Mac 8T Kit Motor Change

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GarySevan   1 µW

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Mac 8T Kit Motor Change

Post by GarySevan » Jul 31 2019 7:38pm

Hello to all,

Being new to e-bikes in general I took the liberty of registering an Endless Sphere Account in the hope of securing an insight or two from one or two of the knowledgeable denizens here regarding a matter of a hub motor switch-over.

And to wit...

I recently managed to secure a used Mac 8T kit at a bargain basement price. Functional, but not perfect. The hub itself needing either repair or replacement. A worn out clutch it would seem. Among some other issues. ( A grinding noise or two on occasion for one. ) The components otherwise are all good. The throttle, the cruise control/on-off unit, 3-Speed switch, controller ( Infineon: 48 Volt / 500 Watt / 6 FET 3077 ).

My idea being to purchase a new hub from BMSBattery.

[ Bafang BPM 48V500W Rear Driving EBike Hub Motor ]

Seen here...

https://bmsbattery.com/motor/351-15707- ... 14-rpm-328

The phase and Hall connectors seemingly a match. Just a need of color to color alignment.

But is my thinking right? Or am I courting potential disaster here?

Frying the new hub in part or whole or the existing controller or some such?

Or will it work? Resulting in a fully functioning kit. ( To the limits of the new hub. )

Thanks kindly for any/all assistance in this matter.

All the best to all,

Sevan
Last edited by GarySevan on Jul 31 2019 11:36pm, edited 1 time in total.

flat tire   1 MW

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Re: Mac 8T Kit Motor Change

Post by flat tire » Jul 31 2019 7:50pm

That should work fine BUT the phases / halls may not match even if you connect the right colors so you may need to try a few combinations. There is a really good flow chart for doing this that I can't seem to find at the moment. Maybe someone else can pull it up.

Also, that motor does not have a rim or spokes so you will need to lace it yourself. I'd recommend just buying a complete wheel unless you have experience lacing and know it won't be an issue. Probably for similar money since that thing's a little overpriced.
Last edited by flat tire on Jul 31 2019 8:09pm, edited 2 times in total.

markz   100 GW

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Re: Mac 8T Kit Motor Change

Post by markz » Jul 31 2019 8:06pm

Grinding noise is probably some broken gears inside the MAC motor.
Its worth opening up the motor and having a look inside. Look at the gears and wiring. The gears can be purchased separately.

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amberwolf   100 GW

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Re: Mac 8T Kit Motor Change

Post by amberwolf » Jul 31 2019 8:29pm

If you open the MAC, you can then check with EM3EV to get a new clutch and gears to replace with a compatible version, and then use the kit as-is, fixed right up.

If you replace the MAC with a different motor, you'll need new spokes that are the right length to put the new motor into the old wheel (or into whatever rim you choose to use).

Plus, BMSbattery has been known to send whatever they feel like rather than what you actually ordered--so if you need a specific motor winding, etc., you may not actually get that, just whatever they had on the shelf, etc.

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neptronix   100 GW

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Re: Mac 8T Kit Motor Change

Post by neptronix » Aug 01 2019 12:36am

I'd pull the motor apart and fix it. The MAC is a better motor than the BPM, and it would be cheaper to fix it.

Trust me, you won't regret fixing the MAC. It's my second favorite motor of all time, and i've almost been building things for a decade now.

That 8T MAC will take about 40 amps peak pretty easily; it can go like hell! there's room to throw a bigger controller at it and extract more power. It really is worth investing in.

Here is the maximum power a MAC can output. The motor has a crazy power to weight ratio.

Efficiency is everything :bolt:

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

ScooterMan101   1 MW

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Re: Mac 8T Kit Motor Change

Post by ScooterMan101 » Aug 01 2019 12:48am

Fix the Mac,

While you change the clutch and gears ( cheep enough ) also replace the 3 are they called Hall Sensors ? What ever the Phase wires are soldered to.
That is a common area of failure on the older Mac's .
( I paid someone a little under $ 100 to replace mine and replace the 3 phase wires with thicker / bigger awg wires . , after that the Mac would handle 40 amps easily.

Plus , Em3ev is 10-20 times better to deal with than BMS , I do not know if I will ever buy from BMS again, probably not. I will not go into details.
My first conversion ... Sold

viewtopic.php?f=3&t=71378&p=1077497&hil ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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dogman dan   100 GW

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Re: Mac 8T Kit Motor Change

Post by dogman dan » Aug 01 2019 9:39am

FWIW, lots of folks call it a grinding noise, when a motor stutters. Stutter could be as simple as getting a better connection on motor wires, the fat ones or the slim.

I'd open that motor and look at that clutch, before I call it a clutch issue and buy a new motor.

It could also be something as simple as the keyway on the axle, connecting the clutch to the motor. That's a one buck part.

GarySevan   1 µW

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Re: Mac 8T Kit Motor Change

Post by GarySevan » Aug 01 2019 10:06am

Thank you to all.

The collective input is greatly appreciated. The advice. The insights. The experience.

Obviously, a great deal I neglected to give any thought to. Much to consider. Inclusive of the warnings regarding doing business with BMSBattery.

And, so, I will attempt the repair. Contacting EM3ev for parts and advice and otherwise continuing to reference this forum's vast and truly indispensable database and YouTube additionally. As having no personal experience with such repair I will definitely need the guidance. And likely a few new tools and such.

:-)

Thanking you all once again for taking the time to respond to my appeal for assistance.

Kind regards,

Sevan

ScooterMan101   1 MW

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Re: Mac 8T Kit Motor Change

Post by ScooterMan101 » Aug 02 2019 1:12am

Watch your fingers , be careful when taking apart and putting back together a hub motor. the Magnets are powerful and will draw the center down into the case fast.
Also
Depending on where you live there could be someone close by that can do repairs for you.
there is a youtube video made by Doctor Bass / DoctorBass who lives in Eastern Canada a few years old now but still current info , he did this on
a different motor but the video will have some good points about motor repair.

Let us know if you see any melted solder in the motor after taking the cover / covers off.

Look for that before ordering a clutch or gears , although they are so cheep that it could be a good idea to replace them anyway.
My first conversion ... Sold

viewtopic.php?f=3&t=71378&p=1077497&hil ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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