Sand blasting springs?

[Steve G.]

I just sent frame and misc brackets to a shop to have them sand blasted and painted. I also sent along the coil springs and leaf springs. My question is - is it ok to sand blast springs? I had heard at one time that the surface might change properties and become more (or less?) brittle. Not sure I am remembering that correctly or not. Any suggestions for finish on the springs? Note my original leaf springs had traces of grey paint on undersides of leafs - espcecially near the center section. On bottom of bottom spring, and on the ends of the top sides of all others, I see black paint - possibly undercoating. Any suggestions are appreciated. Steve

PS - I attached pictures of coil springs - do they look correct for '70 BB with air? Should one end of the springs have tighter loops than the other? Also attached picture of my frame before I sent it off to the body shop.

[Bill C.]

Re: Sand blasting springs?

Steve,

I would not have the rear springs sand blasted, media blasted maybe.
Strip all the paint and have them de-rusted. They were smooth when assembled and after you do the rebuild and repaint of the leaf spring, the pitted look will show up.
Also - check the bottom leaf very closely and look for cracks around the center bolt hole.


The front springs need to be de-rusted, not sand blasted. They were natural rolled steel, smooth and NO paint.
The springs are correct, the top coils are wound closer together.

The half shafts and drive shafts do not need to sand blasted either. The rust needs removal. Sand blasting will leave pitting and that is incorrect. The tubes are extruded steel and has a smooth finish. There have been several really great posts durring the last couple months regarding half shaft restoration. Lots of detail and good ideas as well. Just search TDB.

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Looks like your restoration grew a little over the last 6 months...

[Patrick H.]

Re: Sand blasting springs?

In addition, sandblasting will really change the surface texture and appearance of the driveshaft and half shafts. If you're just going to paint them and don't care, that's fine. However, to get to any semblance of the original smooth finish you'd be much better off cleaning them and either media blasting them, soda blasting them or lightly bead blasting them.

For the front springs, have a machine shop shot blast them and then hit them with CRC-350 or CRC-400. You'll be right on in appearance.

Patrick

[Steve G.]

Re: Sand blasting springs?

Thanks guys. I will call the shop tomorrow and tell them to NOT sand blast these parts. I did research the arichives and found that someone had good results with bead blasting the half shafts. Not sure I can get the parts into the bead blasting cabinet. Is there another method for de-rusting some of these parts? I have a bunch of parts to do:

coil springs
leaf springs
cross members ('boomerang' in front, transmission, rear end support and fuel tank support)
A-arms
brake dust shields / brackets
radiator support
sway bars
Exhaust manifolds
Various engine brackets
Various frame / suspension brackets

I am thinking the cast exhaust manifolds are ok to sand blast. Should the other parts be bead blasted or does that also cause too much pitting? Is there any other way to de-rust / strip the paint besides bead blasting? Wire wheel /angle grinder with cup brush a good option for some of these? Rust remover solutions? Steve

[Tom R.]

Re: Sand blasting springs?

For the front springs, have a machine shop shot blast them and then hit them with CRC-350 or CRC-400. You'll be right on in appearance.

Patrick

What does the CRC-350/400 do?

[Patrick H.]

Re: Sand blasting springs?

Patrick

What does the CRC-350/400 do?

Oil / paraffin protectant.
With CRC, the nigher the number the longer lasting (and I think more paraffin).

[Bill C.]

Re: Sand blasting springs?

Steve,

I used this stuff on my car. Not an acid, Enviro friendly and it REALLY works!

http://www.safestrustremover.com/before-after.asp

Buy around 3-5 gallons. It can be resused several times, once it gets really black/dark looking it needs to get thrown out.
It works best if you keep the solution moving over the parts. I made a delivery pipe (from PVC) and hooked a small fish tank pump to it.
I think it is cheaper if you get a 5 gallon pale. All grease must be cleaned off the parts. Best thing is it will not remove paint, so original inspection marks stay in place.

[Jeff S.]

Re: Sand blasting springs?

[quote=Steve Geldart (49781);435661] I had heard at one time that the surface might change properties and become more (or less?) brittle. quote]

Steve,

What you heard is certainly NOT the case for normal blasting with sand media sufficient to remove surface rust/oxidation.

Spring steel -- (SAE 5160 alloy) -- is often SHOT PEENED following quench & temper heat treat operations. This removes (if present) residual surface tensile stresses & replaces them with compressive surface stress. Compressive residual stress on the surface greatly increases high-cycle fatique performance.

Shot peening & sand blasting are two completely different, unrelated processes. Fine grit sand is a great way to clean spring leaves and leaves a nice 'tooth' for following up with self-etching primer, then the dove gray finish coat.

[Steve G.]

Re: Sand blasting springs?

Thanks. From the sounds of it, I will try to lightly bead blast what I can. For the small parts such as radiator overflow tank and straps, I will try the rust remover (thanks Bill). Regarding the CRC-350 or CRC-400, is that an alternative to clear lacquer / satin finish? Or is CRC-350 or CRC-400 the only way to go for front springs? I read somewhere on the NCRS tech archives that clear lacquer works for unfinished surfaces such as springs, drive / half shafts, and rear ends.

Anyone know what type of finish goes on the transmission cross member, 'boomerang' front cross member, rear end cross member, fuel tank support cross member, and radiator support? I was thinking all the cross members should be the same as the frame (between semi-flat and semi gloss) and the radiator support was semi-gloss. Is that correct?