Con Rod Bearing Selection
- Thread starter scrappy
- Start date
sportbikeryder
Registered
I would go on the looser side rather than tighter. I have never seen a bearing fail from having too much clearance (within reason) on a race motor. Tighter will typically run hotter and be less tolerant of debris in the bearing.
Quite a few people have installed #2 rods with green bearings regardless of crankpin size.
Quite a few people have installed #2 rods with green bearings regardless of crankpin size.
scrappy
Registered
Really? I have been trying to just get the clearance near the .0018 to .0019 but ended up only being able to get .0015/16 or or above .0022. I ended up going with the bearing oil clearance of .0015/.0016 I need to tear down my motor in a few months after i do a break in on the internals that are installed now. I might possibly go with the greens since a machine shop owner hear told me to get the most oil clearance i can while racing. I just didnt know if the .0022 was the farthest out the oil clearance could be without causing crank wobble or some kind of weird or erratic behavior
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jeepinocala
Registered
If you are not sure then have someone who has expeirence check them dont ever pick the looser or tighter one that is a no no when it comes to bearings and also you can try a plastigage but make sure there is no dout at all or you will regret it very much this is no subject for someone with no expeirence with it.
scrappy
Registered
If you are not sure then have someone who has expeirence check them dont ever pick the looser or tighter one that is a no no when it comes to bearings and also you can try a plastigage but make sure there is no dout at all or you will regret it very much this is no subject for someone with no expeirence with it.
I am not sure if the plastigage portion was directed at me or not, but if it was, yes i used plastigage to verify that my measurements were correct.. i even bought brand new plastigage specifically for this one build. I used 2 sets of plastigage to verify that neither strip of plastigage were out of proportion.
When all my measurements were finished all 8 measurements of plastigage read .0015" / .0016" So my final oil clearance on all 4 pins were within .0001" of each other and were in the oil clearance recommendations of .0013' - .0022.
I would have rather been closer to the .0022 but going to the next size bearing would have put me at or a little over .0022
jeepinocala
Registered
Is there a coating on the bearings?
scrappy
Registered
Not that i could tell. i used some cleaning solution to remove any factory oils or leftovers from the production process on the bearings and the crank itself was also thoroughly cleaned (before and after each measurement). It is possible that the measurements that were gained on the Black bearings were mis measured, it is unlikely but it is still possible. However instead of running the risk of having an undersized bearing which was right at or close to .0022" i opted to use the brown bearings which put me at .0015/.0016"
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