Gearbox inspection?

[ntz1111]

Greetings all,

At 70mph i engaged reverse believing it was 6th (don't ask). Every minute or so i heard a deep sounding squeal coming from the gearbox tunnel. Reverse gear had not fully engaged given the spinning internals but i guess the gear teeth were bouncing off each other. The intermittent squeal continued for another 45 min in every gear. After the engine cooled completely no more squeal was heard.

I dropped the gearbox oil. About 20/30 small metal particles (the largest around 1mm across) were found and a 12mm shaving (attached in photo).

I have a Terrain Tamer HD clutch. Its a 2011 1HZ 78 series with last gearbox oil change around 30K km ago with light use.

Do i need to drop the gearbox and check for bearing /meshsynchro damage ? Or am i good to flush one more time and carry on business as usual?

 

[JuanJ]

Hello,

Chances are you chipped a gear.

HZJ78s have the R151F transmission. It is not as tough as other transmissions, and it may have sustained some damage.

It is worth to drop the transmission and have a look.






Juan

 

[ntz1111]

Thank you. While i'm there, are there any components worth upgrading to make the R151 more robust?

 

[JuanJ]

Hello,

Perhaps it is worth checking whether Terrain Tamer has a kit for the R151F transmission. They offer upgraded/reinforced components.

From now on, it is worth repeating to yourself that there are only five gears, no more, no less, and that chipping gears is both easy and costly.






Juan

 

[HZJ75 FARMER]

I would check the price of a new transmission. The R151 is cheaper than many others.
Then check the price of a rebuild kit, plus a couple of gears, plus a coupling between the transmission and transfer which will be worn, plus the 5th/reverse selector lock which obviously didn't work, maybe a 1st/2nd dog clutch because they wear, add a bit of labour and add a bit of extra cash because everything gets worse than you expect when you start pulling it apart.
Then decide which is the most cost effective option.
Then decide how dependent on the vehicle you are.
If the vehicle doesn't need absolute 100% every single day availability, decide if you want to spend the $XXXX now, or chance running it for unknown amount of time until it fails and then spend the $XXXX later, or maybe not ever.
If there's no noise, I would run it and just keep in the back of your mind you might have to rebuild/replace later. It could go for years. But that's just me.

 

[Eurasiaoverland]

I'm not specifically familiar with the R151F, but engaging reverse will mean engaging a reverse idler gear between gears on the main and lay shafts. Since you didn't double lock the box, I would suspect the only damage will be to the edges of the reverse gears, and looking at what you recovered, that was pretty mild. If it has a synchro on reverse, the damage might be on the reverse shift hub/index teeth.

I would be inclined to just keep running it. Reverse gear is not used much, and is anyway a noisy straight-cut gear. But it would seem your reverse restrict pin is not working correctly, so car is needed when shifting out of 5th.

 

[Broski]

I agree any damage done is done. If it is working run it change the gear oil again soon and keep an eye on it.

 

[ntz1111]

Thanks all - I did another flush and still got small debris floating around in there.
Isn't that likely to cause wear on the remaining "healthy" parts of the internals ?
Interesting about the selector lock/reverse pin not functioning.

 

[Broski]

rebuild, replace or flush it tell the oil comes out clean

 

[Eurasiaoverland]

Thanks all - I did another flush and still got small debris floating around in there.
Isn't that likely to cause wear on the remaining "healthy" parts of the internals ?
Interesting about the selector lock/reverse pin not functioning.

In a Lamborghini Miura, the engine and gearbox share the same oil and I've been told that one good gear grind means you should change the oil.

A Land Cruiser is at the other end of the finesse scale and is sold to people around the world who don't know how to drive properly and may not even know there is oil in the gearbox.

If it's not making any noises, I would just keep going. In my opinion the debris which you drain out is already safely at the bottom of the transmission - it's the stuff that might be in the needle rollers, stuck to gear faces, or jammed in the synchros which could cause damage. But if it runs and shifts gears as usual, you're probably fine. Between the end members of 'it's fine' and 'it's ruined inside', there is in my opinion a small chance that it is badly damaged and that it will not be cheaper to replace it, rather than pay someone to rebuild the gearbox and replace half the internals. Therefore, I would run it and see what happens.

 

[Broski]

In a Lamborghini Miura, the engine and gearbox share the same oil and I've been told that one good gear grind means you should change the oil.

A Land Cruiser is at the other end of the finesse scale and is sold to people around the world who don't know how to drive properly and may not even know there is oil in the gearbox.

If it's not making any noises, I would just keep going. In my opinion the debris which you drain out is already safely at the bottom of the transmission - it's the stuff that might be in the needle rollers, stuck to gear faces, or jammed in the synchros which could cause damage. But if it runs and shifts gears as usual, you're probably fine. Between the end members of 'it's fine' and 'it's ruined inside', there is in my opinion a small chance that it is badly damaged and that it will not be cheaper to replace it, rather than pay someone to rebuild the gearbox and replace half the internals. Therefore, I would run it and see what happens.

^^^ This

 

[renago]

I personally would flush it till oil is clean without debris.
Something that might help would be a magnet
Bottom plug .
At least the small debris should stay put , and don’t float around .
How many km do you have on that gearbox ?
They are not super strong !
Generally the bearing holder from motor shaft will chip or break !
But till then just keep cal and carry on
Just my 2 cents

 

[ntz1111]

I passed by a 4x4 mechanic. He shared much of your views after showing him some more shavings- he was of the opinion that if there are no chunks of metal, carry on! It's got 180K Kms more or less.

 

[renago]

just to mention my episode , the front bearing broke and large pieces of alluminio were going around .to a point that a chuck blocked the gear selector .
Removed that chuck , I was still able to regularly use the gearbox for 10.000 km .
Changed for a H151