Big Block Dart Forums banner
1 - 8 of 8 Posts

·
Registered
Joined
·
137 Posts
Discussion Starter · #1 ·
hi i am now working on puting frame caps on my scamp. they came from rust technitions and my question is they are seam welded on the inside but on the out side which would be the bottom two edges are just spot welded every 6 inches after i install them do you think i need to run a bead along each edge before i grind them smooth or do you think the weld on the inside is enough ?    tnku
 

·
Registered
Joined
·
47 Posts
if it were me & I was already under the car spot welding them I'd just go ahead & run some beads after final fitment.... that's just me though.
 

·
Registered
Joined
·
15 Posts
I used a frame cap on my drivers side forward sub frame. I drilled 1/4" holes in it so as to put plug welds to adjacent factory subframe. I felt that only doing a seam weld at the top would not have the cap "see" all of the load that the factory frame experiences. Not to discount the seam weld at the edge though. I did as much along the edge as I could. I didn't go crazy and swiss cheese my cap though. I put plug welds in about every 3 inches and sort of zig zagged altrnating high and low on the subframe. I also put a few on the bottom where I could. I had to cut out about 11" in length X ~1" vertical out of the factory frame. I have pictures but they are too big to post here. Send email address to me if you want pics.

Before drilling out the holes, I called Auto Rust guys and ran my idea by them. They liked it but cautioned me to make sure the holes are big enough so that I could start the weld in the center of the hole and finish in the edge. They felt if the holes were too small, that I might cover over the top without adequate filling of the cavity. After the plug weld is finished, grind it off flush. You can hardly tell its there. I had told Tom about the brushable weld through primer. Its cheaper than the spray on stuff but same chemical.

Here is a trick that I learned. After putting your holes through your cap, slide it back onto the frame to be reinforced and clamp as though welding. Using a marker, scribe the holes onto the factory frame to be welded to. Take the cap back off. Cut pieces of masking tape in little 1/4"x1/4" (or what ever size covers) squares and put over the scribed circles. Paint the outside of the factory frame with the weld through primer. Paint the inside of the cap. Now, carefully remove the masking tape squares. Put cap back on, clamp and weld. I have read numerous places were people paint the whole thing and then get pist off about not getting a weld to start on the painted surface. Then they go back and grind off the places where they need to weld and everything works fine.

In a moparmuscle article where they installed a quarter panel, they ran into this problem. I guess I just saw this issue coming as welding just doesn't work unless the surface is bare and clean.
 

·
Registered
Joined
·
137 Posts
Discussion Starter · #4 ·
BB_cuda said:
I used a frame cap on my drivers side forward sub frame. I drilled 1/4" holes in it so as to put plug welds to adjacent factory subframe. I felt that only doing a seam weld at the top would not have the cap "see" all of the load that the factory frame experiences. Not to discount the seam weld at the edge though. I did as much along the edge as I could. I didn't go crazy and swiss cheese my cap though. I put plug welds in about every 3 inches and sort of zig zagged altrnating high and low on the subframe. I also put a few on the bottom where I could. I had to cut out about 11" in length X ~1" vertical out of the factory frame. I have pictures but they are too big to post here. Send email address to me if you want pics.

Before drilling out the holes, I called Auto Rust guys and ran my idea by them. They liked it but cautioned me to make sure the holes are big enough so that I could start the weld in the center of the hole and finish in the edge. They felt if the holes were too small, that I might cover over the top without adequate filling of the cavity.  After the plug weld is finished, grind it off flush. You can hardly tell its there.  I had told Tom about the brushable weld through primer. Its cheaper than the spray on stuff but same chemical. 

Here is a trick that I learned. After putting your holes through your cap, slide it back onto the frame to be reinforced and clamp as though welding. Using a marker, scribe the holes onto the factory frame to be welded to. Take the cap back off. Cut pieces of masking tape in little 1/4"x1/4" (or what ever size covers) squares and put over the scribed circles.  Paint the outside of the factory frame with the weld through primer. Paint the inside of the cap.  Now, carefully remove the masking tape squares.  Put cap back on, clamp and weld. I have read numerous places were people paint the whole thing and then get pist off about not getting a weld to start on the painted surface. Then they go back and grind off the places where they need to weld and everything works fine.

In a moparmuscle article where they installed a quarter panel, they ran into this problem. I guess I just saw this issue coming as welding just doesn't work unless the surface is bare and clean.

thanx for the advice i would like to see the pics here is my email    [email protected]
 

·
Registered
Joined
·
134 Posts
You should always drill 5/16 holes for plug welds. Bigger if ya need em but not smaller. The brush on weld thru primer also seems to stand up best and you can put it right where you want it and not all over the place as you should'nt paint over it. In my shop we remove the primer from inside the holes prior to welding by having a junk 5/16 drill bit ground flat and then a very very slight cut grind to just graze the spot where the weld goes, to remove any more than just inside the hole defeats the purpose of even using it. Proper corrosion protection after welding is very very important as welding fully exposes the entire area to oxidation immediately after cooling and weld thru primer will reflow right around the weld nugget as it cools. Also don't forget to replace the corrosion protection inside the frame rail when your done with either undercoating ar a wax based product. All this stuff is available from your local PBE (Paint Body & Equipment) Jobber. thanks for being bored to death with my first post. but as a body shop owner I couldnt say nothing on this one.  ;) Jeff  ;)
 

·
Registered
Joined
·
15 Posts
[size=10pt]Actually I used a 3/8" spot weld cutter but felt that it caused too big of a weld and resulted in a larger dome to be ground flat than I thought was necessary. I gave the 1/4" size as a suggestion of a smaller and easier grind off. If 5/16" is the number from the body shop pro, I'll take it as gospel. Thanks

I will send the pics to the guys who requested by email, I been offline a while. Just switched to DSL, what a difference!
 
1 - 8 of 8 Posts
Top