Sorry about that. I fixed it.
Fusible link question
Thread Starter
Racer
Joined: May 2015
Posts: 474
Likes: 25
From: Springfield MO
Fusible link question
On my '68, I think the picture below is the fusible link. The two wires coming out the bottom of the rubber thing go from the starter over to voltage regulator (I think... memory is fuzzy). I think the wire coming out the top is probably for the ammeter (thanks DUB!). So, my question is, how do I repair this? Is the solid rubber cylinder part of the fusible link or is it just a really odd way to splice the ammeter wire into the 12V? I assumed the first part of the ammeter wire was the fusible link?
Last edited by E.Murray; Sep 28, 2015 at 05:23 PM.
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
Funny, this week the insulation of my fusible link at same location broke and caused a short to the brake line near by. A lot of smoke came out of the hood. 
And the other link did not look much better either. The insulation of this wires gets old and breaks.
Ok, now im talking about the ´69 wiring:
At the horn relais come together:
- thick wire from the alternator
- thick wire to the starter and from there to battery
- thin wire (black-white) with fusible link to the ammeter and from there to the starter
- medium thick wire with fusible link to the cockpit and all controls, light etc.
Fusible links are nothing other than thinner wire than the wire that is to protect. But they have a special insulation, I guess it can survive higher temperatures for the case the wire melts down.
Cut the rubber part away, there a normal crimp connection under it. Replace the fusible link with a wire of the same gage, but try to get it with silicone insulation. Or replace it with a fuse holder and fuse. The ammeter should not get more then 3 amps.
And the other link did not look much better either. The insulation of this wires gets old and breaks.
Ok, now im talking about the ´69 wiring:
At the horn relais come together:
- thick wire from the alternator
- thick wire to the starter and from there to battery
- thin wire (black-white) with fusible link to the ammeter and from there to the starter
- medium thick wire with fusible link to the cockpit and all controls, light etc.
Fusible links are nothing other than thinner wire than the wire that is to protect. But they have a special insulation, I guess it can survive higher temperatures for the case the wire melts down.
Cut the rubber part away, there a normal crimp connection under it. Replace the fusible link with a wire of the same gage, but try to get it with silicone insulation. Or replace it with a fuse holder and fuse. The ammeter should not get more then 3 amps.
Drifting
Joined: Sep 2014
Posts: 1,430
Likes: 59
From: Long beach NY
St. Jude Donor '15-'16, '18
These might help
There is special fusible link wiring needed, thanks to members who originally posted these pics.
Last edited by Calo69; Sep 28, 2015 at 09:15 PM. Reason: Add add
Le Mans Master
Joined: Aug 2005
Posts: 6,541
Likes: 1,975
From: Temple Terrace Florida
Fusible links
You can get fusible links at any NAPA store. I would solder them in with shrink tubing. I believe the rule is to go down four sizes for protection. A 12 gauge wire would require a 16 gauge fusible link. I think DUB recently had a great post on this very topic last week. Jerry
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Verdad Gallardo
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
It is always best ...if replacing a burnt fusible link...is to re-crimp in a the SAME GAUGE fusible link along with its LENGTH!
If you are concerned about color of the fusible link being correct...do a google search.
YES...the thick rubber insulator 'block' is just that. it is protecting/insulating the butt connector....AND...providing some support to this fusible link where it comes out past the ends of the butt connector where it has been crimped.
SO...if my customer is not worried about it being 'perfect factory'. What I do is slide on heat shrink tubing and start building it up by adding multiple layers of heat shrink tubing and or carefully wrapping the area with electrical tape so the heat shrink tubing ends up looking like the rubber block.. This obviously gives the fusible link wire that is coming out some support...depending on how far out I bring the heat shrink tubing.
DUB
If you are concerned about color of the fusible link being correct...do a google search.
YES...the thick rubber insulator 'block' is just that. it is protecting/insulating the butt connector....AND...providing some support to this fusible link where it comes out past the ends of the butt connector where it has been crimped.
SO...if my customer is not worried about it being 'perfect factory'. What I do is slide on heat shrink tubing and start building it up by adding multiple layers of heat shrink tubing and or carefully wrapping the area with electrical tape so the heat shrink tubing ends up looking like the rubber block.. This obviously gives the fusible link wire that is coming out some support...depending on how far out I bring the heat shrink tubing.
DUB
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
The fusible-link is the wire BETWEEN the two rubber (probably phenolic) black lugs on the wire. Those lugs...and the insulation around the fusible-link wire...are non-flammable, so that, when the fusible-link melts, nothing catchs fire. The fusible-link wire is merely wire that is one or two AWG sizes smaller than the power feed wiring to which it is attached (if 12 awg wire feeds a component, the fusible-link wire will be 14 or 16 awg).
These links are in locations where a short should not occur, normally...unless there is a critical component failure which COULD cause a dead-short. In that case, the hardware needs to be protected, so a fusible-link (rather than a fuse, which could fail from age on its own) was the preferred method by GM. Dead-short: fusible-link wire melts FIRST--but does not cause any flames to be produced.
So, replacing a fusible-link should be done properly...with another fusible-link. Not only should it be smaller wire, but it should have non-flammable insulation and non-flammable terminators (lugs) separating it from the regular wiring.
These links are in locations where a short should not occur, normally...unless there is a critical component failure which COULD cause a dead-short. In that case, the hardware needs to be protected, so a fusible-link (rather than a fuse, which could fail from age on its own) was the preferred method by GM. Dead-short: fusible-link wire melts FIRST--but does not cause any flames to be produced.
So, replacing a fusible-link should be done properly...with another fusible-link. Not only should it be smaller wire, but it should have non-flammable insulation and non-flammable terminators (lugs) separating it from the regular wiring.