1986 J20 LS Swap

SJohn · Post by **SJohn** » Mon Nov 28, 2022 9:22 am

rocklaurence wrote:I really like those parking brakes. What did it cost ya and how long did it take to install. You almost have a New J20...

Thank you, they definitely weren't a cheap endeavor. I have probably $600 in parts tied up in them and it took about 6 months to develop but the actual install was probably 4 hours for everything - brackets, brakes, and cables. They still need some tweaking and won't hold the truck while in gear but do well for parking on a hill.

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mike472 · Post by **mike472** » Fri Dec 09, 2022 9:05 pm

Can you answer for me, Im really confused on the wiring part of my 5.3 4l60e swap, how did you handle the neutral safety switch? does the pcm take care of that, or did you have to run wiring from the switch on the transmission to the starter? if so, how did you wire it up, did you splice into the wires on the transmission or did you cut the wires away from the pcm and run them from the trans switch? My truck was originally a manual trans but Im using a tilt column from an automatic from a later year. still no neutral switch on the column tho, sorry so jumbled, Im sooo lost!

Yeller · Post by **Yeller** » Fri Dec 09, 2022 9:15 pm

There is no need for a neutral safety, the ECM doesn’t care. But if you want one, If you’re using an auto shift column you can wire the starter wire through the one on the column, there is one on the shift selector on the transmission that can be used as well.

SJohn · Post by **SJohn** » Fri Dec 09, 2022 9:53 pm

mike472 wrote:Can you answer for me, Im really confused on the wiring part of my 5.3 4l60e swap, how did you handle the neutral safety switch? does the pcm take care of that, or did you have to run wiring from the switch on the transmission to the starter? if so, how did you wire it up, did you splice into the wires on the transmission or did you cut the wires away from the pcm and run them from the trans switch? My truck was originally a manual trans but Im using a tilt column from an automatic from a later year. still no neutral switch on the column tho, sorry so jumbled, Im sooo lost!

As Yeller said, you can use the neutral safety switch on the Auto column for the starter. Since I used a cable shifter I purchased the neutral safety switch from winters shifters that mounts in the shifter and I wired it to the starter circuit.

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mike472 · Post by **mike472** » Fri Dec 09, 2022 10:03 pm

ok, i kinda get that i can use one from the column, but there isnt one and there are no bolt holes for it to mount to, so if I use the one on the transmission should I just splice into the wires or cut them away from the pcm? the reason Im concerned is the one wire that goes to the starter circuit from the column key switch is 12 gauge and the wire i believe I splice into on the transmission is probably 16 gauge? SInce you used an aftermarket safety switch then Im assuming you didnt cut or splice the wires that come off the transmission, I guess that is what Im going to have to do, thanks!!

mike472 · Post by **mike472** » Fri Dec 09, 2022 10:05 pm

I just thought of this also, if using the column mounted switch, assuming I could figure out how to mount it, would the detents line up with the transmission, cause the trans does have that extra gear that the column switch wont have?

Yeller · Post by **Yeller** » Sat Dec 10, 2022 6:49 am

Should be the same detent, you probably won’t have first gear available. I should have also mentioned it is my understanding the neutral safety on the transmission is designed to operate a relay, not the starter.

Personally I like the option to be able to start in gear, there are times it is advantageous, although it is far less with these motors, they typically just run lol

SJohn · Post by **SJohn** » Sat Dec 10, 2022 7:42 am

You should definitely add a starter relay, I originally ran the starter circuit through my NSS without a relay and started to have issues with the starter that were very similar to symptoms of a bad starter. The voltage drop from the added wire to reach the shifter and back to the starter was enough to prevent the starter contact from closing 50% of the time. It's also probably not a good idea to pull that amount of current through the NSS.

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mike472 · Post by **mike472** » Sat Dec 10, 2022 11:56 am

Im using the painless wiring for gm trucks 10103 the instructions mention adding a relay but the wire from the trans switch goes to the 12 gauge on the starter

2022-12-10.png

Yeller · Post by **Yeller** » Sat Dec 10, 2022 12:51 pm

That wiring schematic is correct. The NSS is not taking the load, the relay and key switch are. If the relay had direct battery power, the key switch would just go to the NSS. If you copied that exactly it will work just fine.

mike472 · Post by **mike472** » Sat Dec 10, 2022 1:19 pm

ok, whew, thats a relief, wow, thank you soo much!!!

SJohn · Post by **SJohn** » Tue Dec 13, 2022 8:51 pm

I have had 3 extra front fenders in the garage (two separate garages now) since the truck was first towed up from SETX to Dallas over a year ago and finally decided to start working on them. I saved the fenders from the donor trucks to eventually repair or replace the whiskey dented front fenders on the J20. In the final years that the J20 was being driven by it's previous owner it witnessed quite a few run in's with the side of the barn door leaving all 4 (only 2 original remaining) heavily dented. And with the spare fenders picked up along the way the J20 will soon only have half an original fender

. The green truck provided a solid drivers side front fender that will directly replace the original dented one, and the passenger side fender was banged up but the flare was in good shape. However the lower corner piece from both red and green trucks were caved in and unusable but fortunately, even with the crumpled front clip, the blue J10 had a salvageable lower corner piece. So now I am playing fender surgery and have begun busting apart the spare fenders to reassemble a passenger side fender for the J20.

I started with a spot cutter bit in a cordless drill but found that it left a small hole in the panel I was trying to salvage and if I wasn't careful I could drill a big hole through both panels. I wanted the flare to be as unmolested as possible for spot welding back on to the other fender so I switched to a dremel with a metal cut-off wheel. I made a long cut along the lip of the fender about 80% through the metal and ground the spot welds out, then took a pair of needle nose plyers and tore the lip away by rolling it onto the plyers. This left me with just a small amount of material left on the flare to clean up with a flap disk. There is only a small amount of rust on the bottom end of the flare to repair and the red J20 flare is rust free so if needed I can cut a patch piece from it.

After I repair the rust I will tackle removing the original red flare from the J20 and clean all three pieces up, hit the mating faces with some STEEL-IT to try and prevent rust in the seams, and attempt spot welding them together with a HF spot welder. I now have a welder too so if the spot welder fails I will just weld them up with the welder.

SJohn · Post by **SJohn** » Tue Dec 13, 2022 9:23 pm

I am also starting to look into repairing the bed, in particular, the top rails. It looks like at one point the truck likely had a headache rack or tool box crudely mounted on it, and is now littered with holes, cracks and dents. Every corner is busted around the stake pocket. Fortunately the only damage on the front panel is one small bend and no major dents in the headboard. So far the two ideas I have to get new bed rails are; find a local sheet metal shop to bend some sheet metal up or draw up a flat pattern to send off to a place like send cut send to make up for me in maybe four 4 ft sections. They are pretty affordable for smaller pieces but I have not seen their rates for a piece of this size. Will get some quotes and follow up.

SJohn · Post by **SJohn** » Thu Dec 15, 2022 4:41 pm

Bed rails ordered! Called a few local sheet metal shops - some acted like this was a foreign concept and not something they could do while the pictures on their website showed insanely intricate work and massive brakes in their shops. I was able to find one with good reviews and after a quick call they said send over some drawings or pictures and they would get me a quote. After a few minutes in Fusion I had a drawing and sent it this morning. The shop had it quoted within an hour - $250 for 2 and should be ready next week! I did look into Send Cut Send and unfortunately their max bend length is 30". Oshcut, a similar company, could do 76" and for a competitive price but I would rather have to do as little splicing as possible. I may look into it more for offering repair sections on Johnson Production with 48" sections in the future though. The shop is not forming the stake pockets, I have started designing those up in cad and am thinking I will form them out on a small patch section and weld into the new rails.

SJohn · Post by **SJohn** » Fri Dec 16, 2022 6:25 pm

Quick stake pocket design, blanks on the way. Next will be designing forms to bend them up.

SJohn · Post by **SJohn** » Sun Dec 18, 2022 8:40 pm

Next piece acquired for the passenger side fender repair - a blue corner piece. Next will be pulling the fender off the truck and removing the dented flare and corner piece. On track to have a 3 color fender!