Tamiya TRF 801XT Build Thread
12-02-2010, 07:32 PM
#176
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RE: Tamiya TRF 801XT Build Thread
ORIGINAL: secretsg
Dude I just looked thru the older posts. 18T pinion is huge with your medusa motor. 50/18 * 43/10 = 11.94 FDR.
A 2 speed savage with 18T pinion and 49T spur = 2.72 Spur ratio
2.72x 7.33 = 19.93:1 final drive ratio in 1st gear
2.72 x 5.08 = 13.81:1 final drive ratio in 2nd gear
Dude I just looked thru the older posts. 18T pinion is huge with your medusa motor. 50/18 * 43/10 = 11.94 FDR.
A 2 speed savage with 18T pinion and 49T spur = 2.72 Spur ratio
2.72x 7.33 = 19.93:1 final drive ratio in 1st gear
2.72 x 5.08 = 13.81:1 final drive ratio in 2nd gear
Just kidding. Seriously though, I should have PMd you and been patient, and asked. Problem was, I didn't know the tranny gear ratio calc I use to compute FDR (the 43/10 you provide above). Am I dumb and missed it in the manual?What am I better off with then? 14T? 12T gives me an FDR of almost 18, which matches my rollout. Or should I gear higher than 12T since it's a big BL system? My problem is I know the theoretical "make FDR near your rollout" calc, but don't know how to adjust for BL, or big BL setups.
12-02-2010, 08:11 PM
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RE: Tamiya TRF 801XT Build Thread
There is no tranny ratio in the 1/8th scales. It's just a straight S/CB X Diff calc. I counted the pinion and crown gear tooth in the diff. (Alternatively you can use the FDR given by tamiya 16:54 / by 50/13 to get the 4.3 diff ratio)
The savage is much more complicated. Diff + S/Cb + 1st gear / 2nd gear ratio + tranny to output shaft..........
I would give 14T / 15T a shot. I emailed tekin and the recommendation was 1350/1550 for 6s and 1550/1700 for 5s with 14-16T pinion.
The unloaded rpm would look like this:
1350 1550 1700 2200
22.2 29970 34410 37740 48840
18.5 24975 28675 31450 40700
14.8 19980 22940 25160 32560
So your setup is middle of the road in terms of recommended RPM. The 5s/6s would have higher efficiency so I would just go for a safer gearing.
12T with stock spur might be under gearing, and causing too much rpms.
The savage is much more complicated. Diff + S/Cb + 1st gear / 2nd gear ratio + tranny to output shaft..........
I would give 14T / 15T a shot. I emailed tekin and the recommendation was 1350/1550 for 6s and 1550/1700 for 5s with 14-16T pinion.
The unloaded rpm would look like this:
1350 1550 1700 2200
22.2 29970 34410 37740 48840
18.5 24975 28675 31450 40700
14.8 19980 22940 25160 32560
So your setup is middle of the road in terms of recommended RPM. The 5s/6s would have higher efficiency so I would just go for a safer gearing.
12T with stock spur might be under gearing, and causing too much rpms.
12-02-2010, 08:31 PM
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RE: Tamiya TRF 801XT Build Thread
Sorry, I know we don't have a tranny in there, just used the "trans gear ratio" term as a horrible replacement for the calc. Anyway, just to be clear so I understand:
I see how you backed out the 4.3 diff ratio based on the 16.54 FDR tamiya gives with stock gearing. However, how do you get the diff ratio by calculation? Or must use the FDR tamiya provides? Wondering which gears I divide by to get that 4.3. "Ring" gear on the center diff vs. the input pinion going into the front/rear diff housing? Not sure what S/Cb is. (Sorry for being dense).
Sounds like I'll give 14-15T a shot. Thanks for that.
I see how you backed out the 4.3 diff ratio based on the 16.54 FDR tamiya gives with stock gearing. However, how do you get the diff ratio by calculation? Or must use the FDR tamiya provides? Wondering which gears I divide by to get that 4.3. "Ring" gear on the center diff vs. the input pinion going into the front/rear diff housing? Not sure what S/Cb is. (Sorry for being dense).
Sounds like I'll give 14-15T a shot. Thanks for that.
12-02-2010, 08:34 PM
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RE: Tamiya TRF 801XT Build Thread
4.3 comes from the diff gears. The crown(gear connected to diff cup) is 43 while the pinion (gear connected to center outdrive) is 10. So for every 4.3 revolutions of the center drive shaft you get one rotation on the wheels.
S/CB = Spur / Clutchbell or in your case pinion.
S/CB = Spur / Clutchbell or in your case pinion.
12-02-2010, 08:44 PM
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RE: Tamiya TRF 801XT Build Thread
Awesome, got it (and wrote it down) - thanks for that. Makes sense.
Final question: I see your unloaded RPM chart above. I also see that with my setup (4s or 14.8V, 2200 motor), I'm at 32560 RPMs.
What I don't understand is what your chart means. [&:] I guess I see that and don't get how that means my setup is in the recommended RPM range.
Final question: I see your unloaded RPM chart above. I also see that with my setup (4s or 14.8V, 2200 motor), I'm at 32560 RPMs.
What I don't understand is what your chart means. [&:] I guess I see that and don't get how that means my setup is in the recommended RPM range.
12-03-2010, 11:34 AM
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RE: Tamiya TRF 801XT Build Thread
Think I'm going to go with a 14T pinion and the Mamba Monster ESC. Hopefully that'll do it well here on 4s with my motor. Debated the more expensive Tekin Rx8, but I already have the CastleLink stuff set up and am familiar with their interface, so will save a few $$ and stick to that.
12-03-2010, 05:25 PM
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RE: Tamiya TRF 801XT Build Thread
No point for the Rx8 if you don't run the sensored setup.
It helps on jumps on air control and applications involving a lot of braking. Not useful for bashing.
It helps on jumps on air control and applications involving a lot of braking. Not useful for bashing.
12-07-2010, 06:16 AM
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RE: Tamiya TRF 801XT Build Thread
Yeah, I think you'll be cool with that. I'm running the same motor KV (just a different type), and we'll both be on 4s, so I think 14T will do ya ok.
01-12-2011, 06:38 AM
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RE: Tamiya TRF 801XT Build Thread
Most interesting - where did you get it? How's the slipper diff supposed to help? I thought maybe the center diff in general helps on drivetrain stress.
By the way, what is the recommended center diff fluid weight? I put in the stuff from the kit, which, of course, is never good enough in any review you ever read (for any kit that ever includes diff fluid - so I wonder why they ever bother to include it in the first place). Wondering what ill effects I might observe running too light of a fluid. (Dumps all power to the front wheels under heavy acceleration/takeoff?)
By the way, what is the recommended center diff fluid weight? I put in the stuff from the kit, which, of course, is never good enough in any review you ever read (for any kit that ever includes diff fluid - so I wonder why they ever bother to include it in the first place). Wondering what ill effects I might observe running too light of a fluid. (Dumps all power to the front wheels under heavy acceleration/takeoff?)
01-12-2011, 06:56 AM
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RE: Tamiya TRF 801XT Build Thread
I stand corrected. The Oople review guy liked that the kit included 10,000 wt diff oil, and used it in the center. Of course, he whined about not having multiple weights in the kit so you can tune front/rear, but whatever.
Maybe the stock 10k weight all around is good enough for me. If I notice weird behavior, I can reconsider.
Maybe the stock 10k weight all around is good enough for me. If I notice weird behavior, I can reconsider.
01-19-2011, 07:16 AM
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RE: Tamiya TRF 801XT Build Thread
When you guys ordered how long did you wait before the transaction was approved?? Myn has been 2 days and still nothing but (pending)
01-19-2011, 07:41 AM
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RE: Tamiya TRF 801XT Build Thread
Hmm, can't recall, but it shouldn't be too much longer for you. Just wait a bit more and you should be ok - if not, you can always contact them and ask.
On a side note, a ton of my previously uploaded images in this thread are broken now. Thanks a ton, RCU. Uploading them again would suck (slow connection at home, where my pics reside).
On a side note, a ton of my previously uploaded images in this thread are broken now. Thanks a ton, RCU. Uploading them again would suck (slow connection at home, where my pics reside).
01-19-2011, 08:18 AM
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RE: Tamiya TRF 801XT Build Thread
just once (test run) - havent finished the body yet. And it got too cold.....(err, and I broke my Ezrun 80A esc).
So I didn't get a chance to go rough on it, but it was a pretty smooth drive.
So I didn't get a chance to go rough on it, but it was a pretty smooth drive.
01-19-2011, 03:26 PM
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RE: Tamiya TRF 801XT Build Thread
Wow Collector you went all out on the MMM ESC/motors! Where was this great sale and why wasn't I pm'd! 
I'm also interested in the slipper diff how does it help?
I'm also interested in the slipper diff how does it help?
01-20-2011, 02:59 PM
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RE: Tamiya TRF 801XT Build Thread
Dstaks716 I ordered my kit last thursday and have not gotten it yet. I started trying to order the kit in november and after a few unsuccesful attempts I had to order it over the phone. I had to contact them and they cancelled the order otherwise they said the orders gets refunded in 7 days. They were great to deal with but you will need to email them first. When I called in they had my name on a list that said I could call the order in. I will be keeping mine nitro, for now since I have no idea what all goes in to brushless. I haven't looked it up but have a good idea. I was into electric when I was about 12 so its been a while. My 6yr daughter wanted a r/c truck and I couldn't bring myself to buy a walmart one. So she got a Inferno st truggy and she rips it up. I picked up a Ofna picco and its fast but always perferred trucks. So this is going to be perfect just need to figure out a radio and exhaust.
01-20-2011, 03:01 PM
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RE: Tamiya TRF 801XT Build Thread
Dstaks716 I ordered my kit last thursday and have not gotten it yet. I started trying to order the kit in november and after a few unsuccesful attempts I had to order it over the phone. I had to contact them and they cancelled the order otherwise they said the orders gets refunded in 7 days. They were great to deal with but you will need to email them first. When I called in they had my name on a list that said I could call the order in. I will be keeping mine nitro, for now since I have no idea what all goes in to brushless. I haven't looked it up but have a good idea. I was into electric when I was about 12 so its been a while. My 6yr daughter wanted a r/c truck and I couldn't bring myself to buy a walmart one. So she got a Inferno st truggy and she rips it up. I picked up a Ofna picco and its fast but always perferred trucks. So this is going to be perfect just need to figure out a radio and exhaust.
01-21-2011, 01:46 AM
#199
RE: Tamiya TRF 801XT Build Thread
Ive really been busy so I have not tested the slipper since it was installed, the sale was on the Castle website but the MMM are gone and there is an 1580 motor left, I posted this a while back but got no response so I pretty much forgot about it
01-21-2011, 08:45 PM
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RE: Tamiya TRF 801XT Build Thread
ORIGINAL: trackweapon
Dstaks716 I ordered my kit last thursday and have not gotten it yet. I started trying to order the kit in november and after a few unsuccesful attempts I had to order it over the phone. I had to contact them and they cancelled the order otherwise they said the orders gets refunded in 7 days. They were great to deal with but you will need to email them first. When I called in they had my name on a list that said I could call the order in. I will be keeping mine nitro, for now since I have no idea what all goes in to brushless. I haven't looked it up but have a good idea. I was into electric when I was about 12 so its been a while. My 6yr daughter wanted a r/c truck and I couldn't bring myself to buy a walmart one. So she got a Inferno st truggy and she rips it up. I picked up a Ofna picco and its fast but always perferred trucks. So this is going to be perfect just need to figure out a radio and exhaust.
Dstaks716 I ordered my kit last thursday and have not gotten it yet. I started trying to order the kit in november and after a few unsuccesful attempts I had to order it over the phone. I had to contact them and they cancelled the order otherwise they said the orders gets refunded in 7 days. They were great to deal with but you will need to email them first. When I called in they had my name on a list that said I could call the order in. I will be keeping mine nitro, for now since I have no idea what all goes in to brushless. I haven't looked it up but have a good idea. I was into electric when I was about 12 so its been a while. My 6yr daughter wanted a r/c truck and I couldn't bring myself to buy a walmart one. So she got a Inferno st truggy and she rips it up. I picked up a Ofna picco and its fast but always perferred trucks. So this is going to be perfect just need to figure out a radio and exhaust.