Author Topic: Oil or Grease--Needle roller brg. lube  (Read 2196 times)

Offline Brian Rupnow

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Oil or Grease--Needle roller brg. lube
« on: October 10, 2014, 06:27:01 PM »
On the fall engine project I am building, I wanted very badly to go to a grease filled needle roller bearing on the big end of the con rod, with no inner race but with a hardened rod journal, and grease seals on the bearing. This would have let me run a dry crankcase. Unfortunately, no one sells 3/8" needle roller bearings with seals now. This means I will probably have to run some lubrication in the crankcase. I'm rather torn about what exactly to do now. The engine will be a slow revving display engine, not run frequently and not run under load. It was designed primarily to see if I could design and build a side valve (flathead) engine from barstock with no castings. My gut instinct is to give the needle bearing a good coat of grease and run it that way. Of course the problem is that with a sealed crankcase there is no way to check and see IF the bearing required more grease at some point in the future. The other option is to put a filler tube on the crankcase and run a very small amount of lube in it for the big end bearing. The small end bearing is also a needle roller bearing, but it is pre greased and does have seals, so I'm not worried about it (It doesn't ever make a full revolution anyways, just rocks back and forth). The wrist pin is hardened. I run a small percentage of oil in my fuel to keep the Viton o-ring on the piston lubricated, so the only real issue is lubricating the big end bearing. I am thinking of running a small amount of really "clingy" oil in the crankcase, something like chainsaw chain oil. Again though, since the crankcase is essentially closed, and I will be running only a small amount of oil in it, it becomes very difficult to monitor the oil level. I am open for suggestions that do not include remaking any parts.---Brian

Offline chipenter

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Re: Oil or Grease--Needle roller brg. lube
« Reply #1 on: October 11, 2014, 03:52:51 AM »
Have you allowed for crankcase ventilation , something like Doobleboost vacume engines filters will let you lube the big end , but you may have to scale it down a little bit .
Jeff

Offline Manxmodder

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Re: Oil or Grease--Needle roller brg. lube
« Reply #2 on: October 11, 2014, 08:38:30 AM »
Brian, wonder if you fit a viton 'O' ring either side of the needle roller bearing where it cheeks up against the crank webs,that would act as a sealed bearing if you grease filled it......OZ.
Helixes aren't always downward spirals,sometimes they're screwed up

Offline Brian Rupnow

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Re: Oil or Grease--Needle roller brg. lube
« Reply #3 on: October 11, 2014, 06:34:37 PM »
Sorry guys--I forgot to click the "notify" button. I wish there was some way to set it permanently to "notify" by default. I have decided to wear a belt and suspenders!!! I will grease the bearing with molycote, and put a bit of chainsaw chain oil in the crankcase before I seal it up.---And yes,  will I need to add some kind of crankcase ventilation.

Online awemawson

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Re: Oil or Grease--Needle roller brg. lube
« Reply #4 on: October 12, 2014, 03:34:08 AM »
With the size of that con rod you could incorporate a whacking great oil reservoir inside it  :lol:
Andrew Mawson
East Sussex

Offline Brian Rupnow

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Re: Oil or Grease--Needle roller brg. lube
« Reply #5 on: October 12, 2014, 08:14:49 AM »
Awemawson--That would be a novel approach!!! Not possible though, because the needle roller brg. has a metal shell all around the rollers. Lube wouldn't be able to get thru.---Brian