Logo
FULL SITE MENU

Gear ratios

H

holinwtr

Regular Contributor
"I was looking on iboats.com a

"I was looking on iboats.com at complete sterndrive assemblies, and there were a lot of different gear ratios. I'm pretty sure that mine is a 1.65. I have a 165 L6 by the way. What does a higher or lower gear ratio do for the motor? And do I have to change anything else if I were to go with a diff gear ratio? One more thing, the remanufactured ones were 2x more expensive than the new ones, what in the world is going on there?"
 
"Graham;
The right drive for

"Graham;
The right drive for your I-6 is the 1.65.
This simply means that the prop turns thru one rev for every 1.65 engine revs.
The ratio is varied according to engine size and available hp to keep the prop pitch in the normally most efficient range of 15" to 23" or so for most applications.
A bigger engine spins the prop with more power and can get a boat up to a higher top speed, so it uses a lower ratio drive.
A lower ratio drive simply means that at a given engine RPM the prop is turning faster than a higher ratio drive.
I-4's use a 1.94 ratio. The 4.3 V-6 uses a 1.81. Small block V-8's all use a 1.47 ratio.
For a time Merc used the 454 big block with the Alpha drive and it used a 1.32 ratio.

Rod"
 
that motor needs the 1.65 to r

that motor needs the 1.65 to reach it`s rated rpm. in very rare cases you might get away with a bigger pitch but it does the motor no good to be lugging or over reving the gear train.
 
Graham:

The expensive reman

Graham:

The expensive reman. sterndrives were probably Mercruisers while the new less expensive SDs are probably the generic clones made in USA. Users have stated they are a good outdrive for the price.
 
"Thanks for the info fellas.

"Thanks for the info fellas. So do you think that the new less expensive drives are worth while? Or are the parts used to make them not top notch? Actually, none of the new ones had a 1.65 gear ratio, they were all over the spectrum. Only the remans had the 1.65 ratio. So I guess I have to go with a reman?"
 
"Graham:

I contacted the co

"Graham:

I contacted the company that makes the generic OD to see what they would charge to change the bearings, shims seals, water imp. and basically rebuild my OD. They est. $800 and R/T shp. $140 plus hard parts if needed. Give them a call."
 
Back
Top