Rusty coil springs - how much is too much?

[JHZR2]

1991 MB 300D, 234k miles.

Springs are pretty rusty, the paint on these don’t last like on my other same age or older MBs. Not sure why. I have no indication that they were not original.

I pulled one to do a ball joint. I was surprised at the surface rust and the mating end on the CA. The rest of the CA looks great.

Especially the lower section.

I hit it with some Ace Rust Stop paint. Not a great job, just a little brush and then spray. I may change the springs, and if not soon I’ll definitely hit them with lanolin or the woolwax chassis product that dries hard to not wash off.

Not great but that’s ok.

So, how rusty is too rusty? The car won’t see salt ever again, just rain.

 

[KGMtech]

With the natural progression, the springs will fail but that could be next week after a bad pothole or in ten years after a mild speed bump.

Spray them with whatever rust preventative product is handy in your area. A lanolin base will be good and smell like sheep.

 

[SC Maintenance]

Springs don't last forever anyway. Are replacements available? I would be inclined to replace before they eventually fail on their own.

I wouldn't loose much sleep in the meantime. Spring steel is highly tempered.

 

[JHZR2]

Springs don't last forever anyway. Are replacements available? I would be inclined to replace before they eventually fail on their own.

I wouldn't loose much sleep in the meantime. Spring steel is highly tempered.

Yes they are available. MB is not unless you find NOS or good used. The MB classic center may have them. Swedish made Lesjofors (supposedly OEM) and Malaysian made Bilstein at minimum can be easily obtained.

 

[SC Maintenance]

Are they still springy, or does your car ride lower than stock height.

I grew up in an area with heavy salt use and have seen a couple failed spring, but in those cases the entire car was a basket case so I would have to assume yours aren't as bad as those. Still, if your keeping this car forever which is sounds like you are, you may appreciate the better ride if the cost isn't prohibitive.

I replaced the springs on my Xterra after a lot of miles - no rust, they have never seen salt, but the vehicle rode and handled much better afterwards.

 

[JHZR2]

Are they still springy, or does your car ride lower than stock height.

I grew up in an area with heavy salt use and have seen a couple failed spring, but in those cases the entire car was a basket case so I would have to assume yours aren't as bad as those. Still, if your keeping this car forever which is sounds like you are, you may appreciate the better ride if the cost isn't prohibitive.

I replaced the springs on my Xterra after a lot of miles - no rust, they have never seen salt, but the vehicle rode and handled much better afterwards.

Everything is fine. No issues with ride or ride height. Car bounces perfect. May need one rear shock at some point (saw a tiny bit of oil), but otherwise all good. Was primarily concerned because I hadn’t looked closely at the bottom where it touches the CA. That’s where it had a bit of spalling.

 

[JavierH19]

I only see very small chunks flaking off not big ones and the steel looks thick enough still. I'd say they're ok for at least a few more years before checking again.

 

[SHOZ]

I had springs break on the rear of a Ford Taurus and they were not rusty.

 

[JHZR2]

I had springs break on the rear of a Ford Taurus and they were not rusty.

My Saab had a recall due to failing springs. And they were painted and heavily coated. It happens. Mine broke but it was the very end.

 

[oldcodger]

Just because you have them out I would use some rust stabilizer and reinstall.

 

[74DartSport]

They look much beefier than most springs nowadays. Our 2012 Santa Fe broke a front , 12 years 165k miles. They’re plastic coated and much thinner. I think the coating gets compromised, rust and stress breaks it. Yours look like more beef and less likely to break.

 

[JHZR2]

They look much beefier than most springs nowadays. Our 2012 Santa Fe broke a front , 12 years 165k miles. They’re plastic coated and much thinner. I think the coating gets compromised, rust and stress breaks it. Yours look like more beef and less likely to break.

View attachment 240412

View attachment 240413

I suspect they are. Especially since they’re used differently in those wishbone suspensions vs the strut approach like yours shows.

They say that Mercedes uses stronger/longer springs than other drsigns. So I suspect you’re right.

The plastic coatings seem good until they aren’t. I believe the recalled spring on my Saab was plastic coated. When it’s compromised and the bond fails, then there’s a little area to hold water…