1990 Force outboard lower drive issue question

[jerryjerry05]

Sorry I've been gone and haven't read the post.
I can't explain the procedure but can send the manual so you can read all about it.
Send me a PM with your address and I'll mail the books to you. Then when you get the info you can send it back .

 

[gica]

Sorry I've been gone and haven't read the post.
I can't explain the procedure but can send the manual so you can read all about it.
Send me a PM with your address and I'll mail the books to you. Then when you get the info you can send it back .

I have no clue where/how to send PM the message to you was denied. Your option for start conversation is not available.
I found a listing for FORCE 85-150 HP Lower Unit Outboard Factory Service Manual Boat Marine OB4527 and bought it for 25 bucks shipped. I hope that's the one I need. I asked the seller to take pics from the booklet and send me shimming for dual exhaust lower drive 120HP.
Also bought the Permatex blue Prussian paint.

 

[Nordin]

Gica as I see you have the OEM service manual OB4642, read through the chapter 5A about the gear housing. It covers the "old" Chrysler/Force LU which is a single drive shaft LU with no exhaust thru prop shaft, the "new" two piece drive shaft with no exhaust thru prop shaft and two piece drive shaft dual exhaust (thru) prop shaft which are a "computer measured" LU with no specs for shimming.
It has the coded shimming chart.
This computer measured housing has to be shimmed in three parts.
Forward gear shim, drive shaft shim and prop shaft end float.
The chapter covers how to shimming if you change to new forward gear and drive shaft in to old gear housing or change old forward gear and drive shaft in to new gear housing.
The gear housing has no code for it self.
The problem is when you put "old" used gears or drive shafts into old gear housing.
Then you do not know the code of the gear or the drive shaft.
In those case I have shimmed these housings the "old" way with dial indicator and used the specs for Chrysler or Mercury specs.
I have used the specs from the OB4642 manual for single drive shaft no exhaust thru prop shaft and an OEM service manual for Mercury 4 and 6 inline cylinder engines 70-80.es.
BUT as I said earlier in this thread I do not know if this is right or good.
But I have no ide how to do this in another way.
These LU that I have done this way has not fail yet as far as I know.

 

[racerone]

Proper tooth contact is determined with Prussian blue / experience / time / effort.-----Very important for long gear life.

 

[gica]

Gica as I see you have the OEM service manual OB4642, read through the chapter 5A about the gear housing. It covers the "old" Chrysler/Force LU which is a single drive shaft LU with no exhaust thru prop shaft, the "new" two piece drive shaft with no exhaust thru prop shaft and two piece drive shaft dual exhaust (thru) prop shaft which are a "computer measured" LU with no specs for shimming.
It has the coded shimming chart.
This computer measured housing has to be shimmed in three parts.
Forward gear shim, drive shaft shim and prop shaft end float.
The chapter covers how to shimming if you change to new forward gear and drive shaft in to old gear housing or change old forward gear and drive shaft in to new gear housing.
The gear housing has no code for it self.
The problem is when you put "old" used gears or drive shafts into old gear housing.
Then you do not know the code of the gear or the drive shaft.
In those case I have shimmed these housings the "old" way with dial indicator and used the specs for Chrysler or Mercury specs.
I have used the specs from the OB4642 manual for single drive shaft no exhaust thru prop shaft and an OEM service manual for Mercury 4 and 6 inline cylinder engines 70-80.es.
BUT as I said earlier in this thread I do not know if this is right or good.
But I have no ide how to do this in another way.
These LU that I have done this way has not fail yet as far as I know.

I know that manual doesn't specify anything on the forward gear shimming from scratch. It only tells you what to do if you have 2 variables. So either you know front gear code and shim measurement and find the housing code in the chart then you substitute for the new housing or front gear etc. I bought the manual that Jerry mentioned OB4527. He did not mention what it contains but I hope it shows the blue paint old way of doing thing from scratch. I did measure the second LU I took apart and the front gear shims are just a bit larger than the drive I am having the work done on.
I will do something with all this stuff. I am sure Jerry has done this before I wish he was a bit more outspoken on the details hahaha.

 

[gica]

Proper tooth contact is determined with Prussian blue / experience / time / effort.-----Very important for long gear life.

Hey guys, I don't know if you read the comments, but do you think that the drive not being shimmed properly after I originally rebuilt it can cause the motor to die in gear at idle?
And the water coming out of the nipple to be hotter than the second drive I did not touch? Both motors were rebuilt exactly the same way. Same machine shop and bore specs and pistons etc.
Can a drive that's out of specs put a torque on the motor that can stop it under 1100RPM at idle. At speed it runs great. And it is not the carbs or air leaks (sprayed starting fluid everywhere) or electrical I already checked.
hope that's the ticket guys. I have the idle around 1200 and it still stops when cold not so much warmed up but every once in a while.

 

[racerone]

If a motor is in good condition it idles SMOOTH.----When put in gear it will drop about 150 / 200 RPM and idle smooth all day long.----If it stalls a lot something is wrong.----Simple trouble shooting will find the issues.

 

[jerryjerry05]

To start a PM, Just click on my Pic and it should open a page that you can start a PM.
If your motors dies at low RPM's it could be sucking air somewhere.
Do the starting fluid test. Start the motor, spray SF around the intake side of the motor, this includes under the bottom of the carbs and under the coils and packs. If the spray makes any difference in the way it runs?? it's sucking air.

 

[gica]

If a motor is in good condition it idles SMOOTH.----When put in gear it will drop about 150 / 200 RPM and idle smooth all day long.----If it stalls a lot something is wrong.----Simple trouble shooting will find the issues.

I did the trouble shooting and could not come to any conclusions. On a hose in the parking it doesn't do it. It only stalls in the lake. I did spray all around the intake carbs etc. The only thing that I narrowed it down to is the shimming in the drive. I mean it doesn't stall slowly it dies instantly when it gear if I adjust the RPM at the recommended RPM.

 

[gica]

To start a PM, Just click on my Pic and it should open a page that you can start a PM.
If your motors dies at low RPM's it could be sucking air somewhere.
Do the starting fluid test. Start the motor, spray SF around the intake side of the motor, this includes under the bottom of the carbs and under the coils and packs. If the spray makes any difference in the way it runs?? it's sucking air.

I did all that, sprayed it everywhere to no avail. I even switched carbs from one engine to the other. Switched the electronics. The only thing I didn't switch are the LUs. Engine compression 160 on all after rebuilding and break in. I know this should not be a hard issue, but I was perplexed. Anyways if after shimming it still does it, I have no clue what to do.

 

[gica]

To start a PM, Just click on my Pic and it should open a page that you can start a PM.
If your motors dies at low RPM's it could be sucking air somewhere.
Do the starting fluid test. Start the motor, spray SF around the intake side of the motor, this includes under the bottom of the carbs and under the coils and packs. If the spray makes any difference in the way it runs?? it's sucking air.

When I press your picture or name this is what I get

 

[racerone]

Remove sparkplugs.----Rig up a way to measure torque to turn flywheel.-----Record results.-----Remove lower unit and repeat the test.

 

[gica]

Remove sparkplugs.----Rig up a way to measure torque to turn flywheel.-----Record results.-----Remove lower unit and repeat the test.

I have thought of that, and I do have a tool that measures it looks like a torque wrench, and it measures torque forgot why I bought it, must have been for the I/O boat or a car engine rebuild
Here it is halfway done
So as you can see without the drives both engines measure the same.
The LUs are out and apart at the moment so I cannot do it with them yet.

 

[gica]

So, I got the 6-page manual for the lower unit but unfortunately all the info in it is the same as in the service manuals that I have. They don't even show the driveshaft numbers that I have on the gear box which show driveshaft as 2 and the other as a 4.
And no mention on how to find the right size shims if you don't have the front gear code.
No Prussian Blue experiment. That sucks.



This is the chart in the 54642 manual and even that doesn't include the #2 which is one of my drives marked code for the driveshaft!!!
But I can sort of figure it out.