Did Mazda actually make this or was the 3.63 diff strictly open from the factory when sold to the Australian market?
I have an NA Miata with a 6 speed and 3.63 diff installed by previous owner and it's definitely open. This gearing combo feels perfect and 6th is actually usable on the highway so I'd like to retain this setup but with an LSD for track performance. Maybe I could convert it myself or swap in a 3.9 torsen?
It's just a gear that bolts to the side of the differential unit, you can swap in whatever LSD you want.
Yes, there were factory 3.63 Torsens to the best of my knowledge. But you can put whatever diff you want inside that ring gear, as noted.
How are you determining "definitely open"? If you do the classic "put the car on the lift and turn one wheel" test, a Torsen will act exactly like an open diff.
I have a 3.63 torsen in mine. Got it from the guys in Britain.
If you are that worried about it, then get a solid aftermarket on in.
I would be very surprised if they went through all of the issues to install the new R&P into an open diff. It's a good $1000 to do it. I just dropped my MSM off to get one installed in mine.
Someone on the board made a nice little video on Miata Diffs in his classic lab coat.
Keith Tanner said:Yes, there were factory 3.63 Torsens to the best of my knowledge. But you can put whatever diff you want inside that ring gear, as noted.
How are you determining "definitely open"? If you do the classic "put the car on the lift and turn one wheel" test, a Torsen will act exactly like an open diff.
(small voice from the back) because Torsens are open diffs, they just have a variable torque bias that works the way that is beneficial for performance
The way to check without opening things up, for minimal values of "opening things up", is to look into an axle hole and check for a cross pin. Big fat pin going through the diff means it is an open bevel-type diff. This does require that an axle be removed, not a problem when the assembly is on a bench, more of a problem when it is in an assembled car.
I bought a 3.63:1 ring and pinion from Mazda Japan and then disassembled my 4.10:1 Torsen to install the new gears. There's no reason you can't put a Torsen with that gearset.
In reply to Pete. (l33t FS) :
Nerd.
I prefer the direct test. Put the drive wheels on different surfaces. Accelerate.
There's also a spotter's guide on Miata.net.
I just went through this a little bit with a new to new me Miata. I used a boroscope to look inside the oil fill hole to see that what I had was an open diff.
Keith Tanner said:
I prefer the direct test. Put the drive wheels on different surfaces. Accelerate.There's also a spotter's guide on Miata.net.
This is how I determined it was open..
I haven't peeked inside to see if it has the bar or not but from my "2 surface test" it just doesn't seem to hook up like others I've driven.
I'll pull an axle this weekend and peek inside. Maybe something else is going on. The guy who sold me the car said it was a 3.6 Torsen. He supplied no paperwork regarding the diff but tons of records in a binder for literally everything else over the life of the car.
Good to have confirmation about the 3.6 factory torsen at least existing lol.
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