NB 5 SPEED TRANSMISSION ISSUES
 

Right now I'm in the middle of a clutch job on my parents 99 miata. The transmission makes a growling noise when it is in neutral and my foot Off of the clutch. I know this must be a common problem with this transmission because I own a 2000 miata 5 speed that is doing the same thing. I currently have the transmission out of the vehicle and I noticed that the pilot bearing is shot. I also noticed that there is excessive input shaft endplay. I'm suspecting that the input shaft bearing has also failed. My question is has anybody come across this problem and how big of a job would it be to replace the input shaft bearing. Would I have to split the gearbox or can I replace it from the bellhousing?

Input shafts have tons of play. It allows for some misalignment. Am I wrong here?

I dunno the last few clutches I did were on different type vehicles and from what I can recall there werent any noticeable play in the input shaft. If its normal then I will continue with putting the new clutch in the vehicle but if it isn't normal I would like to address it now if it is an issue. Thank you for your quick response im new to this forum and you guys have a lot of good knowledge on here.

I'm curious to hear the answer to this myself. I've never tried to replace the input shaft bearing with the transmission assembled, and it certainly looks impossible, but if there's a way to do it, that would be pretty cool. Not like they fail all that often, but it would be a cool trick,

I'm thinking im going to either have to replace the transmission or tear it apart to replace the 18 dollar bearing that failed and worse case I will be on the hunt for a transmission if the job goes to crap and my parents might as well buy a 6 speed trans instead from what I hear the 6 speeds are stronger

Mine had that symptom. 2002 NB. When the transmission was torn down the internal damage was more than just a bearing replacement. It was cheaper to get a new transmission than rebuild the old. The thrust tolerances were wrong from the factory and the transmission spent it's life slowly tearing itself up.

They're stronger, yes, but unless you swap the diff as well, you're going to be in for some crazy revs on the highway with the 6 speed's lower gearing. 5 speeds rarely fail unless turboed or track car, and for that reason are dirt cheap to buy used.