2WD FJ80 - Am I gonna ruin anything ?

[fattfreddie]

Hello !

Member of this forum since 2012 and I have never posted anything

My 1992 FJ80 with 283K on it recently broke something in the front driveline. I removed and checked (replaced with brand new OEM part) the outer drive flanges, and that did not solve the problem. I believe that it has stripped splines on the driver side Birfield where it meets the diff. Symptoms - terrible grinding noise in D or R when center diff is unlocked, P is like neutral. When center diff is engaged, it drives just fine. Here's my question - am I gonna ruin anything by driving it like this ? Should I remove the front drive shaft if I am gonna drive it very much before I replace the Birfield ? Or is driving it with center diff locked just bypassing the broken "open" front and sending all the power to the rear ? THANK YOU !!!

 

[AgentOrange]

If the center diff is locked, yes, remove the front drive shaft to drive on the street. But if park is behaving like a neutral, something else sounds wrong. Where does the sound seemt to be coming from with someone else outside the vehicle listening?

 

[fattfreddie]

If the center diff is locked, yes, remove the front drive shaft to drive on the street. But if park is behaving like a neutral, something else sounds wrong. Where does the sound seemt to be coming from with someone else outside the vehicle listening?

Thanks for the response @AgentOrange - Noise is coming from driver front toward the center as far as I can tell. Park behaves like neutral when CDL is off, and park behaves like park when CDL is on.

 

[mudgudgeon]

As above, remove the font drive shaft and lock the CDL.
I would also remove drive flanges from the front hubs. This way nothing is rotating inside the diff/ axle housing. ( use duct tape to keep dirt and debris out of the hub)

You can drive the vehicle like this indefinitely.

I drove one of my cruisers for months like this until budget allowed me to buy parts.

 

[CharlieS]

Does this year need the pin7 mod to lock in high range?

I recently blew a rear universal on a trip and drove dirt and highway for 700+ miles with the rear shaft removed and CDL engaged (it has the pin 7 mod) in my '94.

 

[Desert Dino]

Does this year need the pin7 mod to lock in high range?

I recently blew a rear universal on a trip and drove dirt and highway for 700+ miles with the rear shaft removed and CDL engaged (it has the pin 7 mod) in my '94.

the pin 7 mod is for CDL dis engaged in low range

you can allwayes can install CDL switch oin 94 to enable CDL engage in Hi range

 

[cruiserdan]

I would also remove drive flanges from the front hubs. This way nothing is rotating inside the diff/ axle housing. ( use duct tape to keep dirt and debris out of the hub)

Absolutely.

 

[cruiserdan]

Does this year need the pin7 mod to lock in high range?

I recently blew a rear universal on a trip and drove dirt and highway for 700+ miles with the rear shaft removed and CDL engaged (it has the pin 7 mod) in my '94.

No. Applies only to ABS-equipped trucks

 

[CharlieS]

No. Applies only to ABS-equipped trucks

Thank you!

 

[ppc]

Does this year need the pin7 mod to lock in high range?

I recently blew a rear universal on a trip and drove dirt and highway for 700+ miles with the rear shaft removed and CDL engaged (it has the pin 7 mod) in my '94.

Pin 7 mod only disables the automatic CDL locking when switching into low range. Nothing related to high range.

 

[CharlieS]

Pin 7 mod only disables the automatic CDL locking when switching into low range. Nothing related to high range.

Thanks. This thread has been educational for me.

 

[jonheld]

Thanks. This thread has been educational for me.

The FJ80 came with a CDL switch from the factory which enabled you to lock the center in high. It automatically locked in low like every other 80.

The pin7 mod does very little for the FJ80 other than disabling the auto locking in low and allowing manual control of the CDL.
A less invasive way to accomplish the same thing is to simply unplug the low range switch on the transfer case.

On the FZJ80, the transmission is electronically controlled and the pin7 mod changes the shift points as well as allowing manual control of the CDL with the dash switch.

 

[cruiserdan]

The pin7 mod does very little for the FJ80 other than disabling the auto locking in low and allowing manual control of the CDL.

Which happens to be really handy for maneuvering on a boat ramp or turning on slickrock.

 

[jonheld]

Which happens to be really handy for maneuvering on a boat ramp or turning on slickrock.

I totally wrote that comment incorrectly before coffee.
I ran my 91 FJ80 with the low range switch disconnected for at least 20 years. Makes it really easy to maneuver between the east coast trees in low range.
What I had intended to say was that the pin7 mod was not needed on the FJ80 because the transmission is not electronically controlled. Simply unplugging the switch is all that's needed to have full manual control of the CDL.
Sorry for the lack of caffeine.

 

[mudgudgeon]

Sorry for the lack of caffeine.

Don't let it happen again!