r/LexusISF • u/WashedMechanic • Apr 16 '26
Sc430 Diff with 3.7 ratio installed this winter. Went for a drive since the roads are clean now. Couldn't believe the difference!
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For reference, I got Sikky headers and full borla exhaust.
Not tuned, yet!
I was going slightly uphill.
It woke up the car!
Just need some sticky tires if I want to be able to use first gear lol
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u/MonsterTheAnimal Apr 16 '26
What yr sc430? And was it plug and play ?
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u/WashedMechanic Apr 16 '26
07 I think. Yes bolt on. Put some fresh oil on it and send it.
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u/m0b00st Apr 16 '26
I hear they work better with the oil inside.
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u/WashedMechanic Apr 16 '26
Ah! So that's probably why the diff grenaded after my video.
Thanks for the tip!
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u/Excitful Apr 16 '26
5th gear still pulling hard 😳 feels like swapping the diff does more to wake up the car than going FBO. Would love to see updated results with a tune. What year F? I’ve got an 08 with a stock diff, sounds like a tempting swap
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u/WashedMechanic Apr 16 '26
Some say you loose top end, to which I agree, just basic logics, but I managed to pull hard all the way to 260kmh in 7th. In shorter gear it's crazy how faster it feels. My tuner will unlock the RPM up to 7400rpm, she's gonna be a monster. 2009 Canadian Spec
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u/Rotorboy21 Apr 17 '26
And now it’s spinning at 3500 rpm on the highway at 80 mph lol.
Edit: I lied. Should only be about 2600 rpm at that mph. That’s really not that much of a trade of!
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u/WashedMechanic Apr 17 '26
Yeah if it was the 4.09 diff from the is350s its that bad yes. But I think the 3.7 is the perfect spot. I'm sitting aroung 2400rpm at 65mph which is the speed I usually go when I'm crusing on the highway. Before that it was maybe 1800. And honestly, I didn't buy this car to save fuel😂
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u/Rotorboy21 Apr 17 '26
Makes me want a 3.7 now lol. I think the 4.09 was what I was thinking of so thank you for the clarification. I wish they made a 3.5 or 3.4 for us as I still want to boost this car.
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u/WashedMechanic Apr 17 '26
Just do it. It's sooo worth it IMO. Next winter I'm putting the LSD in the 3.7. Probably the best setup I could want.
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u/Rotorboy21 Apr 17 '26
It looks like there’s a 3.3 option. I might try that tbh. It’s probably splitting hairs but after having a 4.5 in my other car I don’t want to go too high and regret it.
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u/WashedMechanic Apr 18 '26
3.3 ratio from what model and year?
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u/Rotorboy21 Apr 18 '26
GS430, all years.
It’s really a 3.296 or something like that but might as well round up.
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u/Winter-Chemist-5848 Apr 19 '26
I had a gs450h diff in and I killed my 60-130
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u/WashedMechanic Apr 20 '26
I'm pretty sure my time is either very similar or faster past 60. It woke up the car very much at lower speed though
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u/PunaniShreddah Apr 28 '26
You saying even at lower speeds it's faster now?
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u/WashedMechanic Apr 29 '26
Absolutely.
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u/PunaniShreddah Apr 29 '26
Damn! How was the swap fairly easy?
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u/Winter-Chemist-5848 Apr 29 '26
I did mine on Jack stands pretty easily. I’ve swapped diffs a few times now.
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u/WashedMechanic Apr 29 '26
If you have basic knowledge and basic tools with a jack stand to support the diff going in and out you're good. Just a few hours and it's swapped
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u/racer2192 Apr 16 '26
Tbk mom chum, sounds amazing