1979 Jeep J20 (Lots of Help Needed)

Area to show off your Custom Build threads.
Post Reply
User avatar

Topic author
superstitiousmelon
Posts: 7
Joined: Wed Jul 22, 2020 4:45 pm

1979 Jeep J20 (Lots of Help Needed)

Post by superstitiousmelon »

I recently returned from a road trip across the country (Georgia to Washington coast) and ended up purchasing myself a Jeep J20 in Washington. It’s a solid truck overall that has surface rust, which of course will need to be treated. Below I’m going to list some things I need help with as I am a newbie to the car game.. just trying to learn!

I also would love if someone pointed me out to some badass website that makes aftermarket parts.


So far, the problems with the truck include the following:

Transmission issue:
(sounds like someone is taking a hammer to the bottom of the car where the transmission is when i don’t feather the gas, but only in the first gear).
-What are the possible problems? Do i need a new transmission? Just need it rebuilt? Possible replacement parts cost and where to get them?

Steering:
Very squeaky and super hard to turn steering at low speeds b/c of no power steering. I need help on what i should buy/add to the car to combat this. I’m trying to get into the classic car game and i pretty much no nothing about what parts i should get and where.
If you could point me in the right direction i would be incredibly grateful.

Surface Rust:
Also, if you have any tips on treating surface rust that would be awesome! Like how should I get all of it off on the body and the frame without taking the body off. I want to keep the patina just get rid of the rust and clear coat the top!

Leaky Seals:
Top windshield leaks (maybe other parts too idk)

Rusted out tailpipe:
probably doesn’t matter what replacement i get? or am i dead wrong.

Cleaning/Restoring AUX gas tank:
Steps? Parts needed?


Sent from my iPhone using Tapatalk
User avatar

Topic author
superstitiousmelon
Posts: 7
Joined: Wed Jul 22, 2020 4:45 pm

Re: 1979 Jeep J20’s (Lots of Help Needed)

Post by superstitiousmelon »

Here are some pics
Image
Image


Sent from my iPhone using Tapatalk

Dr.Bob
Posts: 108
Joined: Thu Dec 26, 2019 8:57 pm

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by Dr.Bob »

NICE! Those are my favorite rims! I'm looking for a set for my '87.

The banging problem is probably not your transmission, but your transfer-case. The BW1339 full-time transfer-case used a chain to direct *all* power to the driveshafts, both front and rear (not just the front like newer cases). When that chain stretches, it can jump the teeth of the gears, causing that noise you hear. The solution is replacing the chain; BJ's has them:

https://www.bjsoffroad.com/QuadraTrac-C ... _1598.html

I thought Power Steering was standard on the J-20; no matter, you can add a pump with the brackets from any AMC V-8, get a rebuilt J-20 steering box (they had bigger components than the J-10 or Wagoneer boxes), and just add the appropriate hoses (make sure to match the fitting style, flare or o-ring, on your pump and box)

I don't have any solution for removing the rust; I wire-wheeled mine down and coated it with POR-15, but that wouldn't look factory for yours.

Windshield leak is likely from rust; solution is to cut out the old metal, form new pieces, then weld it in. Anything else is just a bandaid that won't last.

There are no replacement over-the-counter tailpipes available, so custom-exhaust is your only option.

230ohc
Posts: 430
Joined: Thu Jun 16, 2016 2:27 am
Location: Northern California

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by 230ohc »

Nice truck.

You can treat rust with acid. I like phosphoric acid because it turns oxide into phosphate, once it's applied the rust will start to turn black, when dry it will look ashy Grey. Sand it down a bit, then it can be painted just be careful with it around the pretty painted parts
1964 willys wagoneer
Om617 turbo diesel
Ax15
Dana 300
3.73 dana 27 front
3.73 dana 44 rear

will e
Posts: 5096
Joined: Sat Aug 18, 2012 8:21 am

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by will e »

Welcome to the forum. You will get lots of input on your questions. It's a good group of folks who will help and encourage you.
81 Waggy 'WILL E' Retired
82 Cherokee WT - SOA/SF/high steer/Alcan springs/agr box/Borgeson steering shaft/AMC 401/performer/holley TA/HEI/BeCool/727/ALTAS (2.0/2.72/5.44)/D60 Snofighter(Yukon Zip,hubs,stubs,4.56)/14 Bolt (FF,BF shave, Discs, ARB,Artec Truss)/MTR 37X12.5/Corbeau XRS Baja & 5 point retractable harness/Hella Aux lights/tuffy console/killer32 sliders/Evil Twin bumpers, rack and roll cage/WARN 8000/TT Fabworks steering brace/dual batts/custom TC skid plate/ARB fridge
User avatar

Topic author
superstitiousmelon
Posts: 7
Joined: Wed Jul 22, 2020 4:45 pm

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by superstitiousmelon »

Wow, I’m overwhelmed from the support. These are some great insights and cannot thank y’all enough! I’ll post updates as I progress with the truck.
And you were totally right about the power steering being factory.


Sent from my iPhone using Tapatalk

SJTD
Posts: 1924
Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by SJTD »

Yeah, the glass has to come out to see what you have. Might get lucky and just need a properly installed gasket and touch up but...
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
User avatar

Topic author
superstitiousmelon
Posts: 7
Joined: Wed Jul 22, 2020 4:45 pm

1979 Jeep J20 (Lots of Help Needed)

Post by superstitiousmelon »

Been awhile, but have gotten some things fixed.

The pounding noise was indeed the transfer case. I ended up getting a rebuild kit and put it back in. No longer an issue.

New exhaust system for the truck, which is great because now it won’t suffocate me.

Things i’m currently trying to tackle.

1. The car at times seems like the battery isn’t providing enough cranking amps and it try’s to start up very sluggish
I think it could possibly be that the alternator isn’t charging the battery sufficiently and slowly running it down. The battery i have is rated at 625 CCA’s (is that enough for this big amc 360?)

Ive started looking at how to do the alternator upgrade and it seems like everyone is warning people to do the ammeter bypass. I pretty much don’t know anything about wiring so this task does seem kind of daunting. If anyone can lay it out simply that would be appreciated. I also don’t know if i need to buy a specific CS-144 alternator for the truck, or what other parts I will need.

2. While i’m doing the alternator i thought i might as well upgrade the ignition system. Any thoughts on what parts work the best?

3. I also need to upgrade the headlights. They are not very bright, does anyone have any plug & play headlight part number/product that would fit my truck.

Any and all help is appreciated, thanks so much

Also on another note why does my truck have two manual choke knobs?


Sent from my iPhone using Tapatalk

sirrus
Vendor
Posts: 717
Joined: Fri Sep 13, 2019 11:13 pm
Location: Hillsboro, OR

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by sirrus »

Definitely do ammeter bypass before upgrading the alt, otherwise you’re risking burning it down. Easiest way is to move both ammeter wires to one stud (need to take the instrument cluster out, you’ll see wires going to the back of ammeter), however I’d say it’s better to do a more involved version and provide a short path for charge current to battery/rest of the system from alt, without it traveling to the dash and back. I don’t have the diagram of that handy right now, but I’ve seen it posted here and on ifsja a lot, look around and you’ll find it.

As for alt upgrade I got powermaster 150 amp alternator and I’m happy with it. Used same mounting holes as factory 12si unit, so no fabrication is needed. You’ll need to step up charging wire in size though, I went from stock 10ga to 6ga, as recommended by powermaster.

Sorry, can’t help with ignition.

For headlights, I made a harness with relays and properly sized wires (12ga) and replaced sealed beams with Hella H4 units (I don’t like how LEDs look on those rigs, but those would be even brighter). Night and day, factory lights were laughable, so is the factory wiring. I went with Ecode lights as the light pattern is better and they are easier to aim visually.

As for two choke knobs - are you sure they are for choke? There are two knobs for fresh air vents left and right below steering wheel. Might be a good idea to check those as well as they tend to accumulate a lot of leaves and other crap over the years which plugs the drains and then you have water on the floor every time it rains.

Hope that helps!
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
2021 JLU Willys EcoDiesel - new shiny toy
User avatar

Topic author
superstitiousmelon
Posts: 7
Joined: Wed Jul 22, 2020 4:45 pm

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by superstitiousmelon »

Thank you, yes i definitely was wrong about the “two choke knobs”.

I’m still trying to figure out what switches and buttons do what. I’ll definitely need to clean out the vents. I see i need to remove the E-brake, and the AC to access them.

I’m going to attach some pics if y’all wouldn’t mind helping me identify the switches.

Image
Is the bottom left knob the choke? or am i just plain wrong and there isn’t a choke knob
Image
Anyone know what that button like thing is to the left of the Ebrake?

Image
knob next to the cigarette lighter?

Thanks again, i’ll be looking around for the ammeter diagram.


Sent from my iPhone using Tapatalk

sirrus
Vendor
Posts: 717
Joined: Fri Sep 13, 2019 11:13 pm
Location: Hillsboro, OR

1979 Jeep J20 (Lots of Help Needed)

Post by sirrus »

Button to the left of ebrake looks like headlight dimmer switch (high/low beam switch). Not sure about other ones
Last edited by sirrus on Mon Jan 11, 2021 11:33 am, edited 1 time in total.
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
2021 JLU Willys EcoDiesel - new shiny toy
User avatar

Chubbinius
Posts: 351
Joined: Thu Aug 16, 2018 11:33 am
Location: SD, CA

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by Chubbinius »

Button left of e-brake looks like your high beam switch (floor mounted, click it on with your toe).

You have two kraken/squid release knobs (one on each side of steering wheel)...just kidding, these are your fresh air/vent cables. :)

Hope that helps a little.
1970 1414X Wagoneer "The Pig"
-Custom Special
-Dauntless 350 V8
-D27 front/D44 rear
2006 XK (65th Ann Edition)-DD

Dr.Bob
Posts: 108
Joined: Thu Dec 26, 2019 8:57 pm

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by Dr.Bob »

The knob between the steering-column and the cigarette lighter is not stock; that would likely be an aftermarket choke cable.

itselliott
Posts: 180
Joined: Sun Jun 10, 2012 1:58 pm
Location: VVest Michigan/SE Wisconsin
Contact:

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by itselliott »

Hello from Michigan!...Regarding the ignition...There are lots of simple ways to upgrade. I saw that you rebuilt the T/C so obviously you've got some skills...The most simple is to use the distributor adapter / cap and rotor from a Ford 460 CU IN (80's vintage) and an HEI coil from a mustang Then swap out the jeep(Ford) ignition module to a GM 4 pin. (Or Not...your choice)
Here is 1 very good link:http://www.ifsja.org/tech/electrical/ig ... grade.html
And some pics: http://www.grimmjeeper.com/J-Truck/tfi.html
Scroll to Post #4 for a foto....:https://www.jeepforum.com/forum/f8/stea ... rt-810617/


1 bit of personal thought,,,DO NOT use the new gear of the distributor if you decide to change out to an HEI Distributor ,.use the original gear...many gears have been eaten after a swap.
You do not have the required permissions to view the files attached to this post.
User avatar

Topic author
superstitiousmelon
Posts: 7
Joined: Wed Jul 22, 2020 4:45 pm

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by superstitiousmelon »

Can’t take all the credit on the T case build, had a buddy give me a hand when I was home.


Thanks for all the input and help. I’ll be tackling the alternator & ignition next


Sent from my iPhone using Tapatalk

itselliott
Posts: 180
Joined: Sun Jun 10, 2012 1:58 pm
Location: VVest Michigan/SE Wisconsin
Contact:

Re: 1979 Jeep J20 (Lots of Help Needed)

Post by itselliott »

superstitiousmelon wrote: Thu Jan 14, 2021 10:51 am Can’t take all the credit on the T case build, had a buddy give me a hand when I was home.


Thanks for all the input and help. I’ll be tackling the alternator & ignition next Image


Sent from my iPhone using Tapatal
Kinda surprised that no one has mentioned......BJ's Offroad as a source for lots of FSJ related parts..
They also have a discount for registered members
Post Reply