Hi All,

I finally had time to get back to my '75 project after life kept getting in the way :-) I have about 95% of the car disassembled and have a pretty good idea of all the rust and hidden damage. The floor pans have some surface rust and a couple of spots that might need a patch (eg by brake/clutch pedals). However, the floor inside the tunnel has some pretty good rust that must be dealt with. Odd, but it look like water leaked just inside the tunnel and sat.

Is there a good way to remove the tunnel to access the floor underneath? This is probably not a good idea, but can the floor be cut on both sides of the tunnel, removed, cleaned, painted, and rewelded? Any other ideas?

Thanks,
Dennis

I don't think there's any good way. You can drill the spot-welds and pull it out, which means pulling out the cross-member the same way. A lot of people settle for scraping up what they can access, and using a rust conversion product (phosphoric acid or related stuff) and then epoxy paint on it.

--DD

Thanks Dave.

If the tunnel spot welds are removed, then will the tunnel come out or is it joined to the rear firewall?

Taking out the center tunnel is a major undertaking if you are just trying to mitigate the corrosion of a serviceable floor pan.

Tape up the wiring harness, and remove all control cables. Double check your clutch tube, as now would be the time to repair it if needed. I'll usually reinforce the firewall where it comes through, at the minimum.

This method requires correct respiratory protection, and I'm not talking about a fiber particle mask, you need a respirator for paints and/or acid. As you'll be spraying both.

What I've done in the past is use a undercoating kit with the different spray wands and nozzles. I start with very hot water and rinse it out, then more hot water with a cleaner (wet pickup shop vac as needed to clean up the water), and then rinse off the cleaner with clean water. While wet spray it all with 50/50 solution of Ospho, let it sit for a few mins and re-spray the 50/50 mix, wait a few more mins then rinse with more clean water. Clean up all the mess and spray it all good and dry with air, you can use the wands an nozzles for this too. You can also run your shop vac in reverse to blow it all dry. Let it sit for a day or so to make sure it's all dry. Then spray it with Eastwood's "Internal Frame Coating" really well, 2 or 3 coats. I'd do this with the longs too, just don't use as much water so you don't damage the paper coated heater tubes.

My undercoating/rustproofing kit is about 25 years, so I don't know what's out there now. Mine has 3 different wands, 3 nozzles, and came with 3 poly paint/solution bottles that screw on the gun.

Here's the Eastwood internal coating, it's the stuff to use. https://www.eastwood.com/eastwood-internal-...oz-aerosol.html

Here's the closest thing I could find to what I've got. Looks like you may have to buy extra wands and nozzles https://www.eastwood.com/undercoating-gun-w...and-bottle.html

Eastwood makes a good rust converter that I have used. It turns the rust black and inert. Then you can prime or seal right over it.

Extend by Loctite is a great product I've used for years.

I've seen where a section of the tunnel is cut and folded back for access so wire brush can be used for clean up.
After cleaning, treating and epoxy primer the section is bent back into position and welded.

Guys,

Thanks for all the great advice.

All the cables (clutch, e-brake, heater) have been removed. The harness and battery cable have already been removed, and I'm going to remove the fuel lines, since I plan to replace,

I do have a couple of questions regarding the 50/50 solution of ospho. is there any concern about ospho getting into the joints (eg tunnel and floor spot welded joint) and cause me problems down the road? Or does the repeated rinses get it all out? Is it OK to you a propane torch to lightly dry the area in addition to the forced air?

Thanks,
Dennis

The Ospho won't hurt getting into seams. I wouldn't use a torch, maybe a blow dryer or heat gun.

Getting Ospho in the seams should actually be a good thing as long as the water rinse also gets in there to neutralize it. It will convert any rust it contacts in the seams and leave a protective phophorous coating behind.

Perfect. I'll try it next weekend. thanks all.

- Dennis

While you are in the mood shoot some of that coating in the hollow of the firewall where it meets the floor. This is what it looks like with the floor removed

Strip the tub to bare metal.
Clean up the rust on every surface of the tub, and repair it.

Have the whole tub galvanized. ;-)