Spiral Cut Diff Gears?
05-23-2012, 07:02 PM
#1
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Spiral Cut Diff Gears?
I have been noticing lots of changes to rc that are becoming mainstream, 2.4Ghz, Brushless, Lipo, lay down shocks and so on, and I understand it, now i see many cars (mostly 1/8 offroad) are being equipped with spiral cut diff gears.
WHY? as far as i know in the auto industry, straight cut gears are always stronger, but always louder and that is why spiral gears are used in most passenger cars, however spiral gears in this application are less durable, this is why race cars use straight cut gears in gearboxes and straight cut cam gears, noise is not a issue for this application. spiral cut gears also induce more side-load due to the gear mesh wanting to push away from each other and are less efficient due to high friction.
so I ask, are these gears just quieter or are they any more or less durable than the straight cut counterparts? or is it just another gimmick?
WHY? as far as i know in the auto industry, straight cut gears are always stronger, but always louder and that is why spiral gears are used in most passenger cars, however spiral gears in this application are less durable, this is why race cars use straight cut gears in gearboxes and straight cut cam gears, noise is not a issue for this application. spiral cut gears also induce more side-load due to the gear mesh wanting to push away from each other and are less efficient due to high friction.
so I ask, are these gears just quieter or are they any more or less durable than the straight cut counterparts? or is it just another gimmick?
05-23-2012, 07:04 PM
#2
RE: Spiral Cut Diff Gears?
dunno about it being a gimmick if it was all traxxas RC's would have them, and a sticker that says NOW WITH SPIRAL CUT GEARS to make it sound cool.
But from what I read they can handle more power due to the larger contact area, but put more load on the bearings so kinda seems meh as benefits
Here's one example of the pinion bearing being screwed over (and by an outrunner which is your favorite type
)
http://www.rc-monster.com/forum/show...77&postcount=8
if you look at the main thread there's even pics of the spiral diff carnage on bearings
But from what I read they can handle more power due to the larger contact area, but put more load on the bearings so kinda seems meh as benefits
Here's one example of the pinion bearing being screwed over (and by an outrunner which is your favorite type
)http://www.rc-monster.com/forum/show...77&postcount=8
if you look at the main thread there's even pics of the spiral diff carnage on bearings
05-23-2012, 07:05 PM
#3
Senior Member
RE: Spiral Cut Diff Gears?
ORIGINAL: The_Shark
I have been noticing lots of changes to rc that are becoming mainstream, 2.4Ghz, Brushless, Lipo, lay down shocks and so on, and I understand it, now i see many cars (mostly 1/8 offroad) are being equipped with spiral cut diff gears.
WHY? as far as i know in the auto industry, straight cut gears are always stronger, but always louder and that is why spiral gears are used in most passenger cars, however spiral gears in this application are less durable, this is why race cars use straight cut gears in gearboxes and straight cut cam gears, noise is not a issue for this application. spiral cut gears also induce more side-load due to the gear mesh wanting to push away from each other and are less efficient due to high friction.
so I ask, are these gears just quieter or are they any more or less durable than the straight cut counterparts? or is it just another gimmick?
I have been noticing lots of changes to rc that are becoming mainstream, 2.4Ghz, Brushless, Lipo, lay down shocks and so on, and I understand it, now i see many cars (mostly 1/8 offroad) are being equipped with spiral cut diff gears.
WHY? as far as i know in the auto industry, straight cut gears are always stronger, but always louder and that is why spiral gears are used in most passenger cars, however spiral gears in this application are less durable, this is why race cars use straight cut gears in gearboxes and straight cut cam gears, noise is not a issue for this application. spiral cut gears also induce more side-load due to the gear mesh wanting to push away from each other and are less efficient due to high friction.
so I ask, are these gears just quieter or are they any more or less durable than the straight cut counterparts? or is it just another gimmick?
Spiral cut are more durable, but create more drag...less sensitive shimming tho......Mugen,Kyosho,HB,AE are Spiral......Losi, Serpent,X-Ray are straight cut...
05-23-2012, 07:20 PM
#4
Senior Member
Thread Starter
RE: Spiral Cut Diff Gears?
ok then, so its different when the gears are beveled, still have yet to blow out the diff pinions or rings in my ofna, even when i lost throttle control and landed WOT, and thats WITH a jammin engine. my trick is to half fill the case with light silicone grease (sil-glyde auto grease), no problems with contamination and there isn't any drag issues either, but its messy when it comes time to replace diff oil.
spiral diff gears are still technically bevel gears
spiral diff gears are still technically bevel gears
05-24-2012, 03:49 AM
#5
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RE: Spiral Cut Diff Gears?
Unless the spiral cut gears are hypoid(the pinion is mounted off center to the ring gear), the straight cut gear will be a bit stronger, they also have less rolling friction.
Spirals are quieter, though, and I've heard that they handle high speed better(not sure if this is true or not).
One thing to think about is that while passenger cars and light trucks use spiral cut gears in their transmissions, medium and heavy trucks generally use straight cut gears.
Spirals are quieter, though, and I've heard that they handle high speed better(not sure if this is true or not).
One thing to think about is that while passenger cars and light trucks use spiral cut gears in their transmissions, medium and heavy trucks generally use straight cut gears.
05-24-2012, 05:41 AM
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RE: Spiral Cut Diff Gears?
Please call them helical guys. Tib was right, helical gears are more durable and quieter, but less efficient. Passenger cars mostly use helical, rally cars use straight cut, hence the unbelievably loud whine from a rally car gearbox.
05-26-2012, 12:52 PM
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RE: Spiral Cut Diff Gears?
Helical gears are stronger most of the time IMO. They have more contact area, and its normally cheaper to replace pinion bearings than the pinion gear.
For instance, I just rebuilt the diff's in my brushless MGT. It has helical cut diff gears and they look great still, but the bearings were getting worn after a lot of use. $10 later and they are good as new. If the gears were shot, it would have cost me a lot more...
For instance, I just rebuilt the diff's in my brushless MGT. It has helical cut diff gears and they look great still, but the bearings were getting worn after a lot of use. $10 later and they are good as new. If the gears were shot, it would have cost me a lot more...
05-26-2012, 07:18 PM
#8
RE: Spiral Cut Diff Gears?
ORIGINAL: SyCo_VeNoM
dunno about it being a gimmick if it was all traxxas RC's would have them, and a sticker that says NOW WITH SPIRAL CUT GEARS to make it sound cool.
dunno about it being a gimmick if it was all traxxas RC's would have them, and a sticker that says NOW WITH SPIRAL CUT GEARS to make it sound cool.
