Help identifying sound. Newly rebuilt coilovers installed.
 

I made a new thread because I did not want to derail the other person’s thread. I installed a rebuilt AST 5100 using stock top hats are from a 2017 car (asked damper rebuilder to install the tops hats for me, to make sure I don’t screw it up), new spl front end links and front lower hole camber bolts. Everything else stock. The sound is most audible in the front driver’s side. The sound is a distinct thud in all small dips of the road not metal on metal hitting each other. Only in lower speed like less than 10-15miles/hr in parking area. I did double and triple checked on all nuts and bolts and all are torqued to specs and tight. Couple videos attached. Note: I have not done an alignment. Thank you in advance. Wanted to see if anybody had similar issue and got it resolved. (You may or may not need headphones to hear it. Camera is under wheel well so the sound of engine is loud too.)

https://youtu.be/3kxonwbeOnw

https://youtu.be/3n-K0LElNls

Where are you at on the valving for the shocks currently?

If you're all the way at zero on the rebound, turn it up a couple clicks and retest.

You could have something on the rebound side of things where the piston isn't completely seating and it making the noise. Especially if it's only occurring at low speed and not high speed (like hitting a highway bridge rut or something) - I'd suspect it's something along those lines.

Thank you for your reply. I'll try that again on my lunch. I tried it full stiff setting, midway and full soft but just drove it in street normally. Maybe I need to drive it harder to push that piston seated.

Is your top nut properly tightened?

^ My first thought.

Yes, double checked it too. I tightened to the point that I felt the allen key part is almost gonna give but backed off. Both sides are tight. Or do you guys can suggest a different way to tightened them?

Allen key?

It's an M12 nut

Help identifying sound. Newly rebuilt coilovers installed.
 

Sorry, I was not specific. Used an allen key to keep the shaft still and used a passed through wrench to tighten the nut. Use an impact gun to see if that will tighten it better? Not sure if they used impact gun from the rebuilder to install the top hats but I can try that because I have an electric one.

Use a pass-through torque wrench.

I have a normal torque wrench and crows foot for it that can work on a socket. How many ft lbs is recommended to tighten it?

I have no idea; ask your rebuilder or reference your owner's manual.

Thanks. Will do. I appreciate all the replies.

Looks like 41lbs

http://i1087.photobucket.com/albums/...ps57421016.jpg

Stop top hat =/= stock center nut. Depending on his shaft, it may be different, which may have a different torque spec.

OEM is M12x1.25, but Tein and JRZ are both M14x1.5. AST is typically M12x1.25, but not always.

Very true I haven’t even thought of that.

OP it looks like the 5100 series coilovers use an M12 nut.

Are you using the AST nut on the OEM top hat? It’s a long shot, but the AST nut arent flanged like the OEM nut. I know the factory top hats do not use a washer between the strut nut and upper top hat bearing, so the flanged nut may be needed to avoid spring bind 100% of the time? Long shot for sure, but I’d personally go through the trouble of putting the stock strut nuts on and listen for the noise.

That's the exact noise I had when my top nuts were coming loose. Went away after I tightened them down again.

I re torqued both side and they are in both 41ft lbs. Both side are using nyloc m12x1.25 nut. I tried test driving it again and the noise is still there. I was able to get in contact with the damper rebuilder and said to bring them back in to see if they can replicate the sound in their dyno and recheck them for me.

Since 5100s are inverted, I wonder if the other nut on the bottom is not properly torqued.

- Andrew

FWIW - I had almost this same exact noise on my MCS 2-Way Remotes in the rear.

I chased the noise for 2 years. Thought it was shock but, then figured the sphericals on the top hat were shot. Replace endlinks in the rear too

Noise only occurred at low speed sub 35 mph. Worse as you slowed down and hit more uneven payment.

Sent my shocks into MCS for warranty and revalve because the fronts were leaking oil at the canister (V2 Canister design on V1 Seals)

Found the rear cans “slightly” leaking oil which most likely caused the noise by not letting the piston re-seat. We upgraded to a coated piston offering by MCS that wasn’t available to OTS builds to reduce initial nose in and they’ve been fantastic ever since


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I checked the nut from the bottom, being it as inverted and it was tight too. Hopefully, rebuilder can replicate the noise and figure it out what’s going on. It won’t be til Wednesday due to work. They said I can drop by anytime and they will look at it right away as soon as I bring it to them. I’ll update here.

Those are interesting info. I do not see any leaking oil so far.

Help identifying sound. Newly rebuilt coilovers installed.
 

Just updating. Rebuilder took the dampers in and checked it. They did dyno them even with the whole coilovers assembled. They were unable to reproduced the noise in the said video and graph shows that they are working fine. They replaced the top spring perch for the fronts just to see if that could be the cause due to a little play on them. The noise is still consistent in low speed and does sound like a loose top nut but they are all tight even at the bottom being an inverted dampers when I checked. I tried their advice of just installing the fronts and see if the noise is still there, and yes it was there but not much then when I installed the rears it was more apparent. I gave a triple check again when I installed them and all nuts and bolts are torqued to spec. Next step is bringing the car in and they will check it themselves and help me out sourcing that noise.