Electric motor mount / frame

[MotWat]

Hi!

I've recently bought a go-kart chassis without a gas engine and mount. Now I'd like to find a good way to attach my electric motor (Golden Motor HPM3000) to it. I have a 90º metal bracket that I could use, but I'm not sure how exactly I could attach it to the chassis and whether it's a good plan at all. Any ideas?

 

[mckutzy]

Id work out how and where the batteries/controler and such are going then the motor...
It could always be positioned to the other side or above the bearings ect...

 

[itsid]

batteries under the steering column, motor where the engine belongs.. :thumbsuP:

that bracket is a tad too bulky IMHO.
nice and sturdy perhaps, but jeez what a monstrosity

there's a ready made mount for those type of motors for karts..
kit-elec-shop.com sells them (6mm steel)
nice actually... I think that's the easiest way
evea-kartmasters.fr has a very similar mount to offer.

both are not exactly lightweight though..

Anyways, IDK what machining tools you got access to,
and how easy it'd be for you to cut that chunk of steel into shape..

What I'd do is to find an old engine bracket for your rails
and use that as the base for your motor.
I'm not sure a face mount for the motor is needed..
I think a bracket might do nicely (and easier to fit the engine mount)
but if faceplate is due.. 5mm aluminium with one crossbrace welded in
(if it's the water cooled motor at the front to protect it from gravel,
else at the back to allow for better air flow.)
without a crossbracing you'll need to step up in size ..
the 6mm steel doesn't come from out of nowhere

If you insist on that old beast, I think flipped (the square on the rails)
and the prongs holding the motor
you'd need to spread them a bit to reach the outer boltholes I guess..
but should be doable and far less cutting would be needed plus you can have all four required fixations on the chassis, not just two or three

'sid

 

[MotWat]

Thanks, guys!

Yeah, I think it would make sense to put the motor where the old engine was. There should be more than enough space for all other elements, but I'm certainly going to make sure before I make/buy the frame.

I'm a bit confused about all those terms, Sid. What's the difference between a mount, bracket and faceplate? Also, how would I go about mounting the motor without a face mount, if the only screw holes available are the ones on the front of it?

I've researched the different frames provided by Elec and Evea, but unfortunately they don't seem to fit the mounting holes on my HPM3000 (like this one: https://www.kit-elec-shop.com/gb/mo...y-motors-for-kart-chassis-without-roller.html). I'll write them an email, maybe I've missed something. Also, €155.24 for a mount are hefty! I paid almost as much for the kart itself.

 

[itsid]

Well I think it's easiest if I explain it this way.. -excuse me dear bystander -

bracket - Klammer
faceplate - Stirnseitig

So a faceplate would mount to the front cap of the motor (where the shaft protrudes)
whereas the bracket is just that, a bracket ()[]{} ;
something like a sophisticated U-bolt that fixes the motor to a baseplate
(in my example above an off the shelf engine mounting plate)

And while terms like that are washed out in this language,
sind sie deutlich klarer begrenzt in dieser hier

Face mounted motors are always require more thought..
I think you can just strap it down and be fine, but
case wall thickness, cooling fins and the care that is required to not distort anything,
makes it a bit harder ..
hence me pointing you towards a professionally made motor mount for your motor and
designed to be used on race karts.

It cannot get easier than using those..
second best: copy that layout as closely as possible..
since yeah you're right, the motenergy doesn't fit.. but I was hoping the Agni would
(I checked.. they don't )
Sorry.. I was thinking the bolt hole circle was identical

Ah well then.. use the drawing, change it to your neds and have it plasma/laser cut
for you then... or if you can cut and drill yourself

Yes, they're not cheap,
(some evea look cheap imho.. and need an additional torque bar even... still pricey)
Anyhow, if you consider what your ordinary engine mount costs:
https://cometkartsales.com/Arrow-Complete-Engine-Mount.html
(just a random example of one)

the price is 'reasonable' ...
So that's why I said you should search for a used one matching your rail distance
if you can drop that to say 40 by buying old stuff, you can (even buying a faceplate for 40)
keep it well below 100€

'sid

 

[MotWat]

Ah, I think I get what you mean. Let my try to summarize my current understanding: a mount attaches to the rails, provides a base for a bracket or faceplate and looks like this:

A bracket holds a motor by holding it tight from the top and attaching itself to the mount. It could look something like this:

I was not able to find a bracket made specifically for go kart motors/engines. The closest I could find was this: https://www.qrckarts.com/products/engine-mount-ktm-250sxf-2015-1-2-and-up
...but that's still called a mount.

And finally, a faceplate attaches to the front of the motor (where the shaft is), and is itself attached to the mount. For example:

Have I understood you correctly?

If I have, wouldn't it make little sense to try to pin down my motor using a bracket? The way I understand it, the torque produced can be immense and therefore it would be very hard to attach my perfectly round motor tightly enough for it not to start slipping under the bracket. A faceplate with several screws sounds significantly more stable and secure.

 

[Josh42]

Would you mind giving us an update on what you settled on for a motor mount? I'm considering this engine, but want to plan everything out before pulling the trigger.

Also, what kind of motor/axle sprockets did you use? I'm having a **** of a time finding sprockets for the 20mm shaft bore with a 5mm key. And an even harder time finding axle sprockets to match the limited motor sprockets I've seen!

 

[EpsilonZero]

I'm having a **** of a time finding sprockets for the 20mm shaft bore with a 5mm key. And an even harder time finding axle sprockets to match the limited motor sprockets I've seen!

One of my karts has a 20mm shaft like that and my current plan is to throw it in the bin and replace it when something on it breaks because of the difficulty in finding parts that fit. My only other option was to make keyed sleeves to fit larger diameter bore parts...

 

[MotWat]

Would you mind giving us an update on what you settled on for a motor mount? I'm considering this engine, but want to plan everything out before pulling the trigger.

Also, what kind of motor/axle sprockets did you use? I'm having a **** of a time finding sprockets for the 20mm shaft bore with a 5mm key. And an even harder time finding axle sprockets to match the limited motor sprockets I've seen!

Hi Josh,

sorry to have kept you hanging. I've finished my project a while ago and I'm extremely happy with the result. The motor has a lot of power, at least when coupled with LiPo's that provide it with the necessary voltage. I'm considering making a video that shows the process that I went through when building the vehicle.

Until then - in case you haven't made your choice yet, or someone else arrives at this problem - here's how I managed to get a mount and sprocket that fit the HPM3000:

There are several mounts available on https://www.kit-elec-shop.com/gb/ and https://evea-kartmasters.fr/en/ You can ask them to provide you with a custom mount that will fit the HPM3000, or you can drill the plate yourself when you receive it. Just be aware that a stainless steel plate will be much harder to drill than normal steel.

However, these mounts can be quite expensive. In my case the price amounted to about half of what I've paid for the frame (wheels, axles, rear sprocket, chain, and all). Therefore, I've decided to build one myself. Being a novice engineer, it was a very difficult task that took probably almost as much time in the end as doing ALL the electrical work - so keep that time/cost payoff in mind.

Have a look at the attachments for the my final design.

It's far from perfect. You need to take off the motor to readjust the chain tension. And doing so is not particularly easy to do either. But it works very well for the most part. Unfortunately, when putting a lot of torque on the sprockets, the chain sometimes falls off. Not sure whether that's due to the mount, or the sprocket. Speaking of which...

Indeed, it's a PITA to find a sprocket that matches the motor's shaft. In the end, I found an offer on ebay that almost fully suited my needs. It's not available anymore, but I've added a screenshot of the title in the attachment.

Maybe you'll be able to find something based on those keywords.

Now, why do I say that it "almost" suited my needs? Notice that the title of those offers says "3/4 Bore". This means that the hole in the sprocket has a 3/4 inch diameter. That's 19.05 mm. And the HPM3000's shaft is 20 mm. Whoops!

Sure enough, the sprockets didn't fit straight out of the box. But I was able to enlarge the bore a little using a drill with a carving bit, similar to the first one on the left of the pic in the attachments. Surely there has to be a more elegant and precise solution, but I couldn't come up with one in the little time I had.

And that's how I got a fitting sprocket. As for the rear axle, you just need to make sure that it's for the same chain type as the sprocket (the one I bought is a 219, which is quite popular) and that it has the right number of teeth for you preferred gear ratio.

I hope this helps. Good luck!

 

[EpsilonZero]

Now, why do I say that it "almost" suited my needs? Notice that the title of those offers says "3/4 Bore". This means that the hole in the sprocket has a 3/4 inch diameter. That's 19.05 mm. And the HPM3000's shaft is 20 mm. Whoops!

I was considering one of those motors, too, but the incredible lack of sprockets turned me off. If you didn't get the expanded bore true, that could definitely be contributing to your chain popping off. Mine has never popped off. I'd still be interested in seeing what kind of power and speed you get from one of those, though. Maybe make a video?