(DRIVETRAIN) Miata Diff interchange into 84-85 models
 

Just pulled out the 3rd member of my rear on me SE, and it is shot. Both the ring and pinion gears have excessive wear marks and heat damage. I guess I know why it was humming so bad. Anyway, since it is a limited slip, is it worth rebuilding? Should I take a chance on a used one? Or, assuming I have the money, invest in a performance rear?

Mike

Simplest would be to find a new r&p, then take it to a shop and have them put it back together. I probably have and r&p laying around if you need them. Mine would be the 3.9 gears, not the 4.1 in the SE's.

I would just rebuild, at least you know it's done right rather than buying used & dont know how long that one will last.

:icon_tup:

if you have the money, get a kaza for a 1.8 miata and some new gears. if you want shorter gears, get some kia gears

Trochoid,

Do you mean a 3.933 from an 83-84 12A, or a 3.909, from an 85 12A----just curious :-) Also, what shape are the R&P in? Is there "ANY" visible wear other than normal? I ask this because I thought that my R&P had normal wear until my step-dad told me that it was shot (he's an expert).

Mike

What is the advantage in getting the 3rd member for a 1.8 Miata?

well, it is a superior LSD unit. even the stock miata torsen LSD is better than our stock LSD. if you want even better, get the kaza designed for that miata.

im not sure if the miata gears will work, ill have to guess and say no, but i could easily be wrong

oh shit thats some expensive stuff. looks good but i can put a ford 9" in for that.

http://www.kaazonline.com/8309.html


kaaz's website is here.

http://www.kaazonline.com/

well thats apples and oranges

How about the KAAZ diff that is deisgn for our car? They are available from Mazdatrix.

I don't recall which parts car the gears came out of. Could be 83/84 or 85. I'll have to count the teeth and inspect for wear. PM me if seriously interested.

It appears that the Kaaz diffs at Mazdatrix are for road racing, drifting, etc. They are not for the every day driver. The stock set-up or the torsen is for the everday driver. I may be wrong however.

I will PM you as soon as I know what I am going to do.

Thanks

yo put a kia third member on the car

I was thinking about the miata rear. If I were to go to a junk yard and get a miata 3rd member, which year miata should I ask for? Will my stock axle shafts fit into the 3rd member? What is the differential gear ratio on a miata?

Thanks,

Mike

I've read from some members that the 94-97 Miata 3rd member is a "no hassle" bolt-in replacement for my SE. Is this true? I was also told that not all 94-97 miata rears were limited slip. How do I know which is LS and which is not, assuming the guy at the junkyard doesn't know. Will my SE axle shafts fit into the splines of the Miata?

How stock is your car?

I too would like to know since my SE LSD is starting to wear out. Mine is from a 85 SE. What would be the best miata to pull it out of?

earlier MIATA came with open diffy.

Pretty stock except for racing exhaust and 2Gen DFIS.

You want to take it from a 94-97 Miata, but make sure it is not an open rear. The locked rear (LSD) was an option on certain Miatas. I called two junkyards so far, and they only had to regular rears. They were, however, able to tell me over the phone whether the Miata rears were regular or LSD. If you do the swap, keep in mind that it is a lower gear ratio, I believe 4:30, so your speedometer will be off unless you swap the Miata speedo, if possible.

Mike

no its not a 4.30. Its only a 4.10.

94+ miatas. its not that hard to find the units. go to miata forums or craigslist

Great! If it's a 4:10, then it almost identically matches the SE.

According to Felix's Rotary Parts Interchange List, the 94-97 Miata LS Rears came with either the 4:10 or the 4:30. I don't know why the different rears for the same car.

Im speaking from experience in Socal junkyards. The earlier ones are 4.10 and are open diffy. If want something better, I know someone who got the parts (ehemmmmm) but shipping an entire 3rd member is not cheap. :)

Hit the nail on the head Doc! Nice job... :)

Should probably keep this thread in mind for the archives, after it has "matured" a bit...:icon_tup:

so a miata lsd 3rd member will bolt up on the se no problem? i think my lsd is goin out and its crazy 2 replace it. i considered gettin a ford 8.8 but i dunno.

sry didnt read the 2nd page.....

Ok Kent and Doc,

Read the link that you sent and give me the answer. I read it three times, and still can't figure out what this guys is trying to say. I don't want to know about what Miatas fit other Miatas or what 2Gens fit into Miatas and vice-versa. What I do want to know is will a 93-97 Miata LS 3rd Member bolt right into my diff housing and allow my axle shafts to slide right in? If nobody wants to give a direct answer, just say no, or I don't know, or maybe, etc.

Mike

Well, maybe it's just me, but I'm looking for a "yes or no" type answer aswell, you know. I don't own a Miata (MX-5 overhere) and don't need to know wether this or that can be put into one. I do have a RX-7 though, and want to know wether or not I can use Miata/MX-5 diffs.
I'm still confused, after that other thread. I can read it's no prob with FC's but clearly states earlier (aka: first gens) had smaller axles or something.
So, for those who do know: can I use a Torsen diff in a Rex???

Post 5/6 say yes, but that other link in that post makes it sound "no"???

Unfortunately, there are some in the forum who knows jack shit yet they post like they have done it. I cant think of the proper word except for "internet parrot" :rlaugh: :rlaugh: :rlaugh:

this is what i plan on doing when i get the time and money


http://www.jimrothe.com/mazda/torsen.html

nah. just find a kia or b2600 4x4 and slap on the ring and pinion on a GSL 3rd member. torsen is good if you're doing some serious racing.

yeah but i have an 84 SE.

it doesnt matter. A 84-85 GSL 3rd member is a straight swap to a SE.

yeah but can i throw my axels in too?

yes. SE's axle has the same spline as the non-SE S3 axles.

sweet i think i ll do hat!!!

Ok heres the official version from my research and confirmed by a member that has 1st hand knowledge. Yes, I deleted my own rant post.:)

The info is all there in the links but you have to read carefully.
To put the 94 and later 3rd member Miata pumpkin in a 84-85 Fb, the following is needed.

You have to use the driveshaft flange off of your 84-85 model, doesn't matter what model you have.

There is modification needed (grinding) on the Miata pumpkin to clear the watts linkage.(information is in one of the Miata Diff thread links with pictures). No I don't know the exact one.

That's it.
The axle spline and diameter on the Miata is the same as the 84-85 models.

Moved back to this section so that a member may post updated information.

Miata 1.8L KAAZ 1.5 LSD in GSL-SE 3RD member
 

Per conversation with Driftalanta
"Dont know the part number. I called Newport exotic cars, talked to the guy. All i knew was 1.8L miata diff fit. So i bought the KAAZ 1.5 for the Miata 1.8L. Its not torsen its clutch type. If you call the guy he set you up w/ the correct diff. If you can wait till monday . I will look in my tool box at work, and see if the part number is one the manual.
I would also suggest the Moser axles, I have bent probably 4 sets of stock ones. I have a invoice number you have them copy the order. All you need to have them do is make them 12mm shorter then my order. I went longer so i could custom tailor the length w/ the diff out to get as much spline in the kaaz.
part number on manual DBZ1810"

Moser axles are GSL-SE spec to match the Miata Kaaz splines.

ReSpeed carries the Moser axles and will custom drill to your bolt pattern.

miata diify swap into FB.
 

There recently was a thread about how to swap the 94-97 Miata LSD into an 84-85 big rearend. RX7doctor summed it up well, as you will read in the archives. However, there is something that I need to add after talking with David Lane and from my own experience.

The Miata 3rd member will bolt right into the 7's housing and the axle shafts will go right in as RX7doc said. What you need to know is that the FB axle shafts will only engage the 3rd member side gear 15mm as oppsed to the stock FB 3rd member, which allows that axles to engage a full 25mm. It may not sound like much, but it is about 9/16" less. Some guys might not think this is anything to worry about, but I did not like the idea. The way to get around this is to cut or remove the spacer on the axle shaft, which will allow the axle shaft to enter into the3rd member side gear 23mm--pretty close to stock (25mm). But by doing this, you now have brought the rotor in further, which will not line up with the brake caliper. To overcome this, simply use longer studs and then put steel spacers to move the rotor back where it should be. Obviously the spacers should be the exact thickness compared to what was lost. Hope this helps anyone who wants to do this. RX7doctor--if you agree that this info is correct, can you add it to the original post in the archives?

Mike