A343F problems in a Lexus LX450 (1 Viewer)

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Jul 9, 2007
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Asturias(Spain)-London(England)
Hello.

A friend is experiencing problems with his transmission.

He notices a big slippage in first and secong gear, at a minimum obstacle it revs up a lot and takes a life to keep going. Then at a certain speed it goes ok the problem is just in 1st and second gear.

What really puzzles me is the fact that the transmission brake in P also doesn't work good, if it's too steep it won't break and the car will move.


We don't have any LX450 in Spain, this is imported from the US I think and nobody has ever seen a A343F transmission. How good is it compared with the A442F we are used to? In case it's damaged, can it be swaped with a HDJ80 A442F?

Thanks a lot.
 
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Sounds like it's slipping until the VC engages. I would lock the center diff and see if that "fixes" it.

Stripped drive flange maybe?
 
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Warsaw, Poland
The tranny is OK. Your symptoms seem like a problem with the drivetrain, like a broken birf, broken axle or stripped axle splines front or rear.
 
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A VC is a viscous coupler or "acoplador viscoso" en Espanol. The drive flange couples the end of the axle shaft to the hub. It is underneath the hub cap.

Es su suerte dia. Una "drive flange "es mucho mas barrato que una transmission y mas facile tambien.
 
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OK, we have found some languaje barriers here.

What is a VC?, and a drive flange?. Any link to pics or something as I don't think it will be easy to find in a dictionary?

VC = Viscous Coupler. It acts as a limited slip, basically if one drive shaft is turning much faster than the other then it locks both together.

For the part that's broken, it's likely in the front axle. Could be a lot of things, but I would plan on a full front end job especially if it hasn't been done before. It's impossible to remotely troubleshoot this with any sort of accuracy, the only way to tell is to start digging into things.
 
Joined
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Thanks a lot guys.

I understand all now and specially why you told me to engage the diff lock. That's a good idea. We will try so and check all the drivetrain and specially front axle as you suggest.

But anyway, why does it go without issues in 3rd and 4th gear if it's a drivetrain issue?

About the Viscous coupler, I remember my 91 HDJ81 tranfer case broke and got a '93 HDJ80 transfercase and the mechanic told me that was better than the one before as it had a viscous coupler. Does it act someways like a Range Rover automatic central diff lock?

I remember in my previous Opel Frontera (Isuzu Rodeo) I had to use a special kind of gear oil in the rear diff as it had a LSD. Does that apply to the 80 series Viscous Coupler?

With this system you don't have to use the central diff lock button nearly as often as you had with the early transfer cases, do you? Or am I missing some point? (maybe a lot of them).
 
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Joined
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But anyway, why does it go without issues in 3rd and 4th gear if it's a drivetrain issue?

Because you're already at speed, so it's less noticeable. It's also already been engaged, so it's going to want to stay engaged.

About the Viscous coupler, I remember my 91 HDJ81 tranfer case broke and got a '93 HDJ80 transfercase and the mechanic told me that was better than the one before as it had a viscous coupler. Does it act someways like a Range Rover automatic central diff lock?

Somewhat. This may help:
HowStuffWorks "Viscous Coupling"

The one in the 80 series is a different design, but you get the basic idea.

I remember in my previous Opel Frontera (Isuzu Rodeo) I had to use a special kind of gear oil in the rear diff as it had a LSD. Does that apply to the 80 series Viscous Coupler?

Nothing to terribly special. ;)

With this system you don't have to use the central diff lock button nearly as often as you had with the early transfer cases, do you? Or am I missing some point? (maybe a lot of them).

The idea with the VC system is that when you start slipping, it automatically transfers power to the wheels that are not slipping. So say on snow/ice you're at a dead stop and applying power. If you don't have a VC, and a single rear tire starts slipping, all the power will go to that spinning tire, and you won't move. Now say you have the VC, and a rear tire starts slipping. The VC will engage and direct part (up to half) of the power to the front driveshaft. Likely one of those two tires that now has power has some traction, and you will start to move.

The CDL button basically locks the transfer case completely and splits the power 50/50 between the front and rear drive lines. You would want to lock the CDL in situations where you know you want power to the front and rear, and where drive line windup is not an issue.

So yes, you have to use the CDL button nearly as often with a VC as without. The only real benefit is in low tractions situations where you do not have your CDL locked.

I used the heck out of it when I was driving through Yosemite during one of their worst snowstorms in years. That's an example of when I would use it (in high gear, CDL unlocked, moving at a fairly fast pace, low traction), but it doesn't happen all that often.
 
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Cañonero, I have exactly the same problem inmy LX450. How did you solve it? As you know, in Spain (I'm from Madrid) there aren't so many car workshops which can deal with this problems and I'm worry about it.

I have been told about having to change the transfer box. Which steps should I take to solve the VC problem?

Do you think I can do it myself? Or is something a workshop does....
 
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You can remove the VC or replace it. Replacing it is not cheap. Removing it is.

If you remove it you lose the "limited slip" design, meaning if you're on a slick surface (IE: ice) and start spinning a tire all your power will go to that one tire, instead of being split front and rear.
 

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