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MY2025 Revision Parts

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#24 ·
KanmuriDavid said:
For the MY2025, there were quite a bit of revisions to the suspension as well as cooling. I have created this thread to document all parts that are compatible with MY2023 and MY2024 vehicles, pending actual confirmation. If any information is inaccurate, please let me know and I will address.

View attachment 30895

The ATF cooler will not be relevant to MY2023 and MY2024. The sub-radiator seems to provide auxiliary engine cooling, but it does not actively cool the transfer case. Quite honestly, it's better to get an aftermarket radiator as any cooler additions would require the MY2025 front fascia. If you are so inclined to retrofit the sub-radiator, see @st165's post below:

Sub-Radiator Part Numbers

The most interesting change is the transfer case cooling duct. Per Chief Engineer Naoyuki Sakamoto, this change will not solve the AWD overheat issues, but it should help.

Engine Service Cover with Duct: 51405-12070
Main Under Cover: 51410-12200

View attachment 30894

These changes are all made to help reduce squat and dive; therefore, reducing understeer characteristics mid-corner and on the exit of corners. The rear sway bar was likely changed to accommodate the new springs. The most important change is the rear trailing arm mount as it is an actual suspension geometry change:

Front Shock Absorber (LH): 48520-80832
Front Shock Absorber (RH): 48510-80C88
Rear Shock Absorber (LH/RH): 48530-80B99
Rear Trailing Arm Mount (LH): 48727-06060
Rear Trailing Arm Mount (RH): 48717-06030
Rear Sway Bar: 48812-12580
Rear Coil Spring (LH/RH): 48231-12N20

View attachment 30893

Finally, some more bolt changes to add rigidity to the suspension and steering system:

Lower Ball Joint Bolts (x4): 90105-12429
Steering Column Bolt (x1): 90119-10A34
Rear Shock Absorber Upper Mount Bolt (x4) 90109-10194
Click to expand...
Was this the sum total of the slides from Toyota showing the '25 improvements?
 
#26 · (Edited)
Rampant said:
So is the new transfer case duct just a plastic bit? Any idea how easy this would be to retrofit on a 23 or 24?
Click to expand...
Might be like GR Yaris GRMN 51410-52200 technology is trickling down.
 

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#28 ·
Carl said:
If you're the ugly guy it was probably you ... I kid I kid.



Increased clamping force is all I remember but I'll have to dig for the numbers I saw.
Click to expand...
Clamping load is different, 23-24 have a cover installed load of 9300 N the 25 has a load of 10370 N, not sure if the coefficient of friction has changed. Doing some quick math that would equate to 20-30 lb-ft holding capacity increase assuming the friction material did not change.
 
#29 ·
dleiv said:
Does anyone have an explanation as to why the transfer case gets so hot? It's such a simple part, just a couple of gears inside a box, and this isn't a problem I have heard about with other AWD platforms. Does it have to do with the unequal axle ratios or is it by virtue of the turbo's close proximity, is it just under built for the torque?
Click to expand...
The biggest reason is the lack of a center differential. Other systems that use a similar angle gear setup in the transfer case also generate a good amount of heat in the transfer case. Mazda, Nissan, Honda, Focus RS, other Toyota/Lexus products use similar systems in the sense that the clutch is on the rear axle and it acts as the differential mechanism. ITCC clutches themselves are very robust and can take a lot of abuse and are meant to work in a continuous slip environment. The downside of that means when you have an ITCC that is at full or close to full lock then the differential action between the front and rear is lost and something has to take the brunt of that action. That becomes the transfer case, so you have two gears meshing with various loads applied from both ends, that creates a good amount of heat. Throw on top of that the overdriven gear ratio between the transfer case and the rear differential and that generates even more heat. My current vehicle is a Mazda 3 Turbo and am waiting for my 25 GR to arrive. The GR has the overdrive ratio of .7~%, the Mazda is overdriven more at 1.1% and uses a 7 plate ITCC vs the GR 12 plate. On the Mazda you can monitor the rear diff temp and will also get FWD mode when driving it aggressively in a low grip condition. Like the GR its a predetermined value to try and protect the transfer case. I've had the Mazda go into FWD with rear diff temps anywhere from 180-220*F. You can hit the the trans, rear diff and transfer with a heat gun and get low 200s on the trans, near 300 on the transfer case, coupling and diff around 180. I serviced the rear diff and transfer case every 10k and the transfer case always had more wear on the magnet and fluid was visibly more "worked".
 
#34 ·
Fitted9k said:
Might be like GR Yaris GRMN 51410-52200 technology is trickling down.
Click to expand...
There are pics of the new undertray with the duct. I saw them in the Toyota press images (underneath side) before the embargo lifted. I'll try to find them again...
 
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#35 · (Edited)
For whoever was asking, Savagegeese did a great overall review of their heavily modded GR and go deep into explaining why the dif "overheats" with their tuner. They chopped it apart and found the temp sensor lives in a dry environment, not in the dif fluid and the data they get from the sensor is all over the place as well. It is very off and strange how it all seems to work. We need to wait for tuners to over write it.


video^^^
 
#36 ·
indcline said:
For whoever was asking, Savagegeese did a great overall review of their heavily modded GR and go deep into explaining why the dif "overheats" with their tuner. They chopped it apart and found the temp sensor lives in a dry environment, not in the dif fluid and the data they get from the sensor is all over the place as well. It is very off and strange how it all seems to work. We need to wait for tuners to over write it.

Savagegeese GR build lessons

video^^^
Click to expand...
"This video is private"
 
#38 ·
Interesting how the new rear suspension has the mounting points changed to raise the rear roll center. The rest of the components were likely in concert with this (or vice versa).
The raised roll center will provide additional roll resistance and allow for softer springs and shocks.
The “new” geometry is shared with the standard Corolla it looks like, has been since 2019, before that the C-HR had used the same setup as the ‘23, ‘24 GR.
 
#39 ·
Sleeper said:
Interesting how the new rear suspension has the mounting points changed to raise the rear roll center. The rest of the components were likely in concert with this (or vice versa).
The raised roll center will provide additional roll resistance and allow for softer springs and shocks.
The “new” geometry is shared with the standard Corolla it looks like, has been since 2019, before that the C-HR had used the same setup as the ‘23, ‘24 GR.
Click to expand...
Would the roll center be that affected if the other upper/lower control arms were unchanged? The trailing link alteration would mostly affect anti-squat as they stated, that's clear as day, but lateral loading/roll center would be only marginally affected at best, no?
 
#40 ·
Sleeper said:
Interesting how the new rear suspension has the mounting points changed to raise the rear roll center. The rest of the components were likely in concert with this (or vice versa).
The raised roll center will provide additional roll resistance and allow for softer springs and shocks.
The “new” geometry is shared with the standard Corolla it looks like, has been since 2019, before that the C-HR had used the same setup as the ‘23, ‘24 GR.
Click to expand...
I think my biggest question is should I be concerned using MY23-24 lowering springs given this change (already bought them due to being an impulsive person)
 
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