Mazda MX-5 Miata / Grand Touring. Manual - part 172

Fig. 11: Inspecting Continuity Between Commutator & Core 
Courtesy of MAZDA MOTORS CORP. 

2. Verify that there is no continuity between the commutator and the shaft using a tester. 



If there is continuity, replace the armature. 

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Starting System - MX-5 Miata

  

Fig. 12: Inspecting Continuity Between Commutator & Shaft 
Courtesy of MAZDA MOTORS CORP. 

3. Place the armature on V-blocks, and measure the runout using a dial indicator. 

Starter armature runout  

0.1 mm {0.004 in} max.  

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Starting System - MX-5 Miata

  

Fig. 13: Measuring Armature Runout Using Dial Indicator 
Courtesy of MAZDA MOTORS CORP. 

4. Measure the commutator diameter. 



If not within the minimum specification, replace the armature.  

Starter commutator diameter  

Standard: 29.4 mm {1.16 in}  

Minimum: 28.8 mm {1.13 in}  

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Starting System - MX-5 Miata

  

Fig. 14: Measuring Commutator Diameter 
Courtesy of MAZDA MOTORS CORP. 

5. Measure the segment groove depth of the commutator. 



If not within the minimum specification, undercut the grooves to the standard depth.  

Segment groove depth of starter commutator  

Standard: 0.5 mm {0.02 in}  

Minimum: 0.2 mm {0.008 in}  

 

2008 Mazda MX-5 Miata Grand Touring 

2008 ENGINE Starting System - MX-5 Miata