1958 R26 wiring battery box wiring

[bwprice100]

.
Hi All

Another quick question on my 1958 R26.

I have started to do the wiring on my bike and I have fitted the small loom that goes from the brake light switch and gearbox neutral switch to the battery box.

The small loom for this has an extra wire with a eyelet terminal both ends that I can't identify (see picture). I not sure if it is an earth wire but it is coloured black.

The second question is with regard to the battery earth; where does the wire go from the battery to earth?

Thanks Brian

[bwprice100]

[Rütz]

Hi Brian,
it is an earth wire, for connecting B- to the gearbox-casing.
You do not need it necessarily, as in R26 there should be an earth wire, which leads from B- through the main loom to the dynamo, to be connected to engine-casing there.
The wire you found originally belongs to R27.
I would use it though, as improvement/redundancy. But you can omit it, if you know, that the other wire is good.

[bwprice100]

Thanks for your quick answer Rutz, you can never have too many earths. 

Where does the battery - earth connect?

Brian

[bwprice100]

Sorry, Rutz, I've just reread your answer and now understand that B- means battery minus. Doh


Brian

www.eBolt.co.uk www.ToolroomChucks.co.uk

[Rütz]

Yes, means battery minus, sorry too...   

I thought you wondered about the connection to the gearbox and have edited a picture:

[bwprice100]

Thanks Rutz, you're a top bloke. 

Brian

[BSA Bob]

I'm about to start wiring my R26, as yet there's no wiring at all. However there's electrical continuity between the motor/ gearbox unit & the frame. With a completely rubber mounted engine, how can this be? There's no metal to metal contact in the Hardy disc area. The carburettor & airbocx aren't fitted yet so it can't be that.

[Heiko]

Morning,

there is a brown wire between one screw of the gearbox back plate and the wiring loom for ground connection.

[Kees]

Speedo cable. 

[Heiko]

But that's not the correct way!

[Kees]

He doesn't have wiring yet but still measures continuity. Maybe my answer is wrong because the headlight is rubber mounted too. Something is rubbing metal to metal somewhere. No other way to find out then to  start pulling bolts until the short dissapears. 

[Heiko]

Ahh, klick, good morning, 

also clutch or throttle cable or the engine is not fitted correctly

[rolf.soler]

However there's electrical continuity between the motor/ gearbox unit & the frame.

so what's the problem ? After the wiring the continuity will be there anyway. Engine/Gearbox should be grounded

[BSA Bob]

Thanks for these replies.
As Rolf says, what's the problem? You can't have too many earths. But theoretically this earth shouldn't be there.
The measurements were taken on the bench with the motor, gearbox , swingarm, drive & rear wheel fitted, making up a roller.
There's no wiring at all & no cables.
Sitting on the bike & bouncing around alters the meter's readings a bit. With the bike on the bench, turning the back wheel makes the meter's needle flutter.
I think the ends of the gearbox output shaft & driveshaft may be touching.

[Eppo]

For measuring grounding it isn't a good choice to use some kind of multimeter or simple resistance-measuring-tool. It is much better to use a special "resistance-low"-measuring,
e.g. GossenMetrawatt makes such tools. While multimeters use a simple measuring for resistance these special tools use a more complex method with a definite current flow to calculate the grounding resistance.

But as mentioned before the grounding is important, not the isolation.
So I did install an extra grounding between the grounding of the alternator and frame.

[Heiko]

Sitting on the bike & bouncing around alters the meter's readings a bit. With the bike on the bench, turning the back wheel makes the meter's needle flutter.
I think the ends of the gearbox output shaft & driveshaft may be touching.

Like Kees said: Speedo cable