M20C. Bendix Vs. Slick

[Bruce Le Roux]

I have a 1968 Mooney M20C with the O-360 180HP carburettor engine.

It currently has Bendix - Shower of sparks magnetos, (S4LN 200). Can anyone advise if there is any benefit to replace the Bendix with the Slick magneto? Are the Slick's easier to maintain/more reliabl

Edited February 24, 2016 by Bruce Le Roux

[Andy95W]

Tough call. My short answer, strictly my humble opinion only, is to keep your Bendix magnetos.

I have owned 2 M20C's, the first one I converted to Slicks, my current one I won't. I saw no benefits to the Slick conversion.

I do agree that Slick does make it tempting, with very competetive pricing, good quality, and a simple process.

The Bendix magneto is very robust and simple. When things do break, or need to be inspected, most mechanics have the skills to follow the manual and repair the magneto. And the manual is available from TCM as a free download.

The problem is often finding a mechanic who is willing to open up your magneto rather than just take it off, send it out, and install an overhauled one - in which case the Slick is appealing (although I don't know how your location in South Africa would affect that).

I would compare the Bendix magneto to our hydraulic flaps. Normally, a reliable system that works extremely well. If you have a guy who is willing to work on it when it needs attention, you will never want anything else. If nobody wants to work on it, it can be a leaky mess and you'll be tempted to pay a lot of money to convert to electric flaps with no real benefit.

In both of those scenarios, my advice is to find an old-school mechanic who is willing to do the work. They are out there, and they're not all old.

[Guest]

Keep the Bendix magnetos, Slick/Champion magnetos have many quality issues.

Clarence

[BigTex]

Should of made this a poll..   My vote is to keep the Bendix Mags!

[bonal]

My guys at the MSC prefer the Bendix

[aaronk25]

Champion = no new innovation, same old problems.

Bendix is the best of the 1950 tractor magnetos.....and why are we using 1950s technology? ----but to answer your question do not get rid of your bendix mags.....

Where is Byron to share his experience with the brand new OEM slick mag?

[carusoam]

Byron must be in a place with no internet.

-a-

[jetdriven]

Sorry, I've been sweating it in the hangar removing the factory 1977 rotary cabin vents and building stuff to install 2005 Chevy Tahoe roof vents. It's like having a baby. You realize it's a lot more than you want to do but you're committed.

We pulled of the slicks and put on Bendix mags at 83 hours. Believe it or not, I sold the slicks for 850$ which paid for the Bendix mags. I was out the core cost (125$ on eBay), the cost of the harness (200$) and the time to install (my labor, 5 hours).

7 hours later one quit. Points stuck closed. Kelly strikes again. Adjusted the points and roll on.

The bendix mags have a slight improvement in LoP ops, they got a bit leaner before misfire. They also go the full 500hr between inspections without failure and the 500hr parts are cheap. No 250$ coils and 180$ condensers. This quickly turns into a 1000$ bill or 1500$ plus a ruined trip which I read about all too often.

Also far too often is the call from the magneto shop doing the 500hr, it's gonna be a grand for the repairs or 900$ for a new mag, times two.

I'm a big believer in old school big overbuilt magnetos that don't fail.

[rockydoc]

In the trade, Slick mags were always considered "throw away" mags.  When they needed repairs just "throw them away."  

Bendix mags are like that batter bunny.  i.e. they just keep going and going and going.

[jetdriven]

Here ya go. More airflow and easier to direct.

[Bruce Le Roux]

Thanks a bunch for the advice! I'll be keeping the bendix mags.

[Jim Peace]

I have slick mags on my O360-AID.  My left mag has 590 hours on it, original from engine overhaul and my right has 289 hours.  I don't have any issues.  I just bought the plane a few months ago and I am going to have an annual next month.  What would you do with he left mag if anything?

 

Planning on changing all 8 finewire plugs to new ones as well.  The ones in there now are very very old,,,,and no log entries as to when they were done.....previous owner said they were replaced as needed and all different ages....

[carusoam]

Are you considering....

- 500 hour service

- replacement

- Swapping for Bendix

- Electronic mag

- something else?

Tough choices...

Best regards,

-a-

[Jim Peace]

Are you considering....

- 500 hour service

- replacement

- Swapping for Bendix

- Electronic mag

- something else?

Tough choices...

Best regards,

-a-

I was thinking of 500 hour service or replacement

[rockydoc]

I was thinking of 500 hour service or replacement

Plan on the parts required for the 500 hour on the Slick being almost as much a new Bendix.   Bendix is a long term investment.  Slick repair is a band aid.

[ArtVandelay]

I have slick mags on my O360-AID.  My left mag has 590 hours on it, original from engine overhaul and my right has 289 hours.  I don't have any issues.  I just bought the plane a few months ago and I am going to have an annual next month.  What would you do with he left mag if anything?

 

 

I would inspect the left and be done with it, first annual since you bought it? I would save $ for other squawks that they find.

[ArtVandelay]

Plan on the parts required for the 500 hour on the Slick being almost as much a new Bendix.   Bendix is a long term investment.  Slick repair is a band aid.

What!?!  I just had both my slick mags inspected....$458....parts & labor.

[rockydoc]

What!?!  I just had both my slick mags inspected....$458....parts & labor.

You are one of the lucky few!

[ArtVandelay]

I think this is one of the myths that get passed down pilot to pilot, my slicks had about 1200 Hrs on them since last 500Hr.

 

Jim: let us know which way you went and if you go with 500Hr, how much.

[philiplane]

I have Bendix mags on my own planes. On the other hand, customer planes equipped with Slicks help pay my kid's college bills.... 

 

GO SLICKS!

[Jim Peace]

I think this is one of the myths that get passed down pilot to pilot, my slicks had about 1200 Hrs on them since last 500Hr.

 

Jim: let us know which way you went and if you go with 500Hr, how much.

Here is a dumb question. Can you have two different mags?

Can I replace the older one now with bendix and then later on do the other?

[Andy95W]

I think the Slick mags are installed by STC, so I would say doubtful that your mechanic would allow one of each. I wouldn't, but more because it's just kinda... odd.

If you were one of my customers, and you REALLY wanted to go back to the Bendix I would recommend either 1.) wait until engine overhaul, or 2.) do the 500 hr. inspection now on the older mag and replace both when your other mag gets to 500 hours.

I am a big fan of Bendix magnetos, but there really isn't anything wrong with the Slicks, it just isn't worth the money to switch to them. Once you have them, though, there's really nothing wrong with keeping them. Lots of people convert to Slick or got their engines brand new with them.

A 500 hr. inspection on your Slick mag should cost less than $300 unless internal damage is found. BTW, the cost to inspect the Bendix should be about the same. Buying a new Bendix mag is probably around $1500 each, or buying an overhauled Bendix probably about $600 + $200 core charge (since they won't want your Slick mag as a core).

[Bob_Belville]

Are Bendix an option for the IO360A1A on M20Es?

[Andy95W]

Yes, the engine originally came with Bendix magnetos.

[philiplane]

Slick has at least four Service Bulletins calling for inspections of mags and parts since 2006. These parts were failing at very low time in service. Dozens of mags I examined at or below the 250 hour threshold called out were within a few hours of failure due to problems with points, point cams worn out, rotors with loose tangs, distributor blocks with loose or worn out bushings, carbon brushes wearing out and snapping off, and partially stripped gears (due to the loose bushings). Several had already jumped a tooth and were out of time. Slick mags used on Continental IO-360ES engines  had several failures of the hold-down clamp area on the housing. This allows the mag to basically fall off the engine and lose most of the oil in the process. A trip around the pattern lost 5 of the 7 quarts in the pan. This housing failure was not an overload or improper maintenance procedure, it was a result of poor casting and a void or crack. The several I saw had less than 500 hours since new and were on brand new engines.

 

There are also problems with the coils, particularly in the output tab that the rotor's carbon brush rides on. Factory misalignment is quickly wearing out the tab, which mandates a $300 coil replacement. 

 

Slicks built before 2006 seem to be unaffected, but mags built or serviced after that date have questionable parts. I have seen no evidence that they have solved these QC problems yet. Champion bought Slick a few years ago, and they have been so wrapped up with the crappy spark plugs that they may not have solved the mag QC problems. Time will tell, we just need more people willing to be test pilots for Slick.

 

If you operate Slick mags you would be wise to do the 500 hour inspection at 250 hour intervals until you are satisfied that the problems are gone. 

 

Worst of all, Slick parts prices are high enough that you can easily spend $500 at each 500 hour inspection for points, condenser, distributor block and rotor and labor. Throw in a coil and you are at $800, per mag.