Kanzaki trans for 3qm30 Yanmar 1978

[SV Cygnus]

Nut won’t stay on Kanzaki trans for 3qm30 Yanmar, 1978 yr

Aloha a friend has asked me to help with his boat. A mechanic took the bolt off the back of his transmission and replaced the seal, put it back together. The owner tried to take it out of his slip and the nut came off. Mechinic has no clue.
I don’t see a slot for a snap ring only about 1-1/2 threads outside bolt. Can’t see what’s supposed to keep this bolt on. Owner asked me to chisel threads to hold it and I did. Not sure that’s enough. Anyone know what is supposed to hold this on?

[jimbunyard]

According to the manual

http://www.hunter37.com/Yanmar_3qm30.pdf

torque,and lots of it, at 100kg/m or 723.3 ft/lbs (believe the .3 is not critical) as well as (I believe) staking the threads, which they term 'caulking'. Procedure is on page 9c20, or 223

Good luck getting (or measuring) that kind of torque without the proper tool...

[SV Cygnus]

Originally Posted by jimbunyard

According to the manual

http://www.hunter37.com/Yanmar_3qm30.pdf

torque,and lots of it, at 100kg/m or 723.3 ft/lbs (believe the .3 is not critical) as well as (I believe) staking the threads, which they term 'caulking'. Procedure is on page 9c20, or 223

Good luck getting (or measuring) that kind of torque without the proper tool...

Jim, thank you. I wanted to know if you would know where this but could be purchased? I got back to the owner and he said they thought the existing nut was old and torqued too many times maybe stretched an he could find a new one.

[a64pilot]

I can’t download the manual due to bandwidth, but have to call into question over 700 ft lbs of torque, you sure?
Even a 3/4” powerdyne torque multiplier can only go to about 600 ft lbs, to get 700 I’d think you would need a 1” drive.

[Wotname]

Originally Posted by SV Cygnus

Jim, thank you. I wanted to know if you would know where this but could be purchased? I got back to the owner and he said they thought the existing nut was old and torqued too many times maybe stretched an he could find a new one.

The nut is most likely original however I highly doubt it has been off more than a couple of times, if that.

I also doubt it has been over torqued; it is pretty hard to get up 723 ft lbs at the best of times. I have never seen a torque wrench that goes that high but I assume they exist.

If it still comes undone with the correct torque, I would be using some blue loctite and if that doesn't work, red loctite.

[a64pilot]

Been a very long time, early 1980’s so I had look it up, but the Huey’s main rotor was held on with one great big baseball sized nut, called the Jesus nut, this Jesus nut was torqued to 650 ft lbs, with a powerdyne and it’s a huge nut.
This nut weighed at least 5 lbs if memory is correct.
https://www.uh1ops.com/post/2018/08/...ining-nut-lock

[Wotname]

Originally Posted by a64pilot

I can’t download the manual due to bandwidth, but have to call into question over 700 ft lbs of torque, you sure?
Even a 3/4” powerdyne torque multiplier can only go to about 600 ft lbs, to get 700 I’d think you would need a 1” drive.

Here is the appropriate page from the manual and I note they show a hammer being used to achieve the 100 kg m.

[a64pilot]

Originally Posted by Wotname

I also doubt it has been over torqued; it is pretty hard to get up 723 ft lbs at the best of times. I have never seen a torque wrench that goes that high but I assume they exist.

A powerdyne is such a wrench, it had have adapters specifically to fit what was being torqued hold it in place. Believe it or not but you spun a 6” or so lever very many times and read a gauge that I believe read hydraulic pressure but read in torque.
I’ve seen torque multipliers that go up to as high as 8,000 ft lbs if memory is correct, used on really huge machines

[Wotname]

Originally Posted by a64pilot

A powerdyne is such a wrench, it had have adapters specifically to fit what was being torqued hold it in place. Believe it or not but you spun a 6” or so lever very many times and read a gauge that I believe read hydraulic pressure but read in torque.
I’ve seen torque multipliers that go up to as high as 8,000 ft lbs if memory is correct, used on really huge machines

- my day is complete - I have learnt something new today.

[a64pilot]

Originally Posted by Wotname

Here is the appropriate page from the manual and I note they show a hammer being used to achieve the 100 kg m.

I still don’t believe it, has to be some kind of misprint, assuming that wrench that is being hit with a hammer is 6” long and it looks it, then there is going to have to be 1,400 lbs of force applied

[a64pilot]

Originally Posted by Wotname

- my day is complete - I have learnt something new today.

Google torque multiplier wrench
Here is one a Proto, pic never loaded as my connection is slow, but 150 ft lbs in, 8,000 ft lbs out
https://www.protoindustrial.com/en/i...r-8000-ft-lbs/

On edit, I bet you load something up to 8,000 ft lbs, and you pretty much have a bomb if it slips

[Wotname]

Originally Posted by a64pilot

I still don’t believe it, has to be some kind of misprint, assuming that wrench that is being hit with a hammer is 6” long and it looks it, then there is going to have to be 1,400 lbs of force applied

I agree it does seem strange especially when you consider the size of the nut (and thread diameter)!

I wonder what is another way to confirm this or otherwise?

Fake news from the manual

[jimbunyard]

Originally Posted by SV Cygnus

Jim, thank you. I wanted to know if you would know where this but could be purchased? I got back to the owner and he said they thought the existing nut was old and torqued too many times maybe stretched an he could find a new one.

P/n from Yanmar is 177099-09010, these people seem to have it,

WRENCH #177099-09010 - J-Way Enterprises

but I'd call first; the picture doesn't look like it fits the nut. And the price is about 250.00. Unless you know a machinist, they've kinda got you over a barrel.

Might be worth a try to go Wotname's route, get it as tight as you can with whatever means possible and locite that sucker on.

Slugging wrenches are readily available, perhaps an appropriately-sized one
could be ground to get it up to a couple hundred ft/lbs and loctite could hold the rest.

Or maybe J-way has the wrench, it fits, and your friend has deep enough pockets...

[jimbunyard]

Originally Posted by Wotname

I agree it does seem strange especially when you consider the size of the nut (and thread diameter)!

I wonder what is another way to confirm this or otherwise?

Fake news from the manual

Well, listed torque for a 20 mm, 10.9 rated bolt is 480 ft lbs.

Nonetheless, certainly seems excessive to me, especially for a splined-flange retaining nut.

[skipperpete]

I’ve always thought the manual was a missprint ....and the tension wrench I use on Cummins NT855 headbolts barely reaches the yanmar spec. I’m a loctite hater but this nut is one place it really is needed. The spline needs to be sealed with gasket maker or silicone and the nut needs to be loctited and tightened using a locking bar on the flange and a ¾” drive socket and bar on that annoying nut. I made my own special tool for about 10 bucks