Blown Diff... now what
 

So I blew my diff.... not that i"m too upset about it, but I was running a 93 with an open diff. It would seem like a Viscous is a direct drop in.. this true? I know the Torsen's also fit, but I do not want to have to go thru the hassle of the swap plus I dont autox. I found planetmiata, who sells the parts for very cheap...Anyone have experience with them?

You could drop in any 1.6 dif, but it will still be weak and you may need to do it again, and again, and again.

yep. the ring gear is weak on the 1.6 diffs. Buy a 1.8.

^ don't forget about the pinion. You could do a 1.8diff swap to an open diff for pretty cheap if your just worried about cost and don't need an lsd.

PlanetMiata is a pretty reliable vendor. I've used them for several parts and have been happy with what I got.

Like olderguy said, replacing with another 1.6 diff is just setting you up for failure again. Also, LSDs are not just for auto-xers and track guys, while you might not really "need" one, with the extra power from FI, it becomes a lot more desirable. In fact, if you are upgrading to a 1.8 diff, it's the same amount of work for both the open and Torsen so you might want to just go with the Torsen. There is also another recent thread here about a rx7 diff which can (but not always) be a cheaper alternative.

Thanks for the input... when swapping to a 1.8 is there any write up on it? Parts needed?

Most of the time, with the swap to the 1.8... you need the half-shafts and a drive shaft as well.... I've have "assisted" in quite a few "upgrades"... and it looks like 90% of the time, the existing 1.6 stuff doesn't "quite" fit. <G>

Take a look at www.solomiata.com, there's some info there from Randy about the various Diff's, etc. Also I think I remember seeing a "know your diff" garage article on m.net too....

Dave,

You need the Torsen/open diff and carrier pumpkin (not trying to be a smartass as some people just sell the innards or carrier, but most of the time comes as a unit). 1.8 Driveshaft (which is shorter than the 1.6 driveshaft), and two 1.8 halfshafts (these come in two varieties of stub shaft + halfshaft or just a one piece halfshaft, the 1.6 halfshaft that bolts to the stub shaft is about 1cm longer than the 1.8 halfshaft so it may work, but I've never heard of anyone trying it).

Install is pretty straight forward.

1) Remove exhaust and any extra bracing bars in the way.
2) Unbolt driveshaft from diff and remove.
3) Unbolt halfshafts from stub shafts on diff and secure with some wire so they don't hit the ground. Remove driveshaft nut on wheel hub. You have to use a small punch to bend the little notch on the nut back out before you remove this nut. IIRC this is a 29mm nut but I'd double check to be sure. This is where some people run into problems b/c in some cars the driveshaft is really stuck in the hub. Be careful using a hammer as it will cause the end to mushroom. I tapped it lightly with a rubber mallet and it popped right out, but some people have had to remove the entire hub. YMMV. Also, helps if you remove the upper a-arm bolt for extra clearance in removal/replacement. Remove halfshafts.
4) Unbolt the tranny from the PPF near the front. Unbolt the two big ass bolts from the back of the PPF. (I broke an impact wrench socket here and ended up using a 6 foot breaker bar so get ready to apply some serious force.)
5) Pry out the spacer (air chisel or chisel and hammer) from the front bolt. You should be able to push the PPF to the side off the diff. Some people use the BFH (big f-ing hammer) method by loosely putting the two bolts back in the PPF and hitting them with a hammer to pop out the top spacers as well. (This is reportedly the way they do it at the Dealer Alternative.) It works, but some people have had issues getting the spacers back in. FWIW, I did it this way without problems, but the factory manual tells you never to do this. YMMV.
6) Remove 4 bolts holding on the diff and have someone to help you lower it off the car with a jack as it is a pretty heavy piece.
7) Install is basically the reverse.

Damn excellent write up.. Thanks a lot! One question tho.. don't I need the pinion bolt?

Now to find a torsen setup....

The PPF is the real pain in the ass. Best price I found was Planet Miata.

A complete diff (diff + pumpkin) should come attached to the pinion already and just have a flange to mate up with the driveshaft, and it is extremely rare that someone sells just the Torsen internals without the front section (with the pinion attached) that fits right into the pumpkin.

Heres a final newb-like question:

Would it be advisable to buy one of the mazdaspeed differentials here?

They are around 680 dollars, and seem like they would directly replace the internals of my open diff. Then again, I could be wrong, as I don't know diffs very well.

i can sell you the diffs out of my 1.8

I had one in my miata but sadly I blew the ring/pinion gears in it in less than a week, moral of the story, they are no stronger than a stock open diff as they are still 6'' rearends.

I paid $400 delivered to ATL (5 yrs ago) for an entire 1.8 setup (half shafts, drive shaft and open diff) from a place in Texas, but I can't remember the name of the salvage yard. :doh: Anybody? I found it via a site called URG - united recyclers group - http://www.u-r-g.com - just click the parts search button.

Good link. Just used it to find a 2001 torsen swap :). Gratzie

wow pretty good prices at some of those places, good find.

You can also check with hdegroof on eBay, I've bought so much crap from that guy over the past three years.

And when I say crap, I don't mean crap as in shitty parts, I mean crap as in mass amounts of replacement stuff for stuff that crapped out on my car.

good link

another good salvage site, using parts request
http://www.usedpartscentral.com