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Old 08-08-2010, 03:01 AM   #1
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Default Double vs. single seal on front engine bearing

I have always bought double sealed front bearings for my engines.
I have left them as they come in the package with the grease inside.
I have a Picco .26 for one of my cars (Revo) and that is the third Picco engine so far.
I have always heard that the stock OFNA bearing in that engine is crap and have always replaced them BEFORE even starting the car.
I have used expensive bearings in the $50 range as well as cheapos for $10 but I'm not that convinced they lasted as long as they should.
Now I have a brand new Picco engine once again and I decided to at least try the stock bearing out.
That bearing has only one seal and it's not that tight. If you hold the bearing towards the sun you can pretty much see right through it.
I have used that bearing for over a gallon now and still no signs of leak or wear! I'm happy with it... is it just luck with THIS bearing or...?

Is the single sealed bearing gonna last longer due to better lubrication or last shorter due to excessive dirt exposure?

Is the double sealed bearing gonna last longer due do better protection or last shorter due to less/worse lubrication?
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Old 08-08-2010, 10:13 AM   #2
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I have gone round and round with this in my own testing and found that most single shielded bearings need replacement in the first gallon or so due to the exposure factor. As you mentioned, especially in offroad racing, the engine case is like a pump and with the case pressure constantly changing from negative to positive and back to negative like a pump, it creates a sucking and blowing effect and when the bearing doesn't have the second seal on the inside of the engine to help with the sealing process, the case pressure forces the fuel and oil into the bearing and depending on the engine, some so signs of leaking from day one and others will get away with it for a little while but it will leak at some point long before the life expectancy is reached causing the dirt and debris to stick to the seal. As the engine cycles, it will push fuel and oil out of the seal during the power stroke and suck a little bit a dirt in during the compression stroke and this is a big reason why people's engines prematurely wear and/or fail because they don't catch the tell tale signs of this process in time because they assume the bearing should go longer than that. I personally use the TKO double shielded bearings in most of the engines I build and for $15, I consistantly get 4-5 gallons out of them without touching them. I think it is one of the best bearings for the money.
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Old 08-08-2010, 11:57 AM   #3
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Novarossi part # 17011

Nobody will dispute that is the best front engine bearing on the market !!!

It has two seals on the outer side of the balls that ride In v grooves and the bearing also uses the step style shield on the first seal. The way the bearing is designed it allows the spinning balls to stay exposed and retain lubrication from the oil in the fuel while providing unsurpassed protection from dirt ingestion and it also holds crankcase pressure like no other


4or5 gallons out of a double shielded (on each side) bearing is pretty good considering the grease that the bearings are packed with flings itself to the outermost part of the bearing and after a short period of time the bearing starts to run dry and seizes at higher rpm's . That's why you get the rust looking marks on your crank around where the front bearing rides on it .
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Old 08-08-2010, 12:03 PM   #4
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Quote:
Originally Posted by houston View Post
Novarossi part # 17011

Nobody will dispute that is the best front engine bearing on the market !!!

It has two seals on the outer side of the balls that ride In v grooves and the bearing also uses the step style shield on the first seal. The way the bearing is designed it allows the spinning balls to stay exposed and retain lubrication from the oil in the fuel while providing unsurpassed protection from dirt ingestion and it also holds crankcase pressure like no other


4or5 gallons out of a double shielded (on each side) bearing is pretty good considering the grease that the bearings are packed with flings itself to the outermost part of the bearing and after a short period of time the bearing starts to run dry and seizes at higher rpm's . That's why you get the rust looking marks on your crank around where the front bearing rides on it .
There you go again, talking about balls.....

On a serious note, I have to agree.
The Nova front bearing is, without a doubt, THE best bearing I have ever used.

Someone was going to get back to me about ceramic BALLS for that bearing....
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Old 08-08-2010, 12:55 PM   #5
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Default very nice explanation

Quote:
Originally Posted by PowerHouse View Post
As the engine cycles, it will push fuel and oil out of the seal during the power stroke and suck a little bit a dirt in during the compression stroke and this is a big reason why people's engines prematurely wear and/or fail because they don't catch the tell tale signs of this process in time because they assume the bearing should go longer than that. .
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Old 08-08-2010, 09:10 PM   #6
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Will the nova 17011 fit in vspecs?
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Old 08-08-2010, 09:30 PM   #7
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Will the nova 17011 fit in vspecs?
Like a glove
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Old 08-09-2010, 11:04 AM   #8
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Isn't the 6.3 mm thickness gonna be a problem or is it just a small enough difference from the standard 6.0 mm to not be a problem.
If I'm correct the most engine use 6.0 mm.

...and now back on topic.
What do you all think of the one vs two seal question?
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Old 08-14-2010, 03:20 PM   #9
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the .3 mm is so close it will not be an issue. We use the TKO ceramic front nearings and have had xlnt results. WE have tried leaving both seals in and removing the inner seal, and have had great results either way. So at this point we just leave in both seals for the extra protection. You will have less resistance with only one seal but its not enough to notice.

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Old 08-14-2010, 03:48 PM   #10
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17011 novarossi!!! I have 8 gallons on this bearing in my plus 4 ,And doesnt leak a drop and feels like new
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Old 08-14-2010, 06:39 PM   #11
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Originally Posted by teamlosi906 View Post
17011 novarossi!!! I have 8 gallons on this bearing in my plus 4 ,And doesnt leak a drop and feels like new
thats all i have to say about that
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Old 08-14-2010, 06:40 PM   #12
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Quote:
Originally Posted by Klimpen717 View Post
Isn't the 6.3 mm thickness gonna be a problem or is it just a small enough difference from the standard 6.0 mm to not be a problem.
If I'm correct the most engine use 6.0 mm.

...and now back on topic.
What do you all think of the one vs two seal question?
the 6.3mm is only on the inner race and is so you dont have to add a shim behind the collet

actual bearing dim. is 7x19x6x6.3mm
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Old 08-15-2010, 10:01 AM   #13
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Talking Front Bearing

Well, I have to ask this question.

I have some .12 engines with a shielded front bearing and not a sealed one.

They don't leak.

Can someone explain that??

Doubled Shielded.

I also have a front bearing I just pulled from an RB engine. I don't know if it

was the stock bearing, but, it was double sealed.

This sucker leaked like no bodies business.

Replaced with a I think a TKO or Protek bearing and runs fine now.

No leaks. Double sealed. Steel ball bearing.

What do you folks think about shielded vs Sealed?? b b

Thanks
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Old 08-15-2010, 10:05 AM   #14
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Sealed are better for offroad mainly to keep the dirt out.

Onroad we don't worry about such things. They usually don't leak even without the seal and if they do, so what. Doesn't hurt anything.
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Old 08-15-2010, 11:32 AM   #15
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Quote:
Originally Posted by Dr. Evil View Post
Well, I have to ask this question.
I have some .12 engines with a shielded front bearing and not a sealed one.
They don't leak.
Can someone explain that??
Doubled Shielded.
I also have a front bearing I just pulled from an RB engine. I don't know if it
was the stock bearing, but, it was double sealed.
This sucker leaked like no bodies business.
Replaced with a I think a TKO or Protek bearing and runs fine now.
No leaks. Double sealed. Steel ball bearing.
What do you folks think about shielded vs Sealed?? b b
Thanks

Thats the thing, it's not the seal on the bearing that keeps the engine run as a leak free engine.
We are saying: -Oh man I need to change my front bearing cause the engine runs hot and can't be tuned.
You change the bearing and the engine is running fine now!

That was not the seal on the bearing causing this. Since you don't even HAVE a seal on your engine. YOU ARE THE LIVING PROOF!
The seals are there to protect the bearing from dirt!
The thing that prevents your engine from sucking in air is another history.
Around the crankshaft the fuel/oil creates a seal that prevents the engine from sucking in air. The crankshaft has to be perfectly centered in the crankcase for this seal to be able to form itself around the crankshaft.
What happens when a bearings is worn is that the crankshaft can rotate some what off center and therefor the fuel/oil film around it brakes and then you have an air leak.

To clarify my point: Take a BRAND NEW bearing and remove all seals and mount it in the engine.
You will now have an engine that runs fine and tunes like you are used to BUT, as soon as you hit that dirt track the bearing will start to collect dust and dirt. it wont take many tanks for it so die.
If you run on-road you will be fine as long as the on-road is a clean road (indoor)
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