GTX Differentials upgrades

[bujbot]

Hey!

I'm thinking I would like to upgrade my differentials if at all possible.

What I know so far:

GTR rear end works, forst gen miata LSD will work if you change the ring gear.

What I'd like to know.

Is there a rear Torsen available?
Is there a front diff upgrade?

I'm thinking the diff-lock function would eliminate a need to upgrade the centre diff.

Thanks!

Nik

[808]

Pretty much.. don't ever run with the center diff locked. it's a great way to cause understeer. No front diff upgrades. Unfortunately I don't remember what's all available for the rear.. I don't think we have a Torsen available I think those are only available in the larger Miata diffs.

[bujbot]

No center lock? ... makes sense, but why was it an option? (I've heard it can stick too and not disengage).

So far I've found that either the rear diff from a BG GTX or GTR, or the 1.6L miata. (Both have the same LSD more or less).

... that's it I think.

I'm thinking I might try and find a BG GTX or GTR rear subframe w/ differential. My subframes a bit rusty.

[808]

It's available to get you unstuck if you're in a ditch somewhere and only getting wheel spin. When watching old rally videos of GTX's you can always tell which had the diff lock on, they're the ones going straight when the road is turning.

[Talkurt]

Would any LSD designed for the first miatas fit the rear as well?

[SgtRauksauff]

If it's the smaller LSD, for the 1.6L cars, yes. the larger one for the 1.8L cars won't fit. but, since it was really easy to swap up to the larger rear setup from a 1.8 car into a 1.6 car, the weak diffs sorta got left behind.

On occasion, you can find a mazdaspeed rear diff, clutch-type, but they're fairly rare and hard to come by. Probably more rare than a GTR rearend, I think.

--sarge

[azgtx]

Check with Mazda Motorsports...they might have some of the 1.5 and 2.0 clutch type LSD's...or even Cork Sport might have a line on one. The 1.5 locks on accel only and the 2.0 locks on accel and decel.

[bujbot]

Good to know. Thanks guys.

azgtx, what came with the 1.6L miata MS? was it 1.5?

[Talkurt]

Is the 1.8 diff setup swapable into the gtx?

[SgtRauksauff]

not without some re-fabrication of the rear xmember to mount a different diff housing. the diff itself is larger, and won't fit in the stock housing. I don't know if the proper gear ratio is available in the larger size. the rear ratio really needs to be the same as the front, otherwise you'll wear out the center diff right quick.

[Talkurt]

If it's the smaller LSD, for the 1.6L cars, yes. the larger one for the 1.8L cars won't fit. but, since it was really easy to swap up to the larger rear setup from a 1.8 car into a 1.6 car, the weak diffs sorta got left behind

--sarge

Sorry this Is what I was talking about. I'll assume you where talking about swapping in a Miata? I'm asking because some day I will do a BPT swap and want to get a LSD for the rear and dont want it to be a weak point. Thanks as always.

[jay]

Any lsd that fits will not be the weak point, the gearbox will be. I'd try to stay away from the viscous lsd's, as they tend to wear out and turn back into open diffs. If you can find a clutch style diff like mazda comp used to offer, that's the hot ticket...

Although I have managed to blow one of those up but unless you're doing rally it should last forever. And heck all I did was de-tooth the ring and pinion, the rest of it survived, I cleaned everything up and it's doing duty in my street car.

[Talkurt]

Yep I realized the gearbox will always be the weak part. A motoiq article got me thinking, has anyone cryo treated/ shotpeen/ wpc treated the gearbox. Wonder if it would make a realistic enough difference to be worth the money. Though it's all in my head my end goal will be about 300hp in a bpt as my daily. I know that's pretty high but it seems doable for the motor. Just maybe not the rest.

[jay]

Been doing that for years, you just gotta be careful with it, and maybe budget for one or two spares.

[SgtRauksauff]

or, find a way to make an EVO or a Toyota box fit nicely...