Replacement Fan Assy

Discussion in 'Trials' started by lamotovita, Jul 8, 2018.

  1. lamotovita

    lamotovita DAMN SNOWBIRD!

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    I thought I recently saw a thread here about different replacement fans or fan motors for Trials bikes, I didn't pay much attention cause I didn't need one at the time. Now I can't find the thread.
    The fan on my Scorpa T-Ride locked up and the fan rectifier melted down in the process. I can find the Spal fan on line, but I'd be interested in a more reliable unit. I don't know why the fan needs it's own rectifier (the bike has a 12V battery) but mine is marked Leonelli 1210, I can't find any listing for that. Any suggestions?
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  2. lineaway

    lineaway Long timer

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    Ya, the thread was talking about Fantic K roo , which almost any fan off a street bike would work. The modern trials bikes fan fits in very tight space. I think there is a saved thread on Trials Central, maybe in the gas gas forum.
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  3. motobene

    motobene Motoing for 46 years

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    I know it's water under the bridge and you need a replacement fan, but perhaps worth re-mentioning:

    Squealing and (in some cases) locking up starts when the original lube between shaft and bearing migrates out and dries up.

    Not in all cases of course. Some will just die no matter what you do.

    Most fan problems come from failing to re lubricate the bearing. A bunch of squealing time and the shaft/bearing interface can clap out. But usually, even well-squealed fans shut up immediately with one pump of oil.

    Best is the preventative, rather than responsive, approach, sneaking between the motor and fan cowling with a pump can tip and shooting a squirt of oil (I use ATF+4, a synthetic) onto the fan shaft one to four times a year.

    I pressure wash frequently from the front and under-tank directly on the fan, but never have had a fan issue.

    I'm not even sure what kind of bearing has been in the fans over the years, ball or journal (bushing). If ball, lubricant loss then water inside will eventually lead to rust lock-up. On a shaft and bushing, the shaft can rust, which also can lock up a fan. Sometimes you can free it up and lube it and it will be fine for months without re lubing. It's probably a bushing, as ball bearings require more than one to stabilize a shaft. If there are two bearings in the things the back one apparently doesn't need re lubing. The front one is the one expose to water and dirt.

    Anyone had one of these apart? Come to think of it I have dead one in the shop that can be autopsied.
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  4. lamotovita

    lamotovita DAMN SNOWBIRD!

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    On the Spal fan in question the plastic fan has a cup that covers the front of the motor so there is no snaking in, the plastic fan is pressed onto the knurled shaft so removing and replacing it repeatedly won't work very well. Where the shaft emerges from the motor I can see a conventional sealed ball bearing, I think I can pry the seal off the bearing, I'll try during the autopsy, but it feels like a magnet came loose in there to me.
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  5. motobene

    motobene Motoing for 46 years

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    That's typical. There is a gap of course, or the fan would not turn.

    I stick the tip of my pump-oil can into the gap, lifting the edge of the fan's plastic cup a bit, and aim for the intersect of the fan and shaft. One good pump. That works despite it being a bit uphill to the bearing when the radiator is naturally tilted down or is vertical.

    If you want more for-sure oiling, angle the bike up significantly before squirting the oil.
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  6. Sting32

    Sting32 Trials Evangelist

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    Cousin took apart the 2012 raga fan, managed to build a way to press off the fan-blades so undamaged in case he could salvage the motor. Then sourced a motor off amazon, and dissected the electric motor (he's kind of like Motobene, geeky engineer type) and posted some to me. the fans seem to have bushing type bearings instead of bearings, the squeel could be silenced for a while with grease but he said the shaft and bearing ended up with excess clearance. He is a machinist & works in prototype department for aircraft industry, so has some amazing skills and access to neat tools and oils and other things I would never have. I hoped he might come up with a solution to the worn bearings, like ball bearing replacements, but he didn't.

    all just fyi
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  7. lamotovita

    lamotovita DAMN SNOWBIRD!

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    Follow up autopsy report.
    Fan motor is sealed and clean. I had to pry the plastic end cap off as it was glued very effectively. Sealed ball bearings at each end of shaft are as good as new. One of two magnets are broken and armature is damaged and burnt, can't say what order things happened in. I find it interesting that the magnets are not glued or otherwise fastened in the motor casing, they are simply stuck magnetically in the steel motor housing and some plastic spacers are used to keep them spaced apart and from rotating inside the housing. The plastic spacers are in fine condition and still do their job. So excellent sealing is great but the quality of the parts sealed inside is questionable.
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  8. motobene

    motobene Motoing for 46 years

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    Great feedback! Interesting on the ball bearings at both ends. Makes sense on the lockup now too, as rust in the front ball bearing (the rear is far more protected) would lead to a lockup.

    I had been assuming single journal bearing but see now that makes no sense. There should be two, and why not ball bearings? The frequency of the freak-out when they squeal is in line with some radial play in a dry ball bearing, with a squirt of oil dealing with the dry part on the critical front bearing. Have yet to take the one dead fan apart. Been too busy manufacturing lights....
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  9. REALGRAVEROBBER

    REALGRAVEROBBER LEAVING GRAVES EMPTY

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    People install computer cooling CPU fans. Can be secured to your radiator with zip ties, and some rubber fuel hose pieces. 12v too. Fitting one, or two smaller may do the trick.
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  10. motobene

    motobene Motoing for 46 years

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    The low-volt computer cooling fans typically don't move much CFM. Do you have a specific model in mind?
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  11. lamotovita

    lamotovita DAMN SNOWBIRD!

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    I should have mentioned that the Spal fans are readily available and can be ordered through most automotive sources in the USA. Other than the fact that mine came apart in pieces, it looks like a pretty well made fan, much heavier duty than anything you'd find on a personal computer. I ordered the same unit that I replaced and will hope for better results this time.
    #11