# Losi 48P Spur Gear? Smaller Than 76T?



## fab24 (Dec 26, 2007)

Does anyone know if anyone makes a spur gear for the Losi XXXT or XXX series RC vehicles that goes smaller than the 48P 76T black spur gear that Losi sells? 

As far as I know this is the smallest they go. I am looking to do some experimentation with a smaller spur gear if I could find something. 

If there are no aftermarket parts that are designed for this specific application that anyone knows of, does anyone know of a current 48P spur gear that is smaller than a 76T that might work with or adapt to the losi set up?

Thanks for any insight or info anyone might have.


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## guver (Jul 31, 2002)

Theses may help you out. They might need to be drilled and faced off to work.
http://www.servocity.com/html/48_pitch_plain_bore_gears.html


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## OvalmanPA (Mar 21, 2000)

Question...........do you need the slipper with what you're trying to do? If not get a slippper eliminator from a company such as SRP and look into another company for a spur gear. I have a Kimbrough that is 69T on my Spec truck but I don't know if that is the smallest available or not.


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## trackman (Aug 5, 2006)

fab24 said:


> Does anyone know if anyone makes a spur gear for the Losi XXXT or XXX series RC vehicles that goes smaller than the 48P 76T black spur gear that Losi sells?
> 
> As far as I know this is the smallest they go. I am looking to do some experimentation with a smaller spur gear if I could find something.
> 
> ...


Check out www.robinsonracing.com

But first, Is this in reference to another post you started back in Febuary 08' titled "Losi/novak 4300 Help Needed" ?

If it is you are way off on your gearing.

The people that told you always start with the smallest spur gear possible I believe is very misleading ; that is Not always the case. 

If you have the XXX-t w/4300 brushless , a 76 spur and 33 pinion is way off. 

By the Novak web site , You need to start with more like an 86t spur and a 16 or 17 pinion.

Here's an idea:

Start out with the 86 spur and start with the recommended 17 pinion.

(#1 will acheive more top end)
#1. Then from there whenever you go up to 3 teeth on the pinion, the forth tooth added on the pinion is about equivalent to 1 tooth down on the spur. 

Or from the starting point of 86 spur and 17 pinion,

(#2 will acheive more torQ)
#2. Three pinion teeth down is about equivalent to 1 spur gear tooth up.

Also take into consideration that a one size larger tire than factory needs to be compensated with 1 pinion tooth down.
Also a 1 size smaller tire than factory can be compensated with 1 pinion tooth UP.

So with all this said I would start with a factory spur and pinion size of the truck at hand , with a pack of Robinson racing pinions Odd size and would also get a spur gear 1 or 2 teeth larger than factory size and also get a spur gear 1 or 2 teeth smaller than the factory size of the truck.


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## fab24 (Dec 26, 2007)

Hey Trackman, Thanks for the Great advice, and referencing the old post. I am not actually running anything standard like say an xxxt. What we are running is basically 10th scale buggies with custom works street trac tires and EDM bodies on a dirt oval during the summer. The old post was about carpet, and I am referring more to the transmission of the vehicle, which are interchangeable between the truck and buggy.

With more powerful lipo batteries, sintered rotors for brushless motors, the smaller tires I am running, the standard starting recommendations are not really that relevent to my situation for truck or buggy.

The bigger problem is I do not get to race nearly as often as I would like due to my work schedule, so I have not experimented enough to know how my car actually likes the way it will handle the different gearing set up possibilities. 

My present set up is VERY FAST on the track I run. It seems to have lots of torque and good top end speed. At present I am out of choices to go any further in the gearing direction I am going.

My Novak GTB has not thermaled so I am thinking there is still a little wiggle room to go on my gearing. The motor comes in at 130+.

Thanks ovalman for the info. I run my slipper pretty tight, and think the slipper eliminator you refer to might work very well for what I am trying to do.

Thanks all for the input.


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## signman501 (Apr 10, 2006)

Do you know the ratio of the gearbox? I run a terminator w/ 2.60 gb. Mostly I run a 13.5 and GTB using 58p/84s gearing. With a 4.5 I run 37p/100s (I think). We run an average of 230' dirt oval track.


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## fab24 (Dec 26, 2007)

Thank You ALL for your suggestions. I went ahead and got the slipper eliminator from SRP and Robinson gears. They definitely should do the trick.

Thanks especially to you ovalman for the GREAT suggestion.


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## OvalmanPA (Mar 21, 2000)

Oh no problem. If you're racing oval you'll want that slipper eliminator anyway. :thumbsup: Takes away rotating mass and puts a direct connection so to speak between the pinion and tranny. Watch the differential adjustment however, especially on a Losi trannsmission.


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