T3 melting brake line weirdness

[Unk Tantor]

Hello.
I recently replaced tabrake hose of my linked side T3 brakes,. They had previously been swapped for Goodridge 'buildaline" type stainless stell hoses. A leak appeared to have sprung on the line from the rear master cylinder to the spliter on the other side. I purchased a new sytle buildaline, these days they come with a clear plastic coating over the stainless hose, as indeed does my front line , which I replaced a few years earlier.Anyhoo, look ing at the bike today I noticed that the plastic had melted off in the middle. Thats weris thought I. I started the bike and ticked it over with the headlights on, the hose started to get hot!?! After a few minuetes almost too hot to hold comfortably. There is no wire touching the hose anywhere.
Recent alterations have been a LED mainheadlight ( which I've now swapped back to filliment in case that was somehow causing it and a replacement horn and a oFibre glass mat battery (Odyssey) battery.
Any thoughts ? Cheers

[pehayes]

The front forks are electrically isolated from the frame because of the pivot bearings and grease.  Thus, the wire plan usually includes some sort of grounding bypass wire to ensure that anything up front grounds to the main frame.  Is it possible this has been compromised and you are trying to ground through the brake line stainless?  Just an idea.

Patrick Hayes
Fremont CA

[rodekyll]

It's a classic, pehayes, , and you're right, imo.  Before the juice had the brake line route-to-ground it was probably travelling along the speedo and tach cables.  That's a common reason to break the twirley parts and melt the plastic stuff in the instruments.  Sometimes it travels down the clutch or throttle cables.  None are good events, and all are avoidable if you install a 10ga ground wire from the top tree to the frame.

Unk, I'd carry some spares for the cables mentioned.  If they've been weakened, they are going to break.  Also, after you get the ground installed, you might want to change out the brake fluid.  It probably got quite hot, too.

[JoeW]

I think Mr Hayes is on to something, run a ground wire from the headlight bucket to the frame, there should have been one there from the factory. It plugs into the male spade tab that's riveted to the bottom of the bucket.

[Unk Tantor]

Thanks for the advice, I'll check the earth from the headlight to frame.

[Unk Tantor]

 turns out it was the earth from the rectifier which was  supposedly earthed to the rear master brake cylinder
it was not getting to the frame and the thin stainless hose material was getting too hot with the current.