Best way to protect a 4-season 912/911 driver?

[Tom '74 911]

I'm just starting some rust repair on a '69 912 that I'm hoping to turn into a 4-season driver. I might convert it to 6-cyl., but not 100% committed yet to that.

I'm wondering what I should do ensure maximum long term protection to what will be a rust free chassis when I'm done with the metal work?

For example - the front suspension pan will be replaced and I'm not sure what the best way to protect the void that gets created after welding the gas tank support over it? I can use weld through primer on the voids before closing them up of course, but is that the only/best way to go?

A lot of the original undercoating on the tub is flaking/chipping off too. If I strip it all to clean metal, then epoxy prime it, paint it and then do new undercoating, is that the best system to use? I'm not necessarily going for a concourse finish, so I'm open to whatever might be the best way to go, even if it's not factory correct.

I'd like to be able to drive it year around including in the snow every so often and would love to not feel too guilty about it! I'd also like to know that I won't have to revisit new rust issues 10 years down the road. The one exception to my year-round driving desire is winter salt, which I will avoid as much as possible!

Thank you for the help,

Tom








An aside... - I had to drill out the pre-spotwelded threaded bungs on one side of my replacement front suspension pan because it wouldn't fit on my Celette bench as-is. One step forward, two steps back!

[bgyglfr]

I would start by considering the typical rust areas and what causes those areas to rust. I've always thought about making some sort of inner fender to prevent the salt etc. from getting sprayed into the back of the door jamb/rocker area. I would look at trying to solve the water that gets trapped in the window seals too. Pans I would just paint well and actually consider not using undercoating so you can see when there's a scratch on the underside. Also, I've seen plenty of these cars rust in the pans because the undercoating would hold the water against the lower pans.

[Bulldog9]

I would do the following when you are ready to paint.
1. Get the whole chassis and body down to bare metal then do the PPG metal conditioning - 2 step process found in this forum.
2. Seal everything in PPG 2 part epoxy primer
3. Paint everything.
4. Once cured, use a high quality rubber undercoating to at least seal all seams.

Most important, is if you drive where the roads are salted, etc spray everything off regularly, a good carwash with undercarriage spray is a good way to do this.

[jrsully]

after everything is cleaned and undercoated, look into spraying drivetrain and other components with T3 Boeshield, originally made by Boeing Aircraft and excellent weather protectant, been using it for years

[bgyglfr]

I've used Boeshield for years as a chain lube for my bicycles. Never thought of that use.

[Tom '74 911]

The voids that get enclosed as panels get welded together is one area that I'm not sure what to do about. The front suspension pan I showed in the photos in the first post and the rockers are the two most obvious places with voids. The areas on either end of the torsion tube is another. It seems like every 911 that I've really looked into has some rust in all these areas, even if the metal is generally still solid...

Do folks use body cavity wax, paint or some other substance sprayed inside sealed cavities with wand sprayers?

A lot of the rust issues seem to be related to the failure of the seam sealer and undercoating when water gets trapped between the outer coating and the metal... Is it better to just use a super durable paint and forgo the undercoating altogether so water drains and dries more easily?

I've seen a number of rust issues in that weird space in the front of the rear wheel wells where the inner rocker support meets the door latch jamb and the rear of the rocker panel. The factory sprayed a clump of undercoating in there which ended up trapping dirt and water and not allowing it drain.

Seems like if you can cover the metal in the best protective coating available and allow it to drain and dry after it gets wet, you'd stand the best chance of avoiding rust?

[Bob Kontak]

Oil spray.

It ain't pretty but it will protect.