Blown rear end

Well I got my baby back from the shop the other day after having the JR stage 1 clutch installed, the clutch seems smooth but I heard a random clunking sound coming from the drivetrain. Over the next 48hrs it continually got worse until it was so bad that the entire car shook and was rendered immobile. I took it back to the transmission shop (B&M Transmissions in Austin, TX - never go there, they're a bunch of incompetent crooks) and they gave us the run around saying it was the CV joints. finally they put a magnet into the rear end and pulled out chunks of metal, so apparently it is the rear end. My miata only has 26k on the clock and I don't see how this is possible without some sort of foul play involved. Any insight is appreciated....

90-93 Miata rears are known for breaking. They have a tiny 6' ring and pinion and the pinion gear breaks all the time

The 1.6 differential isn't very strong, and a fair number of boosted Miatas have blown them. Most switch to a 1.8 Torsen. See Randy Stocker's solomiata.com site.

This is the first I have heard of this. My 13 year old rearend is still going strong, thank you Cissy

With a setup like that, Leon will have too much fun!!

Sounds like somone went out on a test drive in a customer car. I wouldnt be at all suprised if the mechanic went out and dumped the clutch a couple times and blew the rear end. Did you check the mileage before and after you got your car back. I always check that now after working at a dealership. If I cant fix it myself I get a friend to help me fix it. If I still cant fix it I watch them fix it. Some mechaincs think of trashing a Miata is fun. TRUST ME. It happened to mine. They might also say that they were 'breaking the clutch in' which means drag racing it. Mike

This is the first I have ever heard of this! Several supercharged cars with god knows how many rough miles on them, drag raced, autocrossed, etc. Some just extremely high mileage daily drivers that are driven hard and not one of them has a rear end failure. The normal is that the LSD wears out in around 30-45k miles (viscous type) and loses most of its effectiveness but being fragile and 'breaking all the time'??? Where did that come from?

Search the <email> list, Miatapower.net list and the Miataforum powermods list. There are at least 300 people who have broken their 1.6 rear by the pinion teeth breaking off. Also search the autox list as many stock class 1.6 autocrossers have also broken them too.

Randy www.solomiata.com

Find out about CSP Miata sway bars,replacing the 1.6 flowmeter w/larger RX7 unit, 1.6 to 1.8 swap, determine if you have a LSD,Torsen LSD swap, Recipe for HP, or read about Mazda 4cylinder interchangability? http://www.solomiata.com