View Full Version : PN Racing 70T Motor Gearing?

2009.03.26, 02:11 PM
I was just wondering what you guys/girls recommend as the right 64pitch gearing for PN Racing 70T motor in an MR-02 should be. The course has one long straight and some tight turns.

2009.03.26, 02:25 PM
I used 53/12 and it worked well. Might be a good starting point.:cool:

2009.03.26, 02:53 PM
I used 53/12 and it worked well. Might be a good starting point.:cool:

this is what I run on mine. it's a nice medium, good torque and top speed without suffering to much of either.

2009.03.26, 04:50 PM
YEs, all my stock car also run 52/12, I knew Lukas run 52/13, back to back i had test it, I like 52/12 very much.

In KO Mini Class, my F40 like flying everybody said, but I can tell ture every body, my handout motor is choose from Insideline crew, I'm no break in my motor, becuase my breakin stnad just break in EJ motor and his friend motor, I just use my used TRP 900 battery.

2009.03.26, 05:59 PM
The TRP 900 cells seem to have more top end (voltage), so there is more speed with a lower gearing. With my R1Wurks cells, there is more punch, but less top end. This plays into effect when choosing gearing. I use 52/14 on my MR015 that I raced at the KO race. It is a little tall, but the car is very light and has great acceleration. For the mini class, I used a 52/13. Since the car is about 10g heavier. Same acceleration, but a little less top end. In qualifying, I am pretty sure that I had a little more speed than PN, but he could take the corners much faster, and had a little more acceleration out of them.

In general, I choose gearing by where the car tops out on the straight. I want it to top out before the middle of the straight. If it tops out 2/3 down the straight, then that is too high. Also, if there is more time lost in the infield than gained down the straight... you may want to gear down a little. Going with a larger ratio has more deceleration when you come off the throttle as well, which plays well with smaller tight layouts with a lot of slower corners. If there are a lot of high speed corners, then gear it up a little more.

2009.04.05, 05:47 PM
What about a speedy 07bb. I am running a 12/52 pitch or should I try a 11/52 pitch. The motor seems to run hot witha a 11/52.

ocean rodeo
2009.04.05, 07:33 PM
Stick with the 12 thats pretty much the gearing to run with that motor in a 02

2009.04.05, 08:10 PM
There is no set in stone gear ratio for a specific motor. Gearing changes depending on the track layout, grip, weight of the car... there are many factors that come in to play when choosing the gear ratio.

I ran a 12/52 last night with my 07bb, and felt that I should have geared it down a little. I was way too fast for the layout. I think an 11/52 would have been much better. I couldnt use full throttle until midway through the main. We have about 30 feet of straight too.

2009.04.05, 09:01 PM
I always run 8-9 for 2 wide L size track and it works just fine.

2009.04.06, 01:57 PM
Stick with the 12 thats pretty much the gearing to run with that motor in a 02
For most layouts, that's a good starting point I guess. I find myself using the 64p 13t pinion more nowadays. :) At Inside Line the ATM USA Standard motor is also used, so I geared up my car to 13/52 to stay on track with them. Granted, the MRCG is light, so I didn't lose much acceleration, but 12/52 gearing would have given up too much time on the straight to make up in the corners. Fast Pace Racing has the wider, more flowing PN layout now so I also used 13/52 there.

Although one consideration when picking gears should be to also avoid really even ratios -- 13/52 = 1/4, which pits the same gear teeth against each other, and can lead to accelerated gear wear. I believe that you should use 13/53 instead, it's not a lot of change but should (in theory) preserve your gears a bit better (the 64p gear set is already relatively fragile...).

ocean rodeo
2009.04.06, 03:16 PM
off topic edit

2009.04.06, 04:13 PM
Um, in these cars, we dont have a slipper... We have a ball diff, which should NOT be used as a slipper. You will flatten the balls, groove the plates. Overall, ruin the diff fast.

ocean rodeo
2009.04.06, 05:41 PM
off topic edit

2009.04.06, 06:26 PM
I think it is misleading information, especially when you call it a slipper... there are many people that read these forums that are new to Mini-Z and RC, and they can get the wrong idea of how the cars are supposed to work. A slipper is used WITH a diff. A diff should not be used as a slipper. Yes, it will work... but there are many drawbacks to doing so. If it HAS to be used as a slipper, then you are covering up a fault in the setup by running the diff so loose.

Runnning an F1 shock is not a problem, I use one on a few of my MR02's... ;)

Im not trying to single you out, but I just wanted to clarify for the people that are trying to learn about the cars, that this is not recommended to run the diff this loose, unless you are planning to rebuild the diff on a weekly basis. You want a little slip with the diff in your hand, but not on the track. If I hear my diff slipping at all when I get on the throttle, I know its too loose. I set it just to the point that it doesnt slip when I nail the throttle from a stand still.

If you are running the diff that loose, why not run it tighter with a slower motor? Sounds like you are running it loose to take away the effect of the acceleration and make it more manageable.

ocean rodeo
2009.04.06, 07:17 PM
off topic edit

2009.04.06, 08:28 PM
This type of setup may work on a smaller track. But if you race on a large track :eek: I dont think it will. Most of my setups are for large tracks. I know what works where I race, and normally can adjust to other tracks with one or two changes to gearing, and front tires.

I will not loosen my diffs, I did that early on in the game to make the car easier to drive out of the corner, and I allways wondered why I was so slow out of the corners even with the fastest motors. On a small track you can get away with having a loose diff, since it will let you turn in harder, and make it easier to get out of the corner. On a large track, you need a tight diff.

This thread is for 70t motor gearing... so, I think we should stop this discussion here, and return back to the main topic.

In the last race, I tried inch up wheels on the back of my 70t pan car. Which already has 14/52 gear ratio... I felt a slight increase in speed on the straight, but I think I was better with the standard wheels as I was topping out a little too late, and the acceleration out of the tight corners wasnt as good (also the car got a little loose if I pushed it too hard). The car carries a lot of speed through the corners, so I can get away with gearing it very high. I used the inch ups for two reasons, 1. to get more top speed and 2. to rake the car forward to get a little more aggressive turn in, as more % of mass will be on the front wheels. This accomplished both, however, I may gear down slightly to get a little more punch back. I think my laptimes would be faster...

ocean rodeo
2009.04.07, 04:18 AM

2009.08.06, 11:51 AM
gear it to the moon 14/52

2009.08.06, 05:05 PM
At the PNWC race, I ran 12/52 on my stock, 13/52 on Pan and F1, and 14/52 on my 90mm...

The best motor that I had was my stock car. It seemed to have as much speed geared at 12/52 as the others had at 13/52. The worst motor I got was my 90mm, which I geared to the moon to have good speed on the straight.

2009.08.06, 06:54 PM
I ran 12/52, in finals I try 13/54 not bad, little hot on motor after 1o mins.

Davey G
2009.08.07, 11:01 AM
I tqd the PNWC New Jersey regional by using 54/13 in 70T.