Rear Knocking Sound

[guynecologist]

Got a knocking sound coming from the rear of the 2002 Yaris I own, happens over small bumps/holes at lowish spead.

Have investigated and can't find any obvious wear in lower suspension bushes, the shocker top mount seems ok with no movement.

The plastic shroud covering the top of the shocks does seem floppy and can touch the shocker body, what sort of movement should be in the plastic shroud ?

If not thinking it might be a shocker on the way out.

[Madasafish]

Check the rear springs for breaks near the top or bottom. Ideally with the rear wheel free so the spring is uncompressed.

Apart from that, I am unfamiliar with the Sport layout... If it does have a rear anti rol bar , check all bushes and mounting points for wear..

[guynecologist]

Thanks for the reply.

It has got a rear anti-roll bar now after I fitted one week or so back, it's not that though as it was making the noise before. Checked the rear springs and both look fine. Went to Toyota today and ordered a new shock absorber top mount and the plastic shock absorber shroud assembly today to see if that cures it.

If it's not that I guess it may be a wonky shocker.

[stantheman1]

Just a thought it could be the exhaust, either the heat shield above the back box has become loose or one of the mountings has worn / broken. You can easily check by gripping the tail pipe and giving it a gentle tug up and down to see if it replicates the knocking sound you're hearing.

Regards

Theman

[guynecologist]

Well the noise is still there after replacing the nearside rear shock top mount assembly where noise is coming from. The shock absorbers itself seems OK, manually compress its piston/strut and it extends itself back out to full length quite quickly.

[alfiejts]

My A3 had a metallic rattle at the back. As suggested above, one of the rear springs had broken and the short bit that cracked off had dropped into the suspension arm and was bouncing around creating the rattling noise.

The rest of the spring appeared OK and you couldn't tell by just looking at the spring that it had happened.

I only realised by measuring the height of the rear wheel arches - from the floor to te top of the wheel arch - and realising that there was a 2-3cm difference between one side and the other.

It was only when I dropped the rear suspension arm right down to change the spring that I managed to find the short (5cm) piece of spring that had broken off and could recover it from ratttling around inside the lower suspension arm.....

Suggest you check the hight of each side to make sure they're the saame to check the same issue.....

You won't necessarily bea ble to see a loose spring if part of it has snapped because the body will just drop down and rest on the bit that's left....