Strange, anyone know what might cause this?

[FFRSpec72]

Went to replace the rear spings last night and found this on the driver side rear shock, there were no marks on springs or any parts around the shock, so no idea what may have caused this issue.

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[kabacj]

Looks like the coils are binding and tipping inward under compression to me. the marks correspond to the spacing of the spring coils when compressed. its kind of strange that the spring would bend inward like that, however you can test by installing shock on the car and jacking the car by one wheel compressing the shock/ spring as much as possible see if the coil bends toward the body of the shock.

There is also that little wear mark on the end of the spring near the body. Thats a little suspicious as well. I would want to know how that got there.

I assume the springs on the shock are the only ones that have ever been on there? I would think that there is some other force on the spring when it hits the shock body. only very offset spring landings or maybe a bad spring would cause it to compress with a kink like that.

Thats my guess.

John

[FFRSpec72]

The spring has no marks (all of the powder coating is intact), so it was not rubbing the shock collar, the mark on the spring comes from how the koni's are mounted on my MkII as the body is down, so the sping is right up aginst the mount. I have checked the travel and no binding or issues. So yes these springs are teh ones that came with the koni upgrade, I have just switched.

[AJ Roadster NJ]

Hard to tell from the photo, is that a white cake- or powdery-type substance in the adjusting threads? Just a thought, but is your battery right above it? Might you have corrosion happening that is settling down onto the shock?

[FFRSpec72]

It's actual scraping of the collar, so it is ware marks, so the collar in that spot has been worn down

[kabacj]

Yeah I did see that on the end of the threads it almost looks like the end of the spring hits and scrapes as it travels up to the spring perch.

The only way that could happen is if the springs rattle free by a lot at full droop.

I assume the springs dont rattle free at full droop?

[FFRSpec72]

I assume the springs dont rattle free at full droop?

Nope, and no marks on inside spring either, as there would be missing paint or marks on the inside of sping if it were scraping

[Bob Cowan]

The dye on the alum threads is not nearly as tough as the powder coating on the springs. There is nothing else that could get in there and rub it clean besides the springs. Unless you had a big hunk of FOD stuck in there for a while.

[kabacj]

Ok clearly the spring is not hitting the body. What if something else in the wheel well was causing the damage. It could only hit the threads where the spring did not block it. That would explain the spring shadow type wear pattern. A stainless braded line is very aggressive when touching aluminum. Any chance the brake lines touch at some point in the wheel travel? The brake line or some other thing that’s thin enough to fit through the coils of the spring would wear away a mark like that. The stainless brake line could lay on the spring and not cause noticeable wear on the powder coat but really tear up the body as it makes a sanding motion mostly near the bottom of the threads and sometimes one coil up.

This type of damage could happen in one race or race weekend. Maybe the banjo on the brake caliper was at a different angle for one weekend then put back in the normal orientation?

Hope you don’t mind me guessing. When I am stuck I call my Dad and we brain storm to try to figure things like this out. Mostly we think of the same things as the cause, but sometimes one of us comes up with a new idea that the other has not considered.

[mhoward1]

The dye on the alum threads is not nearly as tough as the powder coating on the springs. There is nothing else that could get in there and rub it clean besides the springs. Unless you had a big hunk of FOD stuck in there for a while.

I am thinking this as well. The upper mark seems to match the spring angle. I would have no idea what would cause that though.

[johngeorge]

Guys, I've seen this before and not a big deal, it happens... I doubt you'd need the car that high up.

[Joe]

Do you zip tie your spring to the shock hat? If so, when you jack up your car the end of the spring clears the adjustment sleeve at full droop. When you drop the car down, the spring will slide across the adjustment sleeve and mar it as shown. Do you sometimes hear a loud "POP" noise as you lower your car? That is the spring popping off the edge of the adjustment sleeve, marring the sleeve and then seating on the adjustment ring.