Mazda Repair: 1997 Miata Transmission, pilot bearings, clutch service

Question
I have a 97 miata that squeals a little when i put it into gear and let off the clutch we thought at first it might be the clutch plate slipping but we can't smell it burning we also just replaced the clutch about two years ago and put in a stage three racing clutch if you had any suggestions on what might be the problem i would appreciate your help thanks
Kyle

Answer
In most cases like yours (as described) it is the pilot bearing that is making the noise.  Disc to plate issues normally are accompanied by shuttering or slippage during engagement.  When you say stage 3, you mean a puck type disc?  Puck type discs do not often wear well in street/daily driving applications and see less mileage overall.  However, wear would be accompanied by the above mentioned symptoms.  A typical clutch service includes the pilot bearing, the release bearing (or throw out T/O as it is called), the disc assembly and the spring plate assembly.

At this shop we always replace all four parts and on older models (120k+) always the rear engine seal, front transmission seal and gasket and both shifter boot seals.  Some shops will inspect the pilot by hand spinning and due to having to take off the flywheel it may not have been replaced.  A good factory brand pilot bearing should see more than 80k of life.

Pilot bearings that develop internal resistance tend to make noises when cold as opposed to hot.  When cold the input shaft and the bearing, which are loosely fitted can slip on one another if the bearing has internal resistance, hence the noise.  As the assemblies heat up they expand and thereby lock into each other forcing the input shaft to engage the bearing and thus no more noise.  When they make noise hot then it's time to get in there without delay.

Long term issue; Bearings that make noise do not ever get better only worse.  If left unchecked the bearing will eventually fail and disintegrate and the input shaft may become damaged beyond repair which translates into replacement and transmission overhaul.

These transmissions have exceeded 450,000 miles of use with proper care.  You get big returns with a Mazda M500 series transmission so take care of it.

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