R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 05-26-2011, 06:13 PM   #16
Tech Rookie
 
Join Date: Nov 2010
Location: Central IL
Posts: 11
Default

The spiral cut bevel gears are smoother and quieter than the straight cut bevel gears. I don't believe there is an advantage as far as strength.
statengineer is offline   Reply With Quote
Old 05-26-2011, 06:14 PM   #17
Tech Master
 
j_blaze14's Avatar
 
Join Date: Feb 2008
Location: Tampa, Fl
Posts: 1,693
Trader Rating: 34 (100%+)
Default

true, when the spiral cut are not meshed right they slip and round off. the straight cut seem to just snap off teeth if they go. as long as they are shimmed right and the bearings are good either should last a long while.
__________________
aGama A8 EVO - Werks B2 - Sidewinder
aGama A8E - TrackStar 150a, 2560kv, 3 and 4 cell
FlySky GT3B, Turnigy HV servos, SKY Lipos
AKA, Proline, Hotbodies Rubber
Elite Performance - HORRC.com
j_blaze14 is offline   Reply With Quote
Old 05-26-2011, 06:21 PM   #18
Tech Master
 
pitpop's Avatar
 
Join Date: Mar 2006
Posts: 1,445
Default

The MP9 has straight cut gears and arguably the best drive train that has ever been produced. Just spin somebodies MP9 even with the wheels off, it's pretty amazing. The ST-RR uses spiral cut, and you definitely have to mesh it just right and limit the front brake.
__________________
Cody King's Wrench (and dad :))| Team Kyosho International | Reds Racing Engines | Pro-Line Tires
KO Propo | Byron Fuels | AbsoluteHobbyz.com | Stickit1 Racing | kustomrcgraphics.com
LiveRC.com | OCRC Raceway | codykingrc.com | ROAR Sanctioning Director
pitpop is offline   Reply With Quote
Old 05-26-2011, 06:59 PM   #19
Tech Elite
 
Jeff Werner's Avatar
 
Join Date: Sep 2001
Location: Wichita, KS
Posts: 2,254
Trader Rating: 14 (100%+)
Send a message via Yahoo to Jeff Werner
Default

I run Grease on my ST-RR Spiral gears. Do you treat Straight cut gear the same?
Jeff Werner is offline   Reply With Quote
Old 05-26-2011, 07:02 PM   #20
Tech Adept
 
madac's Avatar
 
Join Date: Apr 2010
Location: Calgary, Alberta
Posts: 229
Trader Rating: 1 (100%+)
Default

My eight-t with the straight cut gears I would go through a pinion shaft every half a gallon on the front and rear and had to make sure the mesh was good and shimmed properly. On my D8 and D8T the spiral cut gears I put them in and the only time I took them out was when I was changing the diff fluid out, never found any filings come off of them and haven't changed them since I got the new buggy and truggy. I imagine maybe I may have done something wrong with the straight cut gears but even the other guys at the track helped me with shimming and setting it up but that didn't make any difference in the wear. I like the gear mesh of the spiral cut gears maybe I just have bad luck with the straight cut gears.
__________________
Team Associated B5
Spektrum DX3S
madac is offline   Reply With Quote
Old 05-26-2011, 07:59 PM   #21
Tech Master
 
Join Date: Jan 2009
Posts: 1,779
Trader Rating: 2 (100%+)
Default

Talking about full size car, here's a picture of a Porsche Cayenne's diff, note the helical/spiral cut gears...

__________________
Powered by: MASTERCARD and VISA

If you're in control, you're not driving it fast enough!

XRAY / NOVAROSSI / SANWA / AKA TIRES / BYRON FUEL
ganymede is offline   Reply With Quote
Old 05-26-2011, 08:07 PM   #22
Tech Master
 
johnny t's Avatar
 
Join Date: Nov 2008
Location: Chicago
Posts: 1,289
Trader Rating: 10 (100%+)
Default

You do a helical style cut of a gear to reduce noise pretty much. these days you have to be conscious of passenger comfort in our little cars.

I wish those manufacturers would drop the sexy looks and increased drag of a helical cut and go straight cut, they are not doing us any favors me thinks. Race cars are straight cut.
johnny t is offline   Reply With Quote
Old 05-26-2011, 08:12 PM   #23
Tech Prophet
 
tc5 man's Avatar
 
Join Date: Oct 2007
Location: levittown pa
Posts: 16,873
Default

i like helical cut diff gear better than the straight cut on my rc8t i just used 1 shim on each side" like the manuel says and its good no failures and man is it smooth and it spins pretty free !

now the helical cut diff gear is harder to clean though if needed.
tc5 man is online now   Reply With Quote
Old 05-26-2011, 08:19 PM   #24
Tech Master
 
omarwashington's Avatar
 
Join Date: Aug 2008
Location: Kenmore, WA
Posts: 1,088
Trader Rating: 2 (100%+)
Default



If it works for pencils then its good enough my my diffs
__________________
RCCARS!
omarwashington is offline   Reply With Quote
Old 05-26-2011, 08:52 PM   #25
Tech Master
 
Join Date: Dec 2006
Location: Coral gables, Florida
Posts: 1,265
Trader Rating: 18 (100%+)
Send a message via Yahoo to infanterene
Default

Quote:
Originally Posted by johnny t View Post
You do a helical style cut of a gear to reduce noise pretty much. these days you have to be conscious of passenger comfort in our little cars.

I wish those manufacturers would drop the sexy looks and increased drag of a helical cut and go straight cut, they are not doing us any favors me thinks. Race cars are straight cut.
+1.
infanterene is offline   Reply With Quote
Old 05-27-2011, 12:05 AM   #26
Tech Adept
 
madac's Avatar
 
Join Date: Apr 2010
Location: Calgary, Alberta
Posts: 229
Trader Rating: 1 (100%+)
Default

I don't understand this but real race cars use straight cuts to the diff and the ring gear? I have looked through nascar, indy and formula one teams pages and looking to see this for myself and they had cut away sections of where the shaft and the pinion gear go to the ring gear and they were all helical or spiral gears but got sick of looking after looking at over 40 pages and couldn't find one with a straight cut pinion to diff ring gear. If a Porche has runs spiral or helical gears it can't be that inefficient and the Germans don't do it if it's a waste of time but more likely it's more efficient and probably a better mesh. I don't know. OOOOOOOOOOOOOOHHHHH WELL!!!!
__________________
Team Associated B5
Spektrum DX3S
madac is offline   Reply With Quote
Old 05-27-2011, 04:04 AM   #27
Tech Initiate
 
duck7604's Avatar
 
Join Date: Dec 2010
Location: B.F.E
Posts: 24
Default

The reason behind helical cut gears is more surface area per gear tooth than straight cut gears and they are quieter than straight cut. You guys keep talking like it's something from another planet
__________________
Losi 8ight 2.0EU
Novarossi plus 4 btta
Airtronics MX-3X
Savox Servos
duck7604 is offline   Reply With Quote
Old 05-27-2011, 07:05 AM   #28
Tech Addict
 
Jesse Robbers's Avatar
 
Join Date: Aug 2001
Location: Cincinnati, OH
Posts: 600
Send a message via AIM to Jesse Robbers
Default

That Porsche gear looks like it might be a hypoid gear (the two gear axis don't intersect). Given the same width, the helical gears will be stronger, the running tooth width is wider giving it more strength. Helical gear teeth 'roll' or ease into mesh and out of mesh, this makes them quieter and smoother. Straight cut teeth go into and out of mesh all at once. This creates a bit more noise and vibration because the contact of the tooth width happens all at once. Efficiency, I don't know. I've seen Kyosho, Losi, and Serpent cars free spin very well and they have straight gears. I've seen my HB car spin very good with helical gears, but not as good as the Serpent I saw. Efficiency under load when the car is on the track could be a different ballgame but I think the gear cut style for r/c cars for the end user realistically only comes down to durability (how often you replace gears or gearboxes to keep the gears from skipping).
__________________
Sponsored by: O.S. Speed, KO Propo, Sidewinder, Tekin, Thunder Power, Lunsford, Skipgear.com, Fioroni, Avid R/C, GMK Supply, Competition Heat, Dialed Inc., LiveRC.com, DE Racing, CIG2O, ANDROID Nitro Runtime Calculator App
Jesse Robbers is offline   Reply With Quote
Old 05-27-2011, 10:36 AM   #29
Tech Master
 
johnny t's Avatar
 
Join Date: Nov 2008
Location: Chicago
Posts: 1,289
Trader Rating: 10 (100%+)
Default

Quote:
Originally Posted by duck7604 View Post
The reason behind helical cut gears is more surface area per gear tooth than straight cut gears and they are quieter than straight cut. You guys keep talking like it's something from another planet

We keep talking whether its a technology even beneficial to an RC car. I would say no, helical gears only slow our cars down. MP9s and 8ights proved that to me.
johnny t is offline   Reply With Quote
Old 05-27-2011, 11:20 AM   #30
Tech Addict
 
slow coach's Avatar
 
Join Date: Oct 2003
Location: guernsey C.I.
Posts: 626
Default

tbf its not as easy as saying the losi or mp9 is faster than a helical diffed car, there are to many variables to even consider, bearings, mesh, options fitted, drive ratio etc will all make a substatial difference to how a car free wheels and accelerates.

is there a difference who knows, I went from the MBX5R to the 6 and didnt notice any real difference tbh, they both are very reliable when shimmed correctly, however i must say i never ever shimmed my MBX5 Prospec for about the first 3 years just let them rattle around in the diff till someone told me i should, did i ever break a diff gear no never.
__________________
Kyosho MP9TKI2 soon to be TKI3, Novarossi, SMD, GM Racing, www.grccc.org
a great wife and lovely kids
what more can you ask for
a win on the lottery :D
slow coach is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 05:10 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net