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Post by dave632 on Mar 7, 2015 15:29:04 GMT -7
Did some comparison tests with ball bearings.
Tried some on the rear axle first in a BSRT car. Lots o trouble doing that since there is not much materiel to work with there. Got it working and picked up about .5 mph and about .005 in ET. Put a rear motor ball bearing in and got about the same result. Went from a best of 23.92 to 24.98 after all the changes
ET was around a .01 total. Noticed that the increments were minimal in the 60' if any same for the 330 then in the 660 and finish there were small improvements. Seems like the difference comes in the form of a little more speed in the traps which was worth about an average of .01. Unless the absolute max is needed changes are not worth it. None of my high speed cars had ball bearings. That will probably be my next test.
Not much for all the effort.
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Deleted
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Post by Deleted on Mar 7, 2015 17:23:54 GMT -7
have experienced similar.
roundy round guys get more out of ball bearings than drag guys.
larger scale drag cars seem to get a good advantage with ball bearings in the fastest classes. but not much in lower powered cars.
and keeping them clean, even with shields, is impossible
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Post by dave632 on Mar 7, 2015 19:34:14 GMT -7
Raced 1/10th scale and 1/12th scale RC cars when my sons were younger. There was a definite difference between Bronze or Oilite bearings and ball bearings then.
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lewis
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Post by lewis on Mar 7, 2015 20:10:31 GMT -7
I went with the bearing just because I'm running a balanced arm. I may be wrong but I figure if I'm going to pay for balancing then I might as well make it worth while. The stock wizzard bushings dont fit real tight around arm shaft so that leaves play for the shaft to move. Even with bushings in a Tyco once the oil blows out then you loose your cushion so arm starts to move. If I run bearings and bearing is tight around shaft then there is no play so paying to balance is not wasted. I know bearings are expensive and it may not matter with it without but that's my take.
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Post by dave632 on Mar 7, 2015 20:37:09 GMT -7
There was a definite improvement with the bearings, just not what I expected.
I am going to put a motor set in one of the 50 mph cars and see if it makes more
of a difference there.
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lewis
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Post by lewis on Mar 7, 2015 20:53:57 GMT -7
I dunno if it will help a crap load with speed but will deff keep wear to a minium and make arm alot smoother.
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Post by FlatBlackCamaro on Mar 7, 2015 21:06:27 GMT -7
Dave,
When putting the bearings on is the tolerance tight enough you need to press it on, or heat one and cool the other? I ask because if the shaft just slides through the I.D. of the bearing it could be loose and not utilizing the bearing and it could be acting as a bushing on the I.D of the bearing.
Just trying to think outside the box, hope it helps.
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Post by dave632 on Mar 7, 2015 21:26:24 GMT -7
The bearing I got were probably .0585 instead of .059, very tight fit. Had to run some sandpaper thru the center to get them to slide on since I did not have a file small enough to fit inside them. Certainly not loose. Heating or cooling would probably worked to but I did not want a press fit.
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Post by pceng on Mar 8, 2015 7:59:04 GMT -7
Here's my take on bb's when applied to arms. I look at then as bushings that can rotate. If your oil barrier between shaft and bushing goes friction increases. If you oil barrier between shaft & ball bearing goes friction. Way less than bushing ! Because inside bushing of bearing rotates. But it is still there. FIA cars are using ceramic bearings now because of difference in friction. Far less pores than steel. And way less friction.
The thing I.feel is most important for the shaft to have a "float" to it is movement. Not rotational or up & down & all over because of "slop". But being free.to center itself in magnetic field. Often, maybe more so than not. When juice is applied.and the armature becomes a rotating magnet. The center of magnetic field changes. Arm wants to center itself. So anything that keeps arm from being able to move or slide to this spot is adding drag to arm.
IMO, this point out weighs reasons both pro and con as to fit on shaft. And dictates a need for movement of the shaft. Should say when I speak of bearing being loose. I'm talking about a difference of a ten thousandth or two.
My 2¢ ......... Peter
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lewis
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Post by lewis on Mar 8, 2015 12:01:37 GMT -7
Peter I agree on the centering of field. If you hone the shaft to the perfect spec then the bearing will function as it should and arm will still travel foward to rear as needed. If you hone to much you will get slop. I look at this in more than one way. I kind of compare it to a wheel bearing for a 1:1. Besides the wheel falling off. If you put a wheel directly on a spindle without a bearing. 1.the wheel will not balance and moves alot. 2.you create drag 3.you get alot of wear. If you put the bearing in you can automatically feel a difference less drag little wear and balance is rite on. I can only speak on inline cars since I haven't done any pancakes. I can understand putting bushings in tycos and things that is alot harder to use bearings in but in something that accepts them easy it makes no sense to me why they wouldn't be used (other than price). If you can use one car twice as long then why not? Just my take on this. Only a opinion.
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Post by pceng on Mar 8, 2015 12:55:49 GMT -7
it makes no sense to me why they wouldn't be used (other than price). If you can use one car twice as long then why not? Just my take on this. Only a opinion. Me neither........ price is major reason for not being manufactured with them. ........... Peter |
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Post by dave632 on Mar 8, 2015 13:29:04 GMT -7
Agreed, price is the main reason they do not use them and the performance difference is slight.
Even the 100 dollar chassis do not come with them. You have to get to the 200-300
dollar cars before you start to see them used.
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lewis
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Post by lewis on Mar 8, 2015 15:44:21 GMT -7
My Wizzard p3 chassis dont come with them either but to upgrade from the stock bushings that are supplied with it only cost $10. Granite its $10. I didn't put them in for speed as much as I did for longevity of parts and use. BUT mine is not just for drags the same chassis will be sent for some road races through a friend.
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Post by FlatBlackCamaro on Mar 9, 2015 12:52:01 GMT -7
I fully agree with the arm centering itself in its magnetic field... but the arm in the car is comparable to an alternator on a car to the fact that it also has that magnetic field but on one end also has pressure in one direction or the other throwing that centering effect its creating off balance.
If you tighten a belt too tight youll pull one end of the armature, creating heat and pressure and eventually the bearing will fail and the armature gets into the windings and... the rest is history.
Even if you have .005 slop on a bushing, when energized by the track the arm starts to spin turning the gears as the gears turn and traction and resistance is applied you have force driving the armature off center until the resistance and pressure have decreased due to speed or the wall of the bushing.
Bushings have greater wear tolerance to bearings especially in areas of heat and pressure. However, center the armature in that magnetic field and remove the slop and the armature has less of a tendency to want to bind to the slop, and keep its stance only to turn that free'd torque to the chassis.
I understand that happens within a split second, but in a world where split seconds matter. It just could be edge you need if times are close.
You also have to look at the fact this may have a greater impact on a 4Gear type chassis vs an inline. Simple facts being on an inline you have an arm connected to a axle by a drive and driven gear, with a 4Gear type chassis you have an arm with a gear that connects to multiple gears before getting to the same axle. If you have .0005 slop on the arm ( with current bushings ) when it binds say it creates .00025 on the driven gear to the first idler gear... the two idler gears are pinned until you get to the cluster gear and we all know that thing has ALOT of slop say .005 but you have to figure what slop you have on top you also have on bottom until you get to the stationary crown. Now since all those numbers are fictional theres no need to add them, i just was throwing numbers around so its more clear that the slop on a 4Gear would add up vs that of a more simple chassis.
Hope i helped with some thoughts on the subject.
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Post by dave632 on Mar 9, 2015 15:43:33 GMT -7
The 4 gear chassis actually runs thru 5 gears since the cluster gear has 2 on it.
I have some narrow bearings I want to try on the gear plate ordered. We will see how
that works out.
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