I need a differential and carrier for my 1999 base Miata, so it's an open diff with 4.10 ratio. I know where there is a unit from a 1994 automatic car, so that should be an open diff,3.90 ratio. BUT, the earlier diffs had flanges and I believe my axles just slip into the differential. Will the flanges just slip out of the '94 and my axles slip in? Will the rubber snubber on the pinion shaft transfer from my busted diff to the automatic one? Anybody know ? If I've got this wrong please correct me.
If memory serves, a 1994 automatic would be an open 4.10. 1999 base is a 4.30. Only 6-speed 1999-03 models got a 3.9 in the US and I think they were all LSD.
No worries about the halfshafts. The 1.8 two-piece and the single-piece ones are interchangeable - the only exception is the MSM. I'm not as sure about the rubber doohickey on the pinion shaft.
Thanks Keith. Going from 4.30 to 4.10 would be OK, it's about how much my speedometer is off anyway and I'm not very worried about losing a little grunt at stop lights.It's about the same change as I thought I would get with the ratios I erroneously used. I'll keep looking around to see about the rubber bit.
is there a Kia diff that is like a 3.63 or something?
is it a stock miata? as long as your lengths from the axle to driveshaft area are the same it will fit.
you wont see a problem with 4.10s but any less on a stock miata will be lethargic
I just swapped from 4.10s to 3.27s on mine...but i also have a v8 hah
You can buy a 3.63 R&P from Mazda Competition or source one from Europe.
Isnt that the stock one from Australia as well or something also? like the Aussie 6 speed NB?
http://www.miata.net/garage/diffguide/index.html
found what i was searching for! this link should help you
also
http://www.solomiata.com/RingandPinion.html
Note that the 3.308 in that list does not actually exist.
http://www.miataturbo.net/suspension-brakes-drivetrain-49/3-308-ring-pinion-38717/
there was as of 2009 supposedly?
edit: disregard.
it was there, but proven not to work or something.
carry on
So, I got the differential and cross member out of the car. One side of the cross member/carrier is snapped right off. When it was in the car I had no drive, just a rat-a-tat-tat sound from the year that I assumed was the ring and pinion no longer playing in harmony with each other. This morning I separated the differential from the cross member/carrier expecting to see little metal bits and stripped gears. The darned thing looks absolutely fine, turns nicely by hand and has no discernible slop between the ring and pinion. What else could the noise have been? Neither axle was pulled out of the diff. The splines on both axles look fine. I even put the trans in gear and tried turning the drive shaft to see if maybe it were the culprit . Everything seems normal. I'm stymied on this one. Do I buy a new carrier and reuse the diff? Buy a complete replacement unit? Thoughts from the collective minds of GRM, please.
It's possible that with the broken mounting arm, one of your halfshafts was pulled free of the spines. It's pretty unlikely you'd have a broken arm AND an internal diff problem. Did the car take a hit?
You can have that mounting arm welded up, or replace it with any other 1994-05 housing.
thats what happened to me
i had my 1.6 diff behind the v8 for about a year. heard a sound assumed it was a rnp.
pulled it and the batwing broke. replaced it and it was good for another few months until i put a 8.8 in
All Imported-56 by Flsimages, on Flickr
Keith, when I removed the diff the axles on both sides seemed to be fully seated. Now that would be after I had jacked up the car, so maybe it slipped back into place. The car had recently been hit in the rear, but only moved the bumper cover less than an inch. Maybe it was enough, but it wasn't much of a hit.
V8exocet, mine broke right about where the metal band is on the CV rubber boot.
it happens. the miata versions are designed to break. the rx7 arent
In reply to v8exocet:
I just read that there are notches where it's designed to break, so I went out to the garage and put the broken part up against the housing. Sure enough, there's the notch. Per Keith's comment, I think I'll phone my insurance agent on Monday. At least get them to pay for the parts now that I've dismantled it.
The reason they're designed to break is because the PPF is attached to the trans so your entire drivetrain is one piece. When the arm breaks, it allows the engine to move back as part of the crumpling process. It's pretty common to see the arm broken on salvage cars that took a poke in the nose.
They have been known to break under hard use, but that means HARD use.
A hard "bump" draft has been known to break them as well.
That's about how hard I was hit.
Keith Tanner wrote:
The reason they're designed to break is because the PPF is attached to the trans so your entire drivetrain is one piece. When the arm breaks, it allows the engine to move back as part of the crumpling process. It's pretty common to see the arm broken on salvage cars that took a poke in the nose.
They have been known to break under hard use, but that means HARD use.
I.E. drifting a 300hp v8 haha
