FJ80 only drives with center diff locked (1 Viewer)

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Joined
Apr 20, 2018
Threads
19
Messages
96
Location
Birmingham, AL
Ok so some of you guys may remember me as the guy who bought a very rough project of an 80 series. So far I’ve more or less had to touch every system on this thing. Neglected is an understatement but I’m committed now.

The truck only drives with the center diff locked, I actually didn’t realize this when I first got it because the diff lock light is burnt out and both driveshafts are installed, but sure enough if you turn it off it doesn’t move and won’t engage park.

Here’s what I know: if you turn the front driveshaft by hand the wheels don’t move. Popped the dust covers off and the passenger side brif was missing the C clamp and the flange looked kind of stripped. The brif splines looked alright. I took the hubs apart this weekend and put new rotors, cleaned and packed the bearings, new tie rod ends, steering stabilizer, and new flanges on each side. Fired it up (super excited), unlocked the diff and..... nothing except some pretty crappy sounding noises. Turned the diff lock back on and it’s fine again.

The truck drives around fine, not great. No weird grinding or clicking that I’ve heard. There is kind of a clunk sometimes from the LF type area but my sway bar bushings are gone and I’m kind of thinking that’s what’s causing that. Ive really only put maybe 100 miles on this thing so far, just trying to get it all sorted. Im kind of scared to drive it with the front shaft installed, probably gonna take that out tomorrow just for good measure. I’m at kind of a loss here. Anyone have any ideas?

Also — when I was doing the hubs I cleaned off 30 years worth of grime and leaks, now I can clearly see that my steering box is leaking really badly as well. Rock auto lists a “Lares remanufactured” one for $200 which seems like a good price, don’t really want to pull it and rebuild myself. Any thoughts on that?
 
Front drive flanges are stripped
 
Drive flange...
 
How are the splines on the birfs???
 
Is the front drive shaft spinning when in drive and not moving??
 
Ok, now that I have read your post...

If the if the front drive shaft is turning when in drive, then power in, no power out... pull your third and check the R&P...
 
Ok, now that I have read your post...

If the if the front drive shaft is turning when in drive, then power in, no power out... pull your third and check the R&P...
Interesting. Anything inside the diff and especially the transmission is beyond me. I’ve just never opened one and feel like I’d do more harm then good.

So there’s a ring and pinion on third gear that controls the power for the front axle?
 
So there’s a ring and pinion on third gear that controls the power for the front axle?
The ring and pinion are in your third member as in your front differential. The ring and pinion is what you swap to regear for bigger tires.
 
Damn, I’m being stupid 😂😂

I’ll give that a shot

First, park it in flat ground, chalk the tires and set the parking brake. Then, start the engine and verify the center diff is UNlocked. Then put the trans in drive. Let off the brake and make sure the truck won’t go anywhere. Get out and see if the front drive shaft is spinning. If it is not spinning the problem lies in the tcase. If it is is spinning the problem lies in the axle... you’ve replace the drive flanges and said the birf splines are good. If that is correct then the answer is between the front axle ring and pinion and axles, birfs included...
 
Did you figure this out??
 
Did you figure this out??

It’s a little past my skill level so I have it in a local shop. Talked to him the other day, ring and pinion ordered. Will let you guys know. I’m hoping we don’t get that fixed only to get it working and find out a birfields bad. This is a super crappy truck honestly I probably shouldn’t be trying to fix it up.

Coincidently, I bought a super clean 97 (non locked) today with a bad fuel pump. Hopefully that’s all it is but judging by the condition I’m very optimistic!
 
Thanks for the update, I’d like to see pics of the R&P...

Congrats on the ‘97... check the fusible links!!
 
It’s a little past my skill level so I have it in a local shop. Talked to him the other day, ring and pinion ordered. Will let you guys know. I’m hoping we don’t get that fixed only to get it working and find out a birfields bad. This is a super crappy truck honestly I probably shouldn’t be trying to fix it up.

Coincidently, I bought a super clean 97 (non locked) today with a bad fuel pump. Hopefully that’s all it is but judging by the condition I’m very optimistic!

Are you sure it is the fuel pump I have never seen one die, but if you need one, I have a good one
 
Are you sure it is the fuel pump I have never seen one die, but if you need one, I have a good one

The guy who sold it to me said the strainer had rust in it. I believe they pulled the tank and cleaned it out but never actually changed the pump. It was sitting in the back of a shop for years.

Right now, the pump and the whole bracket it attaches to are missing. I would gladly buy your pump and it would just make my day if you had the bracket lying around too!

It starts with starting fluid. CEL comes up on the dash when you turn the key so hopefully once I put a pump in it it will run. Now if the headgasket and axles are good is another story, but it’s a super clean truck so Its worth saving
 
"----and new flanges on each side. Fired it up (super excited), unlocked the diff and..... nothing except some pretty crappy sounding noises."

dr335I: could you post up photos of the (cleaned) splines of the Birfield stub shafts?
 
The guy who sold it to me said the strainer had rust in it. I believe they pulled the tank and cleaned it out but never actually changed the pump. It was sitting in the back of a shop for years.

Right now, the pump and the whole bracket it attaches to are missing. I would gladly buy your pump and it would just make my day if you had the bracket lying around too!

It starts with starting fluid. CEL comes up on the dash when you turn the key so hopefully once I put a pump in it it will run. Now if the headgasket and axles are good is another story, but it’s a super clean truck so Its worth saving

So the whole assembly with the pump and sending unit gas tank inspection cover is all gone ? take a picture of what you have, it is under the rear seat
 

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