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OS91FS loose front bearing

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OS91FS loose front bearing

Old 07-31-2010, 08:31 PM
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ozspit
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Default OS91FS loose front bearing

I have an OS 91 FS Surpass II which runs beautifully, nice idle, smooth transition and generally very reliable. Its had a lot of use now and the front bearing is a bit loose in the housing (bearing itself is ok) resulting in a bit of lateral prop shaft movement and hence vibration generally resulting in me losing prop nut mounted Al spinners (expensive!)
I have tried Loctite and shimming but these only seem last a couple of flights before the bearing is once oagain spinning in the crankcase housing and the lateral movement and vibration returns.
Apart from buying another crankcase, can anyone suggest a longer lasting fix?
Old 07-31-2010, 10:01 PM
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Live Wire
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Default RE: OS91FS loose front bearing

Other than a new case, JB weld may work. A very thin coat to build up the housing. But I would get a new bearing, the housing may be worn a little.
Old 07-31-2010, 10:10 PM
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w8ye
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Default RE: OS91FS loose front bearing

Get a new case if it is a Surpass II

If it is the older Surpass I , the cases are no longer available
Old 07-31-2010, 10:22 PM
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Default RE: OS91FS loose front bearing

Did you by any chance rebuild the engine using BOCA bearings?? I got some bad ones from them but the front bearing started leaking-FLOWING fuel the first time I I fired up the engine. A new set of bearings from a different bearing company cured my problem. The minute your bearing started spinning your case was probably destroyed. You can try installing a new bearing just to see if it is still a press fit. A good new bearing requires you to heat up the case to tap it in.
Old 08-01-2010, 07:07 AM
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Default RE: OS91FS loose front bearing

I am surprised that using Loctite did not correct the problem. As a result I suspect that the case is cracked in the area of the bearing.
Old 08-01-2010, 01:54 PM
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Default RE: OS91FS loose front bearing


ORIGINAL: Villa

I am surprised that using Loctite did not correct the problem. As a result I suspect that the case is cracked in the area of the bearing.
If it has been spinning a long time the bearing may have worn the case enough to the point nothing will stop it. Oz could measure the ID of the case and call someone like rcbearing.com and see if they have a bearing that is just over sized enough for a press fit into the worn case?? Just a thought?? Have it spot welded in?? Clean the case and JB weld?? Just thinking from a guy that couldn't afford a new case.
Old 08-01-2010, 04:28 PM
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Default RE: OS91FS loose front bearing

should be using red or green locktite as the heat will soften the white and blue
Old 08-03-2010, 06:28 AM
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ozspit
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Default RE: OS91FS loose front bearing

Thanks everyone for the feedback. I did use blue Loctite. I'll try a red. No not BOCA bearings, NHP I think. A new crankcase is about half a new engine price wise and given previous replacement parts, its getting to be a bit like grandpa's axe. I'll try a few of your suggestions and save my money for a new pumped one! Half the fun is in the tinkering!

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