My next chuff project

If the engine has the factory K-Line cruise. You can upgrade to a selectable chuff without using magnets and a reed switch. I performed the mod to a couple of Berkshires and a Pacific. It involves just moving some of the factory wires around. Not sure on how your planning to do this. I have the instructions somewhere.

Dave.  Yes it is K-Line cruise.  Let me know how you did it when you get time.  Thanks.

Dave, I'd be interested in those instructions as well.  Maybe you could consider posting them in the documentation thread in TMCC/Legacy?

Dave, I mistakenly stated that my loco is K-line cruise.  It has the TMCC electronics but not cruise. I worked on my K4 today.  The cherry switch is mounted under the motor and not easily accessed.  Nonetheless, I disconnected the 2 wires and installed the magnets on a front driver.  I must have been a little rough on the reed switch.  It was working when I was testing the magnet placement but when I was making final prep to install, it broke.  So I will order a couple more and finish it down the road.  

The reed switches are VERY fragile, you need to be pretty gentle manipulating them, especially the leads after you glue them down.

I buy mine from Digikey and wire them myself, ends up costing a few cents more than the price of the reed switch.

I followed your recommendation John and have ordered a few more.  I need to order more magnets as well so I can upgrade my Lionel M1a.  

I order the magnets in bunches, they're very cheap, about 10-15 cents each.

My first 4 chuff loco was an MTH scale PRR Decapod retrofitted with TMCC and ERR and 4 chuffs per rev.  It is sweet.  That made my other locos sound just OK.  The consolidation (same diameter wheels as the Decapod) with just one chuff per rev. was really off for my ears. Compared to the consolidation, the drivers on the K4 are quite impressive.  Originally operating with 2 chuffs it was just OK and I could live with it, but the distance the loco traveled between chuffs bugged me.  There are 4 small dark circles on the inside face of the driver rim that make spacing the magnets fool proof. 

I received new reed switches today and installed one on my K4.  It really sounds good to me.  When I get my next batch of magnets I will modify my M1a. 

Nice that they marked the spots for you.

Yes, that was fortunate!  Thanks for your help.

Did you take any pictures of the install?

The short answer is no.  I can take some later that show the magnets and position of the reed switch.  I will not be able to photo the location of the cherry switch.  It was deep back under the motor, and attached to the left side of the frame (upright position).  I did not remove the motor just to cut the wires to the switch.  It was a little challenging to fish those disconnected wires out so I could attach leads and fish them back inside to an appropriate place near a driver.  I used heat shrink around the wires. 

Sorry to go on but a photo later might help explain why I had to glue a shim to the underside of the frame next to the driver.  The edge of the frame by each driver has a thin raised contour.  It's so thin that there is too little surface to glue the reed switch without adding an adjacent shim. 

If you are you considering a 4 chuff modification, there are a ton of posts about DYI from the experts.  The more I read the more comfortable I got about trying.  I have been posting chuff questions for years!    

There are many different solutions to the issue, and as stated, it really depends on exactly what the locomotive driving gear and frame look like.  Some are easy, some are a bit of a PITA.

Well, bad news-good news. Briefly, a couple of times on certain curves the front truck wheels or frame hung up on the wires leading to the reed switch today, causing the truck to derail, short and burn a fuse.  I had checked the travel of the truck several times before but the truck obviously travels and swings out more than I thought.  (I have 072 curves)

So, I relocated the wires leading to the reed switch and while I was inside I tried a few photos.  They are just fair but I used a red pencil to point to a few things.  Oh, and the good news is that it's back on track and all works well.

Into each life a little rain must fall.   Good thing it was a minor issue.

Today I received the magnets for my last 4 chuff project for my PRR M1a.  Opening up the loco, the cherry switch was easily identified and wires disconnected.  Ample leads from those wires to the reed switch were connected and fished toward the front of the loco.  The M1a drivers did not have convenient markings 90 degrees off to evenly space the magnets but it was a minor inconvenience.  It was a relatively easy install and now the loco sounds great chuffing along the layout.  My M1a was my first 3 rail scale loco and it is my smoothest runner.