Constant rattling or banging from left rear suspension

Rgurleyjr

Rgurleyjr

Greenie N00B Member
Greenie Member
Don't mean to bug everyone with questions but need help.

08 mazdaspeed 3 I just bought. There is a constant rattling, banging, or knocking from the rear suspension, sounds like driver's side rear. The car has Megan racing suspension front and rear. It almost sounds like the shock is completely gone but don't think the car is bottoming out.

I jacked it up, spun wheel, looked and banged on every suspension part but didn't see anything loose. Everything looks ok, but the noise happens on every single bump or hole, really every little change it sounds. Seems less noticable the faster the car is going, worse at slower speeds.

With the aftermarket suspension and me not being a suspension expert, defer to you. Anyone have any concrete ideas?
 
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Rgurleyjr said:
Don't mean to bug everyone with questions but need help.

08 mazdaspeed 3 I just bought. There is a constant rattling, banging, or knocking from the rear suspension, sounds like driver's side rear. The car has Megan racing suspension front and rear. It almost sounds like the shock is completely gone but don't think the car is bottoming out.

I jacked it up, spun wheel, looked and banged on every suspension part but didn't see anything loose. Everything looks ok, but the noise happens on every single bump or hole, really every little change it sounds. Seems less noticable the faster the car is going, worse at slower speeds.

With the aftermarket suspension and me not being a suspension expert, defer to you. Anyone have any concrete ideas?
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My searching turned up broken springs, worn sway bar end links, or shocks. Wouldn't all of these be noticeable from underneath inspection or hitting them by hand? Any other ideas of what to check? I hate to replace parts in hope I got the right part and hope someone here had a similar issue.
 
That sounds like a great start. Where are you located?
 
Disconnect the rear endlinks from the sway bar and go for a short drive to see if the noise goes away or gets a lot better. If it does, you have your answer without trying 12 different things to find what's making the noise.

You won't find bad endlinks in most cases by just grabbing them
 
Sho said:
Disconnect the rear endlinks from the sway bar and go for a short drive to see if the noise goes away or gets a lot better. If it does, you have your answer without trying 12 different things to find what's making the noise.

You won't find bad endlinks in most cases by just grabbing them
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Didn't even think of this...will do!
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mangosmoothie said:
Rule out the exhaust banging something?
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Yes, banged and very solid. Def sounds like suspension something.
 
Endlinks are easy to check. Unbolt the side from the control arm, swing the sway bar down a bit and check both ball joint ends of the link for play.

I had a similar noise on 2 occassions, both times turned out to be a loose rear shock. Once at the control arm, another at the upper shock mount.

Depending on how that spring and perch combo are, it could also just be the springs rattling around. My old KW springs used to squeak, creak, and pop. Some poly bushing grease on the spring mating surfaces reduced it significantly until I switched to a different spring type.
 
So before work today, I jacked up and banged around. As I hit in the shock tube above the wheel, it sounds like the noise. I checked the bolts on both ends and tight.

Like I said, it has blue megan shocks and Mazda camber plates. I'm not sure what springs are there, they are just black. I adjusted the knob on that side more soft.

As I went to also adjust the passenger side knob, its completely frozen!

I plan to unbolt the sway bar links this weekend, but now that it seems like the shock or shocks bad, may have to replace them. I know nothing of the adjustable shock system I have. Can I just put OEM shocks in there and be ok? I don't know if the springs have to be changed, or the camber plate? I don't want the performance suspension at all.
 
If they are coilovers, you'll need to replace them with a whole shock/strut and spring combo.

OEM shocks could bottom out if you keep them on a low height. So you cant just slap them on the rear right now.

So if you want to go back to OEM you'll need strut mounts, all 4 springs, and all 4 shocks and struts.

My thoughts, OEM shocks are crap. You can at least get bilstein shocks which are a great upgrade over OEM. Even Koni is a great upgrade over OEM shocks and struts.
 
Mauro_Penguin said:
If they are coilovers, you'll need to replace them with a whole shock/strut and spring combo.

OEM shocks could bottom out if you keep them on a low height. So you cant just slap them on the rear right now.

So if you want to go back to OEM you'll need strut mounts, all 4 springs, and all 4 shocks and struts.

My thoughts, OEM shocks are crap. You can at least get bilstein shocks which are a great upgrade over OEM. Even Koni is a great upgrade over OEM shocks and struts.
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Hopefully you can help as I am clueless about what this car has exactly.

Front has blue strut assemblies, I haven't looked to see if they are adjustable. The rear has an adjustable shock with a knob but Also a separate spring. Can I just replace the rear shocks with a non adjustment type or should I go back with megan or another adjustable one? The rear is much lower than the front. The rear doesnt have coil over struts
[doublepost=1549976334][/doublepost]Also on the ride into work. I noticed the noise wasn't as bad as before so turning the driver's side to SOFT helped. Definitely leaning towards bad shock
 
The way the suspension is designed on these cars, even with coilovers the rear shock only controls damping/rebound, and the spring and adjustable height perch will sit in the rear control arm.

If the shocks say Megan on them, they are Megan coilovers. Like @Mauro_Penguin said, if you're gonna replace the rear shocks, either replace with the same ones...or you have to replace both the shocks and springs with an acceptable combo
 
The way these cars are setup (since you're new to the platform)...

The front is a MacPherson strut combo. Nothing terribly special, pretty standard textbook front end suspension. The rear is a separate set up. You have the shock bolted up to the trailing arm that extends from the rear door all the way to the back. The spring in the rear is sandwiched between the rear subframe and the lower control arm that connects from the trailing arm to the center of the subframe.

From what you are describing, you probably have coilovers. Megan are on the cheap side of the spectrum, so if ultimately you decide to go back to OEM I wouldn't blame you at all. These coilovers are made to sit on a lowered car so the shock has a different length inside to accommodate that, vs OEM which has a longer valve length for more travel. There are also camber and toe arms in the rear that control the motion of the wheel as the suspension compresses, but I doubt you will need to change them.

If you want to go back to OEM, here is the laundry list of what you will need....

Front-OEM strut mounts/nuts (these cars did not come with stock camber plates), strut mount bearings, OEM springs, and OEM style struts. You may need new front endlinks if the coilovers on your car now have different length ones.

Rear-OEM springs, spring bushings that fit onto the subframe, and OEM shocks. Maybe new strut mounts for the rear, but you can probably reuse the ones on there now.

It sounds like more stuff than it really is...
 
Mauro_Penguin said:
The way these cars are setup (since you're new to the platform)...

The front is a MacPherson strut combo. Nothing terribly special, pretty standard textbook front end suspension. The rear is a separate set up. You have the shock bolted up to the trailing arm that extends from the rear door all the way to the back. The spring in the rear is sandwiched between the rear subframe and the lower control arm that connects from the trailing arm to the center of the subframe.

From what you are describing, you probably have coilovers. Megan are on the cheap side of the spectrum, so if ultimately you decide to go back to OEM I wouldn't blame you at all. These coilovers are made to sit on a lowered car so the shock has a different length inside to accommodate that, vs OEM which has a longer valve length for more travel. There are also camber and toe arms in the rear that control the motion of the wheel as the suspension compresses, but I doubt you will need to change them.

If you want to go back to OEM, here is the laundry list of what you will need....

Front-OEM strut mounts/nuts (these cars did not come with stock camber plates), strut mount bearings, OEM springs, and OEM style struts. You may need new front endlinks if the coilovers on your car now have different length ones.

Rear-OEM springs, spring bushings that fit onto the subframe, and OEM shocks. Maybe new strut mounts for the rear, but you can probably reuse the ones on there now.

It sounds like more stuff than it really is...
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Thanks so much. I want to go the cheapest route and thinking new megan shocks look like it. Tho I hate how low it is in the back.
[doublepost=1549991795][/doublepost]This site is awesome. Thanks so much for all the help! I'm very mechanical but new to mazdaspeed. I will do all my own repairs and mods.
 
I have megan coil overs and I have been really happy with them. Their customer service has been great as well. They do sit pretty low on the highest settings.
 
JohnnyTightlips said:
I have megan coil overs and I have been really happy with them. Their customer service has been great as well. They do sit pretty low on the highest settings.
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Their Website is expensive. You know anywhere I can get cheapest rear shocks in their brand?
 
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