JMortensen Posted May 13, 2004 Share Posted May 13, 2004 Well so far I've prepped the rear control arms (removed the bushings and the spindle pins), sectioned my spare set of struts, pulled the stubs, and I'm about to drop the diff out of the car. Plans include the "poor man's toe adjuster", a diff mount like Jeromio has, possibly a fuel cell, and definitely stitch welding the chassis in the back. So the questions are: What is the easiest way to clean the areas to be welded? I bought a plastic wire wheel from HF and I'm thinking I can use this on an angle die grinder? Also I've gotten some advice that I should paint the areas where I've welded so they don't rust with a tough spray can paint. So far I'm thinking of using Hammerite or a similar "durable" spray can paint. Any suggestions about other paints to use would be appreciated (must be spray can). One of the nuts that holds the differential crossmember that is stripped. These are the captured nuts inside the frame. What to do? Should I cut out that section and weld in a piece of sheet metal with a new nut tacked to it? That's about all I could come up with to do to fix. Finally starting to get somewhere with the latest round of mods... Jon Quote Link to comment Share on other sites More sharing options...
Roostmonkey Posted May 13, 2004 Share Posted May 13, 2004 The cleaner you can get the weld area the easyer and better it will weld for you.I'd put a 2" sanding disc on your angle grinder and clean the area down to good metal.The plastic wheels can leave some shiz especially at the seam between the two pcs your welding.I like the epoxy spray paints,they seam much more durable than std spay paints.How about retapping that capture nut to the next size up,even if you go sae on the threads.we wont tell Quote Link to comment Share on other sites More sharing options...
rc's240z Posted May 13, 2004 Share Posted May 13, 2004 I agree with the sanding solution, a two inch disc works great and will get down to clean metal without leaving a residue. Depending on the area, you can shoot a light primer then followup with undercoating spray (available in a spray can format). Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 13, 2004 Share Posted May 13, 2004 The easiest way I've found so far is sandblasting with some coarse black diamond grit. Then a good stiff wire wheel (like the kind for removing weld slag from stick welds) if you can see any traces of undercoat or seam sealer left in the seam. Some places you just won't be able to clean real well though, or you will just miss them. You can MIG weld those places, but you have to hang around in those spots long enough to burn off the paint/sealers so it floats to the top of the puddle. If you do go with just a wire wheel and no sandblasting, try to scrape as much off as you can first. The wire wheels like to just spread the sealers around on the metal. For touch-ups after welds, I just use whatever is lying around. I usually have some industrial black or gray. Rustoleum Industrial is plenty durable and inexpensive and ready available at most Home Depots and such. I try do save anything like painting until I'm ready to close up for the night so I'm not waiting around for stuff to dry. Personally, I try not to put SAE on my car at all. A couple years down the road, I won't have a clue which are or aren't metric and I'll accidentally run an SAE nut onto a metric bolt with an impact gun and ruin my day/weekend. Plus I don't like having to use three different size wrenches to take something off that used to only take 1. You could try drilling the old nut out, and then just putting a new one in the hole that is left. Screw a bolt into it to hold it with while and weld it in. I don't think I'd go so far as to cut it out and welding in new sheet metal. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 13, 2004 Author Share Posted May 13, 2004 Well I suppose I could get a 7/16 bolt with a 9/16 head to negate the different sizes problem, then just paint that hole and bolt day glo orange so that I don't try to force it into another hole... Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 13, 2004 Share Posted May 13, 2004 Another thing I do is heat up the seams with a propane torch before wire wheels and welding to turn any remaining sealers in to ash so it comes off easily instead of mushing around. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 13, 2004 Author Share Posted May 13, 2004 Ooh, good one! Thanks! Quote Link to comment Share on other sites More sharing options...
Sam280Z Posted May 14, 2004 Share Posted May 14, 2004 I would repair the stripped captured nut with a thread insert (helicoil)... Quote Link to comment Share on other sites More sharing options...
Sam280Z Posted May 14, 2004 Share Posted May 14, 2004 I would repair the stripped captured nut with a thread insert (helicoil)... Quote Link to comment Share on other sites More sharing options...
Dayz Posted May 14, 2004 Share Posted May 14, 2004 As soon as you are on clean metal, you don't want it to rust again, so usally I paint it with a primer called " zinchromate", aftre painting, you can weld over it with no problem, because of the zinc base. Thus, your clean metal never rust and you don't have to clean it to weld your chassis. Dayz Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 14, 2004 Author Share Posted May 14, 2004 Thanks Dayz. I've heard mixed results on weld thru primers. Anyone care to comment. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 14, 2004 Author Share Posted May 14, 2004 I remember what I had heard on the weld thru primers. They don't stop rust. In fact almost all primers don't stop rust. Isn't that right? Maybe an etching primer would, and I'm not a body man so I don't know, but aren't virtually all primers porous? Quote Link to comment Share on other sites More sharing options...
Dayz Posted May 14, 2004 Share Posted May 14, 2004 About the zinc base primer, I know that a lots of bodyshop uses it, but it's a little bit more expensive. That is what we put in plane industry, so there isn't no corosion. I can't be perfect, but I know for me it is the best, you can always weld over it without cleaning it !!! From past experience it worked for me. Every one that used it on their plane or their car were very satisfied with it, and haven't seen corosion yet. Maybe there is something better if someone can chim in !! Dayz Quote Link to comment Share on other sites More sharing options...
johnc Posted May 14, 2004 Share Posted May 14, 2004 Get an air angle or die grinder and a 2" and a 3" 3M Roloc mandrel. Buy some 2 and 3" Scotch Brite medium (purple) and fine (blue) Roloc discs and use them to clean off paint, etc. Use Acetone or non-clorinated Brakleen to clean the parts just before welding. Don't use any clorinated cleaners or you'll be making chlorine gas when you're welding. To fix the broken off nut, drill and tap it to the next size SAE and use an SAE bolt on it. I use a mix of SAE and Metric on my car with no ill affects. You tend to remember which is which and you can always tell by the bolt heads or the marking on the nut. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 14, 2004 Author Share Posted May 14, 2004 I've got a bunch of Roloc pads, but I was worried the plastic scotch brite pad material would get in the seams as was previously mentioned about the plastic wire cup brush I have. I suppose if I clean it well it may not matter too much. Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 14, 2004 Share Posted May 14, 2004 To fix the broken off nut, drill and tap it to the next size SAE and use an SAE bolt on it. I use a mix of SAE and Metric on my car with no ill affects. You tend to remember which is which and you can always tell by the bolt heads or the marking on the nut. Tell me it ain't so John! Quote Link to comment Share on other sites More sharing options...
wheelman Posted May 14, 2004 Share Posted May 14, 2004 I'd be careful with the weld through primer as well. Welding it produces zinc fumes which can cause you problems. Make sure the place is well ventilated and/or wear a good respirator, not a dust mask, if you can. As for primers preventing rust, I've heard the same thing, they don't. I haven't had any experience with the zinc-chromate so I won't comment on it but I wouldn't rely on any primer as a long term rust preventative. If it will be a while between when you clean it and weld it wouldn't hurt to shoot it with primer to prevent surface rust but not for long term protection. Wheelman Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 14, 2004 Author Share Posted May 14, 2004 Well I think I'm going to use Rolocs then my wire wheel on the angle die grinder. I'll then follow up with some industrial Rustoleum, and see how it goes. Gotta get the tires outta the garage and pull the gas tank and diff. Looks like its going to rain for the next week and a half, but at least this will give me something to do... One last question on welding upside down. I hear the best thing to do is to use a push motion instead of a pull motion. Any other tips before I dive in. All previous suggestions were appreciated! Quote Link to comment Share on other sites More sharing options...
johnc Posted May 15, 2004 Share Posted May 15, 2004 Tell me it ain't so John! Absolutely. Its damn near impossible and insanely expensive to get military spec metric hardware so I've had to purchase AN/MS stuff and its all in inches. I don't trust any fasteners from hardware stores and will, if desperate, order from McMaster-Carr. I hear the best thing to do is to use a push motion instead of a pull motion. I only use a pull motion when MIG welding if there's no other way. I also push my MIG gun because that's how I was taught at Lincoln Electric. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 15, 2004 Author Share Posted May 15, 2004 As far as the SAE stuff, I've got 3/4" TC rods, 5/8" rod ends in my camber plates, and most everything I buy aftermarket is SAE it seems, so that's never been a turn off for me, but I think gramercyjam has a point about possibly sticking the wrong bolt in the wrong hole, so I think I'll do just what I said and paint that hole and bolt day glo orange. Interesting about the welding. A couple of my buddies took a welding class and they always use a pull motion. I guess I'll try both and see what works best. Thanks again. Quote Link to comment Share on other sites More sharing options...
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