European 2wd 1/8th pan car on-road Classic class

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  • 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!
  • Hm
    Quote: 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...
  • Also true
    Quote: 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....
  • 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.....
  • 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?
  • 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: 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....
  • 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: 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?
  • Quote: 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
  • Quote: 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)
  • Hm
    Quote: 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....
  • Heh
    Quote: 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.
  • 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
  • ????
    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...
  • Quote: 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....
  • Quote: 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