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When i go over bumpy roads, tram tracks, small speed humps etc... A slight, hollow knocking sound comes from the front of the car. I can't really feel it when it happens, but i can definitely hear it when it happens. Roof up or down.

This has been happening for a number of months now, but it is more obvious than before. It wont happen over every bump though. When it does happen, the car can occasionally feel a touch unsettled, like there is a slight to moderate shimmy in the front wheels, mainly drivers side...

I also notice that instead of just having the 110kmph shimmy that is native to the NA6, it also occurs at 50, 60, 80 and 100.

I have had a look around and have not had any luck with answers. I am no technician when it come to this stuff but if i had to guess, i could say it would be the ball joints on their way out? Just a guess though.

Any help or guidance would be greatly appreciated.

Thanks

could be the end links for the sway bars

I was thinking that could be a possibility too... Can anyone else shed some light on this?

Something banging against rthe sway bar possibly?

When I installed a larger Racing Beat sway bar, it was very close to one of my intercooler pipes on the driver's side so I zip-tied a thick rubber pad to the sway bar between it and the intercooler pipe.

Could be a ball joint or wheel bearing aswell.
Try grabing the wheel/tyre with both hand and rock it back and forth and left to right. if its a ball joint or bearing then you should be able to hear the sound by doing this and feel a bit of slack.

Or as Sliq suggested its most probebly the swaybar end links

Maybe control arm bushes. Try getting it up on a hoist and using a bar to see how much movement there is in the bushes, especially the lower front sets. They often start to clunk a bit as the rubber in them weakens after 100-140kkms. The clunk is metal on metal when the rubber compresses too far and it can be accompanied by odd steering behaviour as the alignment is temporarily stretched out of whack. It only gets worse.

manga_blue wrote:Maybe control arm bushes. Try getting it up on a hoist and using a bar to see how much movement there is in the bushes, especially the lower front sets. They often start to clunk a bit as the rubber in them weakens after 100-140kkms. The clunk is metal on metal when the rubber compresses too far and it can be accompanied by odd steering behaviour as the alignment is temporarily stretched out of whack. It only gets worse.

I think your onto something here... The clunking sounds and feels exactly as you have described. The steering definitely feels loose, more so on right hand turns. It has become obvious and has gotten a lot worse since i installed the thicker sway bars. Would this also be causing the shimmy i'm noticing at most speeds?

Im guessing this wont be a cheap fix...

CheyneX5 wrote:Im guessing this wont be a cheap fix...

It depends how you do it. You can get Energy Suspebsion polyurethane bushes for under $200 for a full front/rear set now. Poly bushes perform well in the short term but really require annual removal for regreasing. Stock OEM Mazda ones are good for general road work, they're trouble free but might cost you a couple of oil wells and a sheepstation. Mazdaspeed bushes are probably the best ones going. They are a firmer version of the OEM and suit track and spirited driving better. Cost for these is around $1,000 for a full set. You can check good-win-racing.com and 949racing.com.

Bushes are fair bit of work to replace. You'll need to get the right diagnosis first. It's quite possible that the things the other guys mentioned are causing the problems. If the sway bars are new then have a real close look at their mounts and whether anything is fouling them.

Sorry for the delay in reply...

Thanks for the advice

I am going to get a diagnosis tomorrow, ill keep you updated.

if you wanna check your ball joints get a set of really big multi grips and squeeze the base and the the of the ball joint to see if theres any movement if there is then very high chances are its shagged

How did you go?