1990 Force outboard lower drive issue question

[gica]

I have twins on my boat initially I rebuild one motor and then noticed the second was full of water and rusted bearings so I replaced the front bearing and gear and the top bearing. I put it back and when I put it in gear at idle it would kill the engine. I took it apart and compared to the second drive when off the outboard and it did not spin freely as easy so I took off the thicker shims at the clutch and it did spin the same and play was similar at the prop. The issue with the turning off at idle persisted.
I rebuilt the second motor because it's really easy to do and that motor is perfect drives as it should.
When I use the boat I usually start it with the port good motor and only turn on the one that dies when at speed. They work great together.
The motor that dies at idle is set up with a little higher idle adjustment. It sometimes does not die especially when hot.
I did notice that that motor runs hotter than the other oneBoth motors were rebuilt the same way with all the wires redone and electronics new. Stator and triggers too.
Question:
Is the issue related to the lower drive not being shimmed by the book?
Is there an easy way to shim this drive?
I do have the manual and there are tools needed.The boat is a 24 footer Trophy 2302. It is a great boat for my needs. I have improved everything on it from the dash set up to gauge.
Buying newer engines and or boat not an option right now. Thanks in advance guys.

 

[Nordin]

I suppose you have the dual exhaust two piece drive shaft LU.
The problem with these are that there is no shimming spec. for the LU.
They were computer measured and the forward, reverse and pinion gears, prop shaft and drive shaft has a code with letters and numbers. The same for the gear housing.
Depending on code of gear housing the gears with shaft as a unit you have to matched it from a table (in the factory service manual).
I have rebuilt two or three of these units and I have use spec. from Chrysler late 70.es one piece gear housing and Mercury 70.es/early 80.es spec.
Do not know if it a good way to go but the only way I have found to go.
I do not know if those LU that I did that way have fail, but nobody have complained.

 

[jerryjerry05]

What are you using as a service book or manual??
They put out a Service Manual, Lower Unit 85-150 H.P. OB 4527 Issued in 9/89.
It covers rebuilding the lower units.
I think(not positive) all manuals printed after 1990 all Horse Power have this info in these manuals.
Over heating? get a temp gun and take readings along the head as it runs, compare to the other motor??
Make sure the thermo is the right one.

 

[Nordin]

Jerry I have the factory service manual OB4642 for 85, 90, 120 and 125Hp 1988 through 1991.
OB4643 for the 150Hp 1988 through 1991 and I have the OB4527 9/89 for LU 85-150Hp.
Shimming these LU is not the same steps as "regular" shimming with dial indicator as the older Chrysler one piece LU or Mercury LU form 70.es and 80.es.
Shimming these LU depends on what code the gear housing has and what code the forward gear assembly has.

 

[jerryjerry05]

Nordin, that's what the manual I have covers.
The newer coded gear cases.

 

[gica]

Jerry I have the factory service manual OB4642 for 85, 90, 120 and 125Hp 1988 through 1991.
OB4643 for the 150Hp 1988 through 1991 and I have the OB4527 9/89 for LU 85-150Hp.
Shimming these LU is not the same steps as "regular" shimming with dial indicator as the older Chrysler one piece LU or Mercury LU form 70.es and 80.es.
Shimming these LU depends on what code the gear housing has and what code the forward gear assembly has.

I have the same manual also have the 1992 manual. And I have the Clymer 40 to 150 Outboard Shop Manual.

 

[gica]

What are you using as a service book or manual??
They put out a Service Manual, Lower Unit 85-150 H.P. OB 4527 Issued in 9/89.
It covers rebuilding the lower units.
I think(not positive) all manuals printed after 1990 all Horse Power have this info in these manuals.
Over heating? get a temp gun and take readings along the head as it runs, compare to the other motor??
Make sure the thermo is the right one.

It doesn't overheat anymore I replaced the impeller and overheating is fine but the temp on the starboard motor is higher than the other one by touch at the water nipple.
I took the LU apart today because as I mentioned when I got the boat it had water only in the LU and I decided to open it, there was rust on the bearings.
So I bought a new forward gear that did not have a tag identifying the code.
I kept the 2 shims that were there behind the race and put it in. I also replaced the upper bearing that goes on the drive shaft. Now the motor starts and runs great but when at idle it stops when put in gear. The higher heat at the nipple I SUSPECT is also caused by the bad shimming issue.
So now it's apart again and I want to put back the original front gear.
I measured the 2 Shims behind the front gear race and they each measure 0.26mm so combined they are 0.52mm. Looking at the chart it doesn't seem feasible. I cannot find the marking for the gear casing code. I only have the front gear as 7 and the driveshaft as 4.
What do you suggest?

 

[gica]

The shims behind the front gear are actually 0.18 each I think

 

[gica]

So there were 2 larger shims behind the forward gear race that measure .018mm each. There were 2 spacers that go on the gear side of the front gear one measured 1.44mm and the other 1.66mm. And on the driveshaft, there were 3 really thin ones.
I really don't want to take the other drive apart to look and double check if you guys can help sort this out with me.

 

[racerone]

Find some " prussian blue " AKA " mechanics blue" and check tooth contact.-----Change shims as needed to get correct tooth contact.----Needs to be done or gearcase might come to a " dynamic halt " in the future.

 

[gica]

Find some " prussian blue " AKA " mechanics blue" and check tooth contact.-----Change shims as needed to get correct tooth contact.----Needs to be done or gearcase might come to a " dynamic halt " in the future.

I have the tools for shimming, the spacers and the driveshaft, but the forward gear is the one I don't know. So, as I said on the LU there are 2 codes one for the forward gear 7 and one for the driveshaft 4. Where is the code letter or number for the actual casing. I thought it's on the housing itself, but it is not.

 

[jerryjerry05]

IF??? the code's not on the top of the casing it probably needs to be shimmed the old way.
Looking down at the top of the drive into the holes. On the right hand or stbd. side the code should be at the back of the tear drop shaped hole, next to the drain hole.

 

[gica]

IF??? the code's not on the top of the casing it probably needs to be shimmed the old way.
Looking down at the top of the drive into the holes. On the right hand or stbd. side the code should be at the back of the tear drop shaped hole, next to the drain hole.

Here are the codes from the top. Is the tear drop the tip right by the shift rod?

 

[gica]

I opened the second port side drive completely. So, the 2nd drive has forward gear code 8 on the housing and the shims behind the front gear race measure 0.017. That makes the housing code 9 based on the book chart above.
The STBD side housing has front gear code as 7 and the 2 shims I pulled out together measure approximately 0.012 so the gear housing should be 5 or maybe 6.
So, I don't know how accurate this is but a 7 code gear assembly has smaller size shimming with the 2xshims totaling at 0.012in than the 8 coded front gear assembly at 0.017in. On paper it seems ok.
The spacer on the other side of the front gear the port side has only one measuring 0.056 and the STBD unit had 2X 0.056 and 0.064 which add up to 0.12in which is double the other one.
Again, the final aim is to make sure the STBD Lower unit is good so it can be eliminated as the reason for the motor stalling when in gear at idle. And since I did initially take it apart because it was full of water and replaced front gear assembly the thrust bearing and the front bearing assembly.
I will put the original front gear assembly back because I have its code and measure the rest according to the book.
Hey Jerry let me know what the old way of shimming is. The book does not mention the front gear shimming.
Thanks guys.

 

[gica]

Here are the codes from the top. Is the tear drop the tip right by the shift rod?

Hey Jerry, can you explain the old way deal please?

 

[gica]

Anybody?

 

[racerone]

Google it !----Fitting gears using prussian blue paint----Have at it.

 

[gica]

https://www.vansoutboardparts.com/service-manuals/suzuki-service-manuals/9hp-suzuki-shop-manuals/df9-9-k5-2005-models/9-lower-unit-4/1275-f-lower-unit-gears-1/file

 

[gica]

Google it !----Fitting gears using prussian blue paint----Have at it.

Thanks Race would you happen to know if the gear housing has a code stamped and where it is I cannot find it on either one of my 2 Lower Units for the 1990 Force 120B?
Jerry mentioned something above by the tear drop shaped hole next to the drain. I cannot find it. Thanks

 

[racerone]

Gears must be precisely positioned / fitted using shims.-----Failing to do so and checking with bluing could lead to a " dynamic halt " of the gearcase.