Very rusty parts car had a bunch of suspension upgrades to it (Bilstiens, turbo tie rods, 21 mm torsion bars). My question is one bar looks perfect, but the other some paint has (coating) has peeled off and has some surface rust. So is that a issue?

Doesn't look that bad. Blast it and repaint it.

Yeah, what he said.

I'm no metallurgist but you have a piece of solid 1 " steel ( aprox. ) so I don't think some surface rust is an issue. But did you mark them when you removed them for what side they came out of ? And marked front or back ? I think ( ??? ) a torsion bar will take a set once installed, I don't think you would want to install in a different car in a different orientation than the car they came out of. I say clean them up, prime/paint and install ( in correct orientation ).

Yes I did.

I had a torsion bar break on the road once with a car that had not been used for a long time. The torsion bar broke right where a small rust patch was (I call it a stress raiser). I would only install a near perfect one, although having a torsion bar break on the road is not the worst thing that can happen.

If this is a road car that you give spirited driving on the weekends, then blast it clean and paint it. Put it back in same orientation as others have said.

I think the idea is that it is like scoring glass. The surface is where the stress is, and the torsion bars are heat treated. So they always break at a stress riser coming from corrosion. I have seen it happen in other pieces of steel. But they are expensive and if they didn't rust, but the paint just flaked of, why not? I think peening might be better than sand blasting, but that is just pulled out of .... well somewhat a guess.

Can you post a pic after blasting it (prior to painting if you haven't already done so)?

I wonder how this would relate to axle shafts. I know axles don't experience the same level of twisting, but I've seen axle shafts in worse condition that haven't snapped in half after 'reconditioning'. I realize they are a different animal and CV joints would typically fail before an axle would. It's just a question that came up in my mind

You could have it magna-fluxed to be on the safe side

Mark I'm not going to put them in my 914 as I already have a set in mine. My plan was to post these for sale in the classifieds. I feel that it would be fine to use once cleanup and painted, but I am not expert and that is why I asked.

I have to agree with others here, the ones i have seen break (two so far) all broke right where they had surface rust.

My guess would be (and i'm no metal expert) that once the surface treatment is compromised they shouldn't be used anymore.