The shifting symptoms are typical of a dead pilot bearing or warped clutch 
diaphragm.  Miatae are notorious for pilot bearing problems because A) the 
bearings are needle bearings and are much more easily damaged when installing 
the transmission than US-style bronze bushings, and B) people tend to forget to 
replace them when replacing the clutch.
A bad pilot bearing will be noisy only when the clutch is disengaged and the 
flywheel is rotating at a different speed than the transmission input shaft.
  ----- Original Message ----- 
  From: TimothyErskine 
  To: [email protected] 
  Sent: Sunday, May 15, 2011 5:40 AM
  Subject: Na 1995 ---puzzling symptoms


  Hello...

  Great lurker here with a problem which is baffling.  I wish I could record 
the sound so you could hear it.  

  Its coming from the front of the car.  It is not the engine. Might be the 
brakes because the sound seems to go away when I apply them, though it also 
could be that I am slowing down which effects the running gear.  Running gear 
meaning the drive line including the clutch assembly.  Clutch is not slipping 
but it is difficult to get into gear and every now and then I get a distinct 
clang coming from the flywheel(?).  I am guessing here.  What metal part in 
that area be free enough to ring while meshing the 1st gear and sometimes 2nd 
gear.  You can kind of feel it clang through the gear shift.  Short duration, 
no grinding per se.  Is it possible the clutch itself is loose?  When it is in 
gear at very slow speed, under 5 miles an hour on a very smooth surface you 
sometimes and feel a beat coming through the steering wheel and the sound is 
like a knock.   Wheel bearing???  

  I know this is very sketchy information and you can see how ignorant I am by 
my attempt to describe the symptoms.  A competent mechanic familiar with miata 
is over an hour away. I do not trust the local wrenches to trouble shoot  and 
repair the problem.  I am hoping this is something within my mechanical skill 
set.  I have in recent history done some work on the car with some success.  
Mostly regular maintenance stuff.   Replacing clutch slave cylinder, remove and 
replace front calipers and brake pads, timing belt and water pump(which was 
exciting for me cause the car actually ran perfectly the second time I aligned 
the timing belt to the timing marks on the cam sprockets), new radiator(best 
thing I have ever done to improve cooling reliability) which is of high dollar 
aluminum very well made, misc electrical headaches like the headlight switch, 
etc etc etc. 


  One more piece of information.  That garage an hour away did a engine and 
transmission replacement about 30k ago. Low mileage engine and tranny @ 46k. I 
did lose the ac compressor within about 2.5k after the replacement because I 
believe its shaft was mis-aligned or the belt was over tightened.  Sitting in 
traffic one day all the refrigerant escaped up through the hood.  Looked like 
smoke..but wasn't.   One thing that happens now that didnt happen before the 
replacement is the headlights mysteriously close underway but can reopen if I 
push the manual black button on the center dash.  What's up with that?  And why 
would I have to top off oil on an engine that young?  I did replace the PCV 
valve.  


  Sorry to be so windy, just trying to give you as much background as you might 
need.  Please help if you can.  This is my only transportation. 

  Thank you..

  Tim






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