GR Yaris Balance of tuning and durability limits

FYI people, Toyota launched 2 TSBs (Technical Service Bulletins) a couple of days ago. Attaching the PDFs.
One is for the AWD ECU - to address the overheating issues a lot of people have been experiencing, another one is to replace an engine mount due to people reporting excessive vibrations between 2000-2400 rpm (there will be a temporary fix, and the new engine mount will be released in late 2023/early 2024)
 

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Thanks for sharing. Yes remember seeing these engine mounts coming loose.

As for the awd clutch, seems I'm lucky and my car was produced just after - haven't experienced any faults despite quite some play but no tracking...
 
Is this the mount on the left side in the engine bay?
 
CerN said:
Is this the mount on the left side in the engine bay?
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the one on the bottom right of this diagram (12372A)

Screenshot 2023-09-15 at 12.41.50.webp
 
Interesting. Wonder if the engine mount swap might help address this kind of resonance

GR Yaris - Resonance at 2600 rpm

My car has always had a bit of cycling resonance around 2600 rpm and steady throttle, coinciding unfortunately with about 100 km/h in 6th, but it seems to be getting worse as the exhaust, bushes etc. loosen up. and thing like cables and clips bed-in. It manifests itself as a buzz/hum from at...
www.gr-zoo.com www.gr-zoo.com
 
Just popping in for another update after a couple more months of track use. My car is currently parked up after developing gearbox issues a couple of weeks ago.

Coming into the hairpin at Knockhill I started to find myself with no drive in 2nd gear.. namely because it wasn't in 2nd gear. It's started violently jumping out of gear now when I lift the clutch pedal. This, combined with the grinding into 3rd and 4th now, means i'm looking at gearbox options.

I spoke with Richard at RRG who is looking into a warranty claim but because of my online presence there's every chance Toyota will refuse the claim based on "abuse" despite there being known issues with input shafts, selector forks, synchros and detent springs. Basically if I go the warranty route they would need to seek permission to open the gearbox and inspect it and if Toyota can find a reason not to honour a warranty claim i'd need to foot the bill for a strip and rebuild along with any repair work.

Current options are -

Try for a warranty claim - Would potentially have to pay for labour to strip and rebuild if Toyota don't play ball
Used OEM gearbox - could have the exact same problems within the next two years. Lamspeed can modify the casings for the detent spring issue but that means sending a box to Australia and back, also doesn't get around the slow synchros
Fully built sequential - Talking to XShift, Kotouc and Drenth to see what options I have at the minute, £££
Hybrid sequential - interesting option from Drenth where they send the parts to rebuild the OEM gearbox as a 6 speed sequential, waiting to hear more about what's involved as apparently it is definitely a sequential, not a dog cut gear H pattern setup
New OEM gearbox - I wouldn't waste my money on new prices tbh, not until they can offer something with design changes to fix the known issues from factory

All part of the modifying game unfortunately. My car is still on the stock turbo though and is "only" 340hp, the OEM gearbox only lasted 30k miles before it's become unusable, the grinding has been happening intermittently for a good 15k miles though.
 
GottGry said:
nice, what brand? will you update engine/drivetrain management system as well
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Went with the Kotouc in the end after some back and forth the last couple of weeks.

The car is already on a Syvecs which will be used for ignition cut. This was always the big expense I was putting off for so long but the timing is right now
 
p3.auto said:
All part of the modifying game unfortunately. My car is still on the stock turbo though and is "only" 340hp, the OEM gearbox only lasted 30k miles before it's become unusable, the grinding has been happening intermittently for a good 15k miles though.
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Just for reference, what torque are you running? Gearbox doesn't care too much about peak power (=torque x rpm), it's torque that gets them...
 
Onehp said:
Just for reference, what torque are you running? Gearbox doesn't care too much about peak power (=torque x rpm), it's torque that gets them...
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Oh I know, it’s just easier to talk in terms of peak power as most cars on standard turbos will have the same or similar power band. As you say it depends where peak torque is too. Can’t remember exactly but it’s about 400-450NM peak around 4500rpm.

The synchro issue is just a poor design, torque won’t kill them. Only solution is to slow down gear changes.

The detent spring issue again is a poor design, would happen to a standard car too.

The input shafts I agree will be more likely to fail due to increased torque but synchros and detent springs could happen to anyone

As for next steps I’ve gone with the Kotouc 7 speed sequential, just discussing ratios with them to best suit how I drive. Expensive but replacing gearboxes every 2 years is also expensive and I do like rally car noises 😏
 
yuri1312 said:
the one on the bottom right of this diagram (12372A)

View attachment 20298
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@Sam I guess the trouble you had with yours must have helped Toyota see a pattern of failures associated to that part or its one bolt coming loose.

If am right in your case the symptom was a clunk kind of noise (as if from suspension) rather than vibration.
 
p3.auto said:
The synchro issue is just a poor design, torque won’t kill them. Only solution is to slow down gear changes.

The detent spring issue again is a poor design, would happen to a standard car too.
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Even if some upgrades have been made over time, the gearbox was still originally destined for the likes of Camry V6 and the like, a comfort rather then race box...
Gonna slow down my changes a bit again, with your solid cable bush foremost and also hard base bushings of the shifter, I can at least feel better when the box is no longer liking my shift speed...
 
Onehp said:
Even if some upgrades have been made over time, the gearbox was still originally destined for the likes of Camry V6 and the like, a comfort rather then race box...
Gonna slow down my changes a bit again, with your solid cable bush foremost and also hard base bushings of the shifter, I can at least feel better when the box is no longer liking my shift speed...
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Yeah it’s not really a purpose built box and it’s a shame because it really gets in the way of enjoying the car to its fullest. But that’s fine, I’d wager the majority of drivers aren’t trying to get every millisecond out of their gear changes so I guess it’s fine for 90+% of owners, just a shame it doesn’t seem to have much headroom for performance 🥲
 
With this and the programmed rev hang, I’m deliberately slow with my change.

It’s not a box that likes to be hurried, I’ve never felt right slamming it like I’ve seen some do on YouTube etc.
 
Duke said:
With this and the programmed rev hang, I’m deliberately slow with my change.

It’s not a box that likes to be hurried, I’ve never felt right slamming it like I’ve seen some do on YouTube etc.
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I have flat foot shifting mapped in but it almost defeats the purpose if I can’t change gear quickly
 
Spirited said:
@Sam I guess the trouble you had with yours must have helped Toyota see a pattern of failures associated to that part or its one bolt coming loose.

If am right in your case the symptom was a clunk kind of noise (as if from suspension) rather than vibration.
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Wouldn't be too surprised, given I've heard reports that official dealership workshops in different countries have been facing the issue for some time now. same thing probably goes with the overheating clutch pack issue.
 
yuri1312 said:
Wouldn't be too surprised, given I've heard reports that official dealership workshops in different countries have been facing the issue for some time now. same thing probably goes with the overheating clutch pack issue.
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The overheating clutch pack is actually a sensor issue, there's a technical bulletin out for early models to have the AWD controller updated which only happened a few days ago (if you weren't aware). Explains why some get the issue and others don't, it's not actually overheating. Mine's never had the issue but I think my build date is after Toyota made the changes.
 
p3.auto said:
The overheating clutch pack is actually a sensor issue, there's a technical bulletin out for early models to have the AWD controller updated which only happened a few days ago (if you weren't aware). Explains why some get the issue and others don't, it's not actually overheating. Mine's never had the issue but I think my build date is after Toyota made the changes.
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If it is a sensor issue, why the fix is updating the AWD ECU via the OBD? Wouldn’t make more sense to replace the actual sensor?
 
MRA3 said:
If it is a sensor issue, why the fix is updating the AWD ECU via the OBD? Wouldn’t make more sense to replace the actual sensor?
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Having had to account for stuff like this in the past I can easily imagine it’s something like the smoothing algorithm in the ECU not handling transient signals from the sensor very well, i.e. the ECU sees a number of ‘high’ readings in x timeframe and flags an over-temp warning, when in fact it was just a couple of spikes and the pack is not in fact overheated.

That, coupled with a natural variation in sensors not seen during development, could account for it, and explain why an update to the ECU to better tolerate the variability from a wider range of sensors would fix it.
 
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