fc 3rd member im putting 2+2 together to figure it out
 

oook ive searched lots on this topic and im gonna ask now, since i know what im getting into, i have an 84 housing, and 84 3rd member, (no ltd slip, base model) no 4x114.3 bolt pattern. (which i need)

ive done some searching about what 3rd members will work., aka bolt into the 84-85 housings,
heres what ive come up with,

miata gears from 94&up will bolt in, the entire 3rd member will fit if you grind out a link to allow the wats to work (very simple bolt in) slines to axles all line up and work except that you lose a tiny bit 10 mm of spline contact space on the axles

these same miata gears will fit into any 86-92 (fc 2nd gen) of the N/A variety

I would love to find a somebody selling a cheap miata torsen that will fit my car, but to be hounest i dont have the time to wait for a deal and i cant afford to fork out 800$$ for a new one, also i wanted to be very specific, and get the 2001 model torsen as it also comes with 4;10 gear ratios, which i need,

soo im putting 2 and 2 together and assuming that the 86-92 N/a ltd slip rear end out of lets say a gxl or w/e model came with ltd slip, will fit into my 84-85 housing with gsl se axles giving me ltd slip (which i dont have) and 4;10 gears (which i also dont have)

lets just assume it is impossible for me to get a gsl se 3rd for some reason,

my question is

will this lsd unit work at all, aka, bolting right into my base model (with gsl se axles)



hope somebody out there knows cause ive searched and i cannot find a definate answer
thanks
Paul

Wrong...

The GEARS from the FC will not fit...

The Miata guys bolt the clutch pack LSD from the 84-88 RX-7's or Viscuous LSD from the 89-91 RX-7 into their stock ring gears...

The FC uses a long pinion that's different than most other Mazda rear ends.

You can use your stock ring and pinion and use an FC differential package though.

But you still have a Drum brake rear. The flange on the end of the axle housing is different than the disc brake housing flanges.

You also don't have to be specific. Just find an Auto wich was 4.10:1 rear end, or 1997-1994... I believe those were also 4.10:1...

I'm not sure about the 6 speeds. I think those were 3.90:1...

It's too alte for me to look up Felix Miata's website. You can google it or I can find out later.

cool thanks for the help,

just to clarifty

I cant use the fc gears,
but i can get -se gears from somewhere, and use the fc lsd pakcage with it, inside my base models 3rd member housing?

or i can just find myself a miata torsen from somewhere, and spend some big coin on it.
thanks again for the help

Paul

LSD Miata gears swap only with Turbo II gears as far as I know. I know for sure that 2001-2005 only swaps with TII.

another quick question, what are the reasons that the turbo2 lsd wont fit, i tried to find the thread about it but i think its gone,

i think that the spines are too big for one,

and something about the pinion gears being too big,

but call me crazy, what if you could modify the se carrier, to fit the larger pinion gears (if thats what didnt fit) and use custom axles from moser, or another axle shop would the

keep in mind modify the axle carrier wouldnt be a big deal as i am a fabricator, so making a larger slot for larger gears wouldnt be a big deal, i guess my question in regards to this is,

will the fc 3rd member housing, iether t2 , (both have the same bolt pattern) or N/a bolt up to the se axle housing, just blank, no gears in it at all, will the bolt holes line up,

thanks again, i know its been gone over before, and dismissed because of the axle spline differences,

thanks again,
Paul

Quote:
Originally Posted by Pele
Search for Miata Torsen. FC uses long pinion, no go. Nuff said.




Stop and think about what you said for just a split second..... how does a long pinion gear have ANYTHING to do with the torsen unit itself???

The LSD/torsen differential unit is swappable from an 84-85 first gen, all non turbo FCs, and the 7" ring and pinion miata.

Although the non turbo FC uses that long pinion gear, it still uses a 7" ring gear wich allows it to swap over

Where you have to be carefull, is that the Turbo fc, uses a larger ring gear that doesnt allow that lsd unit to swap over ...

this is the thread i was talking about, but can somebody tell me why i cant just modify my axle to hold this larger ring gear, am i sadly confused about something, i know it wouldnt be easy, but i want a stronger rear end, and i want to use all mazda components,

thanks
Paul

I was responding to this:

Sounds like you have a plan though... You can use any 7 inch ring gear and it's associated pinion with any 7 inch ring gear's differential...

If you're looking for a stronger axle that's still Mazda, does Ford count? You might be able to scavenge a 9 incher from a Mazda Navajo... Which is in fact, a Ford Exploder.

But you'll get 5 lug and rear disc, put TII brakes on your FC subframe and you're good to go.

Miata torsen isn't TOO expensive... I paid $250 for mine... WITH the 4.3:1 gearset.

Or you could go even cheaper and use the FC LSD on 1st gen gears...