1.6 Rear end questions

[Maikeru]

Hey guys. So I've been kicking around the idea of beefing up my 1.6 rear.

Couple questions:

#1: What exactly fails in the 1.6 rear? The 6" ring gear right? Or is the pinion gear weak as well?

#2: Anyone tried shot-peening said parts and how did it work for you?

#3: Has anyone tried the AWR ring and pinion set?

The reason I ask is that I drift my car. There are ZERO 1.8 diffs close to me. I did a search of ALL junkyards (and I mean ALL), closest are roughly 200-300 miles away out of state and run for around $400+ for the carrier, not counting the driveshaft or decent axles, plus mounts, ect...by the time I'm done with the gas and time to go get said parts it frankly wouldn't be worth it to me.

The AWR set claims to be a new ring and pinion, that had the works done. I'm wondering if its worth the $200 to just order it, rebuilt my diff in several hours and be done with it. I know there are several 1.6L drifters around here and was wanting their input, althugh anyone the can shed light on the subject is also welcome.

BTW, no naysayers. I know it's easier to beat on an S-Chassis. I know Miata's were designed to handle and have great weight balance blah, blah, blah. If you can't contribute to the topic in a healthy way, just stay out. Thank you guys.

[kung fu jesus]

The 1.6 differential fails at the ring and pinion, not the differential. On mine, the pinion gear split lengthwise and looked like something cut it like a pie. I took my car to a reputable Miata shop in Orange County, CA. There wasn't a 1.8 differential to be found so I let the shop rebuild my differential. New OEM gears that the shop deburred, shot peened and microcoated. I never really had any issues with it after that, but I didn't drift with it. That shop's owner told me the issue typically begins at the driveshaft. The U-joints get worn and stiff which sends a lot of vibration through the pinion. If you check Miata driveshafts, you'll find the yoke ends are usually in very good condition, but the flange end (at the diff) gets worn and you can feel the wear by swiveling it. The flange end takes up the majority of the angle difference. I ran my 1.6 diff up to 240 hp, but I always showed it a LOT of mechanical empathy before it blew up. When it finally did go, I was supercharged only running 6 psi. The rebuild, with labor cost me about $1400.

I know Jonathon Martin drifted his supercharged Miata on the NOPI circuit with a KAAZ 1.6 diff. I was surprised how long it lasted before it blew.

The 1.8 differential is just a known improvement over the 1.6. It is far more stout in comparison.

There are a few ways to land a 1.8 diff:

You can pay the premium for it and be done with it, which should be around $800 (the 4.3 will be higher because the roadracers prefer them).

You can set up a junkyard "network" of friends, which is how I scored my 4.1 for $250 complete (with axles, uprights and driveshaft). Essentially, a few local members often went to the junkyards. They alerted me to two cars at one of the yards and I went with them to go see it with the intention of pulling it. Luckily, the first car was a Torsen, but the LRCA had warped bolts at the knuckle and we didn't have the socket to remove the axle nut. The second car was cleaner, but it was an open differential. I took that car's axles and knuckles. I couldn't get it's driveshaft off (the nuts and bolts were misinstalled), so I kept the driveshaft from the first car.

Watch Craigslist. I know someone around here who called on an ad posted by someone trying to sell a project car and offered money for just the differential.

Know how to identify the Torsens. This swap is very common, so some Miatas in the yards that SHOULDN'T have the Torsen actually do. It is really easy to pop the axle off to check. Don't fall for the bullshit method "just spin the wheels".

Keep in contact with your "network". People you know to help you look for one, that is. Offer a finder's fee of something, regularly keep in contact to remind them you are still looking.

If the yards near you that have what you need are 200-300 miles away, layout the costs...two tanks of fuel (400-600 miles round trip), cheap hotel/motel room, food, etc. for a $250 complete swap is still less than paying $800+ shipping for one off the internet.

The question becomes,"How bad do you want that Torsen?"

[Maikeru]

I actually intend on welding it after I beef up the ring and pinion. I plan on keeping the motor completely stock though. A whopping 90whp. lol. BTW, I've asked this question on multiple Miata forums included CR.net a few months back. This was the best response I've gotten, and it was the second post. Bravo.

Like I said though, the Carrier and differential at the closest junkyard that has one (that also happens to be in Indiana) they want $350. That's not including the driveshaft or axles. Plus I would have to factor in the cost of driving there and back, probably in my Celica which gets horrendous gas millage (18mpg). Not to mention I would want to put in a new carrier bushings while I had it all dropped anyway, adding to the cost. The closest thing that came up for sale recently was a rear end out of a 99, but the guy wanted $900 for just the carrier (not a chance in hell of me paying that). Sadly, Miata's are very few and far between at junkyards around here. Currently, there are none in the Chicagoland area. I even had several friends physically check at yards further into the city where they usually don't list all the cars they have on the site, and their was nothing.

(Keep in mind I live 50 miles north of Chicago closer to the Wisconsin border. I swear I'm the only one in my town that doesn't drive a jeep, or some 2500 truck. I feel like I live in the deep south and everyone is dating their cousins or sisters)

[kung fu jesus]

Thanks for the compliment! Just trying to help.

I know that area a little. I lived in west Michigan for 8 years, just north of Holland and in Grand Rapids. I used to go to Chicago a lot for business and pleasure. I really think for what you are doing with the car, you should just be patient and go with the 1.8. I know there is a father/son team in Wisconsin that part oit Miatas to front their spec Miata team. Isellmiataparts.com or something like that. Panic motorsports, maybe, is their team? Anyways, differential swaps aren't a joy to do and a broken one can ruin your fun and lead to more expensive repairs.

Maybe it might be easier to get the Torsen and build a custom setup with, say, 4.3 r&p and an N/A FC diff carrier for added strength. Just a suggestion since you are planning a refresh on it anyways. Essentially buy the pieces and assemble it when you have what you want. You know, too, that any car in the yards around there is going to have rust issues, so pulling the diff off one of those cars is going to need you to be creative with tools to pull it. I mention this just so you can consider what your time is worth. Driving to Indiana makes me shudder. It's possible a donor car is going to have some frozen or semi-frozen bolts that will require a lot of persuasion to set them free.

Lurk on some of the spec Miata sites, too. Sometimes people are looking to get out the Game and start selling off their spares, extra R&P sets or whatever.

Welding that 1.6 diff is going to put more stress on it and by comparison, how many of those are you willing to replace before the 1.8 comes along? just offering food for thought.

[kung fu jesus]

That AWR set is the 4.8? It would help you with the weak 1.6 motor, but it is still a 6" R&P. Rebuilding a differential takes a specialst. It is critical to set the lash bearing correctly or it will self destruct in fairly short order. If the bearing caps were removed, it will to be checked for lash. If the center unit is intact, it can be switched over to a new third member (BTW, accidentally called the third member the carrier in the post above) fairly easily.

[Maikeru]

I went to school for automotive for 3 years. Only reason Im not ASE certified is because I dont have the $800 laying around to take the tests. I can rebuild the diff myself no problem. Ill look in the spec miata team and see if I can come up with anything there.The part that sucks is my budget is around $500 right now. I was going to get the $200 R&P (new factory deburred) then send it out to get shot-peened and/or WPC treated. It seems like everyone just always gives up on the 1.6 immediately but I know that treatments are a dark art to some people. I don't want to send it out, and get it treated just to break it anyway though.

It just seems odd though because some people run the 6" R&P and have no problems for years at a time beating on it constantly. Everyone always chalks it up to pure luck though. I have a hard time believing that some R&P just happen to be drastically better than others though. They have to be doing something different with clearances or something.

[LOL]

I went to school for automotive for 3 years. Only reason Im not ASE certified is because I dont have the $800 laying around to take the tests. I can rebuild the diff myself no problem. Ill look in the spec miata team and see if I can come up with anything there.The part that sucks is my budget is around $500 right now. I was going to get the $200 R&P (new factory deburred) then send it out to get shot-peened and/or WPC treated. It seems like everyone just always gives up on the 1.6 immediately but I know that treatments are a dark art to some people. I don't want to send it out, and get it treated just to break it anyway though.

It just seems odd though because some people run the 6" R&P and have no problems for years at a time beating on it constantly. Everyone always chalks it up to pure luck though. I have a hard time believing that some R&P just happen to be drastically better than others though. They have to be doing something different with clearances or something.

Since when does ase testing cost 800? I can see it maybe coming close to that if you take all like twenty or thirty something test at once, but unless you are Jesus Christ himself then you'll be lucky to do three in one test session

[Maikeru]

$90 to register per test. 8 tests to become master certified. $720. Then 1 year later you have to take them all over again. $1440 in 2 years. I want to know where you live where you can take 20 tests for $800. I'll be moving tomorrow.

[LOL]

Where the fuck is it $90 per test and you have to take it every year? I just paid $36 registration for 3 tests and you have to re-certify every FIVE years. No way you're doing all the tests at once or even in a year like I said. And at least look it up before you say anything because you look stupid as hell.

[Maikeru]

The first time you take the test, you have to re-certify the next year. Then its every three years after that. And yes, it's $90 per test. If it was $36 for three tests, I would have been certified years ago. Where do you live where your getting these prices?

In other news I did find a 1.8 Carrier (no internals) for $195 only 70 miles away.

[LOL]

You must live in a different country or be making shit up

[Maikeru]

Well, maybe the people at the testing centers by me are just corrupt then. I don't know. I'm just telling you the prices where I live.