I want to go faster.

Moderators: robnewyork, bassiclyLouDog, gameboy

#6244
My next door neighbor and I modded a pair of Razor Ground Force go karts with the idea that we would be able to ride them with our kids (they would get stock ones). We got our inspiration from dmack's post here:http://forum.modifiedelectricscooters.com/viewtopic.php?f=10&t=1014.

That's what we told our wives, anyway....BTW, our kids are only 2.5 & 3.5 years old. So, they won't be driving anytime soon. With the project cost justification taken care of, we bought Currie 36v 1000watt motors (http://tncscooters.com/index.php?route= ... uct_id=512)and 60volts, using 24v-60v speed controllers (http://tncscooters.com/index.php?route= ... uct_id=188). We got our inspiration from dmack's post here:http://forum.modifiedelectricscooters.com/viewtopic.php?f=10&t=1014. It was pretty simple to do with a just a little cutting and drilling and wiring, voila! Done.

Here's a quick and dirty temporary set up with the controller, (5) 12v7Ah batteries & motor strapped to the Kart:
Image
We plan on cleaning it up a little. My neighbor welded a battery tray and plans to weld a bracket on to vertically mount the controller. We cut the motor/battery cover for use a chain guard so that little kids don't get their fingers caught.

Here's some crappy video of our first test ride after zip-tying every thing together. It's around midnight at the college near our houses. It seems like the only time we get to ride these things is at night after the kids go to bed:)
I'll try and post some better daytime pics/video later.


At 60v, these little go karts have some killer torque off the line. It will leave a 20+ft long black strip and actually leave smoke the tires! It will even pop the front wheels off the ground momentarily. They are a blast to rip around a parking lot doing slalom runs between concrete planters etc. Hell, we can even do a small, one revolution doughnut. The best thing about them is that we can easily pick them up and stick them in the trunks of our cars and head to a school yard or an empty parking lot.

The only problem is that the top end speed is a bit lacking at only 19.5-20 mph(gps) We are using the 11 tooth sprocket that came with the motor and the 32 tooth sprocket and the 4.5" wheels that came with the Kart.

We have 14 & 15 sprockets for the motor on order along with chain links and a chain tool. That should get us to maybe 23-25 mph.


We want to put larger diameter wheels and tires to get us a little more top-end speed and make better use of the available torque. Does anyone know of any other wheels that we can fit on these little Karts? I'd love to get a 6-7" wheel/tire set up on them.
#6265
this is flippin' sweet! and video to boot! i love it!
i've tried this controller. it made my motor smoke. looks like you're having fun with it. I remember the noise it was loud. I made my dirt bike shoot to life though. on 48v it was a killer.

wish I knew how to help you out, but i have no kart experience. sounds like you guys know how to weld so i'm sure you can fab up something.

p.s.
watch that throttle! how did you rig it to the steering handles?
#6333
I'm building a similar setup but I have two razor ground force drifters. If you're leaving rubber on the road I wonder how dangerous my PVC wheels will be with that much TQ.

I bought my son the drift razor in order to teach him car control and how to counter steer. Hopefully he enjoys driving it. I'm using this as a steeping stone to Shifter karts. A stock razor should be a safe way to start teaching him (6 years old).

The razor my wife and I will drive has custom side mounted battery trays, extended steering wheel, 4x12v 12ah batteries, 36v 750 watt motor and 46v controller and a throttle. I'll try to get pictures up tonight.

No videos yet, everything is ready except I'm waiting or the controller to show up.

I'm a little scared after seeing your Kart take off. My wheels should spin for years and I should have no issues swinging the rear out at 15 mph :mrgreen:
#6468
looking for replacement wheeels too, ill likely just machine store bought wheels to fit the hub and keyways.. pain in the butt not having ready to go wheels..awesome kart!!!!!!!!!!!!!!!!! most impressive modded razor ive seen.. im currently doin a 2 motor drifter, with all the stock electronics for both systems.. only throttles will be linked , and perhaps chargers but 2 sepererate controllers and motors.. NEED TO FIND A REAR SPROCKET , THEY NO LONGER SELL EM , JUST THE MOTOR SPROCKET!! quite annoying
#6477
Awesome build! This thread is relevant to my interests :)

I'm looking to do something to speed up my son's ground force. He weighs only 55 lbs or so, so I'm not looking for 60V. Also probably going to do this in stages, versus going all out at first. Eventually will probably swap out the motor, the speed control, the throttle etc. But thinking of starting with the batteries first. One thing that sucks about the go-kart is it takes forever to charge with the stock charger. Also, the SLA batteries are too heavy, and given that I'm a huge fan of LiPO in the RC world I think it might be cool to go that route.

What do you guys think about two of these in series:

http://www.hobbyking.com/hobbyking/stor ... P_30C.html

I've used Turnigy batteries, they are okay for the money, but I have yet to try the Zippy's. I'm having trouble finding higher mah batteries to compete with the 7AH that come stock, save for these Zippy batteries. Anyone had any experience with this brand? Good, bad, indifferent? They also make an 8400 mah LiFePO, but they're a bit more money. Still, might be tempted to go that route for the increased safety.

On to the next questions: 8s lipo would put us at just under 30V nominal, 33.6V at peak. Will the stock controller handle this much voltage? Will the stock motor?

Also, if you all do find an alternate source for wheels, please let me know!
#6497
I machined my own spacers for the drifter to fit the current white rimmed 10 inch harbor frieght wheels ( 5.99 each) i have the front mounted and it rode great..now gettting the rear done this week to quiet the ride and also smooth it out dramatically. With machine tools ive seen one youtube video were they made a short term solutions with cutting out the rear wheel hub and jb welding it inside a tractor supply 8 incher..my issue is now torque and the loss of gear reduction w taller wheels so ik adding
#6498
A second motor, controller etc, all stock just a second set.. ill run both motors onto the stock chain, use the one tensioner, already have 2 chargers and 2 throttles, and wont need duplicate items like brake assemblys etc..im trying to keep it dependable for grocery runs and causing havoc so overvolting and shorter ride times is less appealing..if the torque still lacks with 2 motors ill change the axle sprocket to 72 tooth to bring back a normal gear ratio.
By Rayj310
#6524
I just built 2 Razor Ground Force Drifters with 750W Currie motors, Kelly 100 Amp controller, 2 12v 10Ah batteries and I through in a reverse polarity switch because he really wanted reverse. On one of them I added a 14 tooth sprocket. For me the problem going to 36v, 48v, or 60v was weight and volume. The 750w motor is only slightly bigger and heavier than the 250w stock motor. The batteries weigh more and are little taller but still fit in under the cover. I changed batteries for long drive time not performance. I added less than 10 pounds (8 pounds was from batteries to increase drive time) and kept it contained under the plastic engine cover. Ok, I had to put 1/4" spacers between the frame and the engine cover.

I got substantial performance increase. My son is doing 360's just from power. He just tried the 14 tooth version and it's a significant difference. I was concerned with the 14 tooth sprocket we would loose the low end and not be able to climb hills. Nope. Now the wheels not only break free but they spin faster. He can easily climb hills. He went full speed and I think it scared him, ok me too. He flew down the street cranked the wheel and spun it. He looked at me with a big smile and did it again.

I really don't want him to go faster but I want the power for quickness and to spin the tires. The controller is programmable so I think I can limit the top-end.
#6525
I have the drifter and ground force lol..just added my 76 tooth sprocket to the stock sprocket to correct the gear ratio after adding the 10 inch tires- blahh..i wish i had that torque so im hoping with 76 teeth out back and 2 stock motors ill be able to climb hills alone, or carry my girlfriend ( 104lbs ) when on level terrian..the ground force will be a bare bones rolling stock chassis next week..the drifter will be carrying both motors and controllers and 4 batteries..if my math is correct the setup will be able to pull me uphill no issue..show me a link to your controller, im not familiar.i got the ground force for 50 bux so that was wayyyyy cheaper than upgrading the controller and motor etc on the drifter...the drifter wheels made it soo much louder than the ground force..i read somewhere that the 500w motors really made.no improvement on the stock 24 v systems so if anything ill just start over on the ground force with 1000w and 48 volts..sell the dual motor to fund it hehe
#6527
I got my controller from http://kellycontroller.com The one I'm using is the KDS36100. I can use it for 24 or 36 volt. I bought my drifter used since I planned on changing all the electronics. What I like about the drifter are the rear wheels. I don't have to worry about my son flipping it, he just spins. That's what he likes.

Have you looked into brushless motors? You might get more power from them.

I think the drifter has a tighter turning radius than the ground force. I have not compared side by side but have looked at the ground force in the store.
#6742
Robnewyork,
Would you be interested in machining me the pieces to use the HF 10 inch wheels? If so how much do you think you would charge? If not its fine, I have a guy that wants to sell me a GF fairly cheap but I will need it to bee able to go thru the grass. I have to be able to keep up with my little girl who has the Razor dune buggy.
#6744
Which model? Drifter? Cut the hubs out of the drifter rear tires, send em.. the front is simply making the 5/16 to 5/8 th adapter..delrin worked fine..dont forget the rear gear will need to go up to 72 tooth to make the same final gearing..check my build at robnewyork on photobucket..i made many posts..email me at rmurphyrobert900@gmail.com
Its not hard i just dont wanna cut the hubs out again to machine down..the cutting was a pain in the butt with hacksaw..so the wheels are one endeavour, the gearing is the bigger one..the front need spacers and the harbor rim chopped 1/4 inch..takes 2 seconds..just make sure your prepared to either add power or gearing, but ill be happy do make another set.
#24128
So following Rob's post, I was able to file the drifter rear hub by cutting the rear hub per his instruction and lathe using the razor's drifter. I remounted the cut out hub and ran the razor on a stand and lathed with a rasp file. it worked out pretty well. I paired the lathed hub with harbor freight's 8" non-marring wheel.
#29686
Old and dead post but I was wondering if anyone found an easier traction solution with a near stock circumference. I'm 48v 1000w and we went through the rear wheels in 2 charges. I would like to set up a mock autocross courses but the traction makes it a moot point. Thx in advance.

8mm (T8F) rear wheel sprocket

Looking for a >90T and <10 in. outside diam[…]