F20LEHA Forward gear shimming?

[Gunflint]

I am working on rebuilding a lower unit on a F20LEHA, I am not understanding the forward gear shim formula. I measured the bearing with the forward gear shim gauge and came up with .051mm. This is the first one I have done and would like to get it right any help is appreciated.

[boscoe99]

Are you using the tables and procedures set forth in the service manual? You follow the procedures, do the calculations, install the appropriate shim(s) and then check the back lash. Usually they are spot on.

What did you come up with for measurement (M)?

[Gunflint]

Yes I am using the tables in the manual and I am not understanding the formula. Probably one of those things that I should come back to tomorrow and it will be clear to me

[boscoe99]

What did you come up with for measurement (M)?

Or, have you not gotten that far yet?

Do you have the special tool with which the measurement is taken?

[Gunflint]

Measurement M is .051mm or .002". Yes I have the gauge block to measure it. We have Nine of these motors for rent in a very rocky lake, This wont be the only one I do. Thanks for the help

[Gunflint]

For T1 I came up with .151, The confusion is in the calculated number and rounded number table. calculated number is 5 so should I change the 5 to a 2 for .121mm shim thickness? Seems to be quite a big difference from the examples in the manual.

[Gunflint]

Could anybody confirm that I am doing this correctly with the numbers I gave?Thanks

[rodbolt17]

not sure what your calling a calculated number.
in a PERFECT world without machineing variations there would be no need for shims.
there are some P,F and R numbers stamped on the case.
this represents case variations from perfect.
could be a bearing pocket was machined slightly deep or shallow.
same as the gear when it was hobbed.
same as the bearing when it was ground.

so you measure the gear/bearing, add or subtract the P,F or R value and that is the starting shim point.
typically its close.
I use a gear paste from GM and look at tooth contact pattern as well as my dial indicator to look at lash.

loose lives.

P is pinion gear nominal.
F is fwd gear nominal and R is reverse gear nominal.

[boscoe99]

OK, Mr. Almetelo, 99yam40, TownsendsFJR1300, Sequoiha and others it is time to jump in and help this guy out. I am not smart enough to figure out the Yamaha procedure.

According to gunflint M = .051
T1 = 0.1 plus M (0.1 + .051) =.151

As usual, the Yam manual is not worth much. Here is what it says with respect to determining the shim thickness. Anyone care to guess what shim thickness should be used in this instance?

[99yam40]

I agree that is messed up
And I am no help here tonight
I will look at it again tomorrow after getting back from a fishing trip, but am fairly sure I will still be confused

[rodbolt17]

hahahah anyone notice the chart is wrong?
you cannot have a 10 in the 100ths colum in a base ten counting system.
anyway what they are trying to show is the 2nd digit to the right of the decimal point is how its going to get rounded.
in this case the .151 would be rounded to .12.

I will admit this is about the wackiest chart I have seen in a bit.

that's why I don't sweat fwd and rev gear shimming as much as pinion gear height.
if you get pinion gear height correct you can adjust shims using backlash and gear paste.

as shims are not avalible in .001 ranges then I would round my M numbers up or down to a 2 digit M number.
in this case I would round my M number to .05.
now by adding T1 we would have .15.

looking at the chart we would round the .15 to .12.

that last example of 0 or 9 is way to funny.

IF T 1 is .30 then fwd gear shim would be .28, anyone see a 0 on the chart?

in a base ten counting system you can only have ten digits in a colum.
the mayans figured out 0 1600 years before the Europeans.
and therein lies the confusion on the metric systems method of 10 and how we learned to count in a base 10 system.
when you start a count colum for math or machining it starts at 0 and goes to 9,when you hit ten you start on the next colum to the left.
binary(base 2) isn't bad once you learn 0+0=1.
octal,base 8 is a tad harder and hexadecimal,base 16 made my head swim.
however once you visualize number colums like graduated glasses of water it gets a little easier.

the ONLY reason most of us learn math on a base 10 is because we have,normally, 5 digits on each hand.
if the human race had 6 digits on each hand we would have a base 12 counting system.

that chart is to funny.

[Gunflint]

*** glad to see that I wasn't the only one that thought the formula is goofy. Thanks for putting some time into my problem. Looks like I am going to try and put it together with a .12mm shim and hope for the best! Would you guys that have done this put a little heat on the housing to ease the race install? Not too hot but warmed up. Thank you all again

[99yam40]

hahahah anyone notice the chart is wrong?
you cannot have a 10 in the 100ths colum in a base ten counting system.
anyway what they are trying to show is the 2nd digit to the right of the decimal point is how its going to get rounded.
in this case the .151 would be rounded to .12.

I will admit this is about the wackiest chart I have seen in a bit.

that's why I don't sweat fwd and rev gear shimming as much as pinion gear height.
if you get pinion gear height correct you can adjust shims using backlash and gear paste.

as shims are not avalible in .001 ranges then I would round my M numbers up or down to a 2 digit M number.
in this case I would round my M number to .05.
now by adding T1 we would have .15.

looking at the chart we would round the .15 to .12.

that last example of 0 or 9 is way to funny.

IF T 1 is .30 then fwd gear shim would be .28, anyone see a 0 on the chart?

in a base ten counting system you can only have ten digits in a colum.
the mayans figured out 0 1600 years before the Europeans.
and therein lies the confusion on the metric systems method of 10 and how we learned to count in a base 10 system.
when you start a count colum for math or machining it starts at 0 and goes to 9,when you hit ten you start on the next colum to the left.
binary(base 2) isn't bad once you learn 0+0=1.
octal,base 8 is a tad harder and hexadecimal,base 16 made my head swim.
however once you visualize number colums like graduated glasses of water it gets a little easier.

the ONLY reason most of us learn math on a base 10 is because we have,normally, 5 digits on each hand.
if the human race had 6 digits on each hand we would have a base 12 counting system.

that chart is to funny.

My mind would have never figured that out without Rod pointing in the right direction.
Hope I never see that chart again..
Can not say about any heat as I have never did one, but I would probably cool the race if I did anything. lots easier to put in the fridge or freezer or on ice

[Gunflint]

Rodbolt-My manual didn't say anything about a P F or R value. Guessing that's probably on the larger units. I'm going to say that 10 in the chart is referring to a 0. Thanks for the mayan explanation of that by the way

[Gunflint]

Got it done and ran it for a week, changed the oil in it and it looks good and works good! Thanks again