hi,i just bought the cmb91rs,i used about 8 ltr of fuel and the front bearing is totally damaged and also cause damage to piston/sleeve..what makes the bearing
break that quick?using 18%oil and 20% nitro.(model Technics )
thanks
thanks
cmb 91rs bearings
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 ericwires |
cmb 91rs bearings |
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Posts: 33 (09/20/09 11:57:33) |
Eric Vella
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Dave Marles |
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Posts: 928 (09/20/09 12:57:34) |
Corrosion is the biggest cause of bearing failure.
Dave
Tuning software |
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BoBoKwok |
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Posts: 739 (09/20/09 17:56:44) |
if the engine is not true to the shaft or there is excess movement of engine mount. The steel collar on the crank(especially new motor) may touch front housing
too much so that a little aluminium will go to front bearing. The front bearing is the most easily rusting part in both 45/91RS. A must to clean.
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ericwires |
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Posts: 34 (09/24/09 11:05:34) |
hi,can it be the shaft was making trust on the engine? because i noticed this from the prop nut was touching the tube. the collar wasn't that tight.
Eric Vella
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Dave Marles |
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Posts: 929 (09/24/09 11:21:56) |
The bearing is easily able to take the thrust from the propeller.
Dave
Tuning software |
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HendricX |
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Posts: 74 (09/24/09 16:16:12) |
And as you are running in salt water ..
NO open or steel-shielded bearing .. neither a steel retainer. Composite retainer (THB or TN9) , Rubber-seal one side , C3 fit. Want one ? I can send you one (or more) |
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Fredde Cederberg |
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Posts: 401 (09/24/09 20:04:35) |
I would say, never a steel-shielded bearing or a steel retainer inside an engine, that's asking for trouble.
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ericwires |
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Posts: 35 (09/25/09 11:45:57) |
this is(was) a brand new cmb ,so for sure it had the original bearing,i will replace bearings and sleeve/piston later on as boating season is nearly
over,winter time its too cold to swim for the boat
Eric Vella
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Andras |
bearings: TBH or TN9, rubber or steel seal, etc. | ||
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Posts: 49 (09/26/09 02:31:43) |
Hello,
a bit off topic, but I think it's a very important aspect of boating: quality and type of bearings. 1. I think C3 fit is mandatory - front and rear. 2. Composite retainer as well, but in your experience TBH or T9H is better for our purposes? I used both of them in past years, normally I would go for T9H, but I would be interested in your opinion. 3. About front sealing: rubber means more drag than steel in my opinion, so once again I would be interested in your experience. 4. Normal bearing or hybrid (w/ ceramic balls): I tried many different types, for now strangely enough it seems that hybrid works well as 3.5 rear bearing and as 7.5 front bearing. Tried full hybrid setups, but one of the bearings was always ruined for some reasons. Any ideas why? 5. And last but not least: manufacturer: many of the hybrid products come from China... not always the highest of quality. Do you have any better ideas? For now I'm trying Zwicker (Swiss brand), but I could only get normal (steel ball) bearings with TBH retainers. I'm looking forward to read your posts. Regards, Andras |
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HendricX |
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Posts: 75 (09/26/09 13:27:11) |
C3 / Abec-7 / Class-4 are more suitable for higher revolutions.
(and don't forget our press/shrink-fit) Polyamide (TN) or TN9 (reinforced Polyamide) or Phenolic cage is just fine , Teflon or PEEK makes them unnecessary pricy. Rubber-seal(RS1) is rubbing somewhat , but keeps the pressure in and water out. Steel-shield(Z) will hold grease in ... but we have oil lubrication. As 2RS1 (both sides sealed) are common and easyer to find as RS1 (one side sealed) , I pop the inner seal out. Hybrid or not ? : For the price of a hybride bearing (35us$) i have (almost) 3 Swiss "WIB" bearings @ 11,95. There are 'cheaper' hybrids .. but they have steel cages. Full ceramic ? for about 60us$ ? Don't make me cry ... the hobby is expensive enough without those NASA-parts. And full-ceramics can't stand 'poundering' .. and a loose chip will ruin the bearing. There COULD be good "Eastern" bearings ... but I prefer the major European brands. F A G / SKF / GMN / Steyer / WIB , where for me the price-performance-rate is with the WIB.
Last Edited By: HendricX
09/26/09 13:30:19.
Edited 1 times.
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