Gruber
HobbyMasters
M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Information on Motors, Gearing & Gearboxes
User avatar
By azgearhed
#147969
I'm new to this forum today. I acquired a project several years ago and I just finished it. It is a custom frame and quarter midget body. It got used for the first time last weekend an a gearbox broke. Since I got the project with gearboxes and motors, I don't know what the parts came from. The gearbox has a "12T" on it, the motor has no marking other than made in Hong kong. I'll try to post some pictures.
Attachments
quart1.JPG
quart2.JPG
quart3.JPG
User avatar
By wesleyb82
#147978
What broke? If it's a gear please provide the tooth count and shaft diameter
User avatar
By wired
#147979
Looks like a 3A gearbox from the pics. Check out the "definitive gearbox" thread in the FAQs section to verify. You can identify up your gearbox with the description of the one that matches the one you have.
User avatar
By azgearhed
#147987
The wheel drive is broken enough that I can't count those teeth. The side of the gear case is broken out and the middle gear hub is also broken. The shaft is .437 (7/16) and the motor pinion has 12 teeth. I would like to replace both motors and gearboxes so I can start fresh with unworn stuff. Since this is an all custom car except for the motors and boxes, how do I go about buying them if power wheels won't sell to the end user? How do people "hot rod" these toys if you can't buy parts? If I can identify what vehicle my motors and gearboxes came from, I could possibly buy a parts car and pull off the stuff I need.
Attachments
broke gears.JPG
User avatar
By Hammer-fm
#147990
The 7R gearboxes that are used in most of the newer models are pretty readily available online and sometimes locally (I bought 6 of them from a local repair shp for $20/ea that was getting out of the business). I'm not so certain about 3A and unsure what it takes to switch -- I'd assume that the chassis/frame you are using is probably set up for a 3A box and wouldn't easily take a 7R since it has a different shape and the mounting/retaining is done differently.

The 7Rs have quite a few modification options -- larger motors, steel gears, different pinions, and you can do some amount of upgrading on a small budget if you choose carefully ($50 for 2 new motor-less gearboxes, plus $10 for cheap 775 motors and $10 for pinions). If you can find a craigslist Power Wheels special locally it may be worth trying that route, as that would get you two gearboxes. Note that some of the older Jeeps have original "7" gearboxes which will interchange mechanically with the 7R (eg. you could figure out the mounting, etc.) but aren't as strong.

What diameter are the rear wheels on that, and how fast are you aiming for? That would also influence which 7R flavor to buy if you were buying new ones. You likely will want the 21-22-23T ones from something like a Corvette, unless the tires are >14-15" or you are looking at keeping it pretty slow.
User avatar
By wired
#147993
That is a great looking little car. I see the gearbox fitment is pretty tight. With the assumed weight of the car and the traction of those tires I can see why the gearbox failed. Does the car have a single accelerator pedal or a separate brake pedal? That may be a cheap knockoff gearbox of a powerwheel 3A (a 3B will work also). You can post an ad in our wanted section or source them through AMAZON if you want to buy replacements direct. If you need any other assistance don't hesitate to ask.
User avatar
By azgearhed
#147995
At this point I'd like to thank everyone that replied to my post. Some of the questions I ask are probably a little lame so bear with me. I have built several street rods and am currently running a Camaro at Bonneville and El Mirage, so I have mechanical knowledge. here is some info: I'm looking for mild performance, 4-6 mph, just want as much durability as I can get. I'm not sure of the condition of the motors as they have some metallic "fuzz" around the motor case. When I connect the motors to a 12v battery, they squeal when starting. Is this normal? Someone asked about the tires. They are 13". It was mentioned that the traction they get over plastic tires could be what broke the gearbox. Yea, that and a 3 year old that kept stompin on the gas then lettin off like he was playin a base drum. If I can identify the gearboxes I have I would prefer using that model or one that would "bolt in". I'm prepared to make mounting mods if I have to. Are there 6v and 12v motors? Or is it just the input voltage? Whats the difference between a 3A box and a 7? Thanks to everyone again.
Attachments
box A.JPG
gearmotor.JPG
motorB.JPG
User avatar
By wired
#147999
Please visit the FAQs section. There is a thread titled "the definitive gearbox thread". It will answer most of your questions about those gearboxes. Motors squealing is not good. you could try running the motors with a 9v battery in a bowl of distilled water and then oiling the shaft on both ends. Google DC motor break in. There are videos on youtube that show how to do this. You can buy new replacement gearboxes with motors on AMAZON for pretty cheap. Pair of 19t #7 motor/gearboxes for $49.95 shipped and 3b motor/gearboxes for $39 each. Both are free shipping. If you don't mind used parts we have a decent wanted section.

8-)

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