Losi XX gearing for a 17.5 brushless!!!

[tecnica2001]

Ok as we all know I have the XX buggy.

The novak gearing guide suggests a 6.0 ratio for 2wd buggies with the 17.5 motor.

The XX tranny is a 2.19:1 ratio w/ an 84 spur.

So it would be something like this: (84/30)x2.19= 6.132,

Would I be able to fit a 30-31 pinion on the XX with an 84 spur??

Also, I forgot to add, I'll be running an Lrp sphere and a trak power 4900 lipo

Suggestions, opinions, always welcomed.

[JK Racing]

Are you using the double slipper spur (newest version) or the OG (single slipper pad)?

If the double, drop down to a 78 and run a 27/28 pinion.

There are ways to get even smaller spur gears on there...using Kimbrough pan car spurs & traxxas slipper pucks.

To get into the 6.0 FDR, I have seen guys with modern cars running 33/66 or larger.

[tecnica2001]

No, I have the OG style slipper pad, I can't really choose what spur gear to use, unless I can find some sort of adapter thingy.

So I'm stuck with either a 90,88, or 84, so 84 it is.

I was wondering if the 30 or 31 which will get me the closest to that 6.0 ratio, will fit.

I guess I'll just have to try it out.

[bearrickster]

Just put a XXT tranny on it they are 2:6.1. I have one if you need it at least most of it, no bearings? But I do have a NIP case and gears. I did this to my Pro se wow what a difference its fast.

[scr8p]

ok, is there something that i'm not understanding about brushless? why would you gear your car/truck to what novak says it should be? they have no idea as to the size track your racing on. just gear it so that the motor winds out at the end of the longest straightaway.

am i wrong for looking at it that way? i have no experience with brushless so maybe i am. but i just don't see how finding a gearing for your particular track should be any different with a brushless setup as compared to a brushed motor.

[tecnica2001]

Hey Scr8p,

Novak's gearing suggestion tables are just starting points, they say if the motor gets too hot, to drop one or two teeth to get the temps down. At the same time, if the motor is still cool you can gear them higher to get better top end speeds.

My main concern is whether I can fit the 30-31 pinion in there with the 84 spur.

If you want to stay competitive with a 17.5, you have got to gear the heck out of them.

For example, I ran my XX with the CO27, with the 88/19 gearing, and it was borderline hot.

A brushless with the same gearing would be very very slow, I would have to use a 88/32 gearing to match the speed of the brushed stock motor, and still I think the brushed motor would be a bit faster. To gain an edge on the brushed stock motors, people just gear them(brushless) as high as possible without over heating them.

The problem lies in the size of the spur and the size of the pinion, the larger the spur, the larger the pinion has to be to get that gearing low enough to make a difference in performance with the 17.5.

I don't know If all this bable talk made any sense, I apologize for that

[tecnica2001]

Just put a XXT tranny on it they are 2:6.1. I have one if you need it at least most of it, no bearings? But I do have a NIP case and gears. I did this to my Pro se wow what a difference its fast.

That would defeat the purpose Rick, that would be a good option if I wanted to run the brushed stock motors.

But imagine the gearing nightmare that would cause when trying to gear for a brushless motor.

I would have to gear it 84/36 to get close to that 6.0 suggested ratio

[bearrickster]

I ran mine with a buggy retrofit trans and brushed stock it was fast but no run time. I put the truck trans in it with a 10.5 brushless and it was a missle! so I dont know they through me in w/4wd mod w/ my 2wd I would kill them in the stright but loose in the corners?

[tecnica2001]

Yeah, a 10.5 would be a non issue, as far as gearing goes, cause with a 10.5 I would just have to use a 84/23 gearing, and that fits in the XX no problem.

I might just end up buying a 10.5 or a 13.5 to run, I just wanted to save money and use what I have and still be competitive. I'll be running the XX in the 10.5/19t class on Saturday's trophy race.

and Rick, that T4 it's still holding up like a champ, I'm top 3 everytime I race with the 5.5 brushless

[bearrickster]

Glad to here it! my track has closed for the season it sucks. I wantto see some first and seconds next season with that T4

[tecnica2001]

Oh I usually finish 1st or 2nd, when we're running trucks against trucks, but when we run with buggies, I usually come in 2nd or third, those buggies are quick

[Bongo Fury]

I can only get a 24 pinion on my XX with a 88 spur, so with a 84 spur a 28 tooth would be it. Which would be about 6.6 FDR I believe.

Could use more.... 6 is a good starting point, but you should be able to go to an even lower FDR if you want to hustle it a little. I've been running 5.2-5.6, some guys go to 5 even.....gear to the moon.....In fact I just came back from the shop with a big fat 36 tooth pinion myself, 5.1 here I come. (76 spur, 2.43 XXX)

Yeah, the 17.5 has a lot of low rpm power, they really respond to a lot of gear. It seems like it would lose punch but it doesn't seem to lose much. Just watch the temps.

[tecnica2001]

So since there's no way I could get a smaller spur for the XX, I wouldn't make any sense to run a 17.5 in it.

Hmmm, I have a spare, slipper plate for the XX, I could probably tap it, and just add a regular 78 spur onto it??

A lot of people run these motors without slipper.

Bongo, do you run your 17.5 with a slipper eliminator like they do on the B4s and RB5s??

any other suggestions are more than welcome.

I have a trophy race on Saturday, and I don't have a motor for the 10.5/19t class, in which Imma run the XX, so it's either run the 17.5 or fork up the $85+ for a new 10.5 or 13.5.

[Bongo Fury]

I'm still running the slipper, but it's pretty tight. The XXX can be geared higher than the AE or K cars. Is on my list of things to try though.

A 78 would get you there. Does the newer XXX slipper fit on the XX shaft???? I'll have to take a look when I get a chance unless somebody knows already.

[JK Racing]

So since there's no way I could get a smaller spur for the XX, I wouldn't make any sense to run a 17.5 in it.

Hmmm, I have a spare, slipper plate for the XX, I could probably tap it, and just add a regular 78 spur onto it??

technica, get the double slipper set up from the XXX, it will drop right in, then run the 78 spur from them, or any smaller onroad spur and the traxxas slipper pucks, you should really check into it. I can get a 68 on my RB5 and keep the slipper still .