FJ40 Refresh

[559Fj40]

Well I live a few hours from where I wrench on my rig so I have just been lurking forums and web wheeling these days. Being a broke college student doesn't help speed up the project either. I threw this up awhile back on another forum before I started coming here more often so now I'm going to switch to updating over here.

Backstory:
I built a cookie cutter 1983 Toyota Pickup in highschool; duals, lockers, junkyard springs, etc.. I acquired this 1975 FJ40 in August 2018 from my uncle whose owned it since it was new. It had been sitting in his yard rotting for 10+ years when I picked it up. With my new project I ditched the pickup because my 6'4" self doesn't fit in a single cab

Heres some pics of it before it was parked

The day I picked it up

It is your standard Fj40 build.
-Chevy 350
-sm420-toy tcase
-lunchbox lockers in 40 axles with disc brakes
-36 in iroks

I tuned it up, replaced some rotting rubber and I started daily driving it and hitting some easy trails to figure out what it needed. I found out over time it needed basically everything. The premier powerwelder alternator was throwing sparks, everything that could leak leaked, old bias plys suck on the highway, the front end seized on a snow run, etc... After a late 2019 snow run where the awful holley projection tbi refused to run right and the hacked wiring harness kept blowing fuses, I decided I needed to buckle down and do things right rather than continue to limp along trail fixes and broken parts.

2020 I rewired the cruiser front to back with an Ez wire harness, and built a new gauge cluster so I could know engine temp/oil pressure/fuel for the first time in years. I've always avoided wiring and had never done more than wire up some 6x9s and an amp in my pickup but I took notes and figured it out pretty easy.

Gauges

Ditched the completely blown factory seats for some PRP Daily Drivers

I also snagged a quadrajet off of another 40 in the yard to get the engine to run a bit happier. The old projection on there would not communicate with its computer and it could not me tuned. At idle the injectors were throwing so much fuel that it was spraying off of the butterfly and splashing around with the air cleaner off.

I've had an issue where the the transmission binds HARD when the drivetrain is under load like on a hill. The transmission needs to be beaten out of first or reverse, depending what gear you're in when you end up under load. First thought was clutch not disengaging. I've chased that trail by swapping in a Centerforce clutch my uncle had, as well as new master, slave, and lines. No luck.

Currently hoping to thrash a few weekends with some friends to figure out my binding issue, rebuild my t case, button up wiring, and rebuild my front end so I have something to drive around at KOH this year. I do have plans to hopefully take this cruiser up a notch in the next year after I get the bare minimum done to have it drivable.

 

[559Fj40]

Also if anybody has any insight on to what might cause an sm420 to bind up in 1st and reverse let me know. I've replaced all of the clutch components and checked the top cover/shift rails as suggested by others. The rear driveshaft is a bit too long so I thought I had it solved there but no luck removing it and just running the front. Parts are hard to source for these transmissions and finding a decent swap candidate is hard too so I would like to exhaust every option before I take on a rebuild or start swapping my drivetrain around.

 

[Wilson]

My relationship with my fj40 started out so similarly. I would consider rebuilding the 420. Worn out bearings/ bushings could be causing the binding/ misalignment in the deeper gears.

 

[DutchVDub]

I love FJ40's, keep us updated on yours please.

As for your transmission, head over to Novak's site. They have a lot of good tech and most any rebuild part you could need. Parts for the SM420 Transmission (novak-adapt.com) The Novak Guide to the GM Muncie SM420 Transmission (novak-adapt.com)

As Wilson said, a worn out bearing or bushing could be the issue. I've also seen where the shift collars can get little grooves worn in them. Also, 1st and Rev are straight cut gears without syncro's so the teeth themselves might need to be cleaned up.

 

[559Fj40]

Well I basically forgot about this thing and went snowboarding 30+days this season instead. But I'm back to it and I have actually made some progress.

I'll knock off some big ticket items quickly.

PRP seats in. Built some simple mounts that mock the factory seat brackets but sit a tad lower. The driver seat sits lower than the passenger. I am not super worried about aesthetics at this point, but I am worried about keeping my head out of the cage so the offset seating will be how it is for awhile. Eventually I would like a fuel cell and I will get both seats sitting level but thats a ways down the road for me.
Now to get to my binding transmission that I left off on. I bit the bullet and decided to get a hands on lesson on how transmissions go together. I went to a buddies house who had a press and did it in an afternoon.

The thing basically fell apart and disassembled itself as I started pulling things apart.

Really nothing to these things.

Did not take too many in between pics. Back together and ready to go, next to the tcase that I blew up gears in in 2019. The t case was rebuilt but I left one of the gears with some chipped teeth in. Replacment gears are hard to find and SOR charges an arm and a leg for used gears. I replaced the garbage gear and left the others. We will see how long it lasts. I've been keeping my eyes open for a complete 3 speed case to just throw some bearings and seals at and have at the ready.

0002 serial number on my t case adapter. Anybody else seen an M&M Engineering adapter before?

I threw the trans in the following weekend and it worked so I am calling it a win.

 

[559Fj40]

Next on the list was trying to cure the extreme 35 mph death wobble I remember having. I figured it was a combination between the unbalanced 11 year old iroks and the fact that every piece of rubber on the front suspension was either non existent, or rotting away. New poly bushings, u bolts, grease-able pins, etc... Took leaf springs apart, new spring pads, painted them up...

No concrete at the house so I work in the dirt. Its basically just training for trail repairs. If I never get used to working in a shop then fixing stuff on the trail will feel at home.

After getting the front suspension freshened up, I decided to go for a drive before swapping tires and wheels to see if it was lack of bushings that was causing my wobble issues

Most important pre drive step was to take the top off.

Wobble was better not gone.

Put on some new to me 37 km2 and some pro comp steelies I found on fb marketplace.

Drove it for an afternoon, wobble is no longer and the road manners with these tires are so much better than the iroks.
Drove to meet some friends and when I got out it looked like I had splashed through a puddle but those don't exist in California in the summer so something was up.
My axle seal on the driver side had given up at some point during my drive which resulted in my driver side tire flinging gear oil everywhere.

Back to my cardboard garage.

 

[559Fj40]

Same day I called up my friend whose working on starting up a mobile detailing business in our mountain area to help clean this thing up a bit.

Next morning early drive to the lake to show off the minor detail job

It's been 2 years now since I've driven this thing and it feels good to be cruising it around again. My wiring job has held up so far which I am happy about. Still need to just do a bunch of maintenance stuff to it, and lots of goals but I've decided no big projects on it. I just wanna drive it and take it to the mountains this summer. Memorial day weekend was my last day snowboarding for the season and the same weekend I started working on all the little stuff. My goal then to have it "reliable" was the 4th of July and I achieved that goal. Still lots to be done but it was enough to stick my girl and her friends in it for the Fourth and hit the lake for the fireworks.

 

[toyotajeep]

That is weird. As others have said, one of my first rigs was basically just what you are doing. Rebuilt the 420 etc. Lots of fun with that rig. It was the first frame off vehicle I built. A long time ago...

I drove it daily for about a year with SPOA and 35's. Fun fun...

 

[559Fj40]

So I have neglected the thread for awhile now, but the cruiser has not received the same treatment. Since I rebuilt the sm420 in the summer of '21 I have put tons of miles on this thing and have had a great time driving it and wheeling locally. I've decided to update the thread because I am going to be doing some Rubithon prep. This will be my first trip on the rubicon.

Before I get to prep I'll cover what I have been up to since '21. Fought same transmission issue that I tried solving with the rebuild but decided to just deal with it and drive it.

Spent the summer wheeling around on some mild local trails and escaping the heat of the Central Valley.

Winter '22 I bought a 3 speed case in order to swap gear sets because I had chipped teeth on some of the gears and I assumed that was what was causing t-case noise as well as some of my binding issues. Turned out not to be the case so I continued ignoring the problem and kept driving it as much as possible.

Into '23 now, I added some lighting, new Yokohamas, and reinstalled the bumper with a rebuilt 8274 to prep for King of the Hammers. Trailered down and had an amazing time bouncing around out in the desert with friends.

A few weeks ago I messed around with the PTO gear spacers in the t-case in a final effort to fix the popping out of gear issue. Turns out I had them in wrong after I rebuilt it 3 years ago and the slight play was allowing the input gear to walk a bit, causing a massive bind. Stupid mistake that resulted in 3 years of drivability issues but its solved now.

 

[Arickvan]

Hey this thread looks familiar

I'm surprised I haven't seen it till now

Killer rig man

 

[559Fj40]

So I meant to keep this updated during the days leading to Rubithon but that obviously didn't happen. I had a lot more planned prep but decided the truck works well and I did not want to stress out and thrash to get a bunch of things done that aren't totally necessary. So I kept it simple, did a few key things, and packed up.

I had a few issues to address before leaving. For the past few months when the rig gets really twisted up my power steering pulley was contacting the steering shaft going into the box.

Clearance is tight to begin with and I figured it was just a combination of all my mounts being 25+ years old, rotten, and destroyed. Replaced the belt and I finally installed a poly body mount kit that I have had in a box since 2020. My fear was broken hardware on disassembly but everything went smooth.

I probably should have washed the thing beforehand to limit the dirt in my eyes but I survived and the install took only a few hours. I also took the time to check the trans crossmember mounts and the motor mounts. To gain any clearance I could I used a prybar to push the engine over a hair before cranking down the motor mounts. I don't know how much it actually moved but I did it anyway.

The next bit of prep was setting up my storage for tools and camping gear for the rubicon. I pulled the rear sit to put my toolbox in. I told my friends they will need to hustle and get their rigs finished because I'm not going to remove all this lockable storage for a backseat again so no more free rides.

 

[559Fj40]

Now a quick Rubithon Recap. This was my first trip to the Rubicon and my dad had not been in 20 or more years so we were both basically going in blind. We were registered as a "Renegade Run" because we weren't sure if we would be too slow for a fast group or too fast for a slow one... We had planned to leave home and get to Loon Lake before dark on Wednesday but that turned into us not leaving the house until after 8pm.

We made it to Loon Lake Dam just before 2am, dumped the cots on the side of the road, and got a few hours of rest before unloading and hitting the trail around 7/730 am.

Came into gate keeper and followed behind a 200 series and a few 80's. I was trying my best to keep pace with them but any part that was a non obstacle I had no chance of keeping up but then would catch up to them at various ledges or rock gardens where the big vehicles were a little bit slower being that they seemed to get hung up or diffed on more rocks that the swb 40. This only lasted until the top of walker hill though because they were just so much faster through the sections loaded with the small nuisance rock.

After an early lunch watching people play at soup bowl we ran into a group of three jeeps and an f-toy stopped on the side of the trail. The f-toy had sheared the knuckle studs on the driver side and totally wiped out the trunion bearing. I decided to unload and dig out what I could to help. I had some random knuckle hardware and trunion bearings as well as a magnet to fish out all of the exploded bearing out of the birfield/knuckle ball.

After hanging out for an hour or two and helping out we loaded up and continued on. While watching some hummers run little sluice, the Breakfast run caught us. We hopped into the back of the line and I got my first taste of a rubicon traffic jam.

Followed this group into Buck which was going to be our original camp spot, but not wanting to wake up early to get ahead of them, we decided to push on to the springs.

 

[559Fj40]

Going through the Buck Island area was fun wheeling but in hindsight, I should have stopped more to appreciate the lake because I can barely paint a picture in my head of what it looks like. Eyes were down trail and I just kept motoring along.

Crossed the bridge before full darkness so I'm counting that as a success.

We setup camp out past the slabs but before the creek crossing for dirty dozen. Spent the next few days hanging out, talking to people at the marauder bar, and catching up on sleep from the previous days of prep, work, and travel. I should have taken pictures of the aftermath, but Friday night our camp was hit by a bear while were away. Losing some bread and snacks is a bummer but the real issue is while he was ripping the action packer apart, he knocked my fuel can over which dumped all of my spare fuel out through the vent.....
This made the decision of wheel back to loon or Cadillac and highway an easy one. The 350 and edelbrock 4 barrel were very thirsty and there was no shot I was going to make it back to loon via the trail without that extra fuel.

Dinner on Saturday was great and my dad and I struck out at the raffle. The Marlin Hood auction was fun to watch and it was funny to hear my old neighbor is the one who painted it.

Sunday morning was an early wakeup to try to beat any traffic. Cadillac was a cake walk but we did catch up to a group of 80s hung up in a random rock garden on the road out sometime after observation.

Tax dollars at work

After this it was a pretty casual drive out following a group from the Central Coast. Well it was casual until I ran out of fuel less than a half mile from the staging area. Was stopped for less than 5 minutes before a group came by and I snagged a couple gallons from Lee from the Cruisin2Camp podcast.

After that it was a nice and easy drive to Tahoe City for fuel and a gas station breakfast. Then we had an uneventful but long trip back to the trailer.