An interesting noise

[spikyone 139]

I'm going to take my car in to get it looked at anyway, but wanted to see if anyone had any bright ideas as to what might be causing an "interesting" noise.

I noticed it on a spirited drive home late at night; braking left into a reasonably tight roundabout and downshifting to 2nd it sounded as though someone had attached a tin can to the back of my car with a piece of string, and it carried on until I got the steering lock off and started accelerating. I couldn't replicate it when turning right, or when just turning left hard, it only comes when I brake left and downshift. It sounded like it was coming from over my left shoulder.

I've checked the boot for anything that might be moving around, and taken a look underneath the car as best I could, with nothing obviously wrong. Anyone experienced anything similar or have any ideas what could cause it? Anything I can easily check?

[Mike 458]

I can usually here the scissor jack handle and the wheel wrench hitting each other, could be that maybe? Granted I can hear things more with the plastic thinner boot floor 

[spikyone 139]

Definitely not coming from those as far as I can tell; everything seems to be held in pretty well in the boot.

If it weren't for the fact that my mileage is reasonably low (22.5k), my guess would be wheel bearing or shocks.  I'm no expert on diffs, but the thought also occurred that it could be coming from that.  Least likely would be brakes.  The fact the symptoms only occur when the NSR is unloaded and I'm braking seems to suggest they're the most likely.  If it's bearing/shocks/diff at the mileage I'll be pushing for it to be fixed under warranty, it seems pretty early for those to be failing.

[surrey86 352]

Odd sounding noise, maybe check the brake disc dust shield isn't loose? 

[nerdstrike 186]

Maurice's suggestion is a good one. You could also consider looking underneath. Give the exhaust pipes a tentative wiggle, look for dangling bits of plastic and/or loose wheel arch liners.

I'm wondering if part of your exhaust is moving around.

[spikyone 139]

6 minutes ago, nerdstrike said:

Maurice's suggestion is a good one. You could also consider looking underneath. Give the exhaust pipes a tentative wiggle, look for dangling bits of plastic and/or loose wheel arch liners.

I'm wondering if part of your exhaust is moving around.

That thought occurred to me too, but the exhaust seemed pretty well fixed in place.  Arch liners and brake disc shields are a good shout too, I'll do some more prodding around later.

Got it booked in for Wednesday so if I can't find anything I should have an answer then, at least.

[spikyone 139]

No luck from any of those, but a bit of a play showed the symptoms aren't quite what I thought; it's actually making the noise as I downshift under harder braking. The noise starts as soon as I put the clutch pedal down. I'm getting it going right and left whilst downshifting, didn't get the chance to try doing it in a straight line. 

Possibly unrelated, there were also some drips under the car, coming from the centre roughly in line with the "fender garnish". Seems to be water, so it may just be condensation from the A/C system, and I don't usually look underneath every time I park so it might be perfectly normal. Other fluid levels are fine.

[spikyone 139]

Update: I took it to Toyota this morning, one of their techs came out for a ride, I replicated the noise.  He asked if the wheels were aftermarket and suggested it was something to do with them affecting the ABS.  I strongly disagree; I wasn't doing anything that I would have expected to be triggering the ABS even on Primacies, never mind PS4.  There were no warning lights on the dashboard, and at 225/40/R18 the difference in diameter vs. stock is no more than the difference between new and worn tyres.

On my way back from the dealer I also tried taking a couple of tighter corners a bit harder (but not on the limit by any stretch) in 3rd, probably doing around 30-35mph, and was able to trigger the noise without any downshift, so it's definitely nothing to do with the clutch.

Toyota have said they will investigate when it's in for a service in a couple of weeks, but in the meantime I'm going to be looking for someone with a big flat driveway so that I can get properly underneath and have a better look myself.  If only I lived nearer to RRG...

[nerdstrike 186]

The last car I had was quite picky about its wheel sizes, but the stability system only got upset if you had different rolling radii on the axles, e.g. front 225/45 r18 and rear 235/40 r18

Could it be the diff? Cornering hard and braking with clutch down both change load the on it. I'm not at all sure why a diff would clatter though, unless it was totally broken and you'd have noticed that.

You've got a tricky noise alright, would love to hear the cure.

[Andrew Smith 156]

Your dripping water will be the a/c, I noticed mine had a steady drip around about in line with the front of the passenger foot well. The suggestion of abs is a fair call as it does seem a bit too eager to trigger especially when braking over bumps or when turning in and if you add a down shift in then that would only add to locking up. Having said that you would be seeing the flashing light  if it was abs. Does it make this noise when braking really hard in a straight line?

[spikyone 139]

16 minutes ago, Andrew Smith said:

Your dripping water will be the a/c, I noticed mine had a steady drip around about in line with the front of the passenger foot well. The suggestion of abs is a fair call as it does seem a bit too eager to trigger especially when braking over bumps or when turning in and if you add a down shift in then that would only add to locking up. Having said that you would be seeing the flashing light  if it was abs. Does it make this noise when braking really hard in a straight line?

I haven't noticed it happening when braking in a straight line, and it's making the noise when I'm turning enthusiastically on a neutral throttle.  I'll take it out later and turn off the VSC/TC, I might even try the pedal dance, but the car feels far more planted than it did on the Primacies so I'd be really surprised if it's ABS/TC/VCS.  They lost grip all the time, and I never got any sort of noise with them.

Right now, I'm with @nerdstrike on it coming from the diff, unless there is something loose that isn't noticeable without jacking the car up.  The Toyota tech thought it was coming from OSR, whereas from the driver's seat it sounds like NSR, so it's probably somewhere along the middle of the car.  I have next to zero knowledge on diffs though so wouldn't have the first clue what would cause that sort of noise.

[sam534 62]

Could try removing the ABS fuse, then you would know for sure.

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[nikndel 509]

8 hours ago, spikyone said:

Update: I took it to Toyota this morning, one of their techs came out for a ride, I replicated the noise.  He asked if the wheels were aftermarket and suggested it was something to do with them affecting the ABS.  I strongly disagree; I wasn't doing anything that I would have expected to be triggering the ABS even on Primacies, never mind PS4.  There were no warning lights on the dashboard, and at 225/40/R18 the difference in diameter vs. stock is no more than the difference between new and worn tyres.

On my way back from the dealer I also tried taking a couple of tighter corners a bit harder (but not on the limit by any stretch) in 3rd, probably doing around 30-35mph, and was able to trigger the noise without any downshift, so it's definitely nothing to do with the clutch.

Toyota have said they will investigate when it's in for a service in a couple of weeks, but in the meantime I'm going to be looking for someone with a big flat driveway so that I can get properly underneath and have a better look myself.  If only I lived nearer to RRG...

What a plum the ABS has nothing to do with wheels typical Toyota tech clutching at straws not all of them mind you 🤔

[Ade 517]

Have you got a clip of the noise?

The heat shield above the read back box can rattle.

Also you'd be surprised how much the stock back box on stock rubber moves around under cornering and braking so maybe something there.

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[spikyone 139]

22 hours ago, Ade said:

Have you got a clip of the noise?

The heat shield above the read back box can rattle.

Also you'd be surprised how much the stock back box on stock rubber moves around under cornering and braking so maybe something there.

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Afraid not. I'll see if I can get something over the weekend.

I'm running the TD catback, I think that uses the stock mounts? The tailpipes don't seem to move much but I'll try and get under there over the weekend. When it first happened I wondered whether the tailpipes were rattling off that lower bumper/diffuser panel so I wouldn't be surprised if it's something around there.

[MartinT 514]

They usually loosen the bolts holding the mid-pipe bracket in place to install a new exhaust. Worth checking, mine were loose and it sounded like a can rattling under there.

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[spikyone 139]

Having had no time to look at it over the last couple of weeks, the car was back in with Toyota yesterday for its 3 year service and 1st MOT, and they took a look whilst it was on their ramps.

They said that everything looked good underneath (no mention of the ABS/VSC then).  Apparently there's a "non-original exhaust section"  and they think the rubbers needed adjusting.  It seems to have done the job, although I've only driven it on the commute so far.