MTL F7 Can Motor Upgrade

The MTL F7's are good pullers and run ok for the most part. But they suffer from poor power pickup, sound like a coffee grinder, and sometimes wobble side to side as they run down the track. I was able to address the power pickup and wobbling issues years ago by installing Glen's wheel wipers and following his tune-up advice. Now its time to get rid of that coffee grinder noise.


As said in the AM I Seeing Things Thread This is a work in progress and I am still testing
But here is what I have So Far

I've found several possible candidates for replacing the F7 motor but there are some tradeoffs.
While the 0716D - 12V Coreless Mini Motor is the easiest to install (No mods to the Chassis required) it dose reduce both the top speed and the number of cars that the F7 will pull. Its the one I used in the Video's posted in the other thread If your not planning to pull a lot of cars and just want to eliminate the Coffee Grinder noise this is the way to go. The best part its completely reversable If your not happy with the way it preforms you can just put everything back together the way it was.

The 0816D, 0816D18, 1015D, 1020D each offer a increasingly better RPM and pulling abilities, But each requires modifying the chassis making the installation a bit harder. And once the chassis has been modified it will be very difficult if not impossible to return it to its OEM stock configuration. Also with the 8mm and 10mm motors You will have to mill more of the chassis away either under the motor or up top on one end to make room for a decoder.
As I said above their are tradeoffs. Some times you have to give up a little in one aspect to get what you want in another.

Let's get started
for the 7mm motor install you are going to need to order
0716D - 12V Coreless Mini Motor with duel shafts
AD1015 - Brass adapters for worms and gears with OD 1.5 mm (40mm Length)
and 2 Worm gear M0.3 for 1.5mm shaft (brass)
from https://tramfabriek.nl/motors.html#!/~/
After removing the shell with the chassis laying on its side remove the screw from each end and gently separate the 2 halves. Both trucks will fall free as the halves come apart. Set them aside in a safe place keeping track of which truck came from which end. Next lift the motor straight up careful as the drive shafts will probably fall out as you do.


Note the wood block its laying on is a spring loaded jig I made many years ago to hold the trucks in place while reassembling.

Now gently grab the large black ring gear and pull the plastic bearing off the end next grab the worm gear and gently pull it and the shaft out of the large gear, now remove the larger inner bearing, and set it aside with the end bearing. The large Plastic gear and the worm gear shaft can go in the spare parts box along with the orignal motor.



If the new motor has wires attached your good to go if not solder some short wires to the tabs its much easier to do it now before it's assembled. Next put a light coating of liquid tape on the inside of the round cups where the large plastic gear was so the new motor power tabs can't short out against it.

Now cut the 1mm id to 1.5mm od adaptor shaft in half, be very careful not to crush, collapse, egg, or otherwise bend it in the process. now slip the 2 halves onto the motor shafts.
Lay the motor centered in the frame mark and cut the shafts off even with the end of the bearing journal boxes. Once cut off slip the longer mid bearing on each end followed by the end bearings (the alignment tab should be on the outer ends of the shaft). Place the motor back in the frame with the mid & end bearing tabs in their proper place. Once in place their should be almost no side to side movement of the motor shaft assembly but it need to spin freely in the bearings.
Once you have it all test fitted in place use a sharpie and mark the space between the bearing. Now lift the motor assembly out slip off the outer bearing cap and slide the new brass worm gears on centering them on the sharpy marks you made between the bearings. Put the end bearings back on and reassemble. The shaft adaptor and worm gears I got were nice snug fits and once assembled I did not need to use any glue to keep them from slipping.



If you are using one of the 8mm or 10 mm motors available from the same site you will have to grind away a small portion of the upper shell to make room for the larger diameter motor then assemble the adapter shafts and worm gears same as above.
Once reassembled a drop or two of hot glue between the motor and the frame will keep it from moving around in the chassis.


As you can see not much needs to be ground away for the larger motors. Just be careful and don't let the dermal slip as I did and take a chunk or 2 out of the bottom corners. WOOPS

For DC power i simply ran the wires out each side along the top ridge and connected them to the the chassis with a Ring terminal and the assembly screw. (You may need to scrape the paint coating off under the screw so it makes good contact


For DCC I drilled and tapped a screw to the bottom of each chassis half under the motor. and ran the Blue and white wires out the sides up along the ridge for the front light using a couple dabs of glue to hold them in place.

I have 4 F7's being tested one each with a 7mm, 8mm and 10mm motors. They each had maybe 6 or 8 hours runtime on them before the conversion. The 7mm had a good 4 hours run time before i installed a decoder in it. With the decoder it has another 3.5 hours run time as do the 8mm and 10mm DC versions. All were running just fine when i put them away.

As I said i'm still testing and I have one other designs that I'm working on. I fabricating a mounting box to hold the 8mm motor centered so the shafts are at the same location as orignal motor and using the existing Gears off the motor and factory reduction gear. While it seams to be working well maybe even increasing the pulling power a little it also increased the volume of coffee Grinder Noise.
This is the 4th test model I spoke of but it dose not have much runtime at all as i got busy with my daily job and packed them all away until I have time to work on them again.

When time permits I plan on adding flywheels. I had tried to drill out the center and use one of those offered by Tramfabriek but as I found out the hard way anything less than a 100% perfectly centered hole on a balanced wheel will cause vibration. Now that I have my own hobby lathe, trying to make my own flywheels is back on my to do list.


David

 

David,
You are the definitive master when it come to MTL F7’s. Always appreciate your willingness to share you knowledge as well.

I am one of those that has become partial to the coffee grinder noise coming from my MTL F7’s. But I am curious as to the loss of pulling power. I thought the coreless motors would have good or better power, but I guess not.

Me being one that wants to a lot of cars, how great is the loss or how many fewer cars can you pull?

Not necessarily testing anything myself yet, but if a standard, MTL’s F7 can pull 20 cars by itself with the factory motor, what can the coreless motor pull quantity wise?

 

Thanks for the compliments. Glen Chenier was the real F7 Guru, I learned a lot from him. He was a good friend and Mentor. I just wish I had, had more time to learn from him before he passed.

Robert please keep us posted on how those motors from China work out.

Lance That's a good question. While the new can motors are more efficient, The OEM 5 pole motor spins at a higher RPM and uses a 12 tooth gear on the motor to a 24 tooth ring gear giving it a 2 to 1 reduction which helps with the pulling power vs stall torque. I don't have the proper tools to measure the difference, so my plan is to put them on the track and keep adding cars until one of them stalls or the wheels start slipping.
Unfortunately my 270mm test loop is too small to hold that many cars. So testing for that is on hold until the next time we setup our modular layout.

David

 

I’m going to have to give this a try. I have a few MTL F7s that I would run more if they ran well. One issue the MTL F7 suffers from is that the stock motor, because it is so wide, bows the sides of the locomotive outwards. I also need to install the window glazing in most of them.

Here is a comparison of MTL SP #6325, and AZL SP #6325.

 

Wow!

Almost looks like two different scales, lol!

 

How much does removing the barrel gears change the gear ratio?

 

Thank you David, you put a lot of time and effort into this and it is appreciated!

Robert, I hadn't seen your F7s before, love the see through fans!

Steve W

 

I'm always impressed with your work the details always pop out at you! You have made them look much more better than they were!

 

Well, I got one F7 converted to a 7mm motor, and it is quieter. I never have really had the magic touch to get these things put back together and running well. There seems to be a magic point in the screw tension where if it is too loose, it is loud, then there is a very small window where it it's just right, and a little bit more and it is over tight compressing the bushing onto the shaft so the motor wont turn. So it took me multiple tries taking it apart and putting it back together to get it to where it was running well.

Now that little jig that David shows looks rally useful in getting the trucks align and not getting the wipers in the wrong spot, so I wanted one! And I have a kid, so I have bins full of Legos sitting around which seemed like the perfect thing to use for this. I made myself a Lego Jig for assembling the MTL chassis and it worked pretty well. The spring tension is provided by the tension of the axel rods through the "+" shaped hole bricks. And it really does help get the F7 back together. Another neat feature I stumbled upon was the 1x2 grille tiles in the center, the chassis nub that hold the shell on drops right into the grove and prevents side to side movement.



If anyone wants to build their own, I designed an ideal version in Bricklink Studio which allows the export of step by step instructions with a parts list. If you don't have Legos all over your floor, every part listed should be available direct from Lego pick-a-brick, and you may choose any color you want.

PDF instructions are attached.

-Matt

 

Matt,
Nice use of found objects! I like the instrument displays and black and yellow strip, makes it look official.

Scott

 

Great work on the Lego Jig. I love the little control panel pieces with the clock above them, that and the black & yellow striped block make it look like a official repair /test facility. It defiantly looks a lot better than the scraps of wood and brass I through together to make mine 10 + years ago.

OH and don't feel bad about not getting that magic point where the assembly screw tension is just right the first try. I have probably reassembled 60 or 70 F7's and I still have to go back and re-adjust those screws more often than not.