Sport 1100 earth return path (and other electric things)

[greenman]

Tonight I finally proved it that the earth return path is through the gearbox and not the frame...

 

For quite some time I've noticed that my lights flicker when I change gear from 2nd to third. And I especially notice it when I get the change all wrong and get stuck in the false neutral that lurks there.

So tonight I rolled up outside my garage and shifted down I saw it happen again, this time where I can test out my theory, so sure enough as you change from 2nd to third the headlamp and idiot lights all go out when the gearbox is just off 2nd gear and beginning to engage 3rd. I had to roll the bike backwards and forwards a few times to get the gears to rotate enough to engage the dogs, but finally my theory is proven.

So I'm theorising that the earth return path from the front of the bike to the rear (the battery) goes via the gearbox and not the frame.

how do you design a feature like that in? those tricky Italians!

 

I've also noticed that my indicators work when the ignition key is in the park position. I'm not sure why this was done this way.

I'm sure I'll find a use for this feature as well.

 

DD

[raz]

Seems you are in true need for those extra ground straps everyone mentions.

 

My indicators does not work w/o ignition, but I have a hazard flash switch and that one does.

[Guzzi2Go]

Seems like your ground runs through the neutral switch.

 

EDIT:

Bad phrasing. Looks like intermittent short when neutral switch "kicks in". However, since the fuses stay alive the fault is probably in the powering circuit. Could a relay be disengaged due to neutral switch engaging?

[Guest ratchethack]

Tonight I finally proved it that the earth return path is through the gearbox and not the frame...

 

. . .finally my theory is proven.

 

So I'm theorising that the earth return path from the front of the bike to the rear (the battery) goes via the gearbox and not the frame.

Hm. "Proof" or "theorizing" (either way) I'm afraid this is not sound logic, my friend. And we all know that the travel habits of electrons are always, always, and always on a logic itinerary, being referred to as they often are as "logic circuits".

 

Based on info provided, I've no solution to offer here, but coupla thoughts that might help narrow things down.

 

First, all speculation as to potential coincidences aside, the earth path for the lights is NOT "through the gearbox", and there is no possible earth path for the lights that depends on engagement (or disengagement) of any gear set. In order for this to happen, the paired gearsets in the box would have to be electrically isolated not only from each other and the common layshafts they ride on, but from the gearbox case. Since all gearsets are always engaged, and all gearsets being therefore electrically common with each other at all times, (this being a constantmesh gearbox), the idea of any ground path being made or broken through the gears themselves is impossible.

 

The neutral switch is operated by a plunger operating on a selector cam plate that cannot drop the neutral switch plunger into its detent on the cam plate between selection of 2nd and 3rd gear, (or between any gear selection other than the 1-2 change) even when neither of the sliding muffs for 2nd or 3rd are engaged with their respective shift dogs while changing gears, and even when it "seems like" the box is in "neutral" between gears other than 1-2. In fact, in the 2-3 or 3-2 gear change case, even when there's no drive through the box between 2nd and 3rd, it cannot be "in neutral", and the neutral light cannot come on in this case unless the single wire to the neutral switch has shorted to ground outside the box, or the neutral switch itself has failed. Operating correctly, the neutral switch plunger can ONLY drop into it's detent and complete the ground path when the selector cam plate is rotated into its detent position in the 1-2 gearchange.

 

In other words, being a sequential gearbox, there is no way to achieve a rotation of the gear selector cam plate that would allow the neutral switch to ground the neutral wire between 2nd and 3rd -- only between 1st and 2nd, as designed.

 

Hope this helps.

[GuzziMoto]

Tonight I finally proved it that the earth return path is through the gearbox and not the frame...

 

For quite some time I've noticed that my lights flicker when I change gear from 2nd to third. And I especially notice it when I get the change all wrong and get stuck in the false neutral that lurks there.

So tonight I rolled up outside my garage and shifted down I saw it happen again, this time where I can test out my theory, so sure enough as you change from 2nd to third the headlamp and idiot lights all go out when the gearbox is just off 2nd gear and beginning to engage 3rd. I had to roll the bike backwards and forwards a few times to get the gears to rotate enough to engage the dogs, but finally my theory is proven.

So I'm theorising that the earth return path from the front of the bike to the rear (the battery) goes via the gearbox and not the frame.

how do you design a feature like that in? those tricky Italians!

 

I've also noticed that my indicators work when the ignition key is in the park position. I'm not sure why this was done this way.

I'm sure I'll find a use for this feature as well.

 

DD

Some days I'm not sure if Guzzis engineers are 50 years behind or 100 years ahead.

[pete roper]

The neutral switch is operated by a plunger operating on a selector cam plate that cannot drop the neutral switch plunger into its detent on the cam plate between selection of 2nd and 3rd gear, (or between any gear selection other than the 1-2 change) even when neither of the sliding muffs for 2nd or 3rd are engaged with their respective shift dogs while changing gears, and even when it "seems like" the box is in "neutral" between gears other than 1-2. In fact, in the 2-3 or 3-2 gear change case, even when there's no drive through the box between 2nd and 3rd, it cannot be "in neutral", and the neutral light cannot come on in this case unless the single wire to the neutral switch has shorted to ground outside the box, or the neutral switch itself has failed. Operating correctly, the neutral switch plunger can ONLY drop into it's detent and complete the ground path when the selector cam plate is rotated into its detent position in the 1-2 gearchange.

 

In other words, being a sequential gearbox, there is no way to achieve a rotation of the gear selector cam plate that would allow the neutral switch to ground the neutral wire between 2nd and 3rd -- only between 1st and 2nd, as designed.

 

Hope this helps.

 

Errrrr! Only it's an 1100 Sport with the sfive speed so it doesn't use a cam plate it uses a drum but other than that the principles are the same.

 

As Ratch says it can't be earthing through the gearbox per-se. My guess is that the stock earth path through the pork chops and rear subframe is so shitty that what the poor electrons are trying to do is find an alternative path back to the battery and they are doing this by going back thgrough any part of the loom they can and that will, on occasion probably involve parts of the loom connected to the neutral light indicator prong!

 

I've had 1100 Sports where you could turn on the ignition and everything would look fine but as soon as ou hit the starter button everything would go black and the starter wouldn't engage. When you released the starter button the indicators and tail light would glow dimly but the dash lights would stay out until you turned off the key and turned it on again. Another one you hit the starter button and the hazards flashed!

 

How and why this happened or was even possible I've never bothered finding out. I could guess it was an earth problem and looking at the Heath Robinson earthing system, (Cable from gearbox to pork-chop. pork chop bolted to painted frame, porkchop also bolted to rear subframe,front subframe which instruments and headlight earth through bolted to painted frame, final earth strap from rear subframe to battery bolted to painted subframe, all bolts between pork-chops and frame rusty and corroded ) it was obvious why. A couple of earths from the front ub-frame to the block and then a big earth strap from a bell housing stud direct to the battery negative and 'Voila!' it all worked fine again.

 

Pete

[Guest ratchethack]

Errrrr! Only it's an 1100 Sport with the sfive speed so it doesn't use a cam plate it uses a drum but other than that the principles are the same.

Sorry, my bad.

[greenman]

Yes as per Mr Ropers reply, I require more earths please.

I already have one directly from the battery to the regulator. I'm going to add one from the engine block through to the reg as well, and possibly from the gearbox to the battery too.