Shorter Turbo2 diff ratio- Aside from spending $2500 at Mazdatrix, any other options?
 

As title really!

Is there anything shorter than a 4.1 that can be used in the FC Turbo2 diff casing, ideally along with my current 2way?

The 5.12 Mazdatrix sell would be ideal, but it's insane money for what it is.

My other option is a gearbox swap for something with a 1.1 5th, which will cost me less as I have access to one, and it's lighter too, but it means a modified prop, mounts, bellhousing, and other crap I don't want, especially when my current gearbox is pretty bulletproof.

Anything out there I've missed?

Thanks

The RX8 automatic comes with a 4.88.

You have 3 options...

1) mazda makes a 4.3. It was on the Japanese Infini Turbo2, it's about $700 or something from mazda. Probably not short enough for your needs.

2) buy something from an RX8 (I think this is compatible) or something else similar and have the pinion lengthened (this is what mazdatrix does). This is semi-sketchy, you would have to really trust the shop to know what they're doing.

3) buy a ronin speedworks Ford Explorer 8.8" differential swap kit and throw some 5.14s in it ($200 from summitracing) and call it a day

the 04-08 rx8's are 4.44 and the 09-12's are either 4.3 auto or 4.77 for the m/t

RX8 solution sounds good, cheapest I guess, but that pinion thing sounds a ballache.

THAT I've never seen before (to be honest, the FC scene is over here is dead these days), problem is, in the UK at least, Explorers stopped being sold at 01 (end of 2nd gen I think), that kit needs an 02 on diff. And importing a heavy ass diff won't be super cheap.

How easy is it to smash a T2 rear diff setup anyhow? I broke my engine before my diff, and didn't give up even sprinting and drag racing with 275 wide semi slicks, so can't be too bad?

pretty sure the rx-8 R&P wont just fit in a turbo diff. read the details! they have to machine things to make it work

then take a step back and see what it might take to fit the RX8 complete assembly into an FC. some obvious issues will arise such as the dog ear upper mounts and PFF nose mount but the ears are removable and some adapters could be made. the RX7 cover should in theory fit the RX8 housing so that would eliminate the upper mount issue altogether(assuming the 4.7 ring gear fits into the early cover).

there is no quick or easy solution but who knows, maybe a vendor might decide to make a kit. maybe i will look into it as i have a 4.77 RX8 LSD sitting here and my S4 clutch diff is totally shot after 220k miles.

there must be a P type center section that will bolt to the FC aluminum carrier (i think the FD/RX8 doesn?), then you just need to fab the front diff mount… and a driveshaft

the FC cases have mounts integral to the case, the later versions were removable so the whole cover housing would have to be swapped.