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Old 12-23-2008, 11:30 PM   #1
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Default gearing 17.5 in losi xxx-cr

How do you guys gear your 17.5 brushless motors in a losi xxx-cr i have a novak brushless 17.5 and was wondering how i should gear it. Around what kind of ratio should i have etc....
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Old 12-24-2008, 12:06 AM   #2
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http://www.rctech.net/forum/electric...very-soon.html
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Old 12-24-2008, 12:09 AM   #3
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Default XXXCR gearing

I am running 70/34, this is with a LRP 17.5 motor
The 70T is from my Schumacher Mi3 on road car and I have made a insert for it to fit on the shaft.

There is 2 new spur gears for the B4, 72 & 75, should be in the stores soon, using the B4 slipper pads this will fit the CR.

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Old 12-24-2008, 05:44 AM   #4
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sounds like i need to order a special type of 70t spur so that it wont screw up the input shaft ? or am i confusing myself
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Old 12-24-2008, 08:12 AM   #5
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very interesting, missed this 1

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Old 12-24-2008, 01:19 PM   #6
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Default gearing issues

i run on a larger track.. ex pegasus hobbies and i run a novak 17.5 wit lipo and i gear 35/76 for smaller tracks 33 or 34 pinion
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Old 12-24-2008, 01:28 PM   #7
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I have a question it seems like you have to go through some trouble to get a 70t spur on with like a 35ish pinion. Why cant you just put bigger gears to get the same ratio like run 80t spur 39t pinion to basically get the same 5.001 as the 70t spur 34t pinion ?????? seems like youd be saving yourself the trouble of having to buy that adapter ?
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Old 12-24-2008, 01:42 PM   #8
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Quote:
Originally Posted by sszzxx View Post
I have a question it seems like you have to go through some trouble to get a 70t spur on with like a 35ish pinion. Why cant you just put bigger gears to get the same ratio like run 80t spur 39t pinion to basically get the same 5.001 as the 70t spur 34t pinion ?????? seems like youd be saving yourself the trouble of having to buy that adapter ?
You can't fit that big a pinion under the gear cover, when Associated release the 72 T spur, it will fit straight onto the losi, you just need to get the associated slipper pads as well.
May be losi will release a smaller spur gear soon.

Merry Christmas

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Old 12-24-2008, 03:26 PM   #9
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With a trans ratio of 2.6 with 72/34 you will still be at 5.50 fdr. That is also with shaving the gear cover to accept a 34pinion. Now drop the 72 to about 65-66 with a 34pinion and your down to 4.97(65) or 5.04(66).

Check out the pinion and spurs at speedtech.
Pinion http://www.speedtechrc.com/store/ebcategory.asp?id=708
Spur
http://www.speedtechrc.com/store/ebp...?catmainid=392
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Old 12-24-2008, 09:12 PM   #10
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Quote:
Originally Posted by andrew-01 View Post
With a trans ratio of 2.6 with 72/34 you will still be at 5.05 fdr. That is also with shaving the gear cover to accept a 34pinion. Now drop the 72 to about 65-66 with a 34pinion and your down to 4.97(65) or 5.04(66).

Check out the pinion and spurs at speedtech.
Pinion http://www.speedtechrc.com/store/ebcategory.asp?id=708
Spur
http://www.speedtechrc.com/store/ebp...?catmainid=392
Your math is off some a 72 spur with a 34 pinion is not a 5.05. It is a 5.5 FDR.

Gearchart.com may help you out some.
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Old 12-24-2008, 10:10 PM   #11
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Accidentally read it wrong. I'll fix that thanks

Quote:
Originally Posted by dodgeguy View Post
Your math is off some a 72 spur with a 34 pinion is not a 5.05. It is a 5.5 FDR.

Gearchart.com may help you out some.
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Old 12-25-2008, 04:08 AM   #12
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so i can buy those spurs from speedtech and it will fit on my xxx-cr with like a 34 or w/e pinion i have ? and id be good to go ?
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Old 12-25-2008, 04:36 PM   #13
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I tried a lot of pinion/spur combinations and ended up at 35/69 (4.79 FDR) with an Xcelorin 17.5. Timing on the ESC is set around 11 degrees. Temps are around 138F after a 5 minute run.

Largest pinion I tried was a 37 pinion. It fitted without shaving the gear cover.

The turbo hub will fit on your XXX-CR (be sure to buy the Losi/Ass one, not the Kyosho version). With a 65 spur, the smallest size pinion that will fit is 33. A spur gear around 68-70 will get you into the ball-park.
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Old 12-25-2008, 06:54 PM   #14
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lol how about 27turn brush stock motors ? i got some custom built 27 turn and i never really race offroad how did u guys used to gear 27t's ? i think i have a 20t pinion in there with the stock 78t spur is that good ?
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Old 12-25-2008, 08:58 PM   #15
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23-24t pinion with a 78t spur for me. This is with a EA C027.
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