than that sem crap you guys like .
then we told him we swapped out the 3m for the sem he did not believe us .
it's not the product as much as it is the way you use it .