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153 Coupe Wiring Improvements


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Posted (edited)
19 hours ago, theKiwi said:

@PFitz - this is interesting!!! My 153 Coupe is almost devoid of wiring, so with a new harness from Rhode Island Wiring it will certainly be worth my while to implement one of these fuse boards. I've looked up under the dash on the car and about the only electrical things I see are:

 

1 - the coil - is this the original place for it as shown in your photo above, or is it moved there from somewhere else?

 

2 - a double fuse holder like you show the picture of a single one.

 

The wiring diagram shows a double 30 amp fuse which is for amongst other things the cigar lighters front and rear, and separately a 20 amp fuse relay which seems to feed the lighting switch, and then the junction block on the lower left firewall. Is the 20 amp fuse relay also up under the dash somewhere? (or meant to be?)

 

Thanks!

 

Roger

Roger.

1. Yes.  Starting in 29, Franklin moved the coil to under cowl, upside down above the gas pedal. Away from the engine heat they live much longer.

 

2. There usually is a double fuse holder under the passenger side of the dash for cigar lighters and dome/rear reading lights. Either on the wood frame above the registration pocket of the passenger kick panel, or on the firewall above about where the front passenger's left foot would rest. BTW don't use a 20 amp fuse in any of the car wiring. #14 wire is only rated at 18 amps and some of the wire runs are long and old. Plus, I've tried and I can't get Franklin cigar lighters to blow a15 amp fuse, so using 20 amp fuses are not needed and not good circuit protection.

 

The "fuse relay" is not a magnetic switch relay like we think of used in modern wiring relays. It's just a single fuse holder, wired in parallel with a heavy resister wire. As you can see more than just the running lights run off that "relay". All the interior and brake lights are on it too. Stop with the head lights on , foot on the brake, and turn on the interior lights to read a map and it'll be about enough amp draw to pop that 20 amp fuse.  There goes all your lights....unless.  If the fuse blows, the resister wire is supposed to enable you to still have some lights and run the car to get home. However, if you don't find and disconnect whatever caused the fuse to blow, the resistor wire will still allow enough current to flow to start  a car fire. It's not a safe way to protect the electrical system, and why Franklin used it in stead of the multi fuse blocks of '28 and earlier, I'll never understand.

 

The relay is just a simple formed sheet metal box with fuse holder. It's the picture I showed above.  The resistor wire is wrapped around mica insulators and attached to the fuse end clip screws inside, thus bridging those two connections. Here's a picture of the resistor and insulating sheets that fits inside  that  box.

 

There's also a piece of sheet asbestos that goes between that fuse relay housing and the firewall pad. Think Franklin knew it would get hot ?   It wouldn't with the second picture, but if other parts of the electrical system short out they sure would get hot. Found that bolt in the fuse holder of a 153, right after a customer bought it and sent it to me to fix a bunch of things on the car, plus rewire it. Another problem with that relay is finding the large fuses that fit it are not easy and the previous owner ( a non-Club member) obviously couldn't find some.

 

Paul 

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Edited by PFitz (see edit history)
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Well at least who ever used that bolt for a fuse,...... used a galvanized bolt. Wouldn't want rust to cause a problem. :wacko:

 

Paul

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  • 2 weeks later...

Paul, back in 2005 you go thru the separation of the lighting wires ('30-'31) into 2 different feeds, removing the 'jumper' switch wire,  re-fusing, etc.
In that regard, have you made sectional elec. schematics of recommended changes, etc.  The manual's schematic really gets fuzzy between the steering col., dash, and junction box and is hard to figure out even before changing, multi-fusing, etc.
Anyway, If you happen to have jpgs of these that would post,  believe it would be helpful since I am planning to do the electrical modifications very very soon. Have become alarmed--lol !! Tks.

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Posted (edited)
3 hours ago, Franklin31 said:

Paul, back in 2005 you go thru the separation of the lighting wires ('30-'31) into 2 different feeds, removing the 'jumper' switch wire,  re-fusing, etc.
In that regard, have you made sectional elec. schematics of recommended changes, etc.  The manual's schematic really gets fuzzy between the steering col., dash, and junction box and is hard to figure out even before changing, multi-fusing, etc.
Anyway, If you happen to have jpgs of these that would post,  believe it would be helpful since I am planning to do the electrical modifications very very soon. Have become alarmed--lol !! Tks.

Yes, the 30-31 head light switch is actually two switches in one. The jumper wire just feeds power for one side that has the power feed to the switch, to the other half of the switch. By using two feed lines you can take some of the load off one fuse and feed wire and spread it over two. Plus if a fuse blows you don't lose all your lights. 

 

No I don't make up a schematic. It's simple enough to just make up another wire from the fuse block to the head light switch.

 

I buy rolls of the same color code wires as used in the orginal harnesses, from Rhode Island Wire Service. I use that for changes in wiring and for any accessories like horns and driving lights. Plus it's needed to make up the pig tails inside the light buckets from bulb socket to light bucket harness connecters.  

Yup just looking at the schematics in the owner's manuals is too small to make out some details. However, if you enlarge the schematic in the back of the owner's manual, either by scanning it into your computer - or downloading a copy from the Club's website - it retains a lot of detail you can then see clearly. In fact, the drawing is so accurate down details like  what wires go to which side of the amp gauge - passenger or driver side - so you don't reverse the amp gauge reading polarity. And where each wire connects at the firewall junction block.  Same on the earlier Series for their firewall fuse blocks. I've blown the drawings up  to 8-1/2 x 11 page size to keep in my electrical work binder. Even at just that size you can clearly see  what wires go where.

 

Added to that, the Rhode Island Wire Service drawings that come with each harness give the color code and wire gauge size of each wire, and what each end of each wire connects to. Very easy to install correctly. 

Edited by PFitz (see edit history)
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Posted (edited)

And if you go to the Club website and search the factory drawings, you can find "sketches" of body wiring - search for 

 

body wiring sketch

 

or just

 

body wiring

 

to find diagrams such as this

 

image.thumb.png.6932724b9b20e07cfa3b30d900c02b7a.png

 

Roger

Edited by theKiwi (see edit history)
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Posted (edited)

One of the other advantages of adding a fuse block is that you can put the ignition switch and coil circuit on a fuse. Franklin stopped doing after Series 12,  when in '29 they switched to using that one fuse "relay" that I posted pictures of above.

 

FYI, a 7.5 amp fuse is available and plenty big enough for the coil - even at the increased engine starting amperage draw.  

 

And forget Franklin's using 20 amp fuses. As I've mentioned before, 14 ga. wiring is only rated for 18 amps. It's not good to have a fuse rated higher than the wiring in a circuit.  15 amp fuses won't blow with anything standard in the car - even with the cigar lighter or the horn when they are in proper working condition. Using the smallest fuse that won't blow in a circuit is the safest way to go.

 

BTW, the 6 amp short-length fuses used in the back end of Delco Remy generators are no longer available. But they can be ordered that length in 5 amp and I've yet to have one blow with a generator in proper working order. If it blows the 5 amp, the generator needs to be inspected why.

 

Paul

Edited by PFitz (see edit history)
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On 6/3/2020 at 10:31 AM, PFitz said:

 As I've mentioned before, 14 ga. wiring is only rated for 18 amps.

I am getting more and more in the habit of beefing up every wire by a gauge (excepting horn circuits) - when I have looked at some of the wiring diagrams something or another always strikes me as too small (or I am running dual taillights verse original single and have more power demands).  Marsha at Rhode Island Wire is even getting use to me ordering custom harnesses.  A lot of people have said it was designed a certain way for a certain purpose , though my opinion is it did what it was supposed to do, but even in 1930's they had to cut corners to save money.

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Posted (edited)

14 ga wire to run 6 volt lights and such, is not the problem. It was the standard in the industry up until the later switch to smaller 16 ga wires used with 12 volt systems. The problems were using too large a fuse. Or as Franklin did starting in 1929, eliminating a fuse from some circuits such as I mentioned the ignition system. For wires that draw more than 14 ga.,  Franklin used 12 and 10 ga - both with a good margin of safety for handling the load that those wires were designed to carry.  

 

When measuring the actual loads on a wire, I've never seen the need to change Franklin's wire gauge size. And with Series 12 and earlier there are enough fuses to give protection to all the circuits ,..... provided the 20 amp fuses shown in the wiring diagrams are down-sized to only what that circuit actually needs.  I've rewired dozens of Series 10 through 16 and not one circuit needs more than a 15 amp fuse - including upping head lights to using the 32 x 50 cp bulbs, or feeding a turn signal unit with four-way flashers. If it blows a 15 amp, there's something wrong in that circuit, or some things have been added, or combined, that draws more than 14 ga wire should be safely handling. But for just replacing what is standard on a Franklin, 14 ga is fine.

 

And even breaking up all the circuits to have their own fuse, there are still circuits, such as the starter system and the carburetor fuemers, that are not protected by the "weak link" of a fuse. That's why it's recommended to install a battery kill switch. Even many judging events recognize the added safety of that and don't penalize for the addition of a kill switch.

 

FYI to all.

The carburetor fuemers/primers should never be connected to a power source. Not only are they not needed with more flammable modern fuels, they risk starting an engine fire.

 

Paul

Edited by PFitz (see edit history)
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  • 3 weeks later...

Paul - yes, thanks very much for that. It will be very helpful once I get my harness. After the trials and tribulations of the last few weeks (hospital and other things) I finally got with Marcia at Rhode Island Wiring and got that underway, including including a trailer plug into the rear harness for my Mullins trailer.

 

Again Thanks!!

 

Roger

 

 

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