My baby's off to sandblast land

[Seppi72]

Just got home from trailering my car to the sandblaster. It turned out to be fairly easy and straight-forward, even though we had prepared for something more elaborate.

I've had the shell on a rotisserie (see attached photo) for about a month as I was finishing up the removal of the last bits of hydraulic lines and wiring harnesses as well as scraping off undercoating (oh, what a F-U-N job that is). We were expecting to have to use an engine hoist to place the shell on a body dolly to make the transfer, but my body guy thought that the rotisserie was strong enough to handle things for the 5 mile trip.

We pushed the loaded rotisserie onto a flat-bed trailer (remarkably easy, I have to say - we didn't even need to use the winch) and used straps and "come alongs" to hold things down and in place. Then it was off down the roads (admittedly back country roads). No muss, no fuss, no bother.

My baby's now at the sandblaster and we'll likely start on things tomorrow. Blast, inspect, treat if needed, and epoxy prime each day. With luck, we'll have this portion of the job done by next weekend and we can then take the whole thing down to the body shop for the real fun-and-games to begin.

You know, after thinking and dreaming about this for the past 25+ years, now that it's well and truly underway, it just seems unreal. I can hardly wait to document the process.

Any and all tips and tricks regarding the sandblasting of S30 models are welcomed.

[Zak's Z]

Hey, The metal is thin on the body panels, so choose proper blasting media so you don't warp the metal or work-harden it too much. I assume your body shop will take care of this but make sure you re-apply seam sealer where its all been blasted out.

[geezer]

Good points Zak. Also as JimmyZ mentioned in your other thread Bob, sandblasting is not a good method of paint removal on a Z. It is best to spend a day with some good quality "skull & crossbone" stripper and a respirator. Don't worry about removing every little bit of paint in corners or tight spots. The metal is better reinforced in these areas, so it is safe and much easier to sandblast these areas. Rust removal is where a sandblaster rules. The guy doing your sandblasting probably knows all this, unless he's new at it. What kind of facility and equipment is he using?

[240znz]

I had mine sand blasted and the results were good. Roof was stripped chemically.

But you could consider plasma cutting those sections that you'll be replacing before you blast. That way you can see what's behind and get that sorted while your at it.

It is also very important to get rid of all the excess sand. Sand will collect in the foot well fresh air vent cavity (both ends). You may find that a small section of garden hose (200mm) duct taped to a vacuum cleaner will help get it out. I used several different diameters to get unto all (I hope) of the cavities. Ugly rust monster likes sand filled nooks and crannies.

But more imporantly, you will need to seal the car ASAP after blasting.

[Zak's Z]

All good points also. Sandblasting my Z didnt actually remove all the paint or rust. I had to be careful and didn't want to over-blast it so to speak. Its almost impossible to blast thru the filler that was on my car, and also couldnt get thru the undercoating. I ended up using chemical stripper on the roof. The best tool I had was a drill wheel that has long fiber bristles on it. That was the best thing to remove paint and most light rust. I tried the 3M paint stripping wheels, and a few others..but those worked fastest and best. Mind you I took my car completely down to metal. Every bit of it except the back of the underside which I plan on doing when I do the suspension.

It took a long time and was alot of work, but I feel way better sending my body into the shop bare. Also I should mention that after I stripped it I etched the metal (I used Por Metal-Ready) then I cleaned it all and shot a quick coat of rattle can primer on it. The body shop was good with what I did and just took over when I dropped it off.

[Zedfoot]

Be carefull moving that shell on a rotisserie. My shop, www.bodybybiggs.com refuses to use one as they have had cars (American, mind you) bent out of shape that way. Apparently you don't find out untill final asembly when doors and panels don't quite fit properly.

Go to http://www.flickr.com/photos/janeeric/sets/72157606153458051/ for the whole story on media (broken glass in this case) blasting. No need to strip undercoating, the glass is sharp enough and with lots of air (80 HP compressor) the metal doesn't heat up.

[AggieZ]

Beware the sand that remains. It will hold water and create the rust you want to avoid. If your shell is sandblasted, be sure it dries in a humidity free environment and is gone over with high pressure air blasting. Also, the minute grains might put a bit o' grit in a surface of paint.

Sandblasting is like going to the beach... the sand is going to get into every nook and cranny just to irritate you. :cheeky:

[JimmyZ]

A shop vac is great for removing sand. Trying to blow all of the sand out moves it around to areas you have done. One area to watch for is the internal space right above the bumper. The door posts and window pillars never seem to be completely sand free. You may want to fashion a shop vac attachment out of a long length of 1/2-3/4" tubing. You can fish this up and around as well as use it for blowing out.

See if the blaster can blow things out as best he can with his 90cfm rig. (If he's using a commercial compressor) I'm sure he will but it would save a little time in cleanup.

You'll probably spend a day or two doing the suck and blow thing before you have most of the sand out. (God that sounded awful!)

Good luck!

Jim

[dat260]

Be carefull moving that shell on a rotisserie. My shop, www.bodybybiggs.com refuses to use one as they have had cars (American, mind you) bent out of shape that way. Apparently you don't find out untill final asembly when doors and panels don't quite fit properly.

Go to http://www.flickr.com/photos/janeeric/sets/72157606153458051/ for the whole story on media (broken glass in this case) blasting. No need to strip undercoating, the glass is sharp enough and with lots of air (80 HP compressor) the metal doesn't heat up.

You have PM.

Cheers,

[Seppi72]

The work happened over the course of about four days last week and we finished up yesterday afternoon with the final epoxy priming. Now we just have to wait for room to pen up in the body shop and we'll transport the shell there for rust repair.

In truth, as JimmyZ and AggieZ said, getting all the sand out was a major task and took well over eight hours of my time alternating between the air hose and a shop vac. I also found that "spinning" the shell on the rotisserie really helped to get the sand moving so it could be removed. Even so, every time we rotated the shell to prime, there was more sand showing up. Fortunately, none of it got caught up in any fresh epoxy.

As for treating residual rust, I ended up using Ospho. I used an artist's brush to apply it along every spot welded seam since there undoubtedly has to be rust in those locations. I used a 1" bristle brush to get up into the shock towers where the sand couldn't be directed. Again, having the shell on a rotisserie made this task quite easy (and no phosphoric acid dripping onto my face). I used a 1" foam brush to apply epoxy to these same hard-to-access areas.

The other regions of concern were the frame rail tubes underneath the rear deck. There is no way to get sandblasting in there, so I resolved to treat the interior portions with Ospho. The sandblast guy had an old siphon gun originally designed to apply undercoating. This had a 3/8" diameter, 1. 25" long cylindrical aluminum tip with two slots cut about halfway through into the end so that the discharge would be a fan spray coming out at a right angle to the cylinder axis. I used threaded hose barb fittings to secure the spray tip to a 3-foot length of reinforced 1/8" ID vinyl tubing. A similar fitting at the other end attached the tubng to the siphon gun outlet. I attached the tip so the the discharge slots were aligned with the identification info printed along the hose. This way, I could tell which way the slots were facing. A little experimenting with water showed that a nice mist was created at the tip with about 70 psig air.

For the frame rails running parallel to the axis of the car, with the shell in the "normal" attitude, I inserted the tip and tubing through the holes underneath the shock tower braces from inside the car; either running forward or backward as needed. I fed the tubing to the end of the run and gradually withdrew the tubing while the spray was discharging. Knowing that the tip was facing upwards, I anticipate that it hit the "roof" and sidewalls and ran down to coat the "bottom" of each rail interior. Any excess Ospho ran out of the water drain hole at the end of each run and was caught in plastic pails.

On the passenger side, there's a cross tube in the aft leg that allows a fuel line to pass through. For that leg, I also had to insert the tip from the end drain hole. Fortunately, there's a corresponding hole in the rear deck that gives access. This had to be slightly elongated so I could insert the tip.

For the cross member frame rail, we turned the shell 90 degrees, inserted the spray tip towards the "up" end of the rail and sprayed while I slowly rotated the tubing and tip inside the rail. We kept this up until we saw a goodly amount of Ospho run out of the lower end. We then rotated the car so the other end was "up" and repeated the process. This method, I believe, is the best way to treat any interior rust short of dipping the entire car.

There's some rust through to repair on the aft crossmember (the one that runs parallel to the rear bumper just inside the sheet metal) so I'll Ospho that when the bad section is cut out.