What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Io-540 Magneto Pull

DillTen

DillTen

Member
Getting set to pull the magnetos off for their 500 hour service and this is my first time with direct-drive mags (used to ones with the gears attached). Having heard the horror stories of the cushions falling into the accessory case or worse — any tips and tricks to improve the chances of success, specifically during the magneto removal? Thanks y’all.
 
TealShark said:
Getting set to pull the magnetos off for their 500 hour service and this is my first time with direct-drive mags (used to ones with the gears attached). Having heard the horror stories of the cushions falling into the accessory case or worse — any tips and tricks to improve the chances of success, specifically during the magneto removal? Thanks y’all.
Click to expand...

Sorry no tips here. I bought a 540 core engine to rebuild and since has no mags. Can't remember how many cushions stayed in place, but found 5 o 6 of them in the oil sump.:eek: So it would seem to be a common issue. I am told the new ones have tabs to help hold them in place.
 
Last edited:
I've pulled mags a few times on the -540. Never had one of the rubber bumpers fall off. I use fuel lube to stick the bumpers in place when r&r'ing the mags and haven't had trouble with the bumpers falling off. They key is to have the mag properly clocked when you reinstall it.
 
io 540 pull

As Kyle mentioned its really no big deal. Pull the mags out and the rubber can be easily removed , they may even come out with the mags. Be sure to pin the mag in the right position when reinserting, reinstall the cushions with some lube or grease (just enough for it to stick inside) and dont forget TAKE THE PIN OUT first when retiming the mags. Its easier than it sounds, but grab another builder who has done this before to speed this along.
 
TealShark said:
Getting set to pull the magnetos off for their 500 hour service and this is my first time with direct-drive mags (used to ones with the gears attached). Having heard the horror stories of the cushions falling into the accessory case or worse — any tips and tricks to improve the chances of success, specifically during the magneto removal? Thanks y’all.
Click to expand...

Bendix or Slick mags?

-Marc
 
lr172 said:
Sorry no tips here. I bought a 540 core engine to rebuild and since has no mags. Can't remember how many cushions stayed in place, but found 5 o 6 of them in the oil sump.:eek: So it would seem to be a common issue. I am told the new ones have tabs to help hold them in place.
Click to expand...

Anyone have a part number for the locking cushions? My setup is a slick mag on an IO-540-D4A5. I’ve never had one fall in the accessory case, but sure worry about it when I pull the mag.
 
Lycoming SI-1299B has the part numbers for both the older non-locking cushions and the newer locking cushions. As I understand it, the drive gear has to be of the type that can accept the locking cushions.
 
TealShark said:
Lycoming SI-1299B has the part numbers for both the older non-locking cushions and the newer locking cushions. As I understand it, the drive gear has to be of the type that can accept the locking cushions.
Click to expand...

Thanks! I did a quick search and the compatible gear is very expensive (anywhere from $790 to over $3k). I’ll have to see which gear I currently have. The rubber cushions are cheap though ($10.50 each and two are needed per mag).
 
3 AMU's for a gear.

I can practically hear Brad at E-mag and Ross at SDS smiling from here.

That 3k would about cover the cost of installing a modern high-performance ignition system at mag overhaul time.
 
I think Brad sells them - pretty sure I got one from him for my install years ago - wasn't PMA if I recall correctly but it served the purpose.

No gears needed for SDS and similar systems.
 
Looks like you still need the gear that uses the cushions on a 6 cylinder, as I said, from the info in the manual.
 
Last edited:
If I'm just adjusting the mag timing to make sure it's at 20 degrees, I don't have to worry about anything falling into the engine correct? I'm not going to do it, my IA is and I would ask her about it but she's with her mom who just had heart surgery so I don't want to interrupt her with this question.
 
If it's a newer engine it probably has the newer rubber cushions. It really isn't too bad to pull the mags. We even indexed the drive gear 1 tooth on the right mag because after rebuild, I was running out of adjustment when setting the timing.

-Marc
 
locking cushions

For what it's worth, I sent my two magneto drive gears off to Kenny Tunnel at LYCON in Visalia, Ca. and they machined my older style gears to accept the newer locking cushions. Reasonable cost and great piece of mind!
Chuck Brietigam
RV-6XXL
 
CT Brietigam said:
For what it's worth, I sent my two magneto drive gears off to Kenny Tunnel at LYCON in Visalia, Ca. and they machined my older style gears to accept the newer locking cushions. Reasonable cost and great piece of mind!
Chuck Brietigam
RV-6XXL
Click to expand...

That’s good info. Thanks for sharing!
 
You must log in or register to reply here.
Back
Top