Any update on acid dipping a 911 shell ?

RS-GT · 07-17-2009, 06:12 PM

Hi,

I made a bunch a search on this forum and on the web for the acid dipping process to remove all the rust and undercoating. The comments are mixed ; Does someone have any comments from past experiences of dipping a 911 body shell ?

Thanks!
JD

spence88mph · 07-17-2009, 06:36 PM

do a search on the 930 forum of the white zuffenhaus build, quite sure they talk about how they stripped that one back to bare metal and if there's a company to follow it's them.

spence88mph · 07-17-2009, 06:36 PM

1984 930 Rebuild, Zuffenhaus

spence88mph · 07-17-2009, 06:40 PM

"we have these cars baked in a large oven - then residue ash (formerly sound deadening, etc) is lightly media blasted off. Doors, hood, fenders and decklid go to e-coat, before paint. Unibody gets powder coat on all the interior and bottom areas.

Then paint as desired."

TimT · 07-17-2009, 07:18 PM

This thread has some pics of a project we are 90% done with.. The tub was dipped by Redi-Strip in Pa.

Dipped project

Its really nice to work on a tub when it is squeaky clean..

RS-GT · 07-20-2009, 08:07 AM

This 930 looks awsome ; I will try to reach Zuffenhaus for more details.

I made reasearch about redi-strip in PA, I found other muscle car forum that also had mixed experiences, some will just use this method other will never ?!?

Does someone know what temperature it takes to "baked" the undercoating and insulating materials ? Does a industrial powder coating oven will works ? I think is 400F...

Thanks !

RWebb · RWebb's Garage

many have said that acid dipping leaves acid inside the unit body, where it will eventually corrode the frame

I would avoid based on that risk - you want your car to last decades, right?

Zeke · 07-20-2009, 09:06 AM

The restoration facility near me won't acid dip cars. He says they never get it out of the pinch seams no matter what. They media blast. They will do individual parts that are not joined, however. Also they will do iron cylinder blocks.

304065 · 07-20-2009, 09:18 AM

BLAST IT!

trak ratt · 07-20-2009, 10:42 AM

Quote:

Originally Posted by spence88mph

"we have these cars baked in a large oven - then residue ash (formerly sound deadening, etc) is lightly media blasted off. Doors, hood, fenders and decklid go to e-coat, before paint. Unibody gets powder coat on all the interior and bottom areas.

Then paint as desired."

Friend had his 911 done. In central PA I think. ~400 gets if nice and clean. Nice thing about this is that there is no residue anything to screwup paint later.

johndglynn · johndglynn's Garage

My local shops dips all their rally cars pre-build and then e-coats. No rot problems. Mine was dipped six or more years ago - no probs with rust. If you dip, be sure to cut the heater tubes out first.

If it was the same price to bake or dip, I would probably bake it then light blast it, to see whether the final finish was better. It is pretty good on the acid dipped cars. Every process has its downsides - I think acid is useful but only if you trust yourself to thoroughly rewax the shell afterwards. The professionals advise double/triple bracing the door apertures too.

RWebb · RWebb's Garage

so, it can go at least 6 years before the acid eats thru...

- just not good enuff for me

Steve@Rennsport · 07-20-2009, 01:06 PM

We've used both methods: Redi-strip and media blasting.

Redi-strip gets the chassis FAR cleaner but the job is only as good as the people doing it. Its more expensive than media blasting but the end result is really excellent. Properly done which means dipped, rinsed, neutralized, and rinsed many more times, you'll not have problems in later years but this is all about "human factors".

Media blasting doesn't remove the undercoating as well but its less risky and less expensive. One thing,.......no matter how well you clean it out with compressed air, you'll be getting facefuls of media dust & material coming out of every orifice, opening and compartment for a very long time. Its the "gift that keeps on giving",.........

Its merely an annoyance.

Horses for courses, as they say...

RS-GT · 07-20-2009, 01:15 PM

Thanks Guys ; but as you can see half will say blast it and others will dip it ?!?! I'm really confused !

Here's the shop I'm looking at, which is the closer to me, they are in Toronto area, I'm in Montreal ; Anybody know them ?

http://www.technostrip.com/car.html

JD

RWebb · RWebb's Garage

Steve - do you use Redi-strip as a complete immersion bath?

sc_rufctr · 07-20-2009, 05:52 PM

After reading this thread I have to ask a question...

I thought one really good reason to not dip a 911 is because the acid can compromise/reduce the protective galvanised coating on the steel.

Someone in the know please comment.

TimT · 07-20-2009, 05:57 PM

The Redistrip we used had 3 big tanks, enough to submerge the whole car. The car sits in the caustic tank for a few days, then get the neutralising bath for a few days, then the rinse tank..

Not sure how much of the acid is left after neutralizing and rinsing, but there is moisture left in many of the rockers compartments etc..

I have noticed some weeping from some of the pinched and spot welded seams and weeps..Not really to concerned..

Shaun @ Tru6 · 07-20-2009, 06:30 PM

You can always do it by hand.

Green 912 · 07-20-2009, 09:52 PM

That makes my ears and hands hurt just looking at it. what a nasty chore that must have been.

I had Redi strip in PA toast and acid dip a 77 911 tub. I washed it out well after getting it home as there was still some solution in on it. It looked like a fresh new part direct from Porsche. Clean bare metal is a nice thing to have when cutting a 911 down to 310 pounds before tubing it up. It was converted into a track only car so I was not worried about the zinc being removed or reduced. (It was somewhat)

RWebb · RWebb's Garage

are you saying the unit body weighed 310 pounds?