anyone ever rebuild thier lower unit?

i'm thinking about rebuilding my lower unit because of klunking sounds...its not bad right now..just hear 2 klunks when i take off and thats it...but i'm sure it will get worst.....from what i have read here it seems to be the foward gear and dog ear clutch.....

someone mentioned sending both to a machine shop and having them refaced...i work at a place that has a machine shop in house so getting this done would not be a problem.

what i'm wondering is how hard is it pull everything out of the LU and rebuild it...seals..gaskets....then putting it back together...is a clymer manual enough??.can you buy these 2 parts still from mercury?..i'd like to do this for under $300 ..is that possible?i plan on sand blasting case and repainting..whole 9 yds....i will still be looking for an extra LU in case i mess it up.

if anyone has rebuilt these please post your experiences with it...thanks

Re: anyone ever rebuild thier lower unit?

It is best to make this a winter project. You should post your model number and HP so someone can help you find a seal kit. The seal kit is around 30 dollars. The clutch and forward gear dogs tend to get rounded and not hold under torque. The purpose of the machine shop versus say a dremel is accuracy. Equal amounts of material need to be removed from each face so that all the surfaces touch. Removing the bearing carrier will be the toughest. A harmonic type puller will work best however it is possible to get it off without one. As long as you use the existing parts I dont think you will need to reshim,

The main thing the manual is going to show you is what order to take it apart but more important the pictures showing all the parts. Mine is a chrysler so it may have changed with the force but on the prop shaft there is s tiny bearing that is smaller then a bb. dont loose this piece.

Get your seal kit and manual before you do the disassembly. If you can get it machined a weekend is all you should need. If you use permatex make sure it is the non hardening type.

Re: anyone ever rebuild thier lower unit?

Have rebuilt one, and replaced parts in a few more.
Never did one that required shimming.

Some will require special tools, like pullers.
Read up on it before you dive in.

Re: anyone ever rebuild thier lower unit?

Chrysler calls them shims force calls them spacers. Merc site has about 10 different size spacers for the forward and reverse gear. My manual says remove the reverse gear and bearing assembly. Install the the required shims (spacer) between the reverse gear and propeller shaft bearings

Re: anyone ever rebuild thier lower unit?

ok great...it atleast sounds "doable"..i have a harmonic balancer puller tool and a clymer manual and a specific manufactures manual......only problem is...winter time is the time i do most of my fishing in virginia..striper season and catfishing...but a few down days is not a problem....

i have a 1990 us marine 120hp, but i dont think my lower unit is the original one..its the lower unit with the intakes on the lower curved surface, 20" one piece shaft.

what are the parts that you would change once you have it apart?...whats the deal with the shims/spacers, do they all need to be changed? special tools?...what is permatex for?

Re: anyone ever rebuild thier lower unit?

Check here for a seal kit
http://www.theshadconnection.com/cgi-bin/page.cgi?page=308

The lower unit is a one piece so you probably wont need Permatex. If gears and clutch are going to be machined you should not need any parts other then the seal kit.

Re: anyone ever rebuild thier lower unit?

A year ago I had my lower unit replaced on my 95 force 70 hp with a rebult one costed about 1500 bucks but on the 4th of july we went out at night to watch the fireworks from the boat and on the way back in at 11 pm at night lower unit started bucking badly so we took it in slow brought it back in to shop and its covered under waranty still so will be fixed for free.
I was going to try to do it myself the first time but there is too much stuff to do and if you get it wrong you will have wasted time and money so I would go with the rebilt one at least it has a waranty that way.