MAC geared hub specs, teardown, and pics

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spinningmagnets
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MAC geared hub specs, teardown, and pics

Post by spinningmagnets » Jun 27, 2013 7:43 pm

The bare de-spoked MAC geared hub can be purchased from cell_man at em3ev.com for $250 + shipping. This link is for the bare motor, but he also has full kits with the hub laced to a wheel.
http://em3ev.com/store/index.php?route= ... ry&path=40

He stocks them in 5 kV's (RPMs per volt), listed speeds are at 36V in a 26-inch diameter tire, and 48V will provide a roughly 30% higher speed.

_6T - 45kph (28mph)
_7T - 42kph (26mph)
_8T – 39kph (24mph)
10T – 32kph (20mph)
12T – 25kph (15mph)

The original tear-down I did was to convert a MAC from a shell-drive to a shaft-drive. Be aware of that if you reference the original tear-down, some parts of that thread will not apply to a stock MAC hub-motor:

Part-1 https://endless-sphere.com/forums/viewto ... 50#p719603
Part-2 https://endless-sphere.com/forums/viewto ... 59#p735959

The threads on the axle are 14mm X 1.50, 35mm long. The cylindrical smooth un-recessed central portion of the axle (which rides on the bearings) is 17mm-diameter. Six screws hold on each of the two side plates, 12 total, chamfered neck, flush-head Phillips, 4mm-0.70, threaded portion is 5mm long

The disc brake flange is the common ISO standard. They are six holes in a circular pattern, BCD-44mm, 5mm X 0.80 (common M5), 7mm deep.

When you remove the flat side plate from the FW side, you can see an aluminum collar around the shaft, it is held onto the stator core by six round-head Phillips screws, thread is 4mm-0.70
MACprint.png
The official MAC blueprint for a rear motor.
MACprint.png (36.84 KiB) Viewed 8802 times
MACdimensions2small.jpg
Drawing is not to scale. Shape is approximate
MACdimensions2small.jpg (30.48 KiB) Viewed 8802 times
The six side-plate holes look like they are evenly and precisely spaced out in a pattern, but...their positions are NOT exact. It is best for each motor to be re-assembled exactly as it came apart. In order to make re-assembly fast and easy, I marked both side-plates with shallow drill-dimples.

First order of business is to remove the side plate screws (size 4mm-0.70, 6mm long threads), so I realized it would be much easier with a solid stand for the motor. The space between the 2 X 4 wood side walls (for the planet-gear protrusion on the non-freewheel side) is 4-3/4 inches square (120mm), and the central hole on the base-plate is 2-inches diameter. Base is 9-inches square.

I almost stripped the first side-plate Philips-head screw I tried to remove, so I dug out my "impact driver". You hit this tool with a hammer, and it will untwist the screw while at the same time it also pushes down to prevent the Phillips slots from stripping out. If these threads have thread-locker fluid on them, the impact driver will help quite a bit. The impact driver is one of the few cheap tools I bought at Harbor Freight.
MAC 003.JPG
Wooden stand with impact driver, whic can loosen screws without strippng the heads.
MAC 003.JPG (92.22 KiB) Viewed 8802 times
steel sun gear 27T
planet gear bearings 608Z, 8mm ID X 22mm OD X 7mm
Plastic planet gears, 54T
Steel ring gear, 135T

stator diameter (air gap) 5-5/16 inch / 135mm
Stator tooth width 22mm
large central bearing #6205, 25mm X 52mm X 15mm

36 stator teeth
32 magnets, 23mm wide, 14mm length following the rim

if you buy a MAC from cell_man at em3ev.com, he has begun purchasing MACs wholesale with thinner lams, so a NEW MAC (as of June 2013) can be used with higher volts/RPMs. The older version worked well up to 48V, new version should work well at up to 72V/2,000 motor-RPMs.
We now have a new and improved version of the MAC motor as well as the standard MAC motor. Our new version MAC now includes the same mods as before, both the upgraded phase wires and LM35 temp sensor, but now also includes an upgraded stator which offers improved efficiency and the ability to operate at higher speeds than were possible with the standard stator
https://endless-sphere.com/forums/viewto ... 13#p722108

There are several places I mention using a large, empty, and cleaned-out peanut butter jar in which to put the many clips, screws, and washers. They are plastic so they won't break when dropped, a smaller vitamin bottle will fit inside for tiny items you want to isolate, the lid will screw on so it won't pop off by accident, my hand will reach the bottom instead of pouring everything out to get one item, and its clear- so I can see the stored items. Besides all that, who doesn't like peanut butter?
MAC 002.JPG
Here is the motor, flat side down and the planet-gear side up.
MAC 002.JPG (125.24 KiB) Viewed 8802 times
MAC 001.JPG
Planet gear side down.
MAC 001.JPG (150.76 KiB) Viewed 8802 times
Last edited by spinningmagnets on Aug 12, 2013 11:44 am, edited 9 times in total.

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Re: MAC geared hub specs, teardown, and pics

Post by spinningmagnets » Jun 27, 2013 7:43 pm

Flip the motor onto its side, and gently tap on edge, while pushing with your thumb. Use a soft hammer to prevent a ding on the aluminum. Rotate the hub a few times and repeat.
001.JPG
tap edge
001.JPG (114.12 KiB) Viewed 8838 times
Once the flat side plate is off, the motor assembly lifts out easily with a little wiggle.
003.JPG
The motor is apart.
003.JPG (94.37 KiB) Viewed 8838 times
MAC9 004.JPG
Remove the circlip on top of the aluminum collar that attaches the shaft to the stator-core.
MAC9 004.JPG (102.53 KiB) Viewed 8813 times
Put foam between the stator-side and the wooden stand to protect the coil wires from scratches (that would cause a short), and set the motor down with the planet-gear side facing up. Do not lose the wavy spring-washer. Remove the circlip with the proper special pliers.
MACcirclip.png
Circlip and wavy washer.
003.JPG
A closeup of the circlip and spring washer,
003.JPG (79.5 KiB) Viewed 8838 times
Wiggle the clutch and planet-gear carrier. You can pull on it pretty hard to remove it. It may help to have a second person tap on it lightly with a hammer while you pull on it with both hands.
005.JPG
Lifting clutch.
005.JPG (110.36 KiB) Viewed 8838 times
Tap on the edge of the square shaft key with a chisel/screwdriver and hammer to loosen it. Pry it off with square-nosed pliers. Put ALL the small parts in a clean peanut butter jar IMMEDIATELY. They have a way of disappearing if you wait till later.
006.JPG
loosening the square shaft key
006.JPG (92.58 KiB) Viewed 8838 times
This is the order the parts are re-installed. Put all the small pieces in a clean peanut butter jar so you don't lose them. This key locks the planet-gear carrier to the axle-shaft, you will need to re-install it during re-assembly.
009.JPG
Small parts order.
009.JPG (91.49 KiB) Viewed 8838 times
If you want to replace damaged phase wires (or upgrade to larger phase wires), I found it difficult to remove the stock phase wires all at once. In this pic I am curling needle-nose pliers to pull on the bundle, and it is damaging the insulation. Spray some lubricant into the hollow axle (something like WD-40), and then pull out only ONE phase wire. After that the rest should be easy to remove. The phase wires should be removed first because the hall wire insulation is much more fragile.
021.JPG
Curling pliers.
021.JPG (122.19 KiB) Viewed 8838 times
If you have cut the stock phase wires, you can unbolt and remove the shaft from the stator-core. The next two pics are images of the normally hidden center section of the shaft. In this first pic, the phase wires protective sheath is still in place, but all the wires have been pulled out.
022.JPG
Shaft center1
022.JPG (64.76 KiB) Viewed 8838 times
023.JPG
Shaft center2
023.JPG (74.75 KiB) Viewed 8838 times
Last edited by spinningmagnets on Aug 12, 2013 11:40 am, edited 5 times in total.

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Re: MAC geared hub specs, teardown, and pics

Post by spinningmagnets » Jun 27, 2013 7:43 pm

The three things holding the stator-core and the magnet-bowl together are:
1) A tight friction fit between the magnetic bowl central bore and the large stator-core bearing.
2) The magnetic attraction between the rotor magnets and the steel stator laminations.
3) A large circlip located on the planet-gear side of the magnet bowl.

To separate the magnet bowl from the stator, first you must remove the large circlip, and immediately put it in the parts jar. In the pic below, the shaft has been removed, but that is not a requirement to separating the stator from the magnet-bowl.
026.JPG
Remove large circlip.
026.JPG (108.88 KiB) Viewed 8929 times
MACaxleNut.png
gear puller.
029.JPG
Separation.
029.JPG (82.21 KiB) Viewed 8929 times
031.JPG
Large spring washer.
031.JPG (134.79 KiB) Viewed 8929 times
Bafang3 012.JPG
stator tooth width.
Bafang3 012.JPG (143.4 KiB) Viewed 8929 times
Last edited by spinningmagnets on Jul 23, 2013 8:58 am, edited 1 time in total.

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Replacing a heat damaged Hall sensor on a MAC

Post by spinningmagnets » Jun 27, 2013 7:44 pm

Damaged Hall Sensor Replacement

Thanks to ES member Spicerack for posting these pictures and info.

Hub Motors can use a surprising amount of amps when on flat land, and doing that will dramatically improve acceleration. I mention flat land because in that situation, the motor is drawing the extra high amps for only a short time, and once the bike has attained its top speed...the cruise phase of the rider simply maintaining speed will use much less amps than when accelerating. This allows the motor to cool down some.

The problem when allowing extra high amps is when you encounter a situation where the motor draws extra high amps for an extended time (the controller will have a maximum allowed amps setting). One example would be on a very long and steep uphill. In that condition, it is very useful to have a temperature sensor inside the motor.

If your motors internal temperature continues climbing, at some point there will be damage to the internal components. Motors should be kept under 160F / 71C for a long life. and 200F / 93C is a commonly used max internal temperature to cut power. Somewhere above 200F / 93C, damage will begin occurring. A frequent failure point is one of the three Hall sensors. When this happens, the motor can be disassembled and the Hall sensors replaced. Even if only one Hall sensor is bad, I recommend replacing all three with authentic Honeywell SS41 sensors.

https://endless-sphere.com/forums/viewto ... 50#p512059

Image
_____________________________________________________

Hall Sensor Replacement thread by SkyknightJohn

"MAC hall replacement. Lotsa pics"
https://endless-sphere.com/forums/viewto ... 16&t=63771

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Re: MAC geared hub specs, teardown, and pics

Post by spinningmagnets » Jun 27, 2013 7:44 pm

Reserved for data and pics

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Re: MAC geared hub specs, teardown, and pics

Post by spinningmagnets » Jun 27, 2013 7:45 pm

Reserved for data and pics

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