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Old 04-21-2008, 11:34 AM   #1
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Default sealed or open bearing for the nitro engine?

Guys. plz enlightened me on this one. im still a newbie.....
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Old 04-21-2008, 12:18 PM   #2
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Of course you want sealed bearing put in the front side and no seal bearing at inside. Sealed bearing types : rubber and metal shield. This keep presurized air inside the engine, thus no air ( and fuel ) leaking out from the front bearing. Rubber shield ( usually made from teflon ) is the best shield protection but they don't last long. Metal shield I guess has slightly air leaking. Rubber shield bearing has less rpm than metal shield bearing due to seal friction. However, a perfect non leaking engine will produce more top end power and easier to tune.

No seal bearing is put inside the engine. Don't need seal because the ball bearing need constant lubrication from the fuel, and you want more rpm, right ?
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Old 04-22-2008, 12:11 AM   #3
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Default sealed bearing

yah, im still a newbie when it comes to nitro rc,..
do i have to de sealed the bearing?
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Old 04-22-2008, 02:23 AM   #4
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should the front bearing have a seal on only the outside?

or leave the seal on both sides of the front bearing?
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Old 04-22-2008, 02:49 AM   #5
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Quote:
Originally Posted by LOSI123 View Post
should the front bearing have a seal on only the outside?

or leave the seal on both sides of the front bearing?
Front bearing have the seal on the outer side only!
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Old 04-22-2008, 02:57 AM   #6
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I have used rubber sealed and metal sealed bearings on all my engines and have found rubber sealed to start leaking after a few hours of use.
I now use metal sealed only but dont remove the rear seal as there is plenty fuel still getting to the bearing.
Some engines also have a groove in the crankcase for this purpose of lubing the bearing.
If wanting less rotational resistance then rubber seal is the preference but you need to remove the rear seal for lubrication and check it regularly.
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Old 04-22-2008, 03:12 AM   #7
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thanks
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Old 04-22-2008, 04:15 AM   #8
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Just could let this one go guys. The ONLY reason for a seal on the small bearing of an engine is to keep the dirt out of the bearing. A engine seals on a liquid lock seal between the case and the crank on the area between the bearings. If you hold a sealed bearing up to the light you will be able to see light around the seal. Boat and air plane engines often have no seal and run jost fine. The seal thing is one of the great myths of RC.
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Old 04-22-2008, 05:53 AM   #9
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Just could let this one go guys. The ONLY reason for a seal on the small bearing of an engine is to keep the dirt out of the bearing. A engine seals on a liquid lock seal between the case and the crank on the area between the bearings. If you hold a sealed bearing up to the light you will be able to see light around the seal. Boat and air plane engines often have no seal and run jost fine. The seal thing is one of the great myths of RC.
i have rebuild my engine and broke-in, as of now it run just fine, but the big bearing that I used is sealed bearing, would there be any problems in the future??
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Old 04-22-2008, 08:27 AM   #10
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Hard to say if the manufacture of the engine specifies a specific bearing, then that is what I suggest be used. There are a number of attributes that the casual engine rebuilder might not catch. Engine manufacturers sometimes use bearings with offset races and/or unique chamfers on inner and/or outer races. Mixing and match engine parts seldom works out.
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Old 04-22-2008, 10:58 AM   #11
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Quote:
Originally Posted by rpoage View Post
Just could let this one go guys. The ONLY reason for a seal on the small bearing of an engine is to keep the dirt out of the bearing. A engine seals on a liquid lock seal between the case and the crank on the area between the bearings. If you hold a sealed bearing up to the light you will be able to see light around the seal. Boat and air plane engines often have no seal and run jost fine. The seal thing is one of the great myths of RC.
I just brought up the same subject in the Mugen/GRP engine thread. If the crank and crankcase create a hydro seal behind the front bearing, we should be keeping the front bearing double shielded and lightly greased? The GRP block seems to isolate lubrication to the front bearing.
http://www.rctech.net/forum/showpost...postcount=1401
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