R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 09-18-2012, 08:35 PM   #2026
Tech Master
 
Join Date: Jul 2005
Posts: 1,125
Trader Rating: 12 (100%+)
Default Off-road vs. "Pan" car Diffs

A couple of observations on DIffs: The Motonica gear diff is a "spur gear" unit, another company had a "worm" type for off-road, called a "Gleason". As Garen said all gear diffs are quite similar.

The ratios Farmer is talking about are the "ring & pinion" ratios and are quite different from what the modern pans run, 48/20 or 2.4:1 for Moto belt drive pulleys vs. 3.3 to 4+:1 for the off-road units as mentioned. Instead of around 47spur/18 pinion (to get a 6.2:1 FDR) you need a pinion in the low to mid 20's for the Kyo/Los 3.3 and low 30's for the Assoc gearing. (Check my math!!!)

I my experience the issue with the silicone oil filled diffs is getting it out and refilling it. One trick is to mix in low viscosity shock oil to dilute the super heavy diff fluid, and as Garen says be sure the fluid is all cleaned out of any pin holes, motor cleaner sprayed in with a "straw" works pretty well. The shimming may need to be done for both the diff gears in the housing and the ring and pinion on the outside. Those big metal gears can be expensive so be sure to pay attention. Hopefully the pan car application will not be as demanding as the off-road application...

Good luck to all!
aarcobra is offline   Reply With Quote
Old 09-18-2012, 09:52 PM   #2027
Tech Addict
 
hitcharide1's Avatar
 
Join Date: Sep 2010
Posts: 651
Trader Rating: 1 (100%+)
Send a message via Yahoo to hitcharide1
Default Hm

Quote:
Originally Posted by Farmer_John View Post
Phil...think less. Do more.

One thing to take into consideration with off road based diffs is internal gearing. I'm also here to tell you that there are at least 4 bearings in a good off road dif and shimming makes all the difference in the world to efficiency..

For example: Associated runs 4.30:1, Losi runs 3.30:1 while Kyosho (in the MP9 anyway is at 3.31:1 Makes a big difference when you go to gear for your final.
True, true...just saying, he's never had a problem with the thing, ever. Remember, I'm shooting for price and durability. The only thing he's ever done to it is, instead of filling it with oil, he filled it mostly with Lucas...and we use that stuff in everything, plus it's really good stuff to assemble engines with.

As for thinking less, I'm not sure how I could do that without stopping thinking entirely...which may be an improvement...
hitcharide1 is offline   Reply With Quote
Old 09-18-2012, 10:05 PM   #2028
Tech Addict
 
hitcharide1's Avatar
 
Join Date: Sep 2010
Posts: 651
Trader Rating: 1 (100%+)
Send a message via Yahoo to hitcharide1
Default Also true

Quote:
Originally Posted by aarcobra View Post
A couple of observations on DIffs: The Motonica gear diff is a "spur gear" unit, another company had a "worm" type for off-road, called a "Gleason". As Garen said all gear diffs are quite similar.

The ratios Farmer is talking about are the "ring & pinion" ratios and are quite different from what the modern pans run, 48/20 or 2.4:1 for Moto belt drive pulleys vs. 3.3 to 4+:1 for the off-road units as mentioned. Instead of around 47spur/18 pinion (to get a 6.2:1 FDR) you need a pinion in the low to mid 20's for the Kyo/Los 3.3 and low 30's for the Assoc gearing. (Check my math!!!)

I my experience the issue with the silicone oil filled diffs is getting it out and refilling it. One trick is to mix in low viscosity shock oil to dilute the super heavy diff fluid, and as Garen says be sure the fluid is all cleaned out of any pin holes, motor cleaner sprayed in with a "straw" works pretty well. The shimming may need to be done for both the diff gears in the housing and the ring and pinion on the outside. Those big metal gears can be expensive so be sure to pay attention. Hopefully the pan car application will not be as demanding as the off-road application...

Good luck to all!
Right now I'm spitballing but here's the general idea. Tom's car, when it's running right, is nearly as quick down the backstraight as anything else on the track, and there's only a three tooth difference in spurs. Remember, we still intend to use gears, albeit single speed, but now we're only pushing a 5.25 pound car and we're doing it with a .21 vs. a .28, the .21 getting higher rpm. So my crude math skills plus general observation is that the gearing should neither dog nor wind out, plus we have gear options as well (and yes, I'm considering the difference between how it reacts as a 4wd vs. how it should a 2wd.)

If I have the thing built before February, I'll take it with me to the Winternats and run a few laps during practice. I know they aren't running pan down there but no reason I can't get a lap or two in, for testing purposes, and to make sure I'm on top of things before racing season starts up here.

By the way, I'm still trying to talk a guy on Ebay out of his MRP diff so I can complete a third GP180. I'd like to be able to sell at least one on Ebay, just so I know what the market worth of the thing is, but I haven't forgotten that you and Lon both want one, and we'll find a way to make that happen....
hitcharide1 is offline   Reply With Quote
Old 09-18-2012, 10:10 PM   #2029
Tech Addict
 
hitcharide1's Avatar
 
Join Date: Sep 2010
Posts: 651
Trader Rating: 1 (100%+)
Send a message via Yahoo to hitcharide1
Default I hate the state of Ohio

I had a bad day monday. Really bad.

Went down to the courthouse and paid my land taxes. All I could think of while doing that was how much rc crap I could buy with that kind of money.

Went down to the DMV, had to renew tags for the van plus transfer the title over for the '08 Chevy I just bought. All I could think of while doing that was I was starting to resent the state of Ohio and how much rc crap I could buy with that kind of money.

Got an emergency call from the ex-wife (that's right, I said EX-wife) who needed a buck. She's the mother of my children and I'm an idiot. So off to Western Union I drove, after hitting the bank, and all I could think of...wait a sec...think I've said this already...PLUS since I met her and married her in the state of Ohio, it's their fault.

Tuesday was a much better day.....
hitcharide1 is offline   Reply With Quote
Old 09-19-2012, 09:46 AM   #2030
Tech Master
 
garen's Avatar
 
Join Date: Jan 2006
Location: GLENDALE
Posts: 1,730
Trader Rating: 7 (100%+)
Default

The Moto gear diff uses no shims inside or outside. Some off road diffs use shims inside (behind the large bevel gears and/or behind the small bevel gears) and nearly all require shims on the outside to get the gear mesh between the ring and pinion just right. Since the P8C is belt drive, no need for the outer shims. I think as long as there is oil in the diff and the screws holding it together are tight, it will be very rare for the Moto diff to fail. Farmer- how do the internal gears look in that diff?
__________________
bpengines-usa.com fioroni-usa.com motonica-usa.com

Airtronics Avid RC Byron Fuels VOX Engines

VMR Tires - available at http://motonica.ipower.com/store
garen is offline   Reply With Quote
Old 09-19-2012, 10:33 AM   #2031
Tech Regular
 
Join Date: Apr 2010
Posts: 448
Default not so much

Thanks for thinking of me and the MRP car. However at this time I feel our six feet are firmly planted in the Motonica car. It's a very good car stock out of the box, then you can make it better. I would say if you went to race a pan car, get a P8C and be done with it.


Quote:
Originally Posted by hitcharide1 View Post
Right now I'm spitballing but here's the general idea. Tom's car, when it's running right, is nearly as quick down the backstraight as anything else on the track, and there's only a three tooth difference in spurs. Remember, we still intend to use gears, albeit single speed, but now we're only pushing a 5.25 pound car and we're doing it with a .21 vs. a .28, the .21 getting higher rpm. So my crude math skills plus general observation is that the gearing should neither dog nor wind out, plus we have gear options as well (and yes, I'm considering the difference between how it reacts as a 4wd vs. how it should a 2wd.)

If I have the thing built before February, I'll take it with me to the Winternats and run a few laps during practice. I know they aren't running pan down there but no reason I can't get a lap or two in, for testing purposes, and to make sure I'm on top of things before racing season starts up here.

By the way, I'm still trying to talk a guy on Ebay out of his MRP diff so I can complete a third GP180. I'd like to be able to sell at least one on Ebay, just so I know what the market worth of the thing is, but I haven't forgotten that you and Lon both want one, and we'll find a way to make that happen....
Das 1/8th Mopar is offline   Reply With Quote
Old 09-19-2012, 11:14 AM   #2032
Tech Addict
 
Farmer_John's Avatar
 
Join Date: Mar 2009
Posts: 597
Trader Rating: 3 (100%+)
Default

Clean, with no visible signs of wear. Which I would expect with this type of diff, as the gears are straight cut and full contact. I've had to do a bit of shimming on nearly every off road diff I've used.

Quote:
Originally Posted by garen View Post
The Moto gear diff uses no shims inside or outside. Some off road diffs use shims inside (behind the large bevel gears and/or behind the small bevel gears) and nearly all require shims on the outside to get the gear mesh between the ring and pinion just right. Since the P8C is belt drive, no need for the outer shims. I think as long as there is oil in the diff and the screws holding it together are tight, it will be very rare for the Moto diff to fail. Farmer- how do the internal gears look in that diff?
__________________
RCHOTPIT.COM...now alive...
Farmer_John is offline   Reply With Quote
Old 09-19-2012, 01:17 PM   #2033
Tech Addict
 
Join Date: Sep 2010
Posts: 574
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by Das 1/8th Mopar View Post
Thanks for thinking of me and the MRP car. However at this time I feel our six feet are firmly planted in the Motonica car. It's a very good car stock out of the box, then you can make it better. I would say if you went to race a pan car, get a P8C and be done with it.
you said it !!! good parts support, quality car. i imagine the others avaiable are good as well
__________________
who cares what the kardashians are doing
5italkart is offline   Reply With Quote
Old 09-19-2012, 01:37 PM   #2034
Tech Master
 
Join Date: Jul 2005
Posts: 1,125
Trader Rating: 12 (100%+)
Default

Quote:
Originally Posted by 5italkart View Post
you said it !!! good parts support, quality car. i imagine the others avaiable are good as well
What others?

Oh, you must mean in them "furrin' " countries!! What available in the GWN? (Great White North)
aarcobra is offline   Reply With Quote
Old 09-19-2012, 05:41 PM   #2035
Tech Addict
 
hitcharide1's Avatar
 
Join Date: Sep 2010
Posts: 651
Trader Rating: 1 (100%+)
Send a message via Yahoo to hitcharide1
Default Hm

Quote:
Originally Posted by Das 1/8th Mopar View Post
Thanks for thinking of me and the MRP car. However at this time I feel our six feet are firmly planted in the Motonica car. It's a very good car stock out of the box, then you can make it better. I would say if you went to race a pan car, get a P8C and be done with it.
I didn't think you wanted an MRP to run, I thought you just wanted one for shelf queen....
hitcharide1 is offline   Reply With Quote
Old 09-19-2012, 05:43 PM   #2036
Tech Addict
 
hitcharide1's Avatar
 
Join Date: Sep 2010
Posts: 651
Trader Rating: 1 (100%+)
Send a message via Yahoo to hitcharide1
Default Heh

Quote:
Originally Posted by aarcobra View Post
What others?

Oh, you must mean in them "furrin' " countries!! What available in the GWN? (Great White North)
Lord willing, next year there'll be something availible in pan in the GWN from us....I'm selling 4wd's but have no desire to try to make those...too much like work.
hitcharide1 is offline   Reply With Quote
Old 09-23-2012, 08:39 AM   #2037
Tech Master
 
Taylorm's Avatar
 
Join Date: Nov 2006
Location: Monclova, Ohio
Posts: 1,641
Default

http://imodel.fr/dxf/4360-dxf-premium-kit-.html
http://imodel.fr/dxf/3833-vortex-kit.html
http://www.rcbazar.net/modules.php?n...ticle&sid=1291
__________________
Current stable... Team Associated SC8, Team Associated RC250 X 3
Tamiya F104X1...Tamiya F104W GP Edition...BMT/RC300 Frankenstein.....Edam Razor2
Checkers or Wreckers......................................................................................
Taylorm is offline   Reply With Quote
Old 09-23-2012, 09:06 AM   #2038
Tech Master
 
Join Date: Jul 2005
Posts: 1,125
Trader Rating: 12 (100%+)
Default ????

Matt, hope you are not trying to show that the pan cars are "avaialble"! lol Do you forget I have the DXF Vortex? Not only did I pay enough to get a compo from Garen, shipping will kill you if you try to buy any parts!!! I knew this going in and did it because I wanted to have a different car, so no regrets here but these cars are never going to become popular until they are at least as available as the Moto. It's the only game in town!

Sorry you won't be in Cinci ;-( I have a couple of projects I want you to see. I'll send you pics...
aarcobra is offline   Reply With Quote
Old 09-23-2012, 11:03 AM   #2039
Tech Master
 
Taylorm's Avatar
 
Join Date: Nov 2006
Location: Monclova, Ohio
Posts: 1,641
Default

Quote:
Originally Posted by aarcobra View Post
Matt, hope you are not trying to show that the pan cars are "avaialble"! lol Do you forget I have the DXF Vortex? Not only did I pay enough to get a compo from Garen, shipping will kill you if you try to buy any parts!!! I knew this going in and did it because I wanted to have a different car, so no regrets here but these cars are never going to become popular until they are at least as available as the Moto. It's the only game in town!

Sorry you won't be in Cinci ;-( I have a couple of projects I want you to see. I'll send you pics...
I know they are not available.... Until class goes country wide.... Options
Will be limited... Yes I remember French fry car...is joe p
Going to Cincinnati?.... I could send the moody stuff with him....
__________________
Current stable... Team Associated SC8, Team Associated RC250 X 3
Tamiya F104X1...Tamiya F104W GP Edition...BMT/RC300 Frankenstein.....Edam Razor2
Checkers or Wreckers......................................................................................
Taylorm is offline   Reply With Quote
Old 09-23-2012, 12:56 PM   #2040
Tech Addict
 
Join Date: Sep 2010
Posts: 574
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by Taylorm View Post
I know they are not available.... Until class goes country wide.... Options
Will be limited... Yes I remember French fry car...is joe p
Going to Cincinnati?.... I could send the moody stuff with him....
best too leave that stuff with sr. no border issues i'm cinci bound friday after work
__________________
who cares what the kardashians are doing
5italkart 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 10:24 AM.


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

SEO by vBSEO 3.5.0