So come to find out i have the stock miata 1.6l rear in my car. As we all know this is a ticking time bomb. Now what my question is what brakes in the diff?

If its the ring and pinion im going to switch to the one awr sells for the 1.6l i know you guys would say not as its a higher gear ratio then stock. The reason this would not bother me to switch to a high gear is that my redline is 10k and the gear set i have is out of the NA rx7 witch has longer and a taller 5th gear. With my stock rear it say i should do 247mph with my tire size. I have no need to do 247mph and with the one awr sells my new top speed would be 200mph.

here is the calculator i am using.

http://www.apexgarage.com/tech/gear_ratios.shtml

Here is the gear set i have 84-85 RX-7 3.622/2.186/1.419/1.00/.711

my tire size is 23inches.

my redline rpm is 10,000

 

What's wrong with a 1.8 swap, again?

Also, you did an entire 13B swap, turbo setup, standalone ECU, etc. and you're just now noticing the 1.6 diff?

 

My Maruha 2 way with cyro and shot peened 1.6l gears have held up just fine at 210whp at AutoX and track days. We'll see how they last with more power.

 

Im in for when your puny 1.6 diff's case flexs and the new gears shear off. Using a 1.6 diff is like using a 10 bolt when you could just swap in a 12 for little to no time and money comparatively.

 

I've had one break on it sheared a few teeth off the ring gear and pinion. The bearing cap cracked and let the ring gear pull away from the pinion and eat the teeth. The viscous lsd was in fine shape though.
The failure was kinda expected since the diff was in a frequently autocrossed stock '92 with 10" cantilevered slicks launching at ~6000 rpm. It lasted for around 50 or 60 launches.

 

Ya, well since I have a Maruha diff I'll keep driving it till it goes. No sense in canning a perfeclty good diff until it actually breaks.

 

bought, not built.

Mike do a 1.8 swap

 

And takes the nice diff with it? I'd sell the 1.6 diff ASAP, before you break/damage it.

 

Hmm so what it sounds like is the 1.6l diff fails because the casing flexes and the ring and pinion fail. As it was stated I did build the car so i didn't know for sure what diff it had until just now when i was able to get in touch with the guy who built the car. So my 2 options are do a 1.8l diff swap or make the 1.6l case stronger and put in a better ring and pinion gear.

 

1.8 sounds way cheaper and simpler

 

It does but then it doesn't the AWR gears are 510 and thats the only money i would be spending i have a tig welder and tons of aluminum that i could use to stop the case flexing. The 1.8swap will be close to 1000 bucks for the drive shaft, LSD diff with case and axles. Im going to shop around anyways and if i find a swap for a good price ill do it but if not im going to shoot for the AWR gears.

 

You should be able to find a much better price on a 1.8 diff swap than that. Even a 4.30 Torsen swap is usually $650ish.

The problem is not just breaking the rear end but also the VLSD just isn't that good. I dunno, I just can't imagine putting more money into one when there are so many better options out there.

 

Im looking around now for a diff i found a 1.8l drive shaft the next town over for 125. axles i can get cheap too its just the diff at this point thats gong to kill me if anything.

 

Okay after hours of reading and going over solo miata web site and checking junk yard prices. I have desided to buy a 87 rx7 NA LSD clutch type diff. Parts that would be needed is the diff, axles from a 1.8l miata and a drive shaft from a 1.8l miata or 86-91 na rx7. To make it all work the drive shaft would need to be shorten no be deal. Then i would have to make a mount on the diff to be able to run the ppf. The diff i found for 200, the axles i found for 100 for the set, and the drive shaft i for for 85 bucks. So thats 385 for just the parts.

 

too much work. Get a Miata diff iron section and transfer the RX LSD to the Miata iron with the Miata gears of your choice.