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NightmareMoon

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Torsen of course but research flange compatibility as they all kept changing between different years and manual / auto cars. Easiest path is get a loaded differential as replacement of the gear / diff is less straighforward than most mechanical work we do on our cars.

Biggsy aboce mentioned OS Giken - in Cali - if I recall correctly - you have a person selling them (Shaftworks USA) that used to work for OSG I believe. He's the best person to talk to about them but you have to know what you want.

Gearing - that highly depends - also on the size of the tire you're running which affects gearing the same way differential gear does.
Since this is autocross thread - this is an important consideration, especially if you're low on power / torque - what's your max speed in 2nd gear currently ? You want to avoid shifting to 3rd and car being slow to accelerate when you slow down being in 2nd gear in a slow corner.

You basically want you're max 2nd gear speed in high 60s / very low 70s mpg (IMO) (lower than that if you're only plan to run local events and have small venue) - so you choose your diff gear ratio based on that taking into account what the tire size you're planning on driving on is going to do.

315/30R18 tires are pretty short compared to most Mustang stock sized tires.
wait.. Flange compatibility? Damnit Ford.
https://www.mustang6g.com/forums/threads/differential-flanges-any-experts.120933/
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Biggsy

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MrMike

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Yep 350 uses a different differential flange than 15-17 manual GT. Same size as 2018+ GT. New flange you'd need is HR3Z-4851-B. The new flange is better balanced and painted at least. Newer driveshafts appear to be powdercoated also.
 

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NightmareMoon

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I assume you figured you were fine with the 350 driveshaft or current one?
yeah I assumed the 350 driveshaft would bolt up to my ‘16 torsen. Both cars have ‘16 3.73 torsens, so why would they be different?

my guess is my differential bushings are probably shot anyway, but part of the fun in going with the Tremec was not having to change gears in the diff to correct the low top speed.

we’ll get it sorted out (eventually)
 

Biggsy

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yeah I assumed the 350 driveshaft would bolt up to my ‘16 torsen. Both cars have ‘16 3.73 torsens, so why would they be different?

my guess is my differential bushings are probably shot anyway, but part of the fun in going with the Tremec was not having to change gears in the diff to correct the low top speed.

we’ll get it sorted out (eventually)
when I was planning on swapping in a 3160 a few years ago Christian Burke at Upland Ford (who has helped several in the community)was selling diffs from cars getting OS Giken diff put in. At the time it was $300 before shipping. At that price it may be worth buying a take off instead of pinion flange troubles (if any)
 

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NightmareMoon

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It's not that big of a job to swap them. The flange nut is deformed into the keyway to lock it on, which is annoying. The new nut is not cheap. $25 on Rock Auto.
i assume you have to drop the subframe and remove the pumpkin??
 

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TeeLew

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i assume you have to drop the subframe and remove the pumpkin??
I was doing the whole she-bang, so I did it out of the car. If you drop the driveshaft and have the car on a lift, then I bet you could do it in the car.
 

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kz

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Solo Nats - where is everybody ? Registration is at cap... NightmareMoon has an excuse - not a great one, but ok..... (joking).

Where are the others ?
 

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Solo Nats - where is everybody ? Registration is at cap... NightmareMoon has an excuse - not a great one, but ok..... (joking).

Where are the others ?
I just got the email. Wouldn’t have been able to sign up until a week from now. Down in LA…apprenticing to a master detailer 🫣 My mind is exploding from all the info I am learning.
 

kz

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I just got the email. Wouldn’t have been able to sign up until a week from now. Down in LA…apprenticing to a master detailer 🫣 My mind is exploding from all the info I am learning.
You can sign up now (if you're posting here), you'll be on a wait-list and likely get in easily.
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