Difference between revisions of "Empulse Powertrain Lash"

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(added information provided by Wismann on the forum, links.)
 
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Riders who are new to the Empulse will notice a jerk when starting the bike from a stop. This is sometimes referred to a "the clunk", but the correct name is "powertrain lash". This page will discuss the causes, and techniques to minimize the lash. It should be stated that the lash is part of the normal operation of a motorcycle transmission and not an indication of a problem with the bike.
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Riders who are new to the Empulse will notice a jerk when starting the bike from a stop. This is sometimes referred to as "the clunk", but the correct name is "powertrain lash". This page will discuss the causes, and techniques to minimize the lash. It should be stated that the lash is part of the normal operation of a motorcycle transmission and not an indication of a problem with the bike.
  
 
= Causes =
 
= Causes =
  
Triumph Street Triple Gearlash:
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In a post by [[Brian Wismann]] on the [http://brammoforum.com/index.php?topic=1855.msg14325#msg14325 Brammo Owners Forum], he indicated that the powertrain lash is "typical motorcycle transmission backlash that is being felt.  It is amplified to some extent because:
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1. The electric motor does not idle like a gasoline engine.
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2. We instruct riders not to slip the clutch during launches for the best performance.
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3. There is no engine vibration damping the feel of the lash being taken up."
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He posted the following three videos in an effort to explain the issue visually:
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*Triumph Street Triple Gearlash:
 
http://www.youtube.com/watch?feature=player_embedded&v=yKlsInsP7r0
 
http://www.youtube.com/watch?feature=player_embedded&v=yKlsInsP7r0
  
Empulse gearlash:
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*Empulse gearlash:
 
http://www.youtube.com/watch?feature=player_embedded&v=9SZkPI4HUnU
 
http://www.youtube.com/watch?feature=player_embedded&v=9SZkPI4HUnU
  
Gearlash internals:
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*Gearlash internals:
 
http://www.youtube.com/watch?feature=player_embedded&v=mn2p_hYX0io
 
http://www.youtube.com/watch?feature=player_embedded&v=mn2p_hYX0io
  
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== Dragging the brake ==
 
== Dragging the brake ==
  
Similar to regular ICE bikes, dragging the rear brake when going a low speeds will prevent the transmission bounce.
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Similar to regular ICE bikes, dragging the rear brake when going at low speeds will mitigate powertrain lash.

Latest revision as of 10:32, 15 February 2013

Riders who are new to the Empulse will notice a jerk when starting the bike from a stop. This is sometimes referred to as "the clunk", but the correct name is "powertrain lash". This page will discuss the causes, and techniques to minimize the lash. It should be stated that the lash is part of the normal operation of a motorcycle transmission and not an indication of a problem with the bike.

Causes

In a post by Brian Wismann on the Brammo Owners Forum, he indicated that the powertrain lash is "typical motorcycle transmission backlash that is being felt. It is amplified to some extent because:

1. The electric motor does not idle like a gasoline engine.

2. We instruct riders not to slip the clutch during launches for the best performance.

3. There is no engine vibration damping the feel of the lash being taken up."

He posted the following three videos in an effort to explain the issue visually:

  • Triumph Street Triple Gearlash:

http://www.youtube.com/watch?feature=player_embedded&v=yKlsInsP7r0

  • Empulse gearlash:

http://www.youtube.com/watch?feature=player_embedded&v=9SZkPI4HUnU

  • Gearlash internals:

http://www.youtube.com/watch?feature=player_embedded&v=mn2p_hYX0io

Remedies

Rollback

When the bike is stopped, push the bike back until you feel the transmission engage. Note that this will be about 6 inches (15 cm), and the feeling of the transmission will be very subtle. Engage the brake and you will be ready to start without any lash.

Dragging the brake

Similar to regular ICE bikes, dragging the rear brake when going at low speeds will mitigate powertrain lash.