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CARC backlash

G

Georgios

Just got it firing!
Joined
Oct 8, 2011
Messages
7
Hello,

my name is Georgios and I am new to this great forum.

A friend of mine rides a 2005 1100 Breva, with very low milage, and he complains about poor driveability of the bike when the throttle is closed and opened again at low speeds, as e.g. in roundabouts.
I suspect excessive backlash from the final drive. Can this be adjusted somehow? Or has anyone another idea solving the problem?

Thank you in advance.

Best wishes
Georgios
 
Not the final drive. Probably excessive slack in the throttle cables. Adjust as much free play out of the cables as possible. Also check that the latest map is installed in the ECU. Last 3 digits should be V12 for an 1100 Breva. The V12 map helps to cure the lose speed behavior problems.
 
He has adjusted the throttle cables to minimum slack. Maybe the map could be a chance, thanks. How can the map be checked?

Anyway, is it possible to adjust the backlash in the final drive? Just for the case, the map will not cure the problem.
 
Nothing is foreseen for that, to my knowledge.

However, AFAIK the V11 has silent blocks inside the cush drive (between the shaft & the wheel). MAYBE it would be possible to put in something similar on a CARC bike?
 
There is no way to adjust the 'Backlash' as it is a result of clearance between the engagement dogs on the pinions and the pinion teeth themselves. Guzzi did suggest swapping the torque rod bush for one with higher hysteresis in its damping component but the main things that seem to affect a change are the previouusly mentioned throttle cable adjustment and mapping changes and also age/distance.

One thing to remember is that the majority of the bearings in the gearbox are 2RS types. Especially when new the seals impart significant drag on the shafts. Going from neutral to first will tend to be particularly clonky at first but the 'Braking' effect of seal friction will also cause velocity changes during other ratio shifts that will make things noisier. The problem will be exacerbated is the machine is only ridden infrequently as the seals won't soften and will tend to 'Memorise' their positions.

Pete

PS the only cush systems on the B11 are the face cam in the gearbox and the bonded rubber jointing in the driveshaft itself.
 
Georgios said:
Maybe the map could be a chance, thanks. How can the map be checked?
Click to expand...


Map revision can be seen using VDSTS. It can also be seen by Axone and Navigator which are dealer tools and are used to update the map.
 
Hi Pete,

thanks for your detailed reply. On a Honda CX 500 final drive it is possible to adjust the backlash by changing the washer. Honda recommends 0,25 mm gap measured on the pinion. I thought Guzzi would have built things similar.

John,

so this only can be checked by the dealer. My friend will be there on Thursday, he will ask.

Thanks also, RJVB.

Georgios
 
Earlier final drives you were able to rebuild. the parts for the CARC are not available separately.

The adjustment you mention on the Honda box would not of noticeably, (When being ridden.) changed the backlash in the driveline. Helical gears as used in a differential or bevelbox have to be set up very precisely to ensure the point of contact on he face of the two gears is in the right place and contact is only 'Pressing' rather than 'Sliding'. To achieve this the x any y axis of the gears are changer in relation to one another by shims. One of these shims will be the 'Washer' to which you refer in the Honda box. They would NOT have an appreciable effect on the 'Clonk' as the clearance betwixt the teeth when set up is measured in thousandths of an inch.

Get the set up wrong and the gears will destroy themselves in very short order.

Pete
 
Hi Pete,

that makes sense to me.
Then we will go the other route via the map, valve clearance, synch the throttles or adjust the TPS. I hope one of it helps. I´ll let you know.

Thanks.

Georgios
 
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