[Mark Jackson]

I am about to put the rear baffle on the fuel tanks. I cleco'ed on the tank-spar attach brackets and they didn't look exactly square. Worried me because they have to line up with the holes in the spar which are exactly square (I measured.)

I can clamp them in place and enlarge the rivet holes a tiny bit, but will that hold once the rivets are on and the clamps removed? It's not off by very much but I don't want to over stress the bolts holding the wing tanks on. Bad idea.

 

[wirejock]

z brackets

It appears you are experiencing a similar problem many have seen before. My brackets didn't line up so after lots of head scratching I went with the Checkaway method and replaced the z brackets. Sure wish Vans would change the manual. Jason does an excellent job of describing the process and I can confirm it results in a perfectly aligned tank. I haven't updated my blog with the process I used but it was very similar.
Basically, don't drill the hole in the brackets for the baffle side. Mount the brackets to the spar. Cleco the tank together. Cleco it to the wing. Strap it down at the joint then drill the inboard baffle to z bracket holes. Cleco in place. Use a drill stop and be very careful. Then remove the leading edge and drill the outboard baffle to z bracket holes. Cleco those. Then remove the tank skin and drill all the others. Cleco as you go. Then reinstall the tank skin. Unbolt the z brackets from the wing and remove the assembled tank. If this is not the issue, sorry for the long post.
Here's a link to his page.
http://www.jasonbeaver.com/rv7/2009/05/fit-tanks-to-spars.html

 

[rapid_ascent]

Here's a tip. Make sure your pop riveter head is going to fit before you start riveting rear baffle and the Z brackets on. Once you get to that stage you'll be rushing around trying to get everything done and you don't want to have to start grinding your tool down. Ask me how I know .

I never came up with the perfect solution. On the first tank I wasn't prepared at all. On the second tank I bought the cheapest pop rivet tool from Harbor Freight and ground one side down. I pulled 2 rivets and the thing jammed up. I took it apart, put it back together pulled one more it jammed again. I threw it in the trash and went back to my using original tool. I still think the approach of grinding down one side of the pop riveter is the correct approach, but don't use the absolute cheapest tool you can find. Some tools from HF are usable some are just junk.

 

[resrob66]

Working on my second tank now....

I see what you're talking about on the bracket not being square. Looks like your holes in the bracket were not quite on centerline when you drilled. In other words the bracket was rotated a little bit when the spar-to-bracket holes were match drilled. The rivet holes look to be offset the same as the bolt holes. I'd bet if you moved the square in the pic over to the holes, the holes themselves would be square. I did the same thing on one of mine. As long as the bracket was bolted in place when you drilled the baffle-to-bracket holes it should line up. You may have a tight squeeze on the rivet.

One way to test is to cleco the brackets to the baffle and test fit the baffle/bracket assembly again on the spar to be sure prior to riveting it all together to the tank.

I somehow convinced myself that I had screwed up all of the brackets recently. For whatever reason, after a few beers the light came on and I realized I was wrong. Of course not until I had called and ordered 7 new brackets......Oh well.

Just an idea to think about.....good luck.
Robert