Does anyone know if there is a way to tell what ratio an RX-8 differential has from external markings?
There's a billion of them of them on sale at any given time, but most of the listings don't say what ratio they have.

 

Here's my thread on it -

https://www.rx7club.com/3rd-generati...-cover-997318/

I think the big thing is getting one from a manual trans car.

Dale

 

The 5-speed cars are 4.3, and the post-2006 (I think?) 6-speed cars are 4.777, but I was just wondering if there was a way to identify them without knowing the trim/year of the donor car.

Nice idea using the cover…

 

For USDM models:

2004-2008 6-port 6-spd manual - 4.444
2004-2005 4-port 4-spd auto - 4.300
2006-2008 6-port 6-spd auto - 4.300
2009-2011 6-port 6-spd manual - 4.777
2009-2011 6-port 6-spd auto - 4.300

the 5-spd manual was never exported to the USDM.

There’s no external ID on the differential if that’s what you’re asking. Otherwise you just count the teeth and determine the ratio, or approximate it by marking & turning the driveshaft flange and noting the number of input turns to make one full axle output rotation.

I’m working with j9fd3s to put together R&P stamped ID#s for various Mazda 8” R&Ps. I haven’t taken photos yet of the RX8 4.444 gearset, and don’t have an RX8 4.300 gearset, but here is the RX8 4.777 gearset:


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if you’re looking for a 4.444 pair I will have a set to provide soon; less than 40,000 miles off my personal 1-owner 2005 chassis.
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i'm hoping the stamping and the part number agree, which means you don't need to know how to count!

 

right on! Hope to complete the rest of the pics soon.

 

Im in Japan, so there’s a mess of rear diffs available. Problem is that most are assemblies, so you can’t count the teeth. Guess I’ll just search for a zenki 6-speed if I decide to go with a 4.444.

 

yes, again in that case you have to compare how many rotations of the pinion flange are required to rotate the axle output one full rotation

4.300 is ~ 4-1/3 pinion flange turns (2:00 position)

4.444 is just shy of 4-1/2 pinion flange turns (5:30 position)

4.777 is ~ 4-3/4 pinion flange turns (9:00 position)

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Kind of hard to do with online auctions.

 

maybe try asking