Engine basics > Engine set up tips
Good bearing turns bad after installation??
Motorman:
You should remove the seals or shields on the rear bearing. Fuel will get in there and wash out the grease then clog the bearing with dried castor.
To remove it just poke a small screwdriver, pin or something in the gap between the inner race and the shield then pry it up. Try to minimize the amount you penetrate into the bearing or you'll hurt the cage. Clean the grease out of the bearing, you don't want chunks of grease giving you hydraulic lock.
You don't need to chill the bearing. The expansion rate of the hot crankcase will far exceed the small amount of contraction of the steel parts. Also the condensation will draw unwanted water to the mix.
If the bearing pocket was made too small, you might have the same problem but, there are fixes for that too.
Motorman 8)
Dave Hull:
Good advice from the MM. This is the wrong application for grease-packed bearings. Too high a DN value (higher rpm) and high temp enough to degrade common greases before the engine lifetime is used up. And since you have a good bearing oiling system already built in to the engine...why negate all those benefits? Greased bearings are useful mostly in applications where you do not have a good oiling system, and want to avoid the expense and complexity of adding an oiling system. Greased bearing systems are not better just because everyone has seen them on car axles....
Bearing seals and bearing shields are two different things. A shield is a stamped metal piece that snaps into recesses machined into the bearing race. It is non-contacting so it has no drag. But while it prevents free flow of oil lubrication (and that's why you don't want it in your rear engine bearing) it does let grease slowly migrate out in a grease-packed application. So that's not "greased for life" in our application, either. A seal is a rubber/plastic closure in contact with both races of the bearing. It will keep in the grease, but it also has drag. Most commercial bearings will be way over-greased for a high-speed, low drag application like this. So the balls can't fully plow the grease out of the ball track, which is what is needed. The grease is there to weep the base oil out over a long period of time, thereby lubricating the contact zone. If the bearing is packed so full that the bearing can't clear the ball track it causes a lot of self-heating of the grease. Something else you don't want. Power loss and putting unnecessary heat into the lubricant. Hopefully that gives some idea of the "whys."
To pop the shield out, I use a short tool that looks like an ice pick. Put the point into the shield, but biased toward the outer race. You don't want to hit the race, and you don't want to hit the cage. Gently tap the tool handle until it just punctures. Then pry it out. The shield material is quite soft and will puncture easily. Make sure you remove both shields if they are installed.
If you have a bearing with seals, you can use the same technique, but it may be a bit more difficult.
I believe BOCA will remove shields from their stock bearings for you before shipping if you ask?
Good luck with your (noisy) bearings.
Dave
Brett Buck:
--- Quote from: Ty Marcucci on May 26, 2022, 12:05:43 PM ---If all else fails, you can start an East Coast Fox .15 hurl contest. LL~ LL~ LL~ LL~
--- End quote ---
As Emergency Commissioner of the Hurl* I would remind you that while we encourage the Hurling of any Fox engine, all official Hurls must be done with a Fox 15 Slantplug that has been approved by Hurl Technical Services. If your engine has ball bearings it is not qualified for either competition or record trials.
As always, thanks for your interest in the international sporting phenomenon known as The Hurl!
Brett
*as always, this is temporary for the duration of the emergency, and I promise to give up my (virtually unlimited) powers as soon as the crisis is over.
frank mccune:
Hi All:
The problem was solved when I took a walk on the Wild Side and spent $13.25 for @ new bearing. Lol
Thanks for all of the great replies!
Frank
Steve Helmick:
It's wonderful to read of a successful outcome, instead of the usual...no report of any sort...either success or failure. y1 Steve
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