9XL/3S gearing help - RC-Monster Forums

JB3231 · **9XL/3S gearing help -** 10.09.2007, 09:15 PM

I just got my 9XL in from Mike and installed it this evening. I'm running 16/66 gearing, the 16 was the only thing in stock right now. I ordered a 20 and 22 a couple days ago from FD so I'll see if they show up. I know I'm a little under geared but it is about like a stock Emaxx right now. I'm running a single 3S 4000Mah Lipo and MM controller.

I really don't want to jump to 4S unless I just absolutely have to. I wanted to use the built in 3S Lipo cutoff from the MM and the Lipo that I already have. I already have the BEC disabled because I was having major problems with it. I'm using a very small 2S Lipo for a receiver pack.

I originally ordered the 7XL and then changed my mind and emailed Mike to change to the 9XL before shipping. His customer service is great by the way. With only 3S should I run the 7XL? I was worried the amp draw would be too much with the 7XL.

The MM 5700 motor smokes the 9XL with the current setup.

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BrianG · 10.09.2007, 09:44 PM

To get any kind of speed out of the 9XL on 3s, you're gonna have to gear up quite a bit and that's gonna draw as much current as running a properly geared 7XL.

Even though you don't wanna hear it, the 9XL would work better on 4s geared right. You could still use the MM cutoff, but you'd need to get a different lipo pack.

If you stay with 3s, I would get the 7XL and try not to gear too high to keep current draw down. Even so, I would run two 3s packs in parallel to increase the current rating.

JB3231 · 10:05 PM

I thought the MM Lipo cutoff only went up to 3S?

If I stay with the current 9XL and 3S for a while can you recommend a gearing setup? I have 16/66 now and ordered 20 and 22 tooth pinions. I'm looking for 40mph minimum. 90% of my running is up and down the driveway and around my cul-de-sac.

Here is a link to my previously sold LST2 with 5S. Wheelie's on command at any speed. That's what I want again. I just didn't want to spend another $1,000 getting there. Maybe I should just build another LST2. I'm just extremely disappointed right now with my current setup.

http://video.google.com/videoplay?do...10769375287089

Arct1k · 10:11 PM

I tried 3s and was happy with it with running 8400mah packs - I listened to god aka brian and went to 4s and WHAT a difference - Didn't stop grinning... You can pick up a 4s 5000mah 25c for $125 and you are off....

http://s168.photobucket.com/albums/u...urrent=018.flv

MM has a 4s cutoff you just need to buy an UBEC - Mike has some good ones or BPP has the new castle one as a backup...

I run 24/65 at the moment but will drop back to 22/65 now I have 4s... Will also be trying a few test runs on dual MM dual 9XL on 22/65 soon...

JB3231 · 10.09.2007, 10:10 PM

What are you running?

Arct1k · 10.09.2007, 10:13 PM

Updated with gearing info - it is a revo but with the emax transmission so will be close to yours...

JB3231 · 10:33 PM

Ok I see that I am really under geared right now. I'll try the 22 tooth pinion when it comes in. It should make a huge difference over the 16 now.

I shouldn't need a BEC if I'm using a seperate receiver pack correct? The BEC just allows you to pull voltage from the main pack for the receiver and servos thus eliminating the small receiver pack?? One less pack to worry about, I like that.

Where are you finding the 4S 5000 for $125? Maxamps is almost $200 for that pack.

Also, what's the voltage limit for the 9XL? I know the MM is only capable of 4S. Just curious.

Arct1k · 10.09.2007, 11:07 PM

4S will take a 9XL to 30k rpm which is about right - 5S would hit 37.5 which is a little high i think.

UBEC stops the need to a rx pack which makes things a bit lighter - I actually just swapped to using a 2s lipo 1200 with the ubec to keep all the juice for the motor!

magudaman · 10.10.2007, 02:18 AM

The mamba max has a custom setting for cutoff voltage so you can set it for what ever you want. I have mine set up for custom cut off on my 5s a123s. Good luck

02:58 AM

I run 22/66 gearing on my FLM Maxx, but it's 4S. The only thing I didn't upgrade was the driveshafts. Stupid me. I only got a 30 second run, because the fronts twisted and the rears broke in half. I'm down till my CVD's arrive.

For 3S maybe try a 24T?

I thought the MM could do 6S if you use a UBEC. The Sept 07 issue of RC Driver has an article with a Losi 8ight Buggy, running a MM on 6S with a ACn Car8 BL motor. It does have a huge fan on the MM though. It's on page 98 of that issue.

zeropointbug · 10.10.2007, 03:08 AM

Yeah, running 3s and geared to get decent speed from the thing, it will draw a lot of mah in a hurry. The MM might suffer.

BrianG · 10.10.2007, 09:48 AM

Quote:

Originally Posted by bluonyx

I thought the MM could do 6S if you use a UBEC. The Sept 07 issue of RC Driver has an article with a Losi 8ight Buggy, running a MM on 6S with a ACn Car8 BL motor. It does have a huge fan on the MM though. It's on page 98 of that issue.

Maybe the earlier versions could, or maybe a modded one, but none of the versions out now will do 6s. Heck, they won't even run 5s anymore. 4s is still good though.

tashpop · 10.10.2007, 02:01 PM

i'm so glad i read this post. i've been looking everywhere for some gears for my project. i never seen the link to finedesigns gears. i wish they had better shipping options, ups ground is a joke especially for a pinion gear. i sent then a note that i'd prefer usps priority if availible.