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Old 03-04-2006, 09:33 AM   #13141
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Originally Posted by g12314
Just checked Tamiya USA's site and they list the 415 4mm chassis as "See your local hobbyshop". Anybody have any details about its release?

Thanks,
Jimmy

Jimmy...that's awesome you are at TCS at Trackside and still find time to check updates online! LOL

4mm chassis...nice.

I was looking at the pic of it on Tamiya's site....does that 4mm chassis have the hole drilled for the MSX center brace thing? From the picture it looks like it doesn't.

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Old 03-04-2006, 09:45 AM   #13142
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Quote:
Originally Posted by Nexus
Jimmy...that's awesome you are at TCS at Trackside and still find time to check updates online! LOL

4mm chassis...nice.

I was looking at the pic of it on Tamiya's site....does that 4mm chassis have the hole drilled for the MSX center brace thing? From the picture it looks like it doesn't.

No hole in that pic but i would presume it will be changed beofre it is put in production.
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Old 03-04-2006, 09:53 AM   #13143
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Old 03-04-2006, 09:57 AM   #13144
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Default 4mm chassis

I've posted a message for Steve in the Speedtech section a few days ago, but I've had no reply.
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Old 03-04-2006, 01:12 PM   #13145
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Originally Posted by bender
The problem with the belt wrap improvements you guys are talking about is that you increase efficiency in one area and reduce it in another.

Buy increasing the diameter of the pulley, the belt doesn't have to follow as tight a bend as previously, and this increases efficiency.

However, as the pulley diameter increases, so does the number of teeth which are in contact with the belt at any given moment, - and this reduces efficiency.

And it's just as complicated if you only change (for example) the diff pulley.

If you increase the size of the diff pulley, you lose efficiency by increasing the number of teeth in contact with the belt, but you gain efficiency by increasing the bend-diameter the belt has to travel over the pulley, but you also increase efficiency at the layshaft pulley because the belt angle to the layshaft has been reduced, therefore there are now less teeth in contact with the layshaft pulley!

Of course, one thing that is forgotten is belt tension, which severely effects efficiency:
bigger pulleys = more teeth in contact with the belt = looser belt tension possible = better efficiency

Err no, more teeth in contact won't change the efficiency, but it will reduce wear on both the pulley and the belt because each teeth has to transmit less power.
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Old 03-04-2006, 02:53 PM   #13146
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Quote:
Originally Posted by TRF415boy
Err no, more teeth in contact won't change the efficiency, but it will reduce wear on both the pulley and the belt because each teeth has to transmit less power.
In my experience it does, and has always done so with any car I've ever raced, and I have over the past 20 years conducted various tests both physical and computer simulated, which prove the theory is sound.

You can disagree if you like, but don't simply post that I'm wrong without even an explanation as to why I'm supposedly wrong
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Old 03-04-2006, 03:42 PM   #13147
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Quote:
Originally Posted by bender
In my experience it does, and has always done so with any car I've ever raced, and I have over the past 20 years conducted various tests both physical and computer simulated, which prove the theory is sound.

You can disagree if you like, but don't simply post that I'm wrong without even an explanation as to why I'm supposedly wrong
Simply put, the teeth once in contact theoretically don't move relatively to the pulley, so there cannot be any change in efficiency because there are more teeth in contact. In reality there are small movements due to the efforts not being constants: imperfections of the track, the drivetrain (like when you turn the driveshafts will induce variations of the load on the belt and subsequently the drivetrain), the motor (due to the design of motors the torque isn't constant during a revolution of the armature). With more teeth in contact those movements will be smaller due to the fact there is more material in contact between the belt and the pulley. Also, with bigger pulleys the centrifugal force on the belt is bigger, which means as the car goes quicker the belt gets looser around the pulley and frees the drivetrain up a bit more.

I think what you're seeing is the change in linear speed of the belt which will decrease efficiency to a certain level. Thing is, this only happens when the driven pulley (aka diff/one way/spool pulley) has its number of teeth risen, because it determines the linear speed of the belt (for a give tyre diameter, which does not vary with rubber tyres, but does with foam).

If you put a bigger centre pulley you will only change belt bending and the rotational speed of the shaft. You will not increase the losses due to the belt making and losing contact with the pulley simply because the number of those contacts made and lost for a given traveled distance is given by the diff pulley's number of teeth.

BTW computer simulation isn't a proof, it is barely a way of getting a ballpark idea of where things might stand (if you're lucky and if you have taken the right parameters and assumptions) .
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Old 03-04-2006, 08:56 PM   #13148
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Quote:
Originally Posted by Nexus
Jimmy...that's awesome you are at TCS at Trackside and still find time to check updates online! LOL

4mm chassis...nice.

I was looking at the pic of it on Tamiya's site....does that 4mm chassis have the hole drilled for the MSX center brace thing? From the picture it looks like it doesn't.

Aside from the hole that Rick mentioned.. it would suck for them to come out with this chassis and then come out with the new steering system which needs different holes as well. On top of that.. carpet season is coming to a close soon (for some) and this chassis would usless til next season. Of course next season Tamiya will have a new car!!
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Old 03-04-2006, 09:37 PM   #13149
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Hey guys,

Why is it that Satoshi/Rheinard, etc, use a bumper that is very narrow?? Do anyone know why?? They either cut up the standard Tamiya one or they run the narrow one made by Square.

Any ideas?
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Old 03-04-2006, 09:54 PM   #13150
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Good question, I've always wondered the same... I have theories... but unsure as to why..
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Old 03-04-2006, 09:59 PM   #13151
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Eirik will know. I got a setup from him once when I got my RCManiax spool a while ago now, and on the setup sheet it showed how far along the bumper he trimmed, so hopefully we'll get the right answer soon enough.
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Old 03-04-2006, 10:56 PM   #13152
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Quote:
Originally Posted by F. Alonso
Hey guys,

Why is it that Satoshi/Rheinard, etc, use a bumper that is very narrow?? Do anyone know why?? They either cut up the standard Tamiya one or they run the narrow one made by Square.

Any ideas?
My personal theory is that it lets them run more aggressive around traffic without taking them out..... ie. more rubbing and racing without taking out the car in front.
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Old 03-04-2006, 11:51 PM   #13153
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hhmmmmm..... interesting theory ! I am curious as to why they run the narrow bumbers too..
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Old 03-05-2006, 03:42 AM   #13154
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Just a guess.... maybe to avoid the bumper bottoming on kerbs/ripple strips when taking that millimetre perfect line around the apex....
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Old 03-05-2006, 03:59 AM   #13155
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Running the narrow bumper will give you more steering!!!!
I dont know how or why....... something with airflow I guess.
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