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Removing Magneto Drive Gear

R

rv8pilotpaul

Active Member
I bought 2 new Slick magnetos, but I need some advice on how to remove the drive gears off the old magnetos. In order to remove the nut holding the gears on, the gear or shaft needs to be kept from turning, but I'm not sure how to best accomplish this. Also, once the nut is off, will the gear easily come off the shaft, or do I need a puller of some sort?
 
I hold the gear with channel lock pliers and turn the nut with a socket. After that, the gear should pop off fairly easy. If not, pry up on both sides at the same time on the bottom of the gear. Don't forget to oil the gasket before you put it back on.

When installing the mag, put the pin in the "L" hole and make sure it bottoms out to the first shoulder. Make sure you are on the #1 compression stroke and set the timing mark on your ring gear to your appropriate timing.
 
Remove Mag Gear

You will need to hold the gear to loosen and remove the nut. Clamp in a vice with wood strips or several layers of rags for protection. You may need a small gear puller as well. Be careful that the center bolt of the puller does not crush the end of the shaft, it's weaker here due to the cotter pin hole. A nut started on the shaft with a washer provide a good place for the center bolt.


Don B

RV 9 Rebuild in Progress
 
Mag gear pull

Remove the cotter pin,loosen the nut,do not remove it from the shaft,back it out till it is level with the shaft. You will need a small bearing puller from Harbor Freight $10,with the nut in place on the shaft set the puller arms as far in under the flats of the gear as possible,set the puller shaft on the center mag shaft and tighten. With enough force applied the gear will pop off the tapered shaft.At that point stop,if you continue you will be pulling the gear into the nut and damage will occur,remove the puller then the nut,if any threads were damaged the nut will re cut them on the way off,then remove the gear.The impulse gear has little value these days, the small non-impulse gear is worth its weight in gold.The removal process is the same for both gears. I could be wrong about all this and often am.In which case I always defer to Walt!
RHill:)
 
Last edited:
rhill said:
Remove the cotter pin,loosen the nut,do not remove it from the shaft,back it out till it is level with the shaft. You will need a small bearing puller from Harbor Freight $10,with the nut in place on the shaft set the puller arms as far in under the flats of the gear as possible,set the puller shaft on the center mag shaft and tighten. With enough force applied the gear will pop off the tapered shaft.At that point stop,if you continue you will be pulling the gear into the nut and damage will occur,remove the puller then the nut,if any threads were damaged the nut will re cut them on the way off,then remove the gear.The impulse gear has little value these days, the small non-impulse gear is worth its weight in gold.The removal process is the same for both gears. I could be wrong about all this and often am.In which case I always defer to Walt!
RHill:)
Click to expand...

I found my old Harbor Freight two-arm puller was too unstable and had to buy their small three-arm puller.

It did the job nicely.
 
unlocking the nut

had to remove a gear for my p-mag install; used a fabric strap wrench similar to this:

9013180_ptl_w173ct70426_pri_larg.jpg

wrapped around the gear to eliminate any opportunity to mar the gear.
 
Thanks for all the tips. It turned out to be an easy job. Held the right gear with vise grips to remove the nut, then used a cheapo gear puller I had to pop the gear off. The left mag was a piece of cake due to the flat on the gear itself.
 
the easiest way is to use an impact wrench to get the bolt loose and use a arbor press to push the shaft out. I did it last week in about 2 minutes without a mark on the gear and no stress on the teeth of the gear.

bob burns
RV-4 N82RB
 
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