Blown strut or other problem after spring install?
 

Hey guys,

So this weekend I decided to lower my FRS, I went about doing the install based on the instructions in the DIY section.

I remember reading about not spinning the shaft in the strut so I was extra careful not to do it in the front, the front appears to be fine.

However in the rear I couldn't get the nut off the shaft with hand tools and I didn't want to get killed by flying parts so I used an impact gun to remove the nut from the shaft. I put everything back together with hand tools making sure not to spin the shaft.

So everything back together I take the car for a spin and immediately notice a clunking/rattling sound coming from the back, really sounds like something is loose and rattling around after every bump. If you grab the rear fender and lift the car up and down you can clearly hear it from inside and outside the car.

I checked the strut mounts and the bolts where the strut connects to the LCA, everything seems to be tight and torqued properly.

So what's wrong then? Did I blow the rear struts using the impact gun (leading theory based on searches) or did I do something else that I'm not seeing or missing? What other symptoms would a blown strut exhibit?

Sadly, that is most likely. They usually leak, but I'm not sure if they will given the damage is usually more internal than just a seal I think with these failures. These OEM dampers seem way too sensitive to this IMO.

BTW next time I'd suggest removing the assembly whole, and then rent (free at many autoparts stores) spring compressors, and then use hand tools.. keeps you and the damper safe. :thumbup:

Sigh. Well the struts are reasonably priced at least (canadian dealer quoted $111/each).

This seems like a very poor design, do aftermarket (Koni) struts have the same problem?

As a general rule don't use an impact gun on any shocks. It tears up the shaft seals.

Sounds like hardware is loose.

Perhaps check all hardware that attaches to the rear lower control arm (inner & outer pivot bolts, sway bar end link, lower shock mount.)

Then check stuff up top like the rear shock tower bolts and then the shock shaft nut.

The trick is this:

When reinstalling the top nut in the rear the best way to prevent the shaft from spinning is to put a LONG screw driver thru the bottom eyelet of the shock. Have a friend( STRONG FRIEND) hold each side of the screw driver with his feel. Then he should PULL UP on the rear shock MOUNT, while you use tools to secure the top nut. We install A LOT of these rears from Impreza's and BRZ's and use an impact gun....very sparingly with regards to impact speed, but the main thing here is when PULING UP on the mount this puts tension on the shaft and it prevents it from spinning freely and then the top nut DOES tighten ALL THE WAY DOWN.

What happened with you in this case( PROBABLY) is you tightened it but as it goes down the shaft it gets tighter and then there is so much resistance that it wont spin any longer on the threads so naturally most think that its bottomed out and its secure. WRONG. Its not and so it makes noise.

This can be done without an impact gun and requires more work but can be done.

Hope that helps you understand why. I say this after having 30-35 people bring their cars in with a rear noise and we show them what and why.

Myles

Do the rears not have a space for an Allen key?

They do. Just remove the dampers assembled, it's easy.

This really sound like the hardware is lose or the spring did not seat correctly.

Are you saying it can be fixed? When I tightened the top nut I used an allen key and an open ended socket, but I only tightened it down to where it was from the factory, not until it was bottomed out.

Does it need to be bottomed out?

Yeah it sounds like the top hat just isn't tightened down all the way.

If you damaged a strut internally to the point where it was clunking it would have pissed all the fluid out and your car would probably be bouncing around like crazy.

+1 on something not installed properly or loose.

Over the past 10 years of installing suspension privately for myself or friends we have had strut shafts spin and have never had a failure because of it. Yes I know isn't good for the shock, but sometimes it happens.

You have to look at problems with the simplest solution first, you just loosened a bunch of stuff, chances are something is loose.

Wow guys thanks for all the help, not tightening the top hat was exactly the problem. Unfortunately I had to take the struts out again to fix it, but everything is back together now and working as it should.

I owe you all a beer, you saved me from wasting $250.

Here's a terrible pic of the car in my underground. Eibach Sportlines.

http://i54.photobucket.com/albums/g8...ps7d1fb433.jpg

the key is to 'blip' the impact with tiny short blips to avoid actually spinning the shaft, and just loosen the bolt. if you stand there and hold the trigger down, you will spin your shaft.