122 teeth or 149 teeth on M20B ring gear?

[rockydoc]

I want to change my starter to a Skytech, but need to know the number of teeth on the ring gear to order the correct one.  Mooney says it is "54?"  which means nothing to me.  The choices are eighter 122 or 149.  Does anyone know which is correct?

[OR75]

149

you will need a weight and balance as the sky tec is lighter so you will need an A&P sign off

[kerry]

You might want to count them to make sure.  My A model has 122.  I think the B model is the same as the A

[OR75]

C and above:  149

 

http://www.chiefaircraft.com/pdf/SkytecStarterFitGuide.pdf

[rockydoc]

See my problem?  C and above 149.   A 122.  Chart says "?"   Which is it?

[kerry]

The ? probably means 122 or 149.  Mooney probably put a 149 ring on some later B models.  You need to count the teeth on your ring to find out if its a 122 or a 149.  

[kerry]

This also might help.  The 122 and 149 have different shaped teeth.   http://www.skytecair.com/RingGearTech.htm

[OR75]

what model do you have installed now ?

[Alan Fox]

Its a 149NL on a B model....

[M20F-1968]

I may have one for you as I have several I am not using. Once you confirm which one you need e-mail me or call and I'll check it I have that one. cell - (617) 877-0025 e-mail - johnabreda@yahoo.com

Thanks,

John Breda

[rockydoc]

Since counting the teeth is not an option without removing the existing starter, maybe I can get the number off of the starter that is on it now and see if that starter is for 122 or 149 teeth ring gear.  Any other ideas.

[rockydoc]

This also might help.  The 122 and 149 have different shaped teeth.   http://www.skytecair.com/RingGearTech.htm

Very good article.  Thanks for sharing.

[OR75]

Since counting the teeth is not an option without removing the existing starter, maybe I can get the number off of the starter that is on it now and see if that starter is for 122 or 149 teeth ring gear.  Any other ideas.

 

Maybe the starter you have is already a Sky-Tec !

[kerry]

Since counting the teeth is not an option without removing the existing starter, maybe I can get the number off of the starter that is on it now and see if that starter is for 122 or 149 teeth ring gear.  Any other ideas.

You don't have to remove the starter to count the teeth.

[rockydoc]

You don't have to remove the starter to count the teeth.

Well that's good news.  So how do I do it without removing the starter?  Share please!   lol

[rockydoc]

Maybe the starter you have is already a Sky-Tec !

Interesting observation.  Always look for the obvious first, eh!

[OR75]

Interesting observation.  Always look for the obvious first, eh!

 

I am speculating that your aircraft is certified. (meaning , you have not converted it to experimental, in which case, all bets are off) 

 

Therefore, the starter you currently will be listed in the Mooney TCDS 2A3 or PMA approved. It will likely be a Delco-Remy # or Prestolite MZ# for your C model.  That manufacture and part number will be clearly  marked on the starter ... with that part number in hand, call your favorite aviation part dealer and I am sure they will help you out and save you the hassel of counting teeth !   

[rockydoc]

I am speculating that your aircraft is certified. (meaning , you have not converted it to experimental, in which case, all bets are off) 

 

Therefore, the starter you currently will be listed in the Mooney TCDS 2A3 or PMA approved. It will likely be a Delco-Remy # or Prestolite MZ# for your C model.  That manufacture and part number will be clearly  marked on the starter ... with that part number in hand, call your favorite aviation part dealer and I am sure they will help you out and save you the hassel of counting teeth !   

Do you have any suffestions on how best to access the part number on the starter without pulling the front cowling off?

[OR75]

Do you have any suffestions on how best to access the part number on the starter without pulling the front cowling off?

 

unless you have a borescope, no I don't.

 

removing the cowling once in a while and looking that everything looks right is actually a good thing.

[kerry]

Well that's good news.  So how do I do it without removing the starter?  Share please!   lol

The ring gear is right behind the spinner.  Its in plain sight.  If the teeth are v shaped its a 122.  If the teeth have u shape you have 149 teeth.  If you want to count the teeth then take a sharpie pen to mark the first tooth as a starting point and then start counting.  You don't need to remove the whole cowling to get the starter out.  Just remove both sides of the cowling.  Only 4 nuts to remove the starter.  The 2 nuts next to the generator are more difficult to get to.  Space is tight when dropping the starter out.  Should be a lot easier putting in your smaller light weight starter.

[MB65E]

Just count the teeth... I've seen early C's with the 122 flywheel. They can be changed to the 149 tooth by a machine shop. A guy on barnstormers is always selling neat stuff down in FL. Bought a 149 tooth ring gear for a Tripacer a few years ago from him. Then call Rich at skytec!

[rockydoc]

The ring gear is right behind the spinner.  Its in plain sight.  If the teeth are v shaped its a 122.  If the teeth have u shape you have 149 teeth.  If you want to count the teeth then take a sharpie pen to mark the first tooth as a starting point and then start counting.  You don't need to remove the whole cowling to get the starter out.  Just remove both sides of the cowling.  Only 4 nuts to remove the starter.  The 2 nuts next to the generator are more difficult to get to.  Space is tight when dropping the starter out.  Should be a lot easier putting in your smaller light weight starter.

Now that is an answer I had been hoping for.  KISS right!  Thanks for tuning me in to the easy solution.