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Is the Fuji diff even worth installing in 2025?

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Old Nov 10, 2025 | 12:07 AM
  #1  
plszmr's Avatar
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From: phoenix az
Default Is the Fuji diff even worth installing in 2025?

Someone is selling a 3.9 FUJI LSD (came out of a 2003 shinsen edition with 98k miles) for $250 (locally so I can inspect it and not pay shipping). It's the complete housing just with no axles. I did some research and I wouldn't even need to buy anything else to complete the swap. I know that the fuji diff is less than reliable, but worst case scenario I can just swap my open diff back in. As much as I'd like to swap in a torsen, the cheapest i've seen locally in the past year is $600 for just the core, so $250 for an entire locking diff is pretty tempting. In a perfect would I would buy this and it would last me long enough until I can get my hands on an OS Giken and 3.3 R&P, but the reputation of the Fuji diffs has me doubting that that's a possibility. Assuming it hasn't spat out a bunch of tabs, would it be worth it to spend the $250? And how long do yall think it would last on a low power car that's doing some autocross and HPDE days?
Old Nov 10, 2025 | 12:32 AM
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At $250 bucks that’s more than worth it for the ring and pinion alone. Coming from an open diff it will be a big upgrade either way. I think the Fuji diffs get more hate than is deserved, tbh same for the VLSD in 1.6 cars ¯\_(ツ)_/
Old Nov 10, 2025 | 07:37 AM
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At ~230whp my 3.6 fuji spit out a tooth after about 4 years of street beating. Too afraid to see whats inside so its on a shelf next to an rx7 lsd.

My take is they're in the bargain bin for a reason but thats not a bad thing. Some people practically give them away but as long as you dont expect it to last forever, no reason to say no when you can blow up 2-3 for the price of one torsen.
Old Nov 10, 2025 | 01:19 PM
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Originally Posted by themonkeyman
At $250 bucks that’s more than worth it for the ring and pinion alone. Coming from an open diff it will be a big upgrade either way. I think the Fuji diffs get more hate than is deserved, tbh same for the VLSD in 1.6 cars ¯\_(ツ)_/
That's a silly comments.
The vlsd doesn't lock due to age PLUS the ring gear explodes at stock power.
The Fuji doesn't lock due to a faulty design, THEN explodes at stock power.

Both should be equally hated.
Old Nov 11, 2025 | 10:50 AM
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After seeing so many chipped fujis I don't even bother selling them complete anymore. Just tearing them apart for the ring and pinion.
I'd say don't bother.
Old Nov 16, 2025 | 05:45 AM
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There is a place in the UK that can repair a fuji that's had the tabs broken off. https://www.ebay.co.uk/itm/326786679493?

After getting an OS Giken on my turbo car, I couldn't stand the torsen on my n/a car. So I bought a fuji and sent it straight away to the link above. In my experience, the repaired fuji behaves much better than the torsen on the road (bumpy and often low grip) but marginally better than the torsen on circuit (at least at stock BP power).
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