Crankshaft bearing question

[J-Madd]

I have an extra crankshaft bearing to replace one I grenaded. I'm sorry I didn't take any pics. It looks just like the regular ball bearing that was on it, except on one side it is closed by a metal seal (it's not really sealed because there is no rubber, i just don't know what to call it.) The other side is normal and you can see the balls and cage. Can I run this?

 

Also FYI: you must be sure the dowel/pins on stock type crank bearings are aligned correctly durnig assembly. I haven't put together a motor that even had those damn pins, but this particular 4 mil crank had them. We smashed the pins into the cases on the inner bearings and actually broke the outer bearing. I didn't think we torqued it down enough to cause that damage, but should've known something was wrong when the cases didn't just fall together

[Larry's Shee]

Unless it was sold to you as a direct replacement for a crank bearing I wouldn'y use it. If it is a correct bearing the plate would go out towards seal so that it would get oil. Never force it , get a bigger hammer !

[J-Madd]

Thanks for the opinion. I kinda have mixed feelings about using it. It's identical except for what I mentioned, but I don't know if it was intended to turn 10,000+ rpms.

[blowit]

Thanks for the opinion. I kinda have mixed feelings about using it. It's identical except for what I mentioned, but I don't know if it was intended to turn 10,000+ rpms.

 

 

The type of bearing you are looking at is called a "shielded bearing". They are typically used in sealed enclosers such as electric motors. The shields act to retain lubricant while the inner lip does not contact the inner race to reduce frictional heat. Shields are designed typically to be used with grease, not oils. I am not sure what to make of your single side shield unless for a specific application. Truth be told, the shield would probably work just fine but I would probably pop it out just so if anything makes it in the bearing, it has a better chance of leaving.

 

You can also cross the numbers on the bearing back to the OEM for max speed recommendations. They are usually about 20% higher in oil than in grease due to the reduced drag coefficient.

 

Mull Engineering

[J-Madd]

The type of bearing you are looking at is called a "shielded bearing". They are typically used in sealed enclosers such as electric motors. The shields act to retain lubricant while the inner lip does not contact the inner race to reduce frictional heat. Shields are designed typically to be used with grease, not oils. I am not sure what to make of your single side shield unless for a specific application. Truth be told, the shield would probably work just fine but I would probably pop it out just so if anything makes it in the bearing, it has a better chance of leaving.

 

You can also cross the numbers on the bearing back to the OEM for max speed recommendations. They are usually about 20% higher in oil than in grease due to the reduced drag coefficient.

 

Mull Engineering

 

 

Thanks Brandon. I knew you would have an answer. I'll check the numbers out and if its rated for the RPMS I'm gonna run it.

[blowit]

Thanks Brandon. I knew you would have an answer. I'll check the numbers out and if its rated for the RPMS I'm gonna run it.

 

 

The RPM level will be largely variant on the level of precision o the bearing. ABEC standards are one of about 4 classifications to rate a bearing's precision thus the rpm max. I will guess about an ABEC 3 on that one. Basically everything from concentricity, grind finish, etc all plays into how much heat a bearing creates at speed. The only killer of bearings is heat so basically RPM is dependent on heat.

 

You will find there are many bearings that do not rate for what a crankshaft spins at. That is because the engine will obviously not stay at max rpm all day every day and that is what the rating implies. You also have to weigh in thinks like heat sinks, air flow, etc. All in all, you are rated for at least 7000 rpm in oil with an ABEC 3, you are likely fine.

[blowit]

To add to the confusion, in order to run precision bearings, you have to have a precision environment. Precision ground shafts, fits, etc. You will find bearings on cranks are not all that precise and if you tried installing an ABEC7 bearing on a crank, it would fail miserably because of the fit. Let say the ABEC7 can handle .0001-.0002" interference and you try to go on the shaft with .0005", you just reduced the bearing clearance and you probably know how well pistons do with reduced clearance. Bearings are the same deal...

 

OMG, I can jaw more than I need to on bearings I guess......

 

 

 

 

B

[Larry's Shee]

Well , I know I just learned something today. Thank You !!

[J-Madd]

Well, I don't really know what numbers/letters indicate the rating. I've googled a few of them and come up with websites that sell bearings, but no mention of OEM use or rating.

 

 

On another note, due to having ruined this bearing, we had to take the top end apart to remove it. (Top end was already on - we just had this motor apart to change the transmission.) What we found was a cracked piston on skirt between the windows. This was a Vitos piston for short rod 4 mil crank. It had very little wear on the intake or the exhaust side, but VItos says this piston is moly coated. I'm not familiar with that coating, so I don't know if it reduced wear, or there was too much clearance which would reduce wear, but cause piston slap and lead to skirt failure. Ring end clearance was 0.016", which isn't too bad on a motor that has been ran a while, I don't think.

 

 

 

 

I have another 4 mil that grenaded the center bearing. Does anyone repair these? Is it remotely cost efficient to do this? Titan racing put a new rod on a crank for a friend of mine for cheap, but I was just checking if anyone else repairs these (besides twister or crankworks - not interested in it being gone for 6 months.)

[AKheathen]

you can cross it on a vxb site. that should be a "z" style bearing, if i remember correctly. the "s" style uses the plastic seals, like your axle bearings. either way, you should be able to ge the rpm rating in both grease and oil, since it's not a sealed unit. what is the part number and manufacturer? how many balls?

as for the crank, it depepnds on the condition of everything else. wildcard, fast, and probably a few other sponsors can do the work, but if you fin that you need much more than the center bearings and seal, which is the least i would put in there having one grenade, then it could run as much, or more than a new crank

[J-Madd]

you can cross it on a vxb site. that should be a "z" style bearing, if i remember correctly. the "s" style uses the plastic seals, like your axle bearings. either way, you should be able to ge the rpm rating in both grease and oil, since it's not a sealed unit. what is the part number and manufacturer? how many balls?

as for the crank, it depepnds on the condition of everything else. wildcard, fast, and probably a few other sponsors can do the work, but if you fin that you need much more than the center bearings and seal, which is the least i would put in there having one grenade, then it could run as much, or more than a new crank

 

 

Well, back to the bearing:

Why are people spending 90 bucks on a max load bearing if this will work? It's about $15. As far as the sheild on one side -> it had one on both sides, I didn't know one had already been removed. We took the other one off as well. There is a string of characters "358d" on the bearing. It also has a UPC 7316573316600, but google didn't find anything. It's made in Argentina.

 

 

edit: It also has "6305-2zn" on it. I found this My link

 

This is not my bearing but even if it is equivalent - it's cheap.

[AKheathen]

i thought you said you had the metal sheilded one, not pllastic sealed.. "s" is plastic sealed, "z"is metal sheild. "n" is for the snapring groove, and i can't remember what denotes that it has the circlip, roller style, or higher load rating, etc. now any old bearing manufacturer won't do. it may work in 90% of aplications as a replacement, but on the crank, i don't want it to flake, wear excessively, ir simply fail because of cheap materials or tolerances. i went in and paid almost $40 for a "max load" form a local place, of a good quality brand. i don't think people ar paying 90 for just the bearing. mabey to have the crnk sent in and swap it out, or you could be confused with the tz flat roller style, which is about right. i would personally go with an 8 baller for higher reving motors. how many balls you have?

[J-Madd]

i thought you said you had the metal sheilded one, not pllastic sealed.. "s" is plastic sealed, "z"is metal sheild. "n" is for the snapring groove, and i can't remember what denotes that it has the circlip, roller style, or higher load rating, etc. now any old bearing manufacturer won't do. it may work in 90% of aplications as a replacement, but on the crank, i don't want it to flake, wear excessively, ir simply fail because of cheap materials or tolerances. i went in and paid almost $40 for a "max load" form a local place, of a good quality brand. i don't think people ar paying 90 for just the bearing. mabey to have the crnk sent in and swap it out, or you could be confused with the tz flat roller style, which is about right. i would personally go with an 8 baller for higher reving motors. how many balls you have?

 

 

Ok try this link. Other is no good. After clicking search for "6305" and it is one of the sheilded bearings that come up. 63052zjem, I think. Click

 

edit: Well hell, none of those have a snap ring grove, but that is the bearing without the groove I think.

[J-Madd]

Ok try this link. Other is no good. After clicking search for "6305" and it is one of the sheilded bearings that come up. 63052zjem, I think. Click

 

edit: Well hell, none of those have a snap ring grove, but that is the bearing without the groove I think.

 

 

Alright, I found it. PUt "6305-2zn" in that search field and THAT is my bearing. It's not as cheap as I thought; so I'm thinking this will be fine.