bmergner

i have a Teague XR drive and i feel my drive ratio is not 1.5 like it should be. i pulled the lower off yesterday, how can i tell what the lower gear ratio without pulling it apart????
i heard spinning it 10 times can and counting the amount of turns can help. the input ( top ) spun 10 times and lower ( output ) spin 8 times. any help would be cOOl...

thanks

Mr Gadgets

With the lower off, you can turn the vertical shaft and count turns on the prop shaft. Turning it 10 times will increase accuracy, but the math is the same.
1.5:1 lower gears = 19/15 = 1.266666
1.35:1 lower gears = 17/15 = 1.13333
1.25:1 lower gears = 18/17 = 1.058823

so turning the vertical shaft the above number of turns will produce one revolution of the propshaft. Multiply it by 10 so you dont have to gauge .0588 turns.

so 12.666 turns should produce 10 revolutions of the propshaft, etc.

hope this helps..
Dick

JaayTeee

A 1.5 is 15/19 tooth count.
which ="s 1.2666:1

So, the vertical shaft will turn roughly 1 1/4 times to
1 propshaft revolution.

bmergner

i don't understand totally, i think. tooth count of the gears i understand i just don't want to pull it apart. i don't understand the math i guess????????

JaayTeee

Do you have the lower split from the upper ?


If it's a 1.5 lower and if you mark each shaft and
a corresponding place on the case by each shaft,
and you turn the propshaft 1 revolution, you should
see that the marks by the vertical shaft and case
are a little over 90* apart now.

If it's a 1.35, they will be a little over 45* apart,
after 1 propshaft revolution

If it's a 1.25, they will be only about 21* apart
after 1 propshaft revolution.

bmergner

it's already split off the drive. i wanted to turn the motor over 1 full turn but the V10 is too close to get any tools on the crankshaft. i then tought since i knew the gear tooth count taking the lower off i would just them. but i don't want to take the lower apart to do that, i thought i could see the gears when i took it off.

so here i go again doing something i know little about. so i was hoping for something easy to see what ratio i have in the lower case. but again i'm lost...

JaayTeee

After re-reading your first post,
I saw that you said the input ( vertical shaft) spun
10 times to 8 times of the prop shaft.
10 divided by 8 is 1.25, which is pretty damm close
to the 1.2666 ratio, which is what a 1.5 lower is.

Sounds like you do indeed have 1.5 lower.

bmergner

i'm stumped... i have 550HP ilmor, should spin at 5800rpm. the boat has a 24 pitch prop, spins only 5200 rpm. i have a issue someplace...... it should hit the rev limiter hard and quick and ilmor direct and teague agree with me. i have something going on which we all thought was gearing in the drive.

JaayTeee

Something doesnt sound right .

When you spun the shaft,like you mentioned in the first post,
were you talking about the input shaft where the u-joints are, or the vertical shaft that goes into the lower unit ?
( the shaft that connects the upper gear set to the lower gear set)

If it's the shaft where the u-joints are connected,
you have a 1.25:1 ratio drive.

bmergner

the upper shaft would be the one sticking out of the lower gear case. pointing up, going into the drive. i spun the shaft that connects the lower to the upper. spun that 10 times by hand, and the prop shaft spun 8 times.