Newby here 1973 J4000

Stock FSJ Tech Area

Herk
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Location: Boise

Re: Newby here 1973 J4000

Post by Herk »

FWIW O'reilly can get the Motorola Units
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tgreese
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Re: Newby here 1973 J4000

Post by tgreese »

We're still here. Glad you're making progress.

I would caution again about fitting an upgraded alternator to a truck with an ammeter. There is plenty of discussion here and at IFSJA about the ammeter bypass. You don't want your new alternator to cause a dash fire.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

ormjeep
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Re: Newby here 1973 J4000

Post by ormjeep »

I apologize for jumping in on this thread, but I yeild few results when I search 1973 J-4000 Wagoneer Truck.

I have been on the hunt for a tailgate and seat for a fixer upper that I bought that came without either. I found a tailgate but it seemed to be the incorrect size. Does anyone have any leads on a tailgate or seat that will fit my 73'?

Thanks in advance.

Herk
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Re: Newby here 1973 J4000

Post by Herk »

Tailgates come in two flavors, 73-87 (rare) and 62-72 (stupid rare). The beds changed from the early single wall (round taillight) to later double wall (long taillight) in 73. Early tailgates were chain only, later had an internal latch and Matador door handle.

candymancan
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Re: Newby here 1973 J4000

Post by candymancan »

Bypass the ammeter like tgreese said and then upgrade the alternator to your hearts content
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

rocklaurence
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Re: Newby here 1973 J4000

Post by rocklaurence »

High-Output alternators do no burn up Amp gauges and cause dash fires. Almost all Amp gauge issues are related to loose wires at the gauge. Also, the alternator pushes power to the battery not through the gauge. The only time amps would exceed the gauge is when there is a Large Load drawing through it. This can be easily prevented by isolating New/Heavier Loads from the OEM 10AWG circuit.
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tgreese
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Re: Newby here 1973 J4000

Post by tgreese »

rocklaurence wrote: Tue Mar 23, 2021 10:41 am ... This can be easily prevented by isolating New/Heavier Loads from the OEM 10AWG circuit.
How do you propose to do this?
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

rocklaurence
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Re: Newby here 1973 J4000

Post by rocklaurence »

Create new circuits for devices via a power tap at the battery [ie power block with relays]. The power sources to trigger the relays would also be powered at the battery and none of the new load would go through the OEM wires. Except: I would have a Master Control relay [MCR] coil that would be powered from the OEM Keyed circuit but it would only trigger the MCR.
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tgreese
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Re: Newby here 1973 J4000

Post by tgreese »

The alternator still sees the load through the battery voltage and its internal resistance. Load on the battery drops the voltage by Ohm's law, sending a signal to the alternator to compensate. You have to isolate the alternator from the battery completely to draw high amps.

Also I believe the problematic part of the ammeter is the shunt, not the connections. The shunt is a calibrated resistance that all the charge or load current passes through. This resistance makes a voltage change (+ or -) which is seen by what is basically a voltmeter (galvanometer). If you double the current through, the power dissipation quadruples; P = I^2R. It would be an unusual situation, but putting 150 amps through an ammeter meant for 35 will create more than 18x the normal heating.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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Stuka
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Re: Newby here 1973 J4000

Post by Stuka »

Technically, 10 AWG wire is only rated for 30 amps. So in theory it should start to heat up before the Ammeter that has a max of 35 amps. But of the dash fires I have seen (after the fact, I have not witnessed one start), the ammeter itself was always the cause.

But if the ammeter is disconnected, then there is no reason to run full system power through the dash. Which also allows for about 10ft of 10 awg wiring to be removed. A voltmeter on the dash will serve the same purpose without the giant fire issues. And then a 150A alternator can be installed without dash fire worries.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ
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