Transmission problems

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Mar 7, 2017 | 08:47 AM

#11

Max Headflow

Seasoned HDF Member

Joined: Dec 2005

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From: poway

Quote:

Originally Posted by RIPSAW

That reference on synchoro hub as noted in my post was for a car. And I have always though that that toe angle was what held the dog drive into the gears in on the older straight cut tooth gears since there is little side thrust like in the modern 6 speed with bevel gears that requires thrust bearings. When you go from throttle to coming off throttle using the engine as a brake, the drive dogs are going to bump back to the other face. So there has to be more then just the toe angle. And you did I think answer my question on that much force on the shift forks which are held in position by the star V on the shift cam

When going to Helical gears (not bevel gears) in the tranny, the transmission design had to change over a conventional straight cut constant mesh motorcycle transmissions.. The basic idea cutting angles on the dogs is the same but the tranny could no longer use an adjacent gear as part of the sliding dog. The sliding gear would bend the shift fork on either acceleration on deceleration depending on how the helix was cut. To get away from the issue, the helical transmission no longer uses sliding gears as part of the dog clutch. They use either a dogged or slotted rings to control gear engagement.

I'm not sure what you mean by "star V" but the HD 6 speed shift doesn't have to do any thing special to keep the ring engaged. The drum and shift forks simply keep the ring from walking out under no load once the gear is selected.

Mar 7, 2017 | 10:25 AM

#12

Jackie Paper

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Joined: Mar 2010

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From: Honah Lee

There is a spring loaded detent paw that engages the V notch in the shift drum opposite end of the shift lever. It has 5 or 6 depending on gear changes. Brain was not in gear on calling them bevel. So now I also understand how they took care of side load. Also I think I see both applications in straight cut and helical gears in this older 6 speed or are all the gears prevented from sliding to engage dogs? The V with spring detent is on one end, the sifter ratchet grabs the pins on the other end of the shift cam in my attachment. Thanks.

Last edited by Jackie Paper; Sep 14, 2018 at 07:48 AM.

Mar 7, 2017 | 12:11 PM

#13

Max Headflow

Seasoned HDF Member

Joined: Dec 2005

Posts: 19,921

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From: poway

Quote:

Originally Posted by RIPSAW

Thanks for the clarification. On your original post, the synchro discussion got me going the wrong direction. Your "star V' is the shift drum detent system. Still the shift detent system is not used typically hold the dogs in engagement. You are correct that straight cut gears can use the same system as helical cut gears.. It adds cost and requires more space / parts tho.

Here is a pic of a 5 speed. You can see that the gears slide to make engagement. You can see the angles cut on the gear dogs to hold the gear. As I understand it the later trannies use less angle so it not as obvious.