Rear disc conversion for Motorino/Davinci/Daymak e-scooter

[OCD]

Thanks for looking:
I've got a Davinci ebike/scooter that I converted to an 84v lithium pack with an 80 amp controller. The Davinci looks like a Motorino but I'm hoping I can buy a new side cover for the hub motor to put a disc on it. There does not appear to be any name, number, etc on the motor other than the Davinci logo. Does anyone recognize it or know of a reasonable solution? The front discs are amazing but can be problematic without a good rear brake on slippery, wet ashphalt in an emergent situation.

 

[amberwolf]

The front discs are amazing but can be problematic without a good rear brake on slippery, wet ashphalt in an emergent situation.

Does the drum brake not work? If it's just weak it might either need use to bed the pads in or just need new pads.

If I could find another freewheel side cover it may able to replace the drum brake side cover, then a spin on adapter would work.

Are you using the pedals? If not you could flip the motor in the dropouts, and remove the existing freewheel to replace with that adapter.

AFAICT, if you *could* put a freewheel cover on the drum side instead of the drum cover, it would be pretty far inboard of the swingarm, and any caliper mount you put on the swingarm would need to be spaced inward quite a bit to reach the rotor....or the rotor would require a lot of spacers and some very long rotor bolts to secure it to the adapter.

 

[Dui ni shuo de dui]

Thanks for looking:
I've got a Davinci ebike/scooter that I converted to an 84v lithium pack with an 80 amp controller. The Davinci looks like a Motorino but I'm hoping I can buy a new side cover for the hub motor to put a disc on it. There does not appear to be any name, number, etc on the motor other than the Davinci logo. Does anyone recognize it or know of a reasonable solution? The front discs are amazing but can be problematic without a good rear brake on slippery, wet ashphalt in an emergent situation.

View attachment 348974

Hi!
First of all, I'd like to say for the record that rear brakes are for the weak.

Now that it's been said, it is actually possible to replace the old drum system with a disk even though the motor doesn't originally provide attachment points.
In order to do that, you need to find or build this kind of kit:


First, you need to remove the motor from the swingarm, then remove all the drum brake system.
Then you insert the part that's on the right side of the picture inside the spot where the drum brake mechanism used to be. Secure it in place with the little square shaped part so it gets tightened firmly to the motor.

Then you can just bolt the disk to it.
The hard part might be to find this kit wherever you live, hopefully it is possible for you.

Then You'll have to find a way to secure the brake caliper, but that shouldn't be too difficult.
You'll also need to change the cable lever to a hydraulic brake pump and run a brake hose from the pump to the caliper, then add brake fluid and purge the air.

I did it recently on a friend's scooter, it wasn't as difficult as it might sound.

 

[OCD Garage]

Good point Amberwolf, that would likely work, I can make/weld whatever caliper mount would be needed. Of course getting caught riding without the pedals would be a large fine where I live. The kit shown above would be ideal (if I can find it).

 

[OCD]

Found the answer after some searching on AliExpress as per Dui ni shuo de dui above. Appears to be a bolt on solution that expands to grip the inside of the drum surface, the store sells all the adapters/discs/calipers/master cylinders/hoses you'll need. I'll post up once I have the parts in my hands:
https://www.aliexpress.com/item/32808961901.html?spm=a2g0o.cart.0.0.329c38daoKEcb3&mp=1
Adapter link here.

 

[OCD Garage]

Parts arrived fairly quickly, have installed drum to disc adapter, disc and caliper mount. Not a made to measure solution after the disc is installed but was only a matter of finding the right combination of spacers to finish the install. I will post up once everything is working. Looks kick-a** though, now have a larger disc on the rear than the front end.

 

[OCD]

Here's a pic of the finished installation on my Davinci scooter. The pieces bolted together easily using the old drum spacer + a few washers to get the rotor centered. I was able to use the old brake brace by rotating the rotor to suit. The rear fender can likely be heated and reshaped to clear the disc when dropped into it's normal position. To complete the installation, I also ordered a pair of universal master cylinders/levers. but didn't know the thead size (10mm x 1.25mm) at order time. I'm short one banjo bolt before I can bleed and road test the rear brake. The rear caliper uses a 10mm x 1.0mm banjo bolt which was included in the bag of installation hardware. One of the new levers/master cylinders is now connected to the old system, bled and works as it should. The whole conversion with both levers/master cylinders, 200mm hose, rotor conversion mount and rotor/spacer/caliper kit was $220cdn + another $10 for the banjo bolt/brake light switch I still need. The scooter will feel a lot safer in the rain and loose conditions instead of having to rely 90% on the front system. In the dry with 84v on tap the increased safety will be appreciated.

 

[harrisonpatm]

I do apologize, but I've used that caliper before and it basically didn't work. Have you gotten yours to work well enough yet? You mentioned that you are still waiting on a banjo bolt before you can properly bleed and test the rear brake, so I hope your experience is better than mine.

But over a year, I basically had weak braking, uneven piston movement, and leaking threads. The paint job cracked off after a few months and the brake pads basically were disentegrated when I got sick of it and removed the whole thing. I hope it goes better for you, but judging by the rust accumulation on the bottom of your rear shock above the calipers, you live in an equally wet area as I do and might expect the same deterioration of the pads. Keep us posted, it's fully possible that everything that went wrong with my calipers was my fault and had nothing to do with the product.

 

[OCD]

Time will tell, things from Aliexpress aren't always bad, sorry to hear your experience was. Fingers crossed, can't be worse than the stock drum which wasn't adequate at 30kmh, never mind 50kmh+. I had no trouble squaring it up and centering the caliper, we'll see in a few days when I get the parts.

 

[Dui ni shuo de dui]

instead of having to rely 90% on the front system.

Having to rely mostly on the front brake is good practice on a 2 wheeler, usually around 70/30. It is very easy to fall under wet conditions using the rear brake so be careful.

But over a year, I basically had weak braking, uneven piston movement, and leaking threads. The paint job cracked off after a few months and the brake pads basically were disentegrated when I got sick of it and removed the whole thing. I hope it goes better for you, but judging by the rust accumulation on the bottom of your rear shock above the calipers, you live in an equally wet area as I do and might expect the same deterioration of the pads. Keep us posted, it's fully possible that everything that went wrong with my calipers was my fault and had nothing to do with the product.

RPM is a pretty decent chinesium brand, I owned a few of their products and honestly the quality is good.
The symptoms you describe sound more like something was wrong with the way it got installed, my guess would be a bleeding issue.
Paint damage usually comes from not cleaning the brake fluid, which is extremely corrosive and tends to ruin any paint it touches.

 

[harrisonpatm]

Having to rely mostly on the front brake is good practice on a 2 wheeler, usually around 70/30. It is very easy to fall under wet conditions using the rear brake so be careful.

RPM is a pretty decent chinesium brand, I owned a few of their products and honestly the quality is good.
The symptoms you describe sound more like something was wrong with the way it got installed, my guess would be a bleeding issue.
Paint damage usually comes from not cleaning the brake fluid, which is extremely corrosive and tends to ruin any paint it touches.

Entirely possible, i'm no expert at hydraulics and disc brakes. That was 2.5 years ago, I've learned more since then. Besides, I also agree with your first comment in this thread:

First of all, I'd like to say for the record that rear brakes are for the weak.

I have regen for my rear brake, and I wanted to add that rear disc brake for, what I thought at the time, added safety. Then I went 2 straight years without touching that disc brake, including some emergency stops. Because as you point out, braking force is almost entirely front wheel anyway.

Fyi, anybody reading this, the takeaway is not "random internet stranger says I don't need rear brakes!" Please do not listen to me

 

[OCD]

Feel free to use only your front brake on wet, gritty roads in an emergency situation. Without adequate rear brake support you'll find yourself on the pavement staring up at some BMW owner in a roundabout coz he figures 'all cars go first', don't ask me how I know...

 

[harrisonpatm]

Feel free to use only your front brake on wet, gritty roads in an emergency situation. Without adequate rear brake support you'll find yourself on the pavement staring up at some BMW owner in a roundabout coz he figures 'all cars go first', don't ask me how I know...

Like I said, I'm not suggesting that anybody follow my example. I'm just saying that rear regen brake and front drum brake is what I do, and it works for me. So far. Knock on wood...anyway I'm improving and using better brakes all around on my next build.

 

[amberwolf]

If the regen rear brake is sufficient force under those conditions to cause the wheel to skid, then it's certainly enough of a brake for those conditions, for the specific vehicle, since you can't get more braking after the skid starts. At that point it's all up to friction between tire and riding surface.

 

[Dui ni shuo de dui]

Feel free to use only your front brake on wet, gritty roads in an emergency situation. Without adequate rear brake support you'll find yourself on the pavement staring up at some BMW owner in a roundabout coz he figures 'all cars go first', don't ask me how I know...

Hehe, I don't think anyone is saying this, but I just wanted to point out the fact that you now have a 220mm disc with a fixed 4 piston caliper at the rear while, meanwhile you have what seems to be a 180 or 200mm mm disc with a floating 2 piston caliper at the front.
I guess I'm trying to say maybe it's time to upgrade the front brake as well

Also, you'd be surprised at how many people think they should apply more brake at the rear than the front. Here in China pretty much every driver never touch the front brake. I see people falling on the ground when emergency braking on the wet almost once a month. That's why I mentioned it

Anyway, enjoy your new brake, it looks great!

Oh and one more thing: make sure the valve cannot hit the caliper. When the wheel turns at full speed, the centrifugal forces can pull the valve towards the caliper. When both come into contact the valve can be damaged or worse, it can be ripped away. It happened to me once, I was riding at around 100km/h, the valve hit the caliper and got cut off, so I lost the tire pressure instantly. Luckily i was able to coast without any problem, but it was not the most pleasant experience.

 

[OCD]

Everything is connected and fully bled now. A total difference from the old drum brake which could barely be noticed when used alone. Now, the rear brake is stong enough to lock up the back wheel at most any speed if desired. A new support was fabbed for the reshaped fender and welded in under the new caliper line, followed by a few shots of black paint to help things blend together. I'm currently awaiting the arrival of a set of 90/90-10 tires which should push the wet/dry performance up another notch. I highly recommend the conversion if you hate your anemic rear drum brake.