Never really thought about this..... - RC-Monster Forums

**Never really thought about this..... -** 10.05.2005, 12:18 AM

What would the correct gearing for my Ofna 9.5 buggy with Lehner 2800xl and 9918 on 12 cells be? I had it 12/52 the last time I drove it, and it had stupid amounts of power all through the rpm range, but seemed to get a bit hot. I'll admit, I never did a temp. check with a gauge (didn't bring it along), but was kind of wondering if I'm geared a bit low with that setup.......going up a tooth would be an easy way to check, right?

I'd kinda like to get this figured out before I completely have it back together, it's torn down because I'm trying to put a LX Comp diff in and it's taken a few more steps than I thought.

coolhandcountry · 10.05.2005, 08:01 AM

You may try going down a tooth as well. The motors do put the power out. They are not that big of a motor either.

10.05.2005, 04:07 PM

I can't really go down any teeth, because the Lehner has a 1/8" shaft and the smaller pinions are for 5mm ones, so I'm limited to only going up. The last time I ran it was in 105* heat though, so you can't really blame it for heating up, but I've got fans I'm going to install to fix this.

I got my new spurs today, instead of the 12/52 gearing, it'd now be 12/51.....which would be ever so slightly higher. I'll try to work on it tonight a bit, maybe even get it running again. :)

coolhandcountry · 10.05.2005, 05:10 PM

If you running the 1/8 shaft. I have seen a 9 tooth pinion. robinson make it. I know it is not as good as mikes. :D

squeeforever · 10.05.2005, 05:15 PM

is it mod 1?

MetalMan · 10.05.2005, 05:40 PM

Robinson makes a 9t 32p 1/8" pinion. But it's not mod1. The lowest for 1/8" mod1 is 12t. David, do you think it's time to upgrade to a Feigao? :) How about a 7xl ;).

coolhandcountry · 10.05.2005, 08:04 PM

Duh! I won't thinking. You right it was a 32p not the mod 1.

10.05.2005, 09:06 PM

Quote:

Originally posted by MetalMan
Robinson makes a 9t 32p 1/8" pinion. But it's not mod1. The lowest for 1/8" mod1 is 12t. David, do you think it's time to upgrade to a Feigao? :) How about a 7xl ;).

Maybe if I do a total revamp, like new battery mounts and all......I kinda hate the ones I have now anyway. A 7xl would sure be sweet though, that mega huge motor can hanging off the motor plate and all......prob. have to make a new motor plate too.....dang.

Dafni · 10.06.2005, 02:05 AM

Yes, the Feigao XL motors put some stress on the motorplates. A L would already push your buggy around with authority.
However, I would choose a motor with a low kv, so you have some room with gearing.

If you like the torque of your Lehner, you could also get a lower kv Lehner and change the gearing.

But, as far as I understand you, basically the buggy drives well, has a nice top speed, gobs of torq, temps stay low ... what do you want more?

In the beginning I thought about a Wanderer XL for a buggy, but now I think an 8th scale BL buggy should stay as light as possible. An optimal setup would be a high-end Lehner, though. But who wants to part with this kind of money?

10.06.2005, 02:38 AM

Well, it hasn't been driven in the recent 80* day temps, so I don't really have an idea of how it runs in normal applications......I don't think it liked 5 minutes of full throttle in 105* baking heat though. :D

Dafni · 10.06.2005, 02:45 AM

Actually, most BL motors are more efficient at WOT, thus stay cooler on open-field runs, with lots of full throttle. It's the partial throttle that heats our low-end motors up.
The ESC, and the batts, well, this is a different story.

10.06.2005, 02:49 AM

It was R/C Car's Skinny driving at a humongous off road track, you decide what to call it. :D Oh, and there was little to no ventilation on the inside of the body aside from some holes in the windsheild.....this will of course change before it goes out next time, there'll be fans on EVERYTHING, even the receiver!! ;)

Dafni · 10.06.2005, 02:54 AM

Fans rule! I just got myself a bunch of 5V fans, handy to wire them on the UBEC line.

Dabid, please say again: What was the GPS'ed topspeed? Close to 40, right?

02:58 AM

38, wasn't even wound out yet though. It was when I had a crapola antenna wire, with a few bare sections, and short length that made the car glitch like mad. I've since replaced the wire, and think I could comfortably top 42 or so, maybe more if I had the room to wind it out all the way.

EDIT: Oh yeah, that's when I was still screwing with 32p gears though, so it was 15/66 with the center not-so-slippery slipper.

10.07.2005, 02:46 PM

Wow, it's been like forever since I drove this car, but I finally took some time this morning and got the car going again.

I put a 51t plastic spur on the LX Comp diff, and instantly saw how much more true it runs.....way better than anything I've ever had in that car. So, with everything bolted back down, I decided to take it out for a run....oh, how I missed this thing!

I need to dump some diff lube fluid in the center diff to get better launches, because right now it's shooting most of the power to the front wheels and having the rear get up to speed like 100 feet later. It still runs great, but I broke a battery bar in a crash and had to put it away. I also did a temp check, the motor was 166, the controller 137, and the little regulator that takes the place of a rx pack was 107. The motor's running a bit hot, but I don't know if that's because it's over or under geared. I don't have much room to go for gearing, I could try to go down with a big Monster Pirate spur, but other than that I can't gear down. I could try a 13t pinion to see how that'd do, but I don't think that's the trick either......my gut tells me it's over geared. :W: