bearings
- Thread starter metal bits
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Hi Hugo,
Did you use a bearing with 2 seals, or just one side? I'd have bet on the inner seal stopping the air flow or at least restricting it.
Not many men can claim to have expanded a condom so much it pushed their foot of the footrest!!!!
H
Howard,
The bearing had just the outer seal. The engine had just been rebuilt by the late Tony Maughan and could not be faulted in any other way. The workmanship and assembly were superb. Unfortunately it was his idea to try the sealed bearing and I think my engine might have been something of a Guinea Pig. It took me a very long time to finally work out what was the problem with it. It was only finally resolved on a later rebuild by Bob Dunn. This is no reflection on the current work of Maughan and Sons and I would happily trust any Vincent engine to them today.
Hugo
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During a period of good 16 months, i found tiny silver slivers of polished metal in the oil filter (during 3 filter changes)
Everything in the timing side looked good, the valves wern´t making funny noises, and oil consumption was steady.
After further investigation, i found the outer primary ball bearing race full of swarf?
On closer examination of the bits i managed to pick out from between the balls it turned out to be the remnants of what appears to be an early type bearing seal in the form of a thin ring of aluminium coated with rubber.
Crankcase pressure (or maybe just wear on the ring) had dislodged it and the ball bearings did the rest.
Trevor is right with the small contact area for PD2 and a very thin contact area for the front primary sprocket inside face when using sealed bearings
After finding a special bearing puller, i managed to remove the ball bearing and replace it with an unsealed one with the cases still together.
At the same time i fitted te seal kit from russel and made up a large dia hardened washer which is trapped between PD2 and the bearing and gives a large surface area for the sprocket thrust face to work against (i had to remove material from the thrust face end to get chain alignment afterwards but only half as much as the washer thickness?)
I´d go for the standard unsealed bearing and a mainshaft seal
Everything in the timing side looked good, the valves wern´t making funny noises, and oil consumption was steady.
After further investigation, i found the outer primary ball bearing race full of swarf?
On closer examination of the bits i managed to pick out from between the balls it turned out to be the remnants of what appears to be an early type bearing seal in the form of a thin ring of aluminium coated with rubber.
Crankcase pressure (or maybe just wear on the ring) had dislodged it and the ball bearings did the rest.
Trevor is right with the small contact area for PD2 and a very thin contact area for the front primary sprocket inside face when using sealed bearings
After finding a special bearing puller, i managed to remove the ball bearing and replace it with an unsealed one with the cases still together.
At the same time i fitted te seal kit from russel and made up a large dia hardened washer which is trapped between PD2 and the bearing and gives a large surface area for the sprocket thrust face to work against (i had to remove material from the thrust face end to get chain alignment afterwards but only half as much as the washer thickness?)
I´d go for the standard unsealed bearing and a mainshaft seal
Easy to say with hindsight, but that's what I'd expect. If you'd had the inner seal in, it probably wouldn't have given that problem. The outer seal probably worked as a non return valve out of the crankcase, the inner one would (possibly probably) have worked the oposite way. A proper seal at that point would restrict the air leaving the crankcase. We call these things sealed bearings, but they are really just shielded bearings.
H
I agree with Howard about most bearings simply being shielded, if you want a bearing that is closer to being "sealed" then you would need "explosion proof", however they are very expensive and I am not sure about the range of sizes. FWIW
Kevin