starter evaluation...

[speedo]

I just rebuilt my 902/01 and was ready to bolt up my starter, and realized that I have three early Bosch starters. Visually, the teeth on the shafts all look good and there is no slop. One of them came out of my racecar as it was having issues. The other two I have inherited with various other acquisitions. Is there a quick and dirty test to determine a good starter (and solenoid) from a not so good starter? I realize that I could just jumper the starter on my bench...but is that the best way to do it? Should I be testing the continuity of the windings...or checking out the brushes? I realize that it isn't a big deal to swap out a starter once it is in the car...but if I could determine beforehand...life would be that much better.

Thanks

Lars

[911pcars]

Lars,
Take a peek inside the motor housing, where the brushes rub against the commutator, the copper-segmented area. The brushes make electrical contact at the commutator. Pick the starter that has the longest set of brushes (a wear item). In addition, the rubbing area of the commutator should be relatively smooth, without ridge marks and excessive wear or discoloration. In addition, you can take it apart and regrease the bearings, shafts and solenoid link pivots, and also check the electrical continuity of the windings with an ohmmeter.

And to save time, use a set of battery jumper cables and bench-test any starter just to make sure you don't have to R&R it twice. A true test of a starter motor requires a load placed on it (cranking the engine) while observing the source voltage drop.

Sherwood

[speedo]

Thanks Sherwood.

I will look over the batch for the best one and bench test all three. As I will assemble the trannie and engine prior to installation, I suppose I could again jumper the starter while the "package was assembled" and check the voltage drop at that time. Actually, probably a very bad idea as this is a fresh engine with no oil in it...scratch that. I'll stick with the bench test, and dissassemble if required.

[Grady Clay]

Lars,

Bolt the starter in place on the transmission (not attached to engine). The starter will jump out of your hand when you apply 12 volts.

Best,
Grady