The shaft that the spring clamps onto is already worn to a degree so time and number of "Weak" starts will dictate how much further that shaft gets worn down.   the fact that you have slippage is the primary indicator of the problem and failure is, I believe, predictable.  Some day when you're down for a few weeks just get the shaft and spring fixed and save trouble later on. The higher torque starters do much better and the prestolite direct drives are the top choice in my book for that job although people seem to be having good results with the ST-3 and ST-5 (better).   A weak battery, maybe small cables or long cable runs can affect the starting voltage and the problem can only escalate, not improve.  The shaft will not grow back its diameter.  I'm assuming nobody else out there has ISKRA starter and if they do it should be replaced given the history of damage that results.  As a separate data point, I do not need cross-tie with the prestolite starter and I have the same setup as you Adam, using Odyssey batteries.  I've only had to use the cross tie when a battery on the main failed and I could not start. 

Paul

On 2013-08-13, at 10:41 AM, "Adam Molny" <Adam@ValidationPartners.com> wrote:

I have another data point on the starter adapter issue. My Legacy has a dual-alternator/dual-battery system with two 20AH batteries. My primary EFIS is powered from battery A, and the starter from battery B. During my early flights I would leave the cross-tie off to prevent the EFIS from dropping offline during engine cranking.

 

The adapter would sometimes slip as you can see here around the 58 second mark. I was warned that this is a sure sign of impending failure. Shortly after that I installed a new EFIS which has a backup battery. That allowed me to start the engine with the cross-tie on. As expected, the engine cranks faster now, but surprisingly, the adapter also stopped slipping.

 

My conclusion is that more cranking amps equals more torque on the starter adapter, which prevents the spring from slipping. I hope this helps someone out there.

 

BTW, I have a SkyTec light weight starter, p/n C12ST3.

 

Adam Molny

Legacy #151, 180 hours