So I seem to have finally beaten this on my car. I'll run through my journey briefly in the hope that someone else can benefit from the long frustrating experience...
Car was stock:
- No noise, until I blew a shock. This was resolved by replacing the shock under warranty. At this point the car was noise / rattle free. (roughly 3 years old / 40,000km)
Suspension modified:
- MazdaSpeed spring kit ( understand this to be a re-badged Eibach Pro Kit), Koni Yellow shocks added (front and rear)
Initially no noise, just an awesome handling improvement Noise develops over the coming 1000's of km. 3 particular noises:
1. A relatively quiet "slapping" noise happens at low speed when entering or exiting driveways. Noise traced to the Windscreen washer hoses not being properly located in their plastic retainers. Easily fixed.
2. An irritating rattle / multiple clucking noise when traversing anything but dead smooth road, seemingly from the LHS of the vehicle. Noise traced to cavitation sounds cause by a worn out and leaking Koni shock absorber. Shocks replaced (both left and right hand side), noise resolved.
3. A loose sounding clucking sound that came and went initially, but got progressively worse. It was accompanied by an increasingly unstable feel from the front of the car on hard cornering. Notably would be ok after having the car on a hoist, for tyre / brake changes etc. A large amount of work went into diagnosis / discovery of the cause including:
- Mazda looking at it under warranty, and believing to have fixed the problem. I believed it also, however it was indeed the above stated behaviour after having the car on a hoist.
- Tunehouse also fixing the issue. Same as above, and also told some body bolts were re-torqued. This actually did help for quite some time (3 months). I would be keen to hear what / where these bolts are.
- Sway bar bushes replaced. The stock bushed looked to be in perfect condition at the time of replacement, but the ~$20 price tag had me trying it as it was low impact on the wallet. No difference to the noise.
- End-links replaced (sometimes called sway-bar links). Ultimately, this has solved my issue. My OPINION as to why is actually to do with the joints themselves. I believe lowering the car, and therefore reducing the range of motion (vertically) that the wheel has, reduced that amount of movement that the joints experience. This affects there ability to self lubricate with the grease inside the joint. This theory explains why, after being on a hoist (where the suspension becomes fully extended) temporarily resolved the issue of the noise, as this allowed the joints to pick up grease again and therefore work properly.
Hope somebody finds that helpful
Note: I've also noticed a small handling improvement over the stock end-links. I ended up going with the Whiteline ones from GSL. They were adjusted to be the same length as the OEM as I'm not having any problems with the sway bar knocking on the sub-frame and I wanted to leave the sway bar with no pre-load. To quantify, I can now hold a corner speed some 15km's higher than previously before losing the front end on full acceleration. The entire front end now just feel "tighter"
Cheers,
--JC