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Discussion Starter · #1 ·
What are your guy's thoughts on this issue?

 

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Discussion Starter · #3 ·
So far these are a couple solutions I have found:


 

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Judging from that video and the duration of the launch... I'm leaning towards more an error code than the system actually overheating.

It's been too inconsistent with the overheating notices... that I have seen. Maybe there is more information.

Some people have done full track days, and rally stages, not to mention the journalists who drove it months back on a track day... and this issue has not come up.

Not saying a hard launch isn't more taxing than driving aggressively on a track, but it seems a bit excessive or misplaced given the launch video I watched.

But, I could be wrong, regardless if this is the case... oil coolers will be the game plan.
 

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From perusing the GR Yaris forums, some people have found that simply heat wrapping the exhaust pipe that runs next to the diff seems to have solved their problems. I think if you combine that with the duct I posted above, you should be able to decrease heat dissipation from the exhaust and increase cooling to the diff with the duct.
 

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Judging from that video and the duration of the launch... I'm leaning towards more an error code than the system actually overheating.

It's been too inconsistent with the overheating notices... that I have seen. Maybe there is more information.

Some people have done full track days, and rally stages, not to mention the journalists who drove it months back on a track day... and this issue has not come up.

Not saying a hard launch isn't more taxing than driving aggressively on a track, but it seems a bit excessive or misplaced given the launch video I watched.

But, I could be wrong, regardless if this is the case... oil coolers will be the game plan.
It’s very similar to the Yaris though in that regard, not everyone was experiencing the overheating issues.

Some people were running them hard on the Nurburgring with no issues, while others drove to the grocery store and saw the issue.
 

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It’s very similar to the Yaris though in that regard, not everyone was experiencing the overheating issues.

Some people were running them hard on the Nurburgring with no issues, while others drove to the grocery store and saw the issue.
makes me think actually what mode would they have been on, what it may be more prone to either 50/50 or 60/40, 30/70
 

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makes me think actually what mode would they have been on, what it may be more prone to either 50/50 or 60/40, 30/70
They were in 30/70
Yeah it’s just a quirk of this AWD system honestly. Guff was asking Sakamoto-San about it at the event. Engineers are aware of it too
 

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Nurburgring guys are mainly in 50/50 but like Jeonsa said, it's just a quirk of how the system works regardless of mode
It’s funny because I was watching this Zygrene podcast discussion with Tedward and Topher. They kept saying the system is robust and never overheats compared to the Focus RS. I was thinking these dudes really don't pay attention to what’s going on. 😂🤣
 

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There are other cars with the electronic controlled center “diff” and
1) they aren’t heavy duty and will over heat too - I remember one magazine testing in sand and quickly disabling several SUVs
2) The GRY/GRC party trick is the over-driven rear diff and thus you generally can never fully lock the clutch pack. So thus you will always have some slip and thus some heat.
 

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So basically an understanding of what the centre diff is doing would help.

Its constantly slipping to one extent or another moving the power around from front to rear so depending on the road surface and the average speed round the track etc the level of cooling required changes. Tight tracks, multiple corners and low average speed and hence poor velocity airflow to cool are not going to be good. Gravel roads are going to be bad, everything including the diffs are working their hardest.

Wrapping the exhaust is not going to do much it also curves and looks like it misses the diff by miles, clearly the centre diff is making a few Kw of heat all on its own so the only way to significantly improve it would be to water cool it somehow. I guess a last resort could be a fine water sprayer that's just automatic over a set temperature. Not huge flow, we are not talking James Bond shit trying to take out the cars behind you by leaving a trail of wet track. Its used on intercoolers so it works. Fine spray and evaporation cooling works well.

Hopefully heat wrapping the exhaust and trying to get better airflow into the area is the first step but if that doesn't work it gets harder to resolve.

Would be interesting to see what temp it cuts to 2WD, possibly as high as 120DegC where then oil in it no longer likes to be. Might be a temperature output available from the ECU if someone can put an OBDII reader on it. The first step would be to find the temp it cuts at. May even be possible to just use a better oil and raise the temperature cut point but you need the temperature its operating at first just before it cuts to 2WD.
 

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I'll 2nd what @MrBiggs said. That's not an overheat condition. The tires squealed which means it never even gave full clamp load to the clutch pack.

It's possible that Toyota built in this fault when the launch exceeded a certain predicted torque threshold. As mentioned above, the guy launched it from the rev limiter, not a reasonable rpm that's near peak torque.
 

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There are other cars with the electronic controlled center “diff” and
1) they aren’t heavy duty and will over heat too - I remember one magazine testing in sand and quickly disabling several SUVs
2) The GRY/GRC party trick is the over-driven rear diff and thus you generally can never fully lock the clutch pack. So thus you will always have some slip and thus some heat.
Spot on. Sakamoto San told Guff they added more airflow towards the rear but it’s one of those “time will tell” scenarios.
 
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