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View Full Version : Bushings Vs. Bearings


eno801
2003.01.04, 07:17 PM
i just made some bushings for the pinion gear . i was wondering if i could go ahead and make bushings instead of bearings for the wheels , imean c'mon how much of a difference can there be on these light small thing with neglible load. i figure bronze bushings will be all right . or maybe beryillium copper J/K LOL

Draconious
2003.01.04, 07:59 PM
at no time is a bushing better or as good, as a bearing... even if they were as good, the slop in the bushings freedom gapping, would make the components too lose... and gear mesh poorly etc... spin a wheel with good bearings, chepa bearings, and the plastic bushings, along with your custm bushings... and you will see for your self.........

eno801
2003.01.04, 08:10 PM
even if i can make the stuff .0005 within tolerance? i can't believe this would affect such a small thing . how much restistance , friction ,slop can you get from such a tiny thing ??????????/

wrcracer
2003.01.04, 08:38 PM
it'll wear after a while, and besides, bearings (especially dry bearings) are almost frictionless, which a bushing has tons of

DAMZer
2003.01.04, 08:49 PM
I'm trying to word this so you don't take offense, so please don't.:) Bearings by their nature reduce the friction by spreading the load on a much smaller surface area. The balls run in a race which is a metal to metal contact. The wear occurs in the ball bearing and not to the shaft running in the bearing. This means that the shaft will last longer and there will be less friction to the shaft. Granted, this is a much smaller scale but the physics still apply.

Believe us or not, bushings with microns of tolerance will not give you the longevity or reduction in friction that a simple 10 buck set of bearings will. I'm sorry, it is just a plain and simple fact.;)

pianoman
2003.01.05, 02:52 AM
My bearings are kinda stiff compared to the plastic bushings...I made the wheels less tighter but still kinda stiff. Will my bearings 'break in' and rotate more freely over time? I don't notice the car going any slower, just the tires don't spin as freely by hand, ya know?

Thanks,

Pianoman

DAMZer
2003.01.05, 09:12 AM
That will happen. Depending on the type of bearings and therefore the lube used and the seals used, bearings can "feel" tighter than bushings. That is not a bad thing!! Most bearings break in after a while and you should notice more of a free spin.

BLiND
2003.01.06, 12:18 AM
you also may have over tightened the nut holding the wheels on, I did that after I cleaned some hair out of my front axles (damn Dalmations) and fixed it by loosening the nut half a turn :)

Draconious
2003.01.06, 04:11 AM
OK lets say you do get them .0000000000005 within tollerance, now you need to even more than before, get any place that hasmore than one bushing inline.. or a miss aligned bushing will act like a break, stopping the axle from turning, this is why taking apart a motor can with no bearings is not always the hottest idea, if those bushings dont go together again perfectly inline... the shaft will actualy have more friction than ever... and there is no way your gona get those bushings perfectly in line in a plastic molded motor pod.. or on the rims.. or any were on a mini-z ;). Basicly my point is making them closer 100% tollerance by any amount would be worse... there would actualy be MORE contact room if you reduce the size of the hole.. the gap NEEDS to be tehre for bushings to work... and of course if it was 0 gap.. it wont work at all 0 revolutions, talk about locked diff ;).



Also the bearings not spinning freely, I will use the front end for an example but the motor pod bearings can also have this effect...
take the front wheel give it a slight spin with one finger... should stop too soon right? Ok take the nut off.... if the wheel still does this then the bearings are total messed up... however if it now spins very freely.. then try putting the nut on not so tight, might need some thread lock to hold it on the shaft... what is happening when bearings dont spin freely on the Z.. is the lock nut and the knuckle are pushing the two bearings together... causing the inner diameter half of the bearings to press against the balls inside them.. this added sideways friction prevents the bearings from working... this is because whoever is redistributing your bearings did not ORDER the right kind of bearing from the manufacturer... they are not designed for being used this way. the side ways pressure is likely also causing the balls in the bearing to rub against the dirt shield in the bearing as well...

A cheap simple mod (ok heres your use for the bushing maker machine) is to make a small mini tube, to place on the shaft in between the bearings that is small enough NOT to rub on the rim, and not to be too much larger then the axle shaft.. this would allow the bearings to push against this,when tightening the lock nuts... infact I think im going hunting for some left over alum. tube right now ;)

Mondo
2003.01.06, 06:19 AM
DAMZer summed it up plain and simple.

Bearings are better and the only thing that needs a "Bushing" is Iraq ;)

Ken Mifune
2003.01.06, 08:35 AM
Bushings, also known as solid bearings, are usually for components that carry a huge load and require very close tolerances. ie. crankshafts; camshafts. They also require a high flow of lubrication.

Roller bearings or ball bearings are used for lighter applications. or isolated areas because they can be sealed or packed for lubrication. ie. wheels; U-joints(drive shafts).

With that simply said, a roller bearing will best suit any area on the Z.

Mondo
2003.01.06, 10:59 AM
Ken is also right,

The bushings used on automobile camshafts and crankshafts are also known as "white metal bearings"

In RC, some cars ship with Oilte Bronze bushings, but these are also referred to as bearings.
They can be found in the standard Mini-Z 130 motor.
They are self-lubricating, but they do eventually wear in the long run

Ken Mifune
2003.01.06, 06:46 PM
White metal is usually sintered aluminum, zinc or magnesium. All bad materials for plain bearings (another term for bushings;) ).

Typical items made from white metal: car emblems; screen door and misc. handles; component housings/parts that need to be more rigid that plastic.

edit- Perhaps white metal bearings are used in American automobiles.:D

herman
2003.01.07, 03:49 AM
at the track, some guy used to put bushings in the front wheels, bearings in the rear wheels...

the bushing in the front would act as some sort of brake while turning into corners...

looks like it worked to some extent for him... good idea actually...