Rolling in Park? (1 Viewer)

[Jedijunk]

First time poster here. What problem would let an 80 Series roll in Park? I recently bought my first 80-series, an LX450 (auto transmission). My first trip into the jungle, the transmission started slipping trying to go uphill, and it when I put it in Park on a hill it started rolling downhill. I assumed those were probably related issues, and I swapped out the transmission for another used one. With the new transmission, it doesn't slip in drive anymore, BUT the rolling in Park problem is still there. Vehicle in Park and in High range, and if it's on any kind of hill it just silently starts rolling. Shift cable seems to be adjusted right. Is there a viscous coupling in the center diff that could be shot? Or is the replacement trans bad too (seems unlikely it would have the same problem as the first one)? What else could cause this problem?

 

[Irish Reiver]

Have you checked that both your driveshaft are there?

 

[Jedijunk]

Have you checked that both your driveshaft are there?

Yes, both driveshafts are there. The transmission I pulled was the (original, I think?) Aisin 30-43LE model. I changed all fluids when I bought the car but it has 243xxx on the odo and the transmission fluid was quite dirty when I got it so I wasn't surprised when it started slipping out in the rough stuff. But this Park problem has me scratching my head...

 

[leonard_nemoy]

I have had this happen with a standard transmission on a really steep hill. I ended up chasing my 98 Tacoma down the road lol

How steep was the hill where your 80 was rolling in park. Extremely steep or just average?

 

[Jedijunk]

I have had this happen with a standard transmission on a really steep hill. I ended up chasing my 98 Tacoma down the road lol

How steep was the hill where your 80 was rolling in park. Extremely steep or just average?

Not just steep hills - even slight hills like sloping paved driveways. There's no sound or feel of slipping teeth. It's like it's in neutral, but possibly (?) slightly more drag. Drive works fine and so does Reverse. When I park, I feel it click into Park after Reverse, the Park indicator appears, and then it starts rolling once I take my foot off of the brakes. This is so odd that it is probably something stupid simple, I just can't think of what.

 

[leonard_nemoy]

Crazy....

Hopefully someone smarter than I can chime in with good advice.

 

[BILT4ME]

It's your drive flanges on the front hubs are stripped. This will allow it to roll downhill when the CDL is not engaged and it will allow it to roll in park for the same reason.

Sorry you spent all that money and time for a transmission when it's a $35 drive flange.

 

[Jedijunk]

It's your drive flanges on the front hubs are stripped. This will allow it to roll downhill when the CDL is not engaged and it will allow it to roll in park for the same reason.

Sorry you spent all that money and time for a transmission when it's a $35 drive flange.

I think you might be right! Searching this forum for "front drive flange" I came across this thread that describes my issue pretty exactly : Fj80 drive flange questions - https://forum.ih8mud.com/threads/fj80-drive-flange-questions.1005735/. If it is just the drive flanges I'm gonna be ticked at the shop that told me to swap out the tranny. They are supposed to be one of the better FJ shops in my area of Cambodia. Sigh. I should have asked here first before taking their advice on the tranny swap.

 

[flintknapper]

I think you might be right! Searching this forum for "front drive flange" I came across this thread that describes my issue pretty exactly : Fj80 drive flange questions - https://forum.ih8mud.com/threads/fj80-drive-flange-questions.1005735/. If it is just the drive flanges I'm gonna be ticked at the shop that told me to swap out the tranny. They are supposed to be one of the better FJ shops in my area of Cambodia. Sigh. I should have asked here first before taking their advice on the tranny swap.

Just seeing this thread. I agree there is a high likelihood that a drive flange is suspect. It doesn't have to be both, ONE will do it if you have open diffs. A simple way to find out is simply to lock your center diff. IF the vehicle doesn't roll back after that then you have your answer.

As an aside...in case you don't already know, lifting the front or rear end without locking the Center Diff (and setting the parking brake) will also result in your vehicle rolling (even though in park).

 

[98 SNAKE EATER]

yep, sounds like drive flange

 

[leonard_nemoy]

I should have asked here first before taking their advice on the tranny

I have found that it is always wise to get a 2nd opinion when dealing with any kind of tranny decisions.....

 

[-Spike-]

I think you might be right! Searching this forum for "front drive flange" I came across this thread that describes my issue pretty exactly : Fj80 drive flange questions - https://forum.ih8mud.com/threads/fj80-drive-flange-questions.1005735/. If it is just the drive flanges I'm gonna be ticked at the shop that told me to swap out the tranny. They are supposed to be one of the better FJ shops in my area of Cambodia. Sigh. I should have asked here first before taking their advice on the tranny swap.

Don't be so sure about the drive flange. The truck shouldn't move at all under engine power without the CDL engaged if the drive flange was that bad. And if the VC has failed (locked), then it wouldn't move in Park even with a bad drive flange. Definitely worth looking at, but don't start buying parts just yet.

 

[BILT4ME]

Don't be so sure about the drive flange. The truck shouldn't move at all under engine power without the CDL engaged if the drive flange was that bad. And if the VC has failed (locked), then it wouldn't move in Park even with a bad drive flange. Definitely worth looking at, but don't start buying parts just yet.

But his VC may NOT have failed........yet.

 

[98 SNAKE EATER]

But his VC may NOT have failed........yet.

This

Even with a stripped drive flange, the VC could still have enough grip to get it moving

Of course if you floor it, it'll go up in smoke

 

[Dave 2000]

So perhaps a little trail here, off reading front flange strips, owner treads on throttle as trans appears to be slipping, the VC overheats and locks up, now in rear wheel drive?

Regards

Dave

 

[-Spike-]

But his VC may NOT have failed........yet.

Then why does the truck move under power but park can't hold it on a slight hill? You can have one or the other, not both.

This

Even with a stripped drive flange, the VC could still have enough grip to get it moving

Of course if you floor it, it'll go up in smoke

VC's don't work like this. When they work, they barely transfer enough power to move the truck if one wheel has no traction, for whatever reason. The overrevving and complete lack of power is very obvious.

So perhaps a little trail here, off reading front flange strips, owner treads on throttle as trans appears to be slipping, the VC overheats and locks up, now in rear wheel drive?

Regards

Dave

A normally functioning VC won't 'lock', it transfers a (small) percentage of power.

All I'm saying is that there may be an issue with the flange, or not, or several issues. Or it could be a stripped flange and the system is doing something it shouldn't be able to- slip in Park but apply power from the engine. Or the OP isn't explaining what is happening accurately.

 

[BILT4ME]

Then why does the truck move under power but park can't hold it on a slight hill? You can have one or the other, not both.



VC's don't work like this. When they work, they barely transfer enough power to move the truck if one wheel has no traction, for whatever reason. The overrevving and complete lack of power is very obvious.



A normally functioning VC won't 'lock', it transfers a (small) percentage of power.

All I'm saying is that there may be an issue with the flange, or not, or several issues. Or it could be a stripped flange and the system is doing something it shouldn't be able to- slip in Park but apply power from the engine. Or the OP isn't explaining what is happening accurately.

"Not just steep hills - even slight hills like sloping paved driveways. There's no sound or feel of slipping teeth. It's like it's in neutral, but possibly (?) slightly more drag. Drive works fine and so does Reverse. When I park, I feel it click into Park after Reverse, the Park indicator appears, and then it starts rolling once I take my foot off of the brakes. This is so odd that it is probably something stupid simple, I just can't think of what."

The above statement by the OP is what makes me think he still has a functioning VC and stripped drive flanges. Coupled with the fact that he CHANGED the transmission with the same results.

 

[Dave 2000]

Then why does the truck move under power but park can't hold it on a slight hill? You can have one or the other, not both.



VC's don't work like this. When they work, they barely transfer enough power to move the truck if one wheel has no traction, for whatever reason. The overrevving and complete lack of power is very obvious.



A normally functioning VC won't 'lock', it transfers a (small) percentage of power.

All I'm saying is that there may be an issue with the flange, or not, or several issues. Or it could be a stripped flange and the system is doing something it shouldn't be able to- slip in Park but apply power from the engine. Or the OP isn't explaining what is happening accurately.

You misunderstood my post. When the VC is cooked and burnt up they do lock.
FWIW for those who don't know, I drove mine off the ramp after fitting a new clutch without one of the driveshafts connected and the car drives as if the clutch is slipping. There is sufficient 'grip' from the VC to move the car but for how long before it gets fried I don't know.

Regards

Dave

 

[-Spike-]

You misunderstood my post. When the VC is cooked and burnt up they do lock.
FWIW for those who don't know, I drove mine off the ramp after fitting a new clutch without one of the driveshafts connected and the car drives as if the clutch is slipping. There is sufficient 'grip' from the VC to move the car but for how long before it gets fried I don't know.

Regards

Dave

Yers, they do lock. Permanently. They don't loosen up when you put the trans in Park.

 

[60 toy ota]

So how about the op puts the tuck in park on a LEVEL surface, lifts a wheel (ebrake off), and without getting underneath anything, turn the wheel and see what's spinning where it shouldn't. Could maybe even do this without lifting a wheel by pushing the truck