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Old 08-10-2007, 06:04 PM   #19021
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Originally Posted by m3ndo5a View Post
The belt tension/er is what help lessen belt hopping......
I almost forgot to address this comment. The tensioner on the 415 is not to reduce belt skipping at all. It's to reduce belt flutter. When the belt flutters, its creates drag which slows the car down. On a car engine, it's to do several things including maintaining correct cam timing.
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Old 08-10-2007, 07:15 PM   #19022
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Actually, contact alone does not equal friction. Contact is just that, contact. If I "touch" my arm with my finger vs. my whole arm, there is no more friction/heat being generated between the two. Friction requires two things. One is of course contact with another object but this alone is not friction. It is when these two objects are also moving against each other, rubbing or apposing. So if I "rubbed" my arm with my finger vs. whole arm your analogy would be correct but that’s not how a belt interacts with a larger or smaller pulley. Once the belt has wrapped around the pulley, the teeth of each body is not producing significant friction, they are just contacting each other. Like I said before, it is the meshing and un-meshing of the pulley and belt, the point in which the belt and teeth meet. It’s at this point there is rubbing. Also, the belt does bend around the pulley and this is friction as well. The tighter the radius the belt must bend around, the more friction is produced. The optional Tamiya pulleys have half the number of teeth which cuts the number of mesh and un-mesh cycles in half.

Wide pitch// mean less friction due to rubbing.....yes half the teeth have to touch


I agree there is a tighter turning radius of a smaller pulley but these pullies are not that much difference in size 35/36/37......so not enough for the drag that you speak of.....35/37 yes....but we will come back to that

1. A Larger pullies will be better for the simple fact is that it will require less work for the motor and not the Fricition of the Belts........just not enough there. All pullies are going to have one going in and one going out

2. It is too marginal to measure....

3. The teeth around the pulley will cause inward pressure. That is why this can be debate.......because this alone causes friction. So the more teeth pulling inward cause a sense of drag.

4. Its too marginal to measure

5. No matter how big the pullie is...the belts will hop, that is what the tension pulley is for....to correct the belts effeciency.

You are correct as to the bending part......My wife corrected me .


She got to stop reading over my shoulder


wife 4sale
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Old 08-10-2007, 07:29 PM   #19023
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Okay your just fishing now.......

Most belt hopping is pretty much center.....that is where you can find the tensioner//.

Maybe Maybe not

I believe what you are refering to is a cam chain and or a timing chain......if your talkinf ???serpenten?? belt slip it will not change you timing. I have replace these on my car plenty of time.....But I do know if the tension is too loose it will squreak.......too tight and it will pop.


But I will let you be right......for I do not want to waste my evening talking about nothing.


Good luck
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Old 08-10-2007, 11:17 PM   #19024
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I can see where your confusion is now. It seem as though you think that a tooth belt system has the same operating principals as a v-belt or serpentine type system. Well, this is not the case. Yes, a v-belt or serpentine belt does operate on a principal of friction because of its flat surface. This system requires more “inward pressure” as you called it also known as “pre-load” which is NOT friction. Also, these systems can not skip, they can only “slip”. If our touring cars had these types of belt systems, you would be correct………… but they don’t.

All R/C cars that I know of have belts that are of the tooth variety and these systems operate on the principal of “force” as apposed to “friction”. A lot like a chain. Tooth belts still require “preload” unlike a chain, but much less of it compared to a friction belt system, again, because tooth belts don’t operate under friction. As all R/C belt car users know, insufficient preload can and will result in “skipping” also know as “jumping” or “climbing”. Enter larger pulleys. BTW, my focus in on the diameter of the driving pulley not the driven pulley so yes, there is a much smaller percentage of change when adding a tooth to the diff pulley compared to adding a tooth to the center pulley.

If this doesn’t point you in the right direction……I give up. Anyway thanks for “letting” me be right. I guess I’ll return the favor and let you be wrong.
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Old 08-11-2007, 06:16 AM   #19025
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Originally Posted by jinsc View Post
I can see where your confusion is now. It seem as though you think that a tooth belt system has the same operating principals as a v-belt or serpentine type system. Well, this is not the case. Yes, a v-belt or serpentine belt does operate on a principal of friction because of its flat surface. This system requires more “inward pressure” as you called it also known as “pre-load” which is NOT friction. Also, these systems can not skip, they can only “slip”. If our touring cars had these types of belt systems, you would be correct………… but they don’t.

All R/C cars that I know of have belts that are of the tooth variety and these systems operate on the principal of “force” as apposed to “friction”. A lot like a chain. Tooth belts still require “preload” unlike a chain, but much less of it compared to a friction belt system, again, because tooth belts don’t operate under friction. As all R/C belt car users know, insufficient preload can and will result in “skipping” also know as “jumping” or “climbing”. Enter larger pulleys. BTW, my focus in on the diameter of the driving pulley not the driven pulley so yes, there is a much smaller percentage of change when adding a tooth to the diff pulley compared to adding a tooth to the center pulley.

If this doesn’t point you in the right direction……I give up. Anyway thanks for “letting” me be right. I guess I’ll return the favor and let you be wrong.
like said you are fishing......

But let me help you about out so you can be even righter..
http://www.tamiyausa.com/search.php?q=belt+friction
"Because tooth belts do not operate under friction"

I posted you a link on low friction belts......I can go with Yokomo Team bomber, Kyosho and so on.....

But guess what, there also Low friction pullies.... the wide pitch is one and not because of the spacing but because of the V-in pulley teeth

But we can clearly see who is confused now

I never say a serpentine belt would Skip...
But you said it would change the cam timing. Not True.. Simple due to its nature to SLIP.

Here is another reason you are fishing
I do not know what kind of car you drive.....But my Car Has a Low Friction Serpentine Belt on it, good for a Million miles. Ofcourse I will never tell you if that is true....she will be sold before then. Most V8 Mercedes comes with them. Doesn't every Car

Simply put
DUDE anything that is apply force and has movement will cause friction. ANYTHING.....and Everything. Even with lotion on it

Where are you Located I would love to race against you and your Theories......I am in RDU North Carolina. Come on down and bring some of those no friction, flutter, jumping, climbling, running , dancing, to the left step to the right step CHA CHA CHA belts and pullies. I am a A main racer club and event TCS...so I would not waste your time with a race.

You have proven something here.....

Guy I am just yanking your chain....its all good talk.

GOOD LUCK

TAMIYA WHERE IS MY MEDAL

Jimmy did you get your????

Last edited by m3ndo5a; 08-11-2007 at 06:39 AM.
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Old 08-11-2007, 07:26 AM   #19026
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Hey guy's I need a bit of help. I just fininish rebuilding my MRE 415.

I have a couple of question. My rear diff does not seem smooth. I rebuilded it like 2 times and still not smooth. seems to be kinda fine. I noticed this when I rotate the spure gear by hand (no motor attached or electronics.)It also feels really ruff too.

the second question. is the ackerman link from the servo to the steering rack. what lenght do you guy's recommend and should the servo saver be aligned perfect up and down. If you have a photo of your chassis with the servo saver with the car steering centered that would be great too.

Thanks in advance.

Andrew

Last edited by cyrrus; 08-11-2007 at 01:32 PM.
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Old 08-11-2007, 10:51 PM   #19027
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No, I did not get my TCS medal yet. I'll give them til the 15th. Then I'll email Gary or someone and ask about it. I think next year I may do Mini and maybe F103GT or whatever. Hank said he has a 103. I'll just wait til next year though before I decide. Seeing as how I'm... retired from racing.. I wanted to run my EvoIV today. But with the tornado damage. I had to wait around for the insurance lady to call. Then helped my dad toss on a tarp over the shed. Tomorrow/today I'll be vacuuming all the broken glass in my car..... So no Fayetteville racing...
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Old 08-12-2007, 05:28 AM   #19028
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I wish to replace the front hub carrier (Tamiya part number 51107) and the front upright (Tamiya part number 51103) with alloy ones if possible. Can someone tell me if there is a company that makes them, and where abouts to get them.
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Old 08-12-2007, 07:30 AM   #19029
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I wish to replace the front hub carrier (Tamiya part number 51107) and the front upright (Tamiya part number 51103) with alloy ones if possible. Can someone tell me if there is a company that makes them, and where abouts to get them.
Rcmart has some selection and RC Champ carriers items from Square. The Square version has 3 holes in a trangle fashion on the knuckle I have one I am happy with it.
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Old 08-12-2007, 07:34 AM   #19030
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Originally Posted by cyrrus View Post
Hey guy's I need a bit of help. I just fininish rebuilding my MRE 415.

I have a couple of question. My rear diff does not seem smooth. I rebuilded it like 2 times and still not smooth. seems to be kinda fine. I noticed this when I rotate the spure gear by hand (no motor attached or electronics.)It also feels really ruff too.

the second question. is the ackerman link from the servo to the steering rack. what lenght do you guy's recommend and should the servo saver be aligned perfect up and down. If you have a photo of your chassis with the servo saver with the car steering centered that would be great too.

Thanks in advance.

Andrew

If all the balls and plates are new the diff has to be smooth. either the items were dirty and you didnt clean them (you cleaned them right without assmuing they are because they are new)

another reason may be the diff ring didnt fit in the groove

you may have placed the thrust bearing and the springs in the wrong out dirve
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Old 08-12-2007, 08:06 AM   #19031
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Originally Posted by jinsc View Post
I can see where your confusion is now. It seem as though you think that a tooth belt system has the same operating principals as a v-belt or serpentine type system. Well, this is not the case. Yes, a v-belt or serpentine belt does operate on a principal of friction because of its flat surface. This system requires more “inward pressure” as you called it also known as “pre-load” which is NOT friction. Also, these systems can not skip, they can only “slip”. If our touring cars had these types of belt systems, you would be correct………… but they don’t.

All R/C cars that I know of have belts that are of the tooth variety and these systems operate on the principal of “force” as apposed to “friction”. A lot like a chain. Tooth belts still require “preload” unlike a chain, but much less of it compared to a friction belt system, again, because tooth belts don’t operate under friction. As all R/C belt car users know, insufficient preload can and will result in “skipping” also know as “jumping” or “climbing”. Enter larger pulleys. BTW, my focus in on the diameter of the driving pulley not the driven pulley so yes, there is a much smaller percentage of change when adding a tooth to the diff pulley compared to adding a tooth to the center pulley.

If this doesn’t point you in the right direction……I give up. Anyway thanks for “letting” me be right. I guess I’ll return the favor and let you be wrong.
Any two surfaces that come in contact with each other will create friction mate. laws of physics state that any force applied will create a force odf the same magnitude in the opposite direction.

so the the teeth are there to create friction so the belt doesnt "slip".

If you want no slip on your drive train remove the belt.

the belts we use are called syncronous Belts or timing belts (this is for people like me who cant spell the damn syncro word) For general in formation on belt systems you can read the documentation in the www.sdp-si.com web site.

and belts carry for on only one side. belts will have a slack side and a force side. belt tensioners have to be placed on the slack side to remove the slack. the tensioner on the force side will only reduce efficiency by increasing drag (friction)on the system which will result in premature failure of drive train bearings and belts. only belt guides are placed on the force side or where the added resistence is acceptable. (talking 2 pulley systems here)

so the so called tensioner is not a tensioner on the 415 but a guide. and what we do with the rotation of the bearing holders is called preloading. the 415 would be very efficient if we reduced some preload and placed a spring loaded belt tensioner on the chassis.

Of course best way to is to test it yourself. crank up the preload on the belts witht he bearing holders and try to rotate the tires. you will see it is very hard. it is because the preload is exceeding the drive train specs and causing excess friction on the system. (not only in the belt but in the bearings as well.) release and you will notice the systems works fine. if you can find a spring loaded tensioner and place is on the chassis you will notice that the systems is still smooth (not as much as a fully free one) but with out belt slack.

so to sum it up.... the more teeth the more friction you will have...
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Old 08-12-2007, 10:32 AM   #19032
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Sept. 2007 Tamiya TRF415 MSXX MR Edition...
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Old 08-12-2007, 10:42 AM   #19033
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Quote:
Originally Posted by cyrrus View Post
Hey guy's I need a bit of help. I just fininish rebuilding my MRE 415.

My rear diff does not seem smooth. I rebuilded it like 2 times and still not smooth. seems to be kinda fine. I noticed this when I rotate the spure gear by hand (no motor attached or electronics.)It also feels really ruff too.
Andrew
Take out the diff and totally loosen the screw. Squeeze the two halves inwards and rotate them. Do you feel any friction/grittiness? If so, then it's either one of the bearings in the diff or the balls/plate are dirty/worn and need replacing cleaning/resurfacing.

If all is smooth when you rotate it yourself, then chances are it's the thrust bearing. Clean it out very well, stuff it with AW grease, and rotate it between two fingers while squeezing. Any little bit of grit will be amplified when it's screwed in, and will likely need replacing if you can't get it totally clean and smooth.

Or, you can live with it for a bit longer and replace it once you notice your diff starts loosening on its own.
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Old 08-12-2007, 11:06 AM   #19034
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Sept. 2007 Tamiya TRF415 MSXX MR Edition...
WTH?!?!?! I thought the TRF415MSXX just have added features from the TRF415 MSX MRE... And now they are making a TRF415MSXX MRE and not TRF416??? What are they trying to do??? Can't they just make a 416 now and not that double X MRE...???
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Old 08-12-2007, 12:13 PM   #19035
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Originally Posted by m3ndo5a View Post
Wide pitch// mean less friction due to rubbing.....yes half the teeth have to touch


3. The teeth around the pulley will cause inward pressure. That is why this can be debate.......because this alone causes friction. So the more teeth pulling inward cause a sense of drag.



She got to stop reading over my shoulder

You can find the necessary force distribution and calculations on teh above page I gave.

and thats what wifes are for
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