Jump to content
IGNORED

Light rattle in gearbox when pushing my bike.


Walterg
 Share

Recommended Posts

Wow!! Thanks for explaining Pete.  Love the bit of history too!
It's completely clear now. 
By the looks of the diagonal and rounded faces on parts #15 and #16 sudden rotational changes direct the energy into the spring washers which will compress and store the energy. When the rotational force lets off again the stored energy is released back to the drive shaft.

image.png

I have to admit I love this stuff!

  • Like 3
Link to comment
Share on other sites

4 minutes ago, docc said:

I had the chance to roll my V11 Sport back and forth, in gear, with the clutch in today. It clicked with every direction change, as expected. No noise in neutral. Seems entirely normal. 

Yes indeed. With mine it sounds very clunky though.

  • Like 1
Link to comment
Share on other sites

On 8/11/2022 at 7:50 PM, pete roper said:

Errr? Not quite.

The driveline shock absorber and is a face cam type. The two cams parts #15 and the collar at the back of assembly #16 rotate in relation to one another. As a torque loading is imposed, either by suspension movement by the shaft or, more seriously by shock loadings imposed by sudden acceleration and gear changing up and down the box, the two cams run up against each other and the Bellville washer tower acts like a spring to absorb the energy. When the load is removed the energy is discharged back through the cams to the shafts.

The free play between 'Power on' and 'Power off' as detectable by rotational movement of the rear wheel when the engine is stopped but engaged in a gear has nothing to do with the shock absorber. It is simply backlash between the engagement dogs of the gears. There has to be backlash to allow the rapidly spinning but differentially speeding dogs to slip into engagement. If they fit precisely together the chances of them slipping into engagement would be negligible. The wider the 'Gap' between the dogs the slicker the engagement but, unfortunately, the greater the hammer loading on dogs and gear teeth as one goes from throttle off to throttle on and visa versa in any gear.

Probably the best example of the dangers of increasing this backlash in a Guzzi gearbox can be found in the early Carb Sports and Daytona 1000 models with the old five speed box. In an attempt to speed up the gear change without spending any money the selector dog collars and pinions went from the long standing six dog engagement to three dog. This leads to ENORMOUS radial travel between power off and power on meaning when the gear is selected and you are accelerating and decelerating the dogs have much longer to themselves accelerate and decelerate before power or braking is delivered and they hammer the living bejaysus out of themselves! This is absolute murder on the pinions and Sport C gearboxes in particular are terribly prone to bashing the case hardening off fifth gear closely followed by third before the rest of the box goes out in sympathy!

The fact that many owners don't get the fact that the word 'Sport' means that you're supposed to ride them like the hounds of hell are chasing you and potter around at sub-4,000rpm lugging the entire driveline, (Which incidentally doesn't have a rubber cush drive in the rear wheel hub.) which simply accelerates the rate at which they beat themselves to death!

After those two models the factory went to a compromise five dog engagement system and reincorporated the rubber cush in the rear wheel. This was a satisfactory compromise. Gear changes were a tiny bit less like dropping a brick in a bucket and the boxes no longer beat themselves to death. This system remained extant until the demise of the five speed and the rise and use of the first of the six speed, four shaft boxes used in the V11.

These "selector dog collars" are the "sliding dogs"/ "shift sleeves" (what the Parts Catalog calls "hoses" (2) and "moveable hoses" (8) ?), along with the "Cush-drive assembly" ("Bellville washer tower" and/or #15/#16?) that were the subject of the early 6speed gearbox recall?

 

engine-driven-shaft.jpg

  • Thanks 1
Link to comment
Share on other sites

8 hours ago, docc said:

These "selector dog collars" are the "sliding dogs"/ "shift sleeves" (what the Parts Catalog calls "hoses" (2) and "moveable hoses" (8) ?), along with the "Cush-drive assembly" ("Bellville washer tower" and/or #15/#16?) that were the subject of the early 6speed gearbox recall?

 

engine-driven-shaft.jpg

Thats correct docc.

Phil

  • Thanks 1
Link to comment
Share on other sites

Well. I'm leaving things as they are now. No more weird sounds and the bike rides wonderfull. I'll fitt the new speedometer cable that arrived today and while I am at it find out why the tachometer was jumping up and down all the time. So time for some electronics.

  • Like 1
Link to comment
Share on other sites

Jumpy tachometer could be internal to the instrument, yet also Relay#2 NO contact or (perhaps more likely in your case) Relay#1 NC contact.

P.S.  - If it's a relay contact bouncing, the headlights would also flicker.

  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
×
  • Create New...