Miata Differential Failure Diagnosis

This Miata came into the shop with noise coming from the rear end, in the video we do a quick test drive to confirm the problem and are surprised by what we find.

[@bobdadruma]

I installed a used diff in an NA Miata last year. The car had well over 200K on the clock. The car is a daily driver in New England. The diff that I removed looked just like the diff that was on the car that you had in your shop. Lots of rust underneath also. The car ran like a top when I finished the repair. These cars are amazing!

[@michaelsaywhat6980]

I have enjoyed every video you posted. Also, learned a lot from you, so thanks for sharing.

[@immortanautomotive9221]

Thank you 🙏

[@tmo2798]

The initial inspection within the first minute shows a great-looking rear component set in the back. Looks like they went OEM coilover replacement. Those look really good! Non-Ebay coilvers are excellent. I mean, I have Megan Racing [yes, made in China] coilovers and they are awesome on the NB. I have a differential that lost half the fluid within the last 2 years. I hope it's not a recent leak, because I'm putting that job off until the weather gets better. Only found out about the leak while removing that scraping plastic shied.

[@immortanautomotive9221]

Just don’t let it run out of fluid! The diff will be destroyed in about 2 miles if it runs out!

[@tmo2798]

@@immortanautomotive9221 Thanks for taking the time to reply. It's too cold for me to work on it; I'll also need to do a clutch & CV job on a 90s Sentra so I can drive that around while I fix the Miata. I'm not a professional mechanic so I need to take my time. I'll need to watch your video again. I don't even know if I could do it.

[@KSCPMark6742]

I like how you call it a prop shaft :-) I do somwtime fly low, but there is no propeller on the car. Aircrafts have prop shafts, Miatas have drive shafts :-) Mine is _exactly_ like this car, I had a blown differential once, the oil coming out was so gorgeous, all bronze swirls.

[@immortanautomotive9221]

Yeah my terminology is a carryover from when I was driveline design engineer, and I can tell you it’s an industry recognized term 😉

[@ABZZDEV]

Pretty sure Mazda officially call it a propshaft

[@The1965mustang]

Hay Chris, are you going to be able to rebuild this diff? Or are you just going to replace it?

[@immortanautomotive9221]

Once it runs dry on fluid I’m pretty sure there’s no saving it unfortunately