I'm stripping my rear hatch and have some rust issues to repair.  There are a few holes that were under the window rubber.  I'm not sure yet how I'm going to repair them.  Cosmetics isn't too much of an issue since they're under the rubber.  The options I batting around are:

1). Cut out the rust and weld in new metal.  I'm a little concerned about my ability to effect a good repair since  I'll have to fab the patch and the locations a little challenging.  Also I will need to cut out enough metal that the repaired area won't all be under the rubber so I'll have to take care to blend everything and make it pretty.

2). Skip the patch and just try to build up metal with my MIG welder.  This will probably be a little ugly and lead to a lot of grinding in places my 4 1/2 grinder doesn't fit to well.  A dremel would fit but would take forever.  The grinding problem probably applies to #1 too. 

3). Fill the holes with fiberglass.  This is probably the most half assed approach, but since the repair will never see the light of day is viable.  

Anybody had take make similar repairs?  How did you do it?

 

I would probably try to MIG them closed. Then use a die grinder with a cut off wheel to knock the welds down. then use a 90 degree die grinder with a  2" 36 grit rowlock to clean the last up. If you have a piece of 1/2" copper pipe, flatten one end so you can hold it up behind the hole. Weld against the copper backer but remember it will get hot fast. My second choice would be small metal patches and dress them the same way...

A weld will always be more permanent and if you have the skills, then complete rust removal is preferred.  

 

What I've done on small unnoticeable places is after grinding/removing any loose material I would then neutralize the area with something like Mar-Hyde One Step. 

 

Then fill any small areas with POR 15 patch.

 

I don't know about longevity though. time will tell.

Do they have the POR15 patch in 55 gallon drums? Might be enough for my resurrection project on this 78 Z. Just joking but I have been very pleased with the POR15 system I used on my Datsun roadster project. I am sure I will be using a lot of their products on this Z. I can not remember if they had any of the rust converter spray. I have seen that product available from other manufacturers.

I MIG'd them closed today.  I had already removed all the rust by blasting it yesterday.  It was hard finding good metal.  It kept blowing through which wasn't a surprise.  I finally got it and the results are good enough for my purposes.  

Looks good

Very nice looking repair job. Did you use the copper pipe trick on the backside? I have read about that procedure before but have never tried it for myself. Your work in progress keeps me motivated on my resurrection piece. Keep up the good work, John-Lugoff, SC

I have several different copy pipes beaten into different shapes. Most are 3/4" with a short piece of wood in the uncrushed end. The wood keeps from having to hold onto the 500dF copper pipe after it warms up. Eastwood sells some premade but they are very easy to DIY

 I bought a welding spoon at H.F. $8.99  Nice tool. It has a slight radius to it. I was able to clamp it behind a short section of seam that suffered from "gaposis". It made that section soooo much easier to fill.
 

  On 11/9/2015 at 6:39 PM, One Way said:

Very nice looking repair job. Did you use the copper pipe trick on the backside? I have read about that procedure before but have never tried it for myself. Your work in progress keeps me motivated on my resurrection piece. Keep up the good work, John-Lugoff, SC

 

No I didn't!  I wish I had remembered that trick.  Probably would've made things easier.  

Alright!  All done.  How's this?

 

 

Looks good. I assume your finish paint for the exterior is yellow? Have you shot any test cards? When I did test panels I found that I needed to shoot white down first to get the yellow to look good, over grey it has a little green color. You're jambing the car out like I have; I used single stage over uncatalyzed white base coat but you have to top coat within 24 hrs. I have planned on 2 stage for the exterior but I think single stage looks more period correct. I still have time to decide since I haven't finished painting the suspension yet...