Question about lower unit bolt.

[DennisG01]

I am a Chemical Engineer. Specialize in aluminum alloys and composites.

I figured as much! All good, though

[byron.akhavi@gmail.com]

A torque wrench is accurate within 20% to 80% of the spec. range. Therefore, if you torque 50 lb. ft. a wrench in the 10 to 100 lb. ft. range is ideal. For lower torque ranges, say 5.2 lb. ft. for the lower unit drain plug and vent plug, a wrench with a low range is required (I use a 1-20 lb. ft. ATECH rated for 12 to 240 inch pounds). When torqueing steel fasteners in an aluminum housing, the digital versions that cover the 20-80 percent range are ideal. Also, kissing the fastener after through cleaning is a must.

For the water pump housing, Yamaha's general torque spec. is 13 lb. ft. for an M8 bolt. However, I use 10 lb. ft. for these bolts since it is a plastic housing (80% of the general spec. value). With the Loctite 572, there will no issues with vibration and it's good and snug without damaging the housing (which is very strong).

[byron.akhavi@gmail.com]

I am a Chemical Engineer. Specialize in aluminum alloys and composites.

[TownsendsFJR1300]

This is why I was surprised when that bolt snapped. The service manual is not correct and the motor is a 2019 model. The manual is specific for my motor and purchased through Yamaha. Older versions called for 13 lb. ft. for the long bolt under the trim anode. This generation calls for 30 lb. ft.?? Maybe I had a defective/stretched bolt?? Not following the manual anymore and just tightening snug. Thanks.

Yamaha, on some of their motorcycles have some in-correct torque spec's for different things.
IE, on my '07 FZ6 (600cc), the rear wheel/sprocket mounting bolts (6), are supposed to be torqued to 61 lbs / foot. This is with a self lock nut onto a stud. On another forum(Yamaha MC) , MANY folks, torqueing to this spec, strip out the stud or nut. I stop at 50, no issues..

Another is the oil drain plug. Yamaha calls for 30lbs/ft , steel drain plug/aluminum block. On the FJR model, many a oil sump has been stripped.
On mine, for that same drain plug, I stop at 12lbs/ft. Arbitrary, perhaps.

Just to open another can of worms, Yamaha doesn't post any torque spec's for a water pump housing. The 4 bolts securing the housing down. ??

.

[99yam40]

at the bottom on my click, it has the locking knob to keep the setting from changing.


headed over to my brothers again today to see if we can find out why the 77 land cruiser will not idle without the choke partially on even after I had the manifolds milled to eliminate the vacuum leaks and exhaust leaks.
Has to be in the carb idle circuit plugged up needing the throttle plate opened more and choke plat partially closed.
I will retorque the manifolds again today after running up to temp to help set the new gaskets.
this thing is a pain to work on.
I did not find any intake vacuum leaks on it yesterday,
the idle cut off solenoid clicks so it should be working, but that does not mean the passage is not plugged up

we shall see.

[DennisG01]

I had to research a bit, as well... and each time I do it since I forget... but I seem to recall (click type) that it has something to do with loosening the tension knob at the butt end and then there's an adjusting screw there... or maybe there's a secondary locking nut under the tension knob... something like that. I'll try to remember to take a look. I think I kept the directions in it's case, now that I think about it - so I wouldn't have to keep looking for the directions online each time. It seemed daunting at first, but once I started doing it, it was pretty straight forward.

[99yam40]

interesting.
I have 3
2 are beam type 1/2" and I never saw a way to adjust those
1 is a click type 3/8" that only goes up to 200inch/lbs I just looked at it and I do not see where it can b adjusted. But the paper work says it can be sent off and adjusted/calabraded

[DennisG01]

how do your calibrate the wrench?
maybe just check to see if it is in spec or do you adjust it somehow?

My torque wrench is a 1/2" - which makes things a little easier since we're talking big numbers and a few pounds one way or the other has no real impact on boat/car stuff. I bought that one primarily for wheel studs on aluminum wheels. But, yes, I can calibrate it - there is an adjusting screw in the handle. I'm a pretty simple guy so I do a simple process using a handheld scale - it's one of those things that you use to weigh your luggage ( verified it is accurate using weights). I have to go back and review the procedure each time I do this, but essentially I put the square drive in the vise, attach the scale 12" away and set the wrench to the middle of the scale. Then I adjust the wrench till things match up - then I do the same thing near both the uppper range and lower range.

Now, luckily, I work at a place where there are some "real" mechanics with Snap-On stuff that get them professionally calibrated on a regular basis. I've checked my process by comparing to theirs and I'm pretty darn close.

If need to do smaller, more accurate torquing... I just borrow there 3/8" or 1/4" wrench...

FYI, for anyone kinda "new" to using a torque wrench... never store it "torqued down"... always bring it back to zero.

[DennisG01]

So, yes, you are obviously doing a proper torque procedure!

What type of engineer are you, Byron? Doing all those gyrations for a simple bolt, you must do some type of engineering work for a living?

[byron.akhavi@gmail.com]

Hey guys. Thanks for the responses. It is greatly appreciated.

I use two digital Snap On ATECH torque wrenches(one that ranges 5-100 lb. ft. and the micro torque 1-20 lb. ft. model).

They have the angle feature that I have no need for with this motor. My Yamaha 240 jet boat is a different story. I do clean the male and female threads. I use a nylon bore brush sized to 10mm and 8mm for the female threads. The bolts are sprayed down with brake cleaner and scrubbed with a wire brush. Then they are blown down with air to dry. I then use a Thread Wizard tool and run them through via impact wrench (just spins against a wire wheel with pre-set holes to 10mm and 8mm).

Then I spray brake cleaner on the nylon bore brushes and run them through the female threads. Then compressed air is blown at an angle (45 degrees) into the mating threads to dry. I use a 10mm and 8mm Yamaha factory bolt that I cut flutes into and then run them through the female threads to confirm the threads are clean and dry. Then Loctite 572 via a circular bead after the 3rd thread and hand tighten in. I then snug them with 1/4" ratchet. Then I torque with my ATECH wrenches to 1/2 torque in the first stage and full spec. via the second stage (I use a star pattern for the M10 bolts). I have the RTD48 thread chaser set but just use the cut factory bolts....they work better for some reason. My torque wrenches are calibrated every 5000 cycles (they have a built in counter).

This is why I was surprised when that bolt snapped. The service manual is not correct and the motor is a 2019 model. The manual is specific for my motor and purchased through Yamaha. Older versions called for 13 lb. ft. for the long bolt under the trim anode. This generation calls for 30 lb. ft.?? Maybe I had a defective/stretched bolt?? Not following the manual anymore and just tightening snug. Thanks.

[99yam40]

I do use a torque wrench on critical things - like mentioned above, heads and covers... aluminum wheels... etc. I also calibrate my wrench.

how do your calibrate the wrench?
maybe just check to see if it is in spec or do you adjust it somehow?

[oldmako69]

It's seldom that important to get it right. If your job or regulation calls for it, sure. If you're sucking down frosty pops while hanging a LU, I'd skip it. Never had a bolt fall out that I put in a little too tight.

[DennisG01]

I was referring to those that say they never have and never will need to use a torque wrench. They can go by "feel".

Gotcha!

[boscoe99]

I was referring to those that say they never have and never will need to use a torque wrench. They can go by "feel".

[DennisG01]

Is this a manly thing? Like not getting vaccinated?

No, not at all. I think 'yer stretching a little with that generalization

I do use a torque wrench on critical things - like mentioned above, heads and covers... aluminum wheels... etc. I also calibrate my wrench.

There's absolutely nothing wrong with someone using a torque wrench on that lower unit bolt - but to do it correctly, in addition to a calibrated wrench (which maybe Byron has), the hole and threads should at least be cleaned. I think the only point was that on bolts like that, you can make life easier by doing it by feel/experience.