merc 1974 1150, lower unit

[dvchristoff]

Hey guys,<br /><br />I bought a 1989 lower unit off ebay for my merc 1150 ( my reverse gear was slipping) and was wondering how difficult the drive shaft should be able to turn. My 1974 I could turn fairly easily by hand but this one is a lot tighter and you can barely turn it. I am hoping that is a good?<br /><br />Also I am going to tear the old one down and I am wondering what part or parts I should look for that are bad?

 

[mellowyellow]

Re: merc 1974 1150, lower unit

r u sure the '89 has the same gear ratio?<br />think it's diff., but not 100% sure.<br />good luck,<br />M.Y.

 

[dvchristoff]

Re: merc 1974 1150, lower unit

Yikes, Before I bought searched lower unit rebuilders web sites and they used the same part # for a rebuilt 1974 and 1989 inline six lower. Hope I did not goof up.

 

[mellowyellow]

Re: merc 1974 1150, lower unit

don't think in '89 it was still and inline 6...

 

[dvchristoff]

Re: merc 1974 1150, lower unit

Checked lower units on iboats again, there showing #1655-7333T24 for both 74 and 89 115's. The housing and bolts are identical. Hopefully they spin the prop at the same speed. Installing at lake today will let know how it comes out.

 

[mellowyellow]

Re: merc 1974 1150, lower unit

hope I'm wrong and it works just fine!<br />like i said, not sure...<br />maybe an expert can chime in here re: gear ratio.<br />good luck,<br />M.Y.

 

[briannh1234]

Re: merc 1974 1150, lower unit

Mine turned real EZ until I installed the water pump. The water pump added a lot of drag.<br /><br />They do make some that are different gear ratio's. Most are 2 to 1. You can change the gear ratio by ordering new gears and installing them into the LU.<br /><br />If you seem to be overreving or underreving your engine after the switch, a different prop will probably fix the problem without resorting to gears.

 

[dvchristoff]

Re: merc 1974 1150, lower unit

Installed and ran lower unit today and everything went great. Gear ratios were the same. This 1974 power of tower (79 powerhead and a 89 lower) drove my 1969 Glastron tri-hull at 41 mph at 5000 rpm with a Hustler 19 prop. Sweet.