View Full Version : Just installed PN 70T stock and has too much drag brake

2010.12.20, 01:19 AM
I've been really getting used to my first Mini-Z over the last two weeks, a new MR-03 US Spec kit. I really like the way it drives. After two weeks of running the stock setup for a few hours a day on a large mini-96 RCP track at home I installed a PN 70T stock motor. I didn't change any other settings (even tires). When I put it on the track it suddenly had a ton of drag brake - like WAY more.

What's the deal with this? Is this remedied by a proper break-in? Is this actually a preferred behavior? Personally, I don't like it but my only frame of reference is the Kyosho stock so it may just be something I should get used to. Also, it seems like the Kyosho stock motor was faster - but that may just be because it was more broken in (or batteries).


Digitalis West
2010.12.20, 02:11 AM
The speed difference could be a break in issue... but that should not cause a ton of drag brake. My first inclination is to check the gear mesh as overly tight mesh will cause both symptoms you are seeing. Check to make sure that there is a little bit of play in the spur gear before it turns the pinion.

The gear ratio may also be an issue. PN70 motors have some more torque (and thus more drag brake) than the stock motor. Most folks run a very tall gear ratio with this motor. If you are using the stock gear sets, use the largest pinion you have. If you are using a 64p gear set, a 13 or 14 tooth pinion is usually good depending on the track.

If it is neither of these things, you can adjust the drag brake on the reciever board with one of th ICS adapters that are available.

2010.12.20, 02:13 AM
Motor bushing aren't always precise and end up being tight on the motor armature. This is what make the motor slower and feel like it has a lot of drag brake. Reflex racing has a tutorial on their website under the articles section, but I use a slightly different method. My motor break in method makes my pn 70t motors extremely fast, smooth and cool. Many people comment on my motors and how fast they are :) Here's my method for stock motors (bushing)

1. Apply reflex white drops to the bushings. Run for about 10 minutes (I don't use the PN break in stand). Put a pinion on the motor and if it still feels a little tight, run it for another minute or so.

2. Hook the motor up to an AAA and have it run while spraying motor cleaner on it. Make sure to spray all of the white stuff out so it doesn't wreck the insides. You don't need to go crazy since you still need to do the brushes.

3.Get a cup full of water (I use from a sink, I honestly don't think it will make a difference vs. distilled) Hook the motor up to a fully charged AA/AAA and run it until the brushes make one thick streak across the comm. For me, it usually takes 10-15 minutes. Make sure to pull the motor out every 5 minutes or so to make sure you aren't wearing the brushes down too fast.

4. Have the motor still running but rinse it out with motor cleaner. Make sure to get all of the water out and any of the white stuff it it's still there. Check to see if the comm is nice and shiny because it is cleaned best when the motor is running.

This method has worked for me for a while and whenever I use a stock motor, I use this method. The benefits of this are more speed (bushings not binding up with the armature), runs cooler (less binding), less drag brake, better run time and a motor that drives very smooth, even with punchy batteries. :D

Also, try to run 64p with your cars, it makes them a lot more smooth. With the 70t, it depends how big the track is to determine the gear ratio, but 14/52 and 14/53 have always worked good for me on small and big tracks. If you run oil on the motor, make sure to clean it regularly because the tire dust will get inside and slow it down. I don't run comm drops anymore because of this, even with modified motors.

2010.12.20, 03:50 AM
OK - so I'll start by installing the 64p spur/pinion set that I ordered. I bought a ton of different upgrade parts from all the different makers but I wanted to take my time installing them one by one so I can really understand what effect they have on the car.

Breaking in the motors sounds complicated. I'm not even sure how I hook a motor up to a AAA battery... I have the PN break-in stand and all of the RR liquids on the way so I'll try the tutorial they have on their site. It seems pretty complete.

I have a PN S6 charger coming. Does it have a motor break-in mode? If not, how do I do that?

If the break-in doesn't help I'll try adjusting the speedo. I have the ICS cables too. I also ordered the RR 70T stock motor with the full blue printing so once that arrives I should at least be able to tell what a properly broken in motor feels like.

Thanks for the help!

2010.12.20, 11:37 AM
Try adjusting the throttle trim slightly forward, and test that you still have ability to get into reverse. You can adjust the drag brake slightly this way. It wont make the PN 70t have as much roll forward as the Kyosho stock or X-Speed, but it definitely helps smooth the car out off throttle. I like a little drag brake, but the PN70t has a lot, so adjusting the trim a little helps me get the car dialed in.

unearthed name
2010.12.20, 08:10 PM
get an ics and set the v.inertia to your liking.

i always like drag brake though

2010.12.20, 10:49 PM
I dont like the feel of v.inertia, but sometimes drag brake is too much. Which is why I adjust the feel of drag brake with throttle trim.

2010.12.21, 02:30 AM
This would all be so much easier if I lived in a city that had an established Mini-Z racing program and I could just learn in the pits. I'm heading down to the bay area for the holidays so I'm going to try to spend a day or two at Fast Pace Racing and ILR while I'm there. I also do business in NYC a lot so I'm going to try and make it out to Maj's and Staten Island next time I go. I need to learn enough to get a program started up here in Seattle.

Digitalis West
2010.12.21, 09:17 AM
I'm heading down to the bay area for the holidays so I'm going to try to spend a day or two at Fast Pace Racing and ILR while I'm there.

Come early on a club race day. This is when the most number of folks will be there and the racing is a really fun experience. There is racing at ILR on Wednesday and Saturday evenings. Racing at Fast Pace Racing is Friday. The crowds at both are super friendly, always happy see someone new and will help as much as they can.

Mike Keely
2010.12.21, 05:47 PM
I have not been to the Staten Island track but Maj's I know is top notch. I live in MD and love to travel to that track. Lots of parts and the guys are very fast there. Can't go wrong at Maj's. I have been to some great races there also.

2010.12.21, 09:08 PM
Awesome - I look forward to visiting both places. I'm also going to try and make it up for the Nats in Maine because I have to be in Boston earlier that week.

Two of my questions from earlier in the thread didn't get answered. I'd love your help on those:

1. When breaking in a motor, how do I hook a battery up to a motor?

2. I just received the PN S6 charger - does it have a motor break-in function? If so, how do I use it?


2010.12.21, 09:35 PM
1. best way is to go to radio shack and get a battery holder. 2 aaa are plenty, 4 will also work. then just wire the motor to the wires coming out of the battery holder.

2. no the pn charger does not come with a motor run feature. you need either a motor master, or i think a duratracs ice charger will also. there may be other charges that run motors but i can not remember which ones.

theres really no need for a dedicated piece of equipment to run the motor, that being said i use the motor master and it works great. i just love toys. and from the post ive seen you put up you do as well.

2010.12.21, 09:43 PM
When I break in a motor using batteries, I put one or two batteries in an empty chassis (battery tray works as well), and pinch the ends of the motor leads with the appropriate end of the battery circuit. Red wire, + side of batt circuit. Black wire, - side of batt circuit.

I have even taped the batt leads to the ends of a battery as well... a battery tray works best, and can be purchased cheap at Radio Shack. They should have one with aligator clips, which you can just clip on the solder tabs of the motor.

I use an LRP Pulsar 2 charger with motor run in.

I am not sure if the PN charger has a motor run in. It says nothing about it on the website, I dont have one. Check the manual where it lists all of the functions.