Gearbox durability

[GILow]

Hi all,

The new Nanni 50 came with a TMC60 P 2:1 gearbox. That had me scratching my head because I ordered a TMC60 2:1 (no P).

So I checked the manual and found the gearbox reverses the direction of the prop shaft in forward gear.

Cue mild panic.

Then I started breathing again and thought… “hang on, I told them I had a clockwise prop (right hand), so surely they know what they are doing”. And then I looked hard at the Kubota and realised it spins counter clockwise on the output shaft so it has to be reversed for the prop.

Which then annoyed me because I thought “sh-t, I could have ordered a left hand prop (the prop is new) and had a straight through gearbox.”

So, would a non-direction-reversing gearbox have been more durable? I mean, the horse has bolted but these are questions that tend to bother me. Knowing I stuffed up is better than wondering IF I stuffed up. (It’s weird, I know, but that’s how I am.)

Matt

[Wotname]

I would say you should have more important things to worry over than that of the durability of the P box compared with a non P box.

However, if this is the biggest issue yo have to be concerned over, I can lend you some of my worries!

TL : DR - no probs!


Hey, aren't you lucky that "they know what they are doing"!

[GILow]

Originally Posted by Wotname

I would say you should have more important things to worry over than that of the durability of the P box compared with a non P box.

However, if this is the biggest issue yo have to be concerned over, I can lend you some of my worries!

TL : DR - no probs!


Hey, aren't you lucky that "they know what they are doing"!

You know how I love a food worry.

But no, probably not the biggest issue I am facing.

[skipperpete]

The brochure clarifies the situation, yes its bi rotational BUT if the astern position of the selector is used as ahead, the duty cycle and load is slightly reduced and an an oil cooler may be required…Nanni advises that they’ll sell you one.

[GILow]

Originally Posted by skipperpete

The brochure clarifies the situation, yes its bi rotational BUT if the astern position of the selector is used as ahead, the duty cycle and load is slightly reduced and an an oil cooler may be required…Nanni advises that they’ll sell you one.

Actually, it seems to have a cooler built in. A pair of 25 mm hose barbs either side, capped with rubber caps and painted blue with the rest of the engine. But I checked the ratings and even at full power I am a few kW short of their threshold for adding cooling in forward or reverse.

From my reading of their rather weird documentation, you can request the barbs instead of the blanking plugs that are normally supplied. Which is odd because it would have been Nanni that requested them yet the engine isn’t big enough to need them. Maybe Nanni order them by default so they can be fitted to the bigger engines. I gave some thought to connecting them but decided they would simply add points of failure to the cooling system.

This stuff gives me a headache.

[FPNC]

There is only one TMC 60 transmission available. Currently, it is factory labeled as TMC 60 P. Older units may be labeled TMC 60 M. The 'P' notation designates the latest iteration of the model.

[boatpoker]

Originally Posted by FPNC

There is only one TMC 60 transmission available. Currently, it is factory labeled as TMC 60 P. Older units may be labeled TMC 60 M. The 'P' notation designates the latest iteration of the model.

I have a TMC 60A purchased last year.

[FPNC]

Originally Posted by boatpoker

I have a TMC 60A purchased last year.

The TMC60A is a 7° down angle transmission. Designated by the 'A'. It is a completely different transmission than the TMC 60 models.

[skipperpete]

Originally Posted by GILow

Actually, it seems to have a cooler built in. A pair of 25 mm hose barbs either side, capped with rubber caps and painted blue with the rest of the engine. But I checked the ratings and even at full power I am a few kW short of their threshold for adding cooling in forward or reverse.

From my reading of their rather weird documentation, you can request the barbs instead of the blanking plugs that are normally supplied. Which is odd because it would have been Nanni that requested them yet the engine isn’t big enough to need them. Maybe Nanni order them by default so they can be fitted to the bigger engines. I gave some thought to connecting them but decided they would simply add points of failure to the cooling system.

This stuff gives me a headache.

It seems that the cooler is simply a bronze tube that passes right through the gearbox sealed by orings with either a cap or hose barb on the ends ( google images) ……so is it safe to assume that the engine raw water suction line connects to those barbs?

[boatpoker]

Originally Posted by FPNC

The TMC60A is a 7° down angle transmission. Designated by the 'A'. It is a completely different transmission than the TMC 60 models.

Have you advised TMC that their TMC 60 A is not a TMC60 ?

[GILow]

Originally Posted by skipperpete

It seems that the cooler is simply a bronze tube that passes right through the gearbox sealed by orings with either a cap or hose barb on the ends ( google images) ……so is it safe to assume that the engine raw water suction line connects to those barbs?

According to the manual it can. But the Nanni uses 32mm suction lines and the barbs are 25. So it would have to come after the water pump">raw water pump which would be very complicated.

[FPNC]

Originally Posted by boatpoker

Have you advised TMC that their TMC 60 A is not a TMC60 ?

I do not speak Italian.

[Icarus]

No there is no cooler build in...you would have to run a suitable cooling tube from one end to the other..
The main thing with these boxes is don't overfill and use ATF fluid.
When shifting from fwd to reverse go through neutral for a couple of second, don't slam it into reverse.

[skipperpete]

Well, it sure sounds like GILow’s gearbox was supplied with the cooler tube, I can think of no logical reason for having 2 hose barbs with plastic caps on the sides of his gearbox housing if there was no through tube joining them.