series seat box and rear box restoration

[Green Hornet 88]

Hey folks, I have a seat box and the box off/out and want clean up ready for painting etc. The seat box had a black tarry residue on it (from horse hair sound proofing? ) its hard as rock. Any suggestions, tips, tricks to remove it? 
With the box ( its off) on the underside I removed the 3 cross members and have had them galvanized and I have painted the underside.  Now I want to assemble,  I would like some thoughts, suggestions on order of assembly?  Should I undercoat?  Before or after I put on the cross members?  I have a number of cans of spray CT tar like undercoat, I can use if any good?  Thought I do this stuff while not attached to the vehicle.  All suggestions are appreciated!
Cheers!

[binch]

Seems like the best time to do it would be while it's disassembled, to get  complete coating. ???

[ugly_90]

I just reassembled another defender seatbox.

On mine, I had the alloy section primed and painted, and riveted it back onto the galvanized sections, using 3M black vinyl electrical tape to cover all of my hidden mating surfaces on the galvanized metal, then using black RTV ontop of the dry side of the tape to keep the seal closer to watertight before rivetting.

The new paint on the alloy, combined with the black vinyl tape and RTV sealant, should prevent corrosion as the space between dissimilar metals is now isolated. Not like land rover did when they made it, rivet first and paint later :(

Use of any electrical tape other than 3M is prone to weak adhesion or poor stretching.

You might try " goof-off " or something similar to strip the old tar off the seatbox, I would expect any chemical remover strong enough for that job to need a few safety and disposal precautions.

Good luck with the hazmat suit.

[Already a Rover]

I've had good luck with the CT undercoating - was recommended to me by my body man, actually.  Interested to hear about your project - I've got a few hours into mine, and hopefully not much more.

Jim

[Already a Rover]

I have some of the stuff to prep aluminum for paint as well....

Jim

[Rambler]

Having stripped the tarry stuff with horse hair off my rear tub last summer, the best method I found was to heat with a heat gun and scrape off with a metal paint scraper.  Then I went over with various solvents.  Got a lot off, but no means all..  good luck.