07 Mazda3 Sedan - Noise coming from rear end of car after installing BC Coils

[12obertbarrera]

Just got my bc coils installed by a professional mechanic. Both front & rear maxed out. I test drove it and everything went smooth, than after 30 mins i started hearing a rattling noise. Sounded more clunking than rattling, sounded like the exhaust was hitting something (also have magna flow cat back exhaust system installed) Any ideas was it could be???

[Mitchell3]

Nope. I have had the same thing with mine. No one could tell me what it was. People would dissemble them and say they checked out. Put it back in and the noise still there. Replacing seems to be the only solution. Its BS.

I almost never had it in the rear though so maybe your lucky and don't have an unsolvable mystery like I did. Did you buy them brand new? You could be under warranty still.

[12obertbarrera]

yea bought em brand new. i read elsewhere on the forums that it could be that the shocks moved out of place.. doubt thats the case. Or maybe exhaust is banging into the frame? smh guess ill have to try other mechanics in the area.

[Mitchell3]

With the car in park, you can have one person make it bounce and another try and look underneath. May be able to eliminate a few potentials that way. I remember at a meeting of mazdas a year or two ago, one member could simply sit in the hatch and make it bounce to get the noise.

Mine of course wouldn't do that, that's too easy. Only would make the noise when driving, so you couldn't see what was doing it. The more I talk about this the more angry it makes me in bringing back these memories haha

[MDMaz3]

I had mine for about 1 1/2 yrs and no issues except for the bearings plate in front struts which BC replaced for the half the cost. Then again I was only lowered 1 1/2 inches, not all the way. Sure the mech set up everything properly and you're not bottoming out the shocks? The shocks are a direct bolt on to the urethane rubber insert to the mount and then adjusted down a threaded insert at the bottom then directly to the car. I can only think with might be they are bottoming out because not adjusted properly for the drop, or bolts not installed into mounting holes properly or have gotten loose. Like I said before, I never had issues. Only other thing comes to mind is that if you are that low and possibly dialed up to high 20's, then something else underneath the car is rubbing or clunking. Take it in to a local shop and see if they can determine what the noise is that's bothering you. I'm sure it won't cost you much for a looksee. Hope this helps.

[12obertbarrera]

I'm trying to read into it more & people are telling me it could be any of this.,

rear end links
strut bar
lower shock bolts
rear strut tightened
loose bolts
control arm bushings

[titan182]

Make sure you check your sway bar bushings as well. Worn out bushings can cause a "crack" or "rattle", which you appear to be describing. I am running prothane greasable bushings on my 2005. Keep em lubed, and they will never let you down.

[Sonic31]

Been living with this stupid rattle forever myself.

Started after I installed my MS3 RSB.

Used MS3 Moog endlinks - Still there
Prothane RSB mounts - Still there
New trailing arm bushings - Still there
New LCA's - Still there
New forward LCA's - Still there
Installed BC's - Still there, but worse

So far the only thing my mechanic friend and I have found is that may be something to do with my calipers, or how I set the length of my rear BC shocks.

Going to be going back in for another investigation in a week or two to see if we can't solve it.

So I feel your pain.

[ricola]

I broke a couple sets of rear shock mounts and that caused a hell of a racket. There's a mild knocking in the rear of my 07 hb but I'll see if its remedied tomorrow after my trailing arm bushings are replaced. One of them was missing completely and the other was 75% rotted away.

[ricola]

Trailing arm bushings done. no more knocking. Did your coils come with mounts or did they use the existing ones?

[azdame]

I have this same issue with my Mazda5. I believe it may also be caliper related. The sound goes away when applying the brakes. Try listening if the sound is present when applying the brakes over a bump. I replaced my caliper guide pins, didn't work.

[Sonic31]

Yeah, I'm just replacing both rear calipers completely (grabbing both from a junkers) replacing the pins, and double checking that my pads aren't loose or installed backwards, or something similarly stupid.

If that doesn't do it, I'll just fix it with my stereo, the volume knob solves any number of problems.

[azdame]

If that doesn't do it, I'll just fix it with my stereo, the volume knob solves any number of problems.

Good one!

I'm going to try trailing arm bushings next weekend on my Mazda5.

Does the rattle go away when applying the brakes for you?

I just want to see if our issues are comparable at all. I'll let you know if the trailing arm bushings help at all.

[Sonic31]

Noise doesn't really change with brakes or no brakes.

I've done the trailing arm bushings, didn't make much a of a difference.

My suspicion is that it's one of the following:

1. Something to do with my brake pads
2. MS3 RSB (if it's this then I have no idea how to fix it, because I have done just about every solution discussed to no result)
3. How I set up my coils when they were installed.

I'll post up whatever results I get from the work on Monday.

[Sonic31]

Well, it's early yet, but after getting my ride height/shock length reset, and having the endlink bolts cranked down as much as possible, clunk is gone.

I really won't call it officially gone till I've driven around for about a month without it, but so far so good!