S3 Race Custom Modified EC250 Complete Rebuild

[GMP]

Maybe not perfectly good English but perfectly good advice.

Jake, where your at now means that you cannot remove the bearings and reuse them without seals. Once you press a bearing out with force across the inner/outer races, its junk.

Just go get some new high quality open bearings from a supplier. You will pay less and get a better, proper part. Put it together right and not worry about it.

If mine lasts through this year, I'll pull it down and do the same. If it goes bang I'll just swap my trusty '07 engine in.

[Darkside]

I'd like to hear more about those hybrid ceramic bearings. Sounds very promising.

[Jiikoo811]

Here comes couple pictures what can happen if mainbearing seal fail...
There is 1mm radial freeplay on this clutchside failure bearing..



Sent from Razr MAXX

[Neil E.]

I don't know how tight the outboard face of the main bearing is to the case, but here's a thought.

Since you picked out the inboard seal, is it possible to get a small tool past the ball spacer and push the outer seal off the bearing? If there is a bit of room outboard of the main bearing, the seal could drop enough to be pulled out the bearing bore. Distorting the seal is no big deal since you are discarding it anyway.

[GMP]

That will not work, the bearing is pressed in tight to the cases. Two new bearings are cheap compared to the damage from a failed one, and all the time involved.

What pisses me off about this is there is absolutely no reason for it. Everyone knows what works and has worked for years. They simply introduced another possible failure mode with no positive returns. Component life tests should be limited to engineering prototypes in the factory, not in production machines. Whoever signed off on that change wouldn't last long in places I've worked, thats for sure.

[Jakobi]

Originally Posted by GMP

Maybe not perfectly good English but perfectly good advice.

Jake, where your at now means that you cannot remove the bearings and reuse them without seals. Once you press a bearing out with force across the inner/outer races, its junk.

Just go get some new high quality open bearings from a supplier. You will pay less and get a better, proper part. Put it together right and not worry about it.

If mine lasts through this year, I'll pull it down and do the same. If it goes bang I'll just swap my trusty '07 engine in.

I didn't have to press on either of the races with the mains. With enough heat and cold bearings they dropped in by hand. I just reversed the proceedure and used the torch around the bearing. Flipped the case over and gave it a few whacks against a folded up towl and the came back out.

I picked the seals off. The flywheel side one is a little different than whats expected. Jilkoo. When you put them in without seals which way did you face this one? Note - its also a C4 rated bearing.

[Jiikoo811]

Originally Posted by Jakobi

I didn't have to press on either of the races with the mains. With enough heat and cold bearings they dropped in by hand. I just reversed the proceedure and used the torch around the bearing. Flipped the case over and gave it a few whacks against a folded up towl and the came back out.

I picked the seals off. The flywheel side one is a little different than whats expected. Jilkoo. When you put them in without seals which way did you face this one? Note - its also a C4 rated bearing.

I cant remember i put just same way than older one's were in cracked case. I am not expert but i guess doesnt matter which way...i just put same way than factory was put them, because havent find that great forum yet..to ask someone
Sent from Razr MAXX

[Jakobi]

Originally Posted by Jiikoo811

I cant remember i put just same way than older one's were in cracked case. I am not expert but i guess doesnt matter which way...i just put same way than factory was put them, because havent find that great forum yet..to ask someone
Sent from Razr MAXX

Thanks. They were installed as per the top pic facing inwards towards the crank. I'm not sure about the flywheel side bearing at all. Looking at it it appears to use a plastic cage for the bearings and I'm not sure it would really allow as much splash lubing from the back side as it would from the front. I'm also sus about plastic?? Research kind of confirms that its likely a Plastic Retainer/Caged bearing too.

I see this turning into wasted $$ now. If I was to replace that one bearing, can I just get another quality ribbon caged bearing same as the other side, in the right size. Is it worth the $$ to drop both in with pricey ceramic jobbies? I think I'll put the whole thing on hold and go see someone in the bearing store when I pick up the crank on Wednesday.

[Jakobi]

I've done some research and I'm going to use the bearings I have without the seals. As stated above, neither of these bearings have been pressed in or out. The just dropped in with heated cases, and came out with heat and smacking the case against some rags. The fit when back to temp was good and no chance of pulling them out.

The flywheel side bearing is an SKF Explorer series with Polyamide 6,6 cage.

From SKFs website: Solid polymer cages are characterized by a favourable combination of strength and elasticity. The good sliding properties of the polymer on lubricated steel surfaces and the smoothness of the cage surfaces in contact with the rolling elements produce just little friction so that heat generation and wear in the bearing are at a minimum. The low density of the material means that the inertia of the cage is small. The excellent running properties of polymer cages under lubricant starvation conditions permit continued operation of the bearing for some time without risk of seizure and secondary damage.
http://www.skf.com/group/products/be...als/index.html
http://www.skf.com/binary/12-36038/6270-EN.pdf

From that it sounds like it will be up to the job. Back on target after dealing with a mega mind bong.

[Jakobi]

PS. Anyone know what kind of temps the main bearings typically see in use?