2009.07.25, 11:06 AM
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#16
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tire schredder
Join Date: Sep 2008
Posts: 864
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CT im impressed with your machine knowledge!!! Tom CT is right, i could make the pinions but they would end up costing more than the spurs because of machine time and to be honest the spur is the one that needs to be more accurate. not only that but when you mold delrin it loses it material characteristics and actually gets soft which is why billet delrin is superior. you guys who are wanting the smaller spur gear, im having a hard time understanding why you cant just run a larger pinion to get the same ratio, in general you want to have a larger spur gear anyway for increased torque and better braking. one of the theories behind having a more efficient drivetrain is that you can actually run a larger spinion gear and get the same run time and higher top end because you dont lose as much power via the drivetrain loss. just a thought!!
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Marcus Williams
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2009.07.25, 11:49 AM
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#17
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The name is Tim
Join Date: Aug 2008
Posts: 417
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i see it now and you are right about it all. for the smaller spur i like gearing my shiz to the moon. i rather loose some torque because i tend to sqeeze the trigger to quickly. i like the turbo lag
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2009.07.25, 12:44 PM
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#18
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tire schredder
Join Date: Sep 2008
Posts: 864
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Quote:
Originally Posted by dvsstrike
i see it now and you are right about it all. for the smaller spur i like gearing my shiz to the moon. i rather loose some torque because i tend to sqeeze the trigger to quickly. i like the turbo lag
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you get the same effect from a larger pinion right? give the RR 53t a try, i think you will be pleasently surprised!
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Marcus Williams
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2009.07.25, 02:42 PM
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#19
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Registered User
Join Date: Feb 2005
Posts: 1,683
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Yo all did give me an idea for the molded PN pinions :P You all will see soon...
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2009.07.25, 05:26 PM
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#20
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Registered User
Join Date: Jun 2002
Location: Redwood City, CA
Posts: 562
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My first thought in looking at this design is that without the bearing, it will allow too much misalignment of the spur gear relative to the diff shaft. The spur wants to tilt anyway due to the force of the pinion on it. This misalignment can easily be seen in the third pic CT posted. This encourages vibration at speed, and could cause the spur gear to rub against the diff plates, adding friction. The bearing helps to keep the spur gear properly aligned for greatest power transmission efficiency.
Of course, I haven't tried them and other people have and like them, so what do I know...
ianc
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2009.07.25, 11:10 PM
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#21
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EMUracing
Join Date: Oct 2004
Location: NYC
Posts: 7,417
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Marcus, there are a few reasons that I want the smaller spur... one being controlling the weight distribution by moving the motor. I already run 14/52 on some of my cars, and that barely fits. With a smaller spur, I would have less issues, and could use the 13t instead and have close to the same ratio as with the 14/52, and not have to raise my motor or damper...
Also, smaller pinion = less weight
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EMUracing
Micro RC Syndicate /DG Designs /GSR /Reflex Racing /Fast By Faqish /MurderTown Racing
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2009.07.26, 01:12 AM
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#22
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tire schredder
Join Date: Sep 2008
Posts: 864
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Quote:
Originally Posted by ianc
My first thought in looking at this design is that without the bearing, it will allow too much misalignment of the spur gear relative to the diff shaft. The spur wants to tilt anyway due to the force of the pinion on it. This misalignment can easily be seen in the third pic CT posted. This encourages vibration at speed, and could cause the spur gear to rub against the diff plates, adding friction. The bearing helps to keep the spur gear properly aligned for greatest power transmission efficiency.
Of course, I haven't tried them and other people have and like them, so what do I know...
ianc
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there is no way that can happen there is no vibration because the pinion is DRIVING the spur, if the pinion is straight the spur is straight hence "floating spur. kyosho diffs do not have the bearing and they dont vibrate. the bearing really does nothing at all unless the diff is slipping it rotates 1:1 with the drive shaft.the spur does not want to "tilt" unless you physically do so. the picture that CT took looks like that because he touched the 2 spurs gears together to show the difference in width.
EMU, i love you like a brother but the dirt that gets on the car would make more of a difference than the weight of moving the pinion in .009" (that is the difference between 52 to 53 tooth spur). to put that in perspective your hair is about .005 to .007 on an inch. if you are seriously concerned about the weight of the pinion cut .100 of the end of the motor shaft it weighs about as much as 2 pinions!!
we just returned from racing and i am sure CT is gonna chime in but on my car the acceleration is phenomenal. CT and i could pull on jacob about 3 ' at the start of the race EVERYTIME!! it was crazy!! and coming out of the slow turns you had to actually back of sooner because the cars acceerated sooo much quicker, i ended up having to turn the EPA down about 10%. unfortunately none of us run stock, i am gonna do some stock testing this week, its gonna make a bigger difference in stock.oh and i almost forgot, i actually geared up 11/53 with the 35t PN, i normally run 9 or 10 and i still got over 20minutes of run time. i normally run 12/53 with the pn70!!!
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Marcus Williams
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2009.07.26, 04:04 AM
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#23
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Registered User
Join Date: Jun 2002
Location: Redwood City, CA
Posts: 562
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Quote:
kyosho diffs do not have the bearing and they dont vibrate.
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True, but they have a bushing sleeve for the diff shaft built in to the spur that's at least 5 mm in length. This effectively precludes any concentric axis of rotation problems between spur gear and diff shaft.
Quote:
The bearing really does nothing at all unless the diff is slipping it rotates 1:1 with the drive shaft.
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It does that. But it also provides position constraint for the spur gear relative to the diff shaft
Don't get me wrong. Christian has some great ideas and this may be one of them. I haven't tried it. I'm just offering my initial thoughts for theoretical discussion. Healthy skepticism as they say...
ianc
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2009.07.26, 04:09 AM
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#24
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Registered User
Join Date: Feb 2005
Posts: 1,683
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I agree with all the things Marcus stated. This design is not new, it has been proven in larger scales through out time. 12th and 10th scale cars don't use a center bearing, because they are simply not needed, they are simply extra rotational mass that contribute nothing but binding to the differential. The pinion drives the spur, and so long as this is the case, the spur will spin true. In the case you have a loose spur "side-to-side" the spacer kit will keep it from wandering.
I understand what EMU says about shifting the weight of the motor further forward or back with different size spurs, but honestly the difference in size between a 51 and 53 is so negligible, that I doubt it will make a true "noticeable" difference in weight placement. If we were talking about a 41 tooth to a 44 in standard pitch (0.5 module) then the difference is huge, but in this case, it is miniscule. The only benefit from a 51 tooth spur would probably be only noticeable in gearing related issues, for fine tuning purposes.
As how they perform, all I can say is WOW!!! Both Marcus and I were pulling Jacob a good 3-5 feet from a dead start at the begining of the race. It was TRULY IMPRESSIVE. I actually out-qualified Jacob tonight by 4 tenths of a second tonight, and should have beaten him in the main if it had not been for some tape getting caught in my rear tire in the main. Considering I have only been to the track twice since the KO GP, I would say they definitely contributed to my car performing better than his tonight. Jacob finished with a 64 lap run on the PN layout in the main, I finished with a low 63 (should have been a low 64), on the same lap as him.
The car was very quiet and very fast. Mr. Feinstein kept saying that Jacob needed a different gear ratio on his car to make it faster. I was using a 9 tooth pinion, with a 35 turn motor. Jacob was using a 33 turn motor with the same gear. My car was by far faster in acceleration and at least as fast in top speed. We both used ORION 750's...
Skeptical as anyone wants to be, these spurs make your car faster, period. It is not about it being a Reflex Product, it is a matter of Physics.
BTW, I just green- lighted the 51 Tooth spur project tonight. I guarantee that if you use these spurs, you will not be dissapointed.
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2009.07.26, 04:10 AM
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#25
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Registered User
Join Date: Feb 2005
Posts: 1,683
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Oh, and BTW, bigger spurs with bigger pinions are more efficient than smaller spurs with smaller pinions...
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2009.07.26, 07:57 AM
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#26
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tire schredder
Join Date: Sep 2008
Posts: 864
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Quote:
Originally Posted by ianc
True, but they have a bushing sleeve for the diff shaft built in to the spur that's at least 5 mm in length. This effectively precludes any concentric axis of rotation problems between spur gear and diff shaft.
It does that. But it also provides position constraint for the spur gear relative to the diff shaft
Don't get me wrong. Christian has some great ideas and this may be one of them. I haven't tried it. I'm just offering my initial thoughts for theoretical discussion. Healthy skepticism as they say...
ianc
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there is no bushing built into the kyosho spur, if you notice the "bushing" you are talking about is the same thickness as the "bushings" around the diff balls!! it is in essence the exact same thickness as the RR spur, its just an illusion. trust me guys i do this all day everyday, the RR spurs ID (inside diameter) is the exact same size as the bearings ID so it has the same effect.
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Marcus Williams
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2009.07.26, 08:15 AM
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#27
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tire schredder
Join Date: Sep 2008
Posts: 864
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let me correct that statement, the center "boss" on the kyosho gear is actually thinner than the boss's on the diff balls negating what you were trying to say what that means is that the spur gear will actually move more than previously thought! if you look closely, the boss's around the dif balls are thicker on one side of the spur than the other. on the thick side the center boss is even with the diff balls but on the other side there is no boss in the center but there are still diff ball boss's.
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2009.07.26, 09:51 AM
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#28
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The name is Tim
Join Date: Aug 2008
Posts: 417
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someone always has a negative to say... the spurs look great. and is a step forward in this scale. all this tech has been proven already in 12th and in 10th
scale pan cars
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Team Associated
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2009.07.26, 12:10 PM
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#29
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PN RacingTEAM Driver
Join Date: Jul 2007
Location: southern calfornia
Posts: 1,530
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SWEET...... send me some so i can make my car FASTER!......
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2009.07.26, 04:50 PM
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#30
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Registered User
Join Date: Jun 2002
Location: Redwood City, CA
Posts: 562
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Quote:
there is no bushing built into the kyosho spur, if you notice the "bushing" you are talking about is the same thickness as the "bushings" around the diff balls!!
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It occurs to me that you are talking about the Kyosho ball diff. I was referring to the stock K gear diff, and if you disassemble one, you will find that there is indeed a bushing about 5 mm long cast into it.
I don't have a K ball diff, so I can't comment on its construction.
Quote:
someone always has a negative to say...
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And someone always confuses discussion with negativity. I'm a very good customer of Reflex and will continue to be. I merely expressed my initial thoughts about the product. It is OK to do that here, isn't it? Or is that not allowed?
ianc
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