View Single Post
Old 02-19-2014, 02:16 PM
Tech Elite
blis's Avatar
Join Date: May 2008
Location: Brisbane
Posts: 3,456

Originally Posted by snuvet75 View Post
I learned that I should lean LSN too.
Regarding inconsistent shifting I still need to find the answer. U may be right about one way but I cleaned thar bearing many times and lubed it properly. It doesn't seem broken either. It's better nowdays but still.does that. It shifts especially if I gun it after letting the car cruise for a brief moment when,at that speed, it should be the first gear that engages.
Alas, perhaps you leaned the bottom too much, if the engine starves as it peaks revs before shifting it may need a little more fuel OR you are still very fat/rich on the bottom and you observed that your shift occurs after clearing the bottom end.. 2 Speed setups are for me the most painful experience in RC. It can take me hours to find the sweet spot and symmetry of the shoe to shift. You do need a consistent engine tune, relatively similar tyre diameters. You could use rubber EP tyres to make for large consistent diameters. This would then create a good reference point for you to know whether you need to tighten or loosen the shoes. It takes no more than 1/8th - 1/4 turn of the tension screws to make a difference once it's right. Finding that spot is the hard part! Better tight than loose, so start with a tighter shoe and take it off the car and set it up first.

Remove the shoe, loosen the screws (DONT COUNT TURNS), loosen it until you can open the shoe with your hands and look at the gap, make them equal.

Then begin to count turns from that point and tighten it until you can barely open the shoe with your hands and check the small gap is the same. At this point put another 1/2 turn in each screw to be sure you are in first gear. Then work backwards with the shoe on the car.

Also, check...
  • Your two speed shoe is the correct way around, if it is asymmetrical then the trailing edge of the shoe should have more mass. (NOTE: Some cars are backwards to my method *eek*)
  • Also check your two speed shoe is symmetrical with spring tension, if one side is tighter than the other side, the shoe wont expand correctly
  • Check you havent oiled the bearing and the oil has dispersed into the drum. I didnt believe it would behave like it does, but it's true, it wont shift and slips.. Usually a lot of residue on the shoes.
  • Check the gap between the shoes and the drum are correct, there should not be a large gap there.
  • It's always safer to tighten loosen your 2 speed to ensure it's in first gear than it is to be shifting too early
  • Ensure your engine is tuned and warmed up before you test any of this
  • Ensure your tyres are not too large, this changes the shift.
  • Always consider the SPEED of the 2 SPEED DRUM, not the engine speed, so any 1st speed gearing changes will afffect shifts
  • If your car's clutch is not failing, or slipping, this could impact shifting too

Realise what an achievement it is to get all this to work correctly, don't look at it as too much trouble, once you master a Nitro car, you have won the biggest trophy of all!!

To finish first, first you must start!
blis is offline  
Reply With Quote