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Author Topic: Engine /Transmission Question  (Read 1864 times)

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2ndwish

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Engine /Transmission Question
« on: May 01, 2011, 07:45:07 PM »

Is it normal to be unable to shift the transmission of an M25XP/Hurth xmission, from forward or reverse to neutral at high RPM (>1500)? I can think of many reasons why you would not want to do it, but is it even possible in normal operation?
T
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lazybone

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Re: Engine /Transmission Question
« Reply #1 on: May 02, 2011, 08:04:53 AM »

I'm embarrassed to admit that (maybe once  :liar) while maneuvering in a panic it has happened to me. 
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Stu Jackson

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Re: Engine /Transmission Question
« Reply #2 on: May 02, 2011, 08:06:02 AM »

I usually shift between 1000 and 1200 rpm.  I sure wouldn't try it at anything above that, although I did once or twice by mistake.  It can be done, but, as you say, not good for the equipment...
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

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Ralph Masters

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Re: Engine /Transmission Question
« Reply #3 on: May 02, 2011, 08:20:10 AM »

In the manufactures manual for the Hurth transmission they state that it can be shifted from forward to reverse at full throatle with no damage to the gears, but should be done only in an emergency.  I have had mine not go into gear going from forward to reverse at about 1500 - 1700 rpm when done absent mined.  One time I need to shif in an emergency at about 1500 when a power boater came out of the launch ramp area and it worked fine. 
I always try to bring the engine to idle then shift, just good practice.

Ralph
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Ron Hill

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Re: Engine /Transmission Question
« Reply #4 on: May 02, 2011, 03:19:21 PM »

2nd wish : You are correct- it gets much harder to shift at rpm's higher than 1500.
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2ndwish

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Re: Engine /Transmission Question
« Reply #5 on: May 03, 2011, 07:05:20 AM »

Thanks for the responses. Sounds to me like some folks experience this and others do not. The documentation from Hurth is clear, it should be able to shift, without damage, at full engine speed. Curious.
T
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Ken Juul

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Re: Engine /Transmission Question
« Reply #6 on: May 03, 2011, 07:27:41 AM »

From the Hurth Transmission manual:  "During normal operation, the transmission should only be shifted with the engine at idle speed. In emergency cases it is also admissible to shift at higher speeds."

At idle it should shift easily.  At higher power settings there is quite a bit of pressure/friction on the teeth of the bevel gears that must be overcome, it will take considerable more force to move the shift lever.  If you are still using the OEM plastic shift/throttle handles, I'm sure Mr Murphy would complicate an emergency shifting situation.
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