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Old 09-06-2011, 06:52 AM   #1051
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He needs to know the internal drive ratio so he can figure out the final drive ratio.


Your 3.3 is not factoring in the internal drive ratio which is usually around 2 or 2.5.

Overall drive ratio : spur diveded by pinion times internal ratio will give you the FDR.
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Old 09-06-2011, 07:12 AM   #1052
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Originally Posted by D Starks View Post
There is a rebuild kit available. Use part number 10553.

Here is a link:

http://www.nitrohouse.com/advanced_s...fb415426a8a1e9

Very nice, I'll be adding this to the site.

Please, if I am missing items on my site, let me know and I will get it on there ASAP.
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Old 09-06-2011, 07:33 AM   #1053
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Originally Posted by Timbulb View Post
He needs to know the internal drive ratio so he can figure out the final drive ratio.


Your 3.3 is not factoring in the internal drive ratio which is usually around 2 or 2.5.

Overall drive ratio : spur diveded by pinion times internal ratio will give you the FDR.
Micro-E was asking for the internal(diff ratio) and that is a fixed 3.3 and not 2-2.5. The spur/pinion is the primary ratio and that is a variable.
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Old 09-06-2011, 10:29 AM   #1054
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43 Ring & 13 Pinion Gear (3.30:1 Ratio)
Thanks rcwck, I think that was the piece I was missing. Soooo, if I have the math correct:

43/13 = 3.30 -- diff ring gear/ diff pinion
51/14 = 3.64 -- spur / pinion
FDR = 3.30 * 3.64 -- 12.01

Wow, interesting, much shorter than 1/10th touring cars. Everyone is always talking about FDR and has an instant guage on how appropriately geared a car is given the motor wind. I don't see FDR discussed much with these cars.

The reason I was curious is that the 14t pinion was wayyy too slow for my last race with a 190' straight. Looks like I'll need to go to a 16t or 17t for my 2050kv motor on a straight like that. FDR of 10.5 or 9.9 respectively.

Just for further curiosity, what are FDRs, motor kv, and track length are folks running with this car??
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Old 09-06-2011, 11:12 AM   #1055
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Originally Posted by Micro-E View Post
Thanks rcwck, I think that was the piece I was missing. Soooo, if I have the math correct:

43/13 = 3.30 -- diff ring gear/ diff pinion
51/14 = 3.64 -- spur / pinion
FDR = 3.30 * 3.64 -- 12.01

Wow, interesting, much shorter than 1/10th touring cars. Everyone is always talking about FDR and has an instant guage on how appropriately geared a car is given the motor wind. I don't see FDR discussed much with these cars.

The reason I was curious is that the 14t pinion was wayyy too slow for my last race with a 190' straight. Looks like I'll need to go to a 16t or 17t for my 2050kv motor on a straight like that. FDR of 10.5 or 9.9 respectively.

Just for further curiosity, what are FDRs, motor kv, and track length are folks running with this car??
Micro-E,

You'll have to go much BIGGER for mph on the straight. Our straight is ~200' and I am around a 22/47 for ~55mph for that KV and a good 4S. Basically gear TALL and check motor/ESC temps. Track temp is a large factor. I'm testing some turbine(EDF) fans that are variable speed TX controlled for super cooling for those hot days. Play with this, it's pretty accurate:
http://www.scriptasylum.com/rc_speed/top_speed.html
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Old 09-06-2011, 11:54 AM   #1056
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Quote:
Originally Posted by Micro-E View Post
Just for further curiosity, what are FDRs, motor kv, and track length are folks running with this car??
Run my car on an open 200ft x 300ft ashfalt parking lot at a mass transit depot.

Motor: 1930KV Tekin T8
Tekin Setup : 30deg boost 9000start - 25500end

4S Bashing Setup : (52-55mph)
23/47 = 2.04 -- spur / pinion
FDR = 3.30 * 1.88 = 6.743

4S Track Setup : (43-48mph)
19/47 = 2.47 -- spur / pinion
FDR = 3.30 * 2.47 = 8.151

Motor: 1930KV Tekin T8
Tekin Setup : 10deg boost 10000start - 32000end

6S Bashing Setup : (58-63 mph)
19/47 = 2.47 -- spur / pinion
FDR = 3.30 * 2.76 = 8.151

Just got my 6S batteries 2 weeks ago and they are stupid fast for my small parking lot. (not enough room to brake)
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Last edited by Capt'N_Slow; 09-16-2011 at 07:46 AM.
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Old 09-06-2011, 02:42 PM   #1057
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Thanks guys! That was some good info.

I was playing around with that speed site and it seems to me that a 19t pinion is good and safe to start with. If I need more umph, I could add in some boost. One of the GTPs I was comparing mine to - I believe - has a 2650kv and a 15t pinion, so a 19-20t puts me at the same theoretical numbers.

This is great to have some decision factors for $10+ pinions other than guessing... (damn, these pinions are expensive!)
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Old 09-06-2011, 03:13 PM   #1058
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I assume my LX-2E has the same transmission ratio as the GTP2E. What are the differences in these two chassis? Both are made by Hong Nor I assume? I love my LX-2E to death, but I love on-road speed runs when I get bored of off-road. Bone stock, my LX-2E has hit 75.5mph with only a 19T pinion (51T spur), (2) Venom 30C 3200mah packs and a T8 2250 on 6S. Going for 80mph this week with a 21T pinion. The stock tires I assume are going to come apart anytime now lol. Trying to decide on a set of speed run tires between the OFNA Belted treads, or the Sweep 55's.

What would it take to fit a GTP2E shell on my LX-2E?

First post here folks, and I have been into R/C for over 25 years.
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Old 09-06-2011, 03:16 PM   #1059
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Originally Posted by Micro-E View Post
I was playing around with that speed site and it seems to me that a 19t pinion is good and safe to start with. If I need more umph, I could add in some boost. One of the GTPs I was comparing mine to - I believe - has a 2650kv and a 15t pinion, so a 19-20t puts me at the same theoretical numbers.
That setup should hit 85-90mph without an issue with a 19T pinion. Which motor do you run? My RX8/T8 combo is insane.
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Old 09-06-2011, 04:35 PM   #1060
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Originally Posted by mtrsprt View Post
That setup should hit 85-90mph without an issue with a 19T pinion. Which motor do you run? My RX8/T8 combo is insane.
I have the Tekin RX8/T8 2050kv combo w/4S lipo. The stock 14T pinion wound out 1/3rd of the way down the straight... I borrowed a 15T and still not enough top speed, I was still passed like I was standing still.
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Old 09-06-2011, 04:43 PM   #1061
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I have the Tekin RX8/T8 2050kv combo w/4S lipo. The stock 14T pinion wound out 1/3rd of the way down the straight... I borrowed a 15T and still not enough top speed, I was still passed like I was standing still.
Right. 14.8V X 2050 = 30,340rpm. I can eat rice with chopsticks and still drive my buggy at the same time on 4S. That's with a 2250 motor.

Sounds like you need something along the lines of a 16-18T. Figure @ 30,00rpm, each tooth will net about 3-4mph on AVG.
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Old 09-06-2011, 05:36 PM   #1062
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I have a couple of really good 3s 5000 50c packs I am going to try next at Charlie race.

I am going to gear it 19t with Tekin 2650 see how it goes.
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Old 09-09-2011, 02:46 AM   #1063
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Just ordered a GTP2-E. Going to swap the electrics from my LX2-E over to it, and go for 100mph.

My LX2-E just went 83.8mph yesterday after the swap to a 21T pinion, and removal of rear wing.

Going to be locking the center differential with hot glue like I did with the LX2-E. Worked like a charm. Much more traction.
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Old 09-09-2011, 04:29 AM   #1064
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Quote:
Originally Posted by mtrsprt View Post
That setup should hit 85-90mph without an issue with a 19T pinion. Which motor do you run? My RX8/T8 combo is insane.
Gotta remember Micro's road racin with a 4S. Mid 50mph is more like it.
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Old 09-12-2011, 08:38 AM   #1065
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Originally Posted by mtrsprt View Post

...
Going to be locking the center differential with hot glue like I did with the LX2-E. Worked like a charm. Much more traction.
You won't need this, it doesn't come with a center diff, it has a spool;
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