Catrike with Grin All Axle front hub motors

ecat

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Apr 8, 2009
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First: Full disclosure. I am a Grin dealer, and the Canadian distributor for Juiced Bikes.

This was the third repower of my 2007 Catrike Expedition. First came an Ecospeed mid drive with 20 ah 36V Ping batteries , it ran well for years until I needed to replace the batteries, and decided to upgrade to 48V. The old Ecospeed didn't really run run well at the higher voltage, (long story) so I eventually decided to try a hub motor. Next came a Crystalyte HS3540 paired with a Grinfinion 40 amp controller and 48V, 26 ah Panasonic 18650PF batteries. This combo worked well, and it was nice to be rid of the wine of the mid drive, but it did have a major flaw. After 15-20 minutes ride time the motor would hit 100 degrees C and go into thermal rollback, until the power level had stabilized at about 1000 watts. I had given it the Statorade treatment, but the motor was somewhat enclosed behind the seat, and with hard case panniers, maybe there was not enough air flow to cool it.
So I was casting around for a better solution and the idea of using the new Grin through axle hubs on the front came up. Justin was keen to see how the motors would work in this application, and offered to make up custom adapters for the trike if I bought the two motors. View attachment 1 So I removed the front spindles and sent them off to Grin, meanwhile removing the Crystalyte, purchasing a new rear wheel, and getting started on a new set of 72V 20 ah Samsung 25R batteries.
I had four 36V 10ah 25R batteries from Expedition that had not sold yet, so I decided to make use of them.
IMG_5805 (1024x768).jpg Two fit easily in the exsisting fiberglass boxes that I had fabricated for the last batteries, and I found some nice Hammond aluminum boxes that fit the other two. For these batteries I used a 72V BMS on each side, so there are two split packs.
IMG_5879 (950x713).jpg This was a pain two wire up, and is way too complicated, with wires running everywhere, but it works.
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View attachment 2
 
Lots of work, for a trike that could have been built simple and easy with one big rear motor.

I guess that you need and like to experiment. Yet I predict that you will build it again. :wink:
 
You are right, I do like to experiment... But I think the dual lightweight front hubs are better than one big bruiser on the back. Minimizing the extra weight on the back of a tad pays off in better handling, plus the front wheels are smaller, so better torque from the motors as well.
 
All respect for Grin, but that does not sound like a very good idea.
Those motors will produce steering forces, they will never pull 100,0% evenly.
Commercial tadpole trike needs more weight to the rear, it"s too front heavy without any motor.
I think they are something like 70/30 from the box. Rear wheel needs all grip it can get, that increases safety. My DIY velo is 35/65.
Still interesting project. Who knows really, might work just fine.
 
Here are the CAD drawings that Grin sent back
image (2) motor render 950.png
The plate attached to the hub motor axle sandwiches between the disc brake caliper and it's mounting plate. It acts as a torque arm, and retains the axle from sliding off the spindle.
image (3).png

And work in progress on the motor axle and attachment to the disc brake attachment plate on the trike. :D

View attachment 1

The new hub motor axle mounted on the trike spindle, with brake caliper included.

image 750.png

More to come...
 
"All respect for Grin, but that does not sound like a very good idea.
Those motors will produce steering forces, they will never pull 100,0% evenly.
Commercial tadpole trike needs more weight to the rear, it"s too front heavy without any motor.
I think they are something like 70/30 from the box. Rear wheel needs all grip it can get, that increases safety. My DIY velo is 35/65.
Still interesting project. Who knows really, might work just fine."

I had the same concerns, torque steer, stress on the headsets... The final product has put the concerns to rest, it is outstanding. No problems with the steering at all. I did have to adjust the torque on the headset bearings once, but the Catrike has always been finicky about getting the bearing pre-load just right. It even drives just fine on one front motor, you can hardly tell that one is switched off from the way it handles.
 
So what about the Ackerman effect?does one hub spin faster in sharp cornering since it has to go farther?do the tires scrub?also how does the regen do going around a curve on loose gravel?
 
Thanks for your question. There is no more scrubbing than with the rear hub. Each motor has its own controller, so it will run at a different speed without a problem. Regen works fine even on gravel. Traction is good even when climbing on gravel. It was actually worse with the mid drive. It will spin a front wheel on dry pavement when acellerating around a corner because of the way trikes unload the inside wheel.
 
OK ,so more pictures...

Grin sent back the spindles, and two sexy motors built into 20" rims, plus two PhaseRunner controllers.
IMG_5818 (1024x768).jpg

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The adapter acts as a torque are and keeps the motor from sliding off the spindle
IMG_5819 (1024x768).jpg

IMG_5823 (1024x768).jpg
The phase wires come out on the outside of the motor and loop back and through the hollow axle.
 

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Interesting application method.

I'm guessing your 2007 Cat has the metal bearings in the Headset. Hope so anyway.

Cats put a lot of caster in, my bet is under power its going to let your arms know with a gentle tug towards center when you put some throttle to it.

Nice anti-rotation plates.

Keep us posted.
 
I changed the top bearings for the plastic ones some years ago to try and get rid of its tendency to wobble. It did work. We shall see how they hold up.
There is not really any noticeable Torquing while applying power, unless one wheel looses traction, then it gives a good yank.
Overall it is very nice to ride, and the PhaseRunners have really nice smooth power delivery over the entire range of the throttle.
More to come...
 
Plastic bearings are sh*t. Not a good solution to your wobbling problem. Best is to use precise SS bearings and a good stiff headset. Then, wobbling also comes from anything loose or untrue. Perfect tire fit, on a perfectly trued wheel, on a straight stiff fork, in a stiff headset with good bearings.... don't wobble. If you still have a slight wobble at high speed after you set everything perfect, the next step would be fitting a steering damper. Of course, on a tadpole you have to take additionnal care of steering linkage and wheel alignment, caster, toe-in.
 
Just a thought...what was the name of those trikes that steered the rear wheel? You could mount this setup on one of them
And have a separate throttle in each hand.imagine the handling of that baby! Acceleration on one wheel and regen on the
Other? ...maybe a fat trike for off-road...possibilities?
 
Hangdog said:
Just a thought...what was the name of those trikes that steered the rear wheel? You could mount this setup on one of them
And have a separate throttle in each hand.imagine the handling of that baby! Acceleration on one wheel and regen on the
Other? ...maybe a fat trike for off-road...possibilities?
So who out there has the cajone's to be the first to build it? rollcage? Seat Belts?
 
Rear steering at high speed is suicidal. :mrgreen:

The best handling for a trike, is a FS leaning tadpole. :wink:
The worse, probably a drift delta tike. Speeding on that, you never know where and how you're gonna stop. :roll:
 
MadRhino said:
Rear steering at high speed is suicidal. :
Agreed...but for off road with fat tires,maybe 72v,40 amp...suspension fork on the rear...throttles for steering...
The thing would be a wild animal...I'm thinking somebody out there would give it a try :mrgreen:

I do foresee a steep learning curve to it though
 
Thanks MadRino, I will keep an eye on the headset bearings and maybe replace them. Does anyone have a recommendation for a steering damper for the Catrike?
 
On with the build...

I installed an aluminum plate behind the seat to mount the controllers, two of the batteries, DC-DC converter and assorted wiring. There were four bottle nuts in the large spine tube left over from the mid drive, so I mounted the plate to these.
IMG_5862 (1024x768).jpg
The two fiberglass boxes are visible under the seat, and two more Hammond aluminum project boxes will hang under the plate. So a total of four 36V 10ah packs configured into two 72 volt 10 ah, and paralleled at the shunt.
IMG_5865 (1024x768) (950x713).jpg
Dual PhaseRunners! The mounting plate acts as a heatsink for the controllers as well. Part of the reason that they are so small, is that they rely on an external heatsink for high power operation
View attachment 5
With the boxes mounted...
IMG_5868 (1024x768) (950x713).jpg
Big enough for 40 18650 25R
IMG_5869 (1024x768) (950x713).jpg
Battery and DC-DC converter installed
IMG_5918 (1024x768) (950x713).jpg
Lots of wiring for the dual controllers and lighting. I used a Grin CA shunt, and a Grin CA3 adapter to keep the full functionality of the CA3, while not plugging the CA3 into the controllers.
View attachment 1
For the phase wiring I used these new bullet connectors from Grin. From experience I know the trusty 45A Anderson's will not hold up the the Phaserunners. These connectors are very compact, but they are a real challenge to solder...
IMG_5997 (950x713).jpg

More to come...
 
Here is another installment of the front wheel drive Catrike build...
So with the batteries installed is was on to testing... It took some time on the phone with Grin to get the Phaserunners working 100% and not flashing error codes or warnings. Here are a couple pics of the settings:
satiator 1.jpg

View attachment 7

After about a week of ripping around testing, the wheels started to feel a little loose, and tightening the headsets did not cure it. Further examination revealed that both of the aluminum spindles had come loose on the headsets. So they were just floating around, and I could have lost a wheel... The aluminum spindles are press fit into the steel headset on the Catrike, and they may also have been epoxied. So the solution was to have my friend the machinist make a pair of steel spindles, that press fit in, then weld them for further insurance.
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View attachment 5

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While at the machinists I had him make up some covers for the phase wires where they exit the motor and loop back inside the spindle. The wires are very vulnerable to damage here, as this is the widest part of the trike.

Cap1.JPG
The cap has spots for recessed LED lights. We changed it from the rendering to have one central spot for three surface mount LEDs.
Cap2.JPG
This is the back side with a cut out for the phase wires.

So with the spindle issue fixed, on to another round of testing :D
The trike has exceeded my expectations for this build. It easily keeps up with local traffic at half power, and at full power it goes into warp drive, the acceleration is fantastic, and it just shoots up steep hills. The power is super controllable with the PhaseRunners working in Torque throttle mode. Is feels nice and smooth at low power, and the power comes on in a linear way across the throw of the throttle.
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Top speed is over 80 Km/h, which is too fast, 50-60 is just fine. I will have to do a timed 0-60 Km/h run, it seems to get there awfully fast.
 
ecat said:
While at the machinists I had him make up some covers for the phase wires where they exit the motor and loop back inside the spindle. The wires are very vulnerable to damage here, as this is the widest part of the trike.

View attachment 4
The cap has spots for recessed LED lights. We changed it from the rendering to have one central spot for three surface mount LEDs.
View attachment 3
This is the back side with a cut out for the phase wires.
Those are nifty--you might talk to Grin about selling them for you, to others using those motors. ;)
 
ecat said:
Top speed is over 80 Km/h, which is too fast, 50-60 is just fine. I will have to do a timed 0-60 Km/h run, it seems to get there awfully fast.

Nice project Dave! More power is hard to resist, hope you stay safe on that beast. Wish I had made it to ElectraFest.
 
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