1989 Force 125 Lower Unit R&R Questions

[Smoofers]

Hi all, this is my first post on this forum and I am somewhat new to outboards. However, I have been building/racing/riding jet skis for a while and am fully confident in my abilities.

My roommate and I ended up buying our neighbor's 1989 Bayliner Capri for $500.

The motor (1251X9E) is an 1989 125HP force and runs beautifully. The only problem is the fact that I am pretty sure the clutch dogs have worn out and will need to be resurfaced. At ~10 knots and up, the motor pops and the whole boat lurches. This will happen about every 10 seconds at low RPM and it gets worse as you go higher (feels like hitting a log). The previous owner thought it was a shifter cable adjustment problem, since he just had the cable replaced and hadn't noticed the problem until after it was replaced (or so he says).

I checked the shifter linkage on the leg of the motor, and as it is set up now, it is already biased towards the forward gear and is tighter than it probably should be (when fully engaged into fwd). This leads me to believe the lower unit will have to be dropped and the gear assembly pulled out.

(I have also purchased a shop manual, should be here in a day or two)

My questions:
-I plan to reface or flip over my clutch dogs/collar. What all would I need to purchase besides a lower unit seal kit? (prev owner said water pump was recently replaced, will still check it though)
-Will I need a new crush washer for the prop shaft?
-What gear oil do you guys recommend?
-Any special tips for removing the prop shaft etc?

Thanks in advance!

 

[Frank Acampora]

Re: 1989 Force 125 Lower Unit R&R Questions

If you are lucky, once you pull out the propshaft and reverse gear, the forward gear drive dogs will be OK and you will not need to remove the forward gear. You can inspect them with the gear in place.

If they are worn, then the forward gear will need to be removed to reface them. This requires removing the pinion. You put a wrench inside on the pinion nut and pack the wrench with cloth or wood to keep from damaging the gearcase. You then need to turn the driveshaft. This is not easy as the pinion nut is torqued to about 85-90 Foot Pounds. I have an old crankshaft that I put on the end of the shaft to keep from buggering up the splines. You probably don't have an extra crank so you must pad the splines with a good amount of paper, grab them carefully with a vice grip pliers and smack the pliers a good one with a mallet or wood block.

Now, the pinion gear is on a splined locking taper so after removing the nut it still will not come off. You need to wedge a couple of pieces of metal in the gearcase, bearing against the end of the shaft. Then, wedge a chisel or something similar between them until the gear pops off. This assumes that you have already removed the water pump and plate. The crush washer can be re-used.

 

[bent]

Re: 1989 Force 125 Lower Unit R&R Questions

Just a thought. Have you thought of checking you spark timing.

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

If you are lucky, once you pull out the propshaft and reverse gear, the forward gear drive dogs will be OK and you will not need to remove the forward gear. You can inspect them with the gear in place.

If they are worn, then the forward gear will need to be removed to reface them. This requires removing the pinion. You put a wrench inside on the pinion nut and pack the wrench with cloth or wood to keep from damaging the gearcase. You then need to turn the driveshaft. This is not easy as the pinion nut is torqued to about 85-90 Foot Pounds. I have an old crankshaft that I put on the end of the shaft to keep from buggering up the splines. You probably don't have an extra crank so you must pad the splines with a good amount of paper, grab them carefully with a vice grip pliers and smack the pliers a good one with a mallet or wood block.

Now, the pinion gear is on a splined locking taper so after removing the nut it still will not come off. You need to wedge a couple of pieces of metal in the gearcase, bearing against the end of the shaft. Then, wedge a chisel or something similar between them until the gear pops off. This assumes that you have already removed the water pump and plate. The crush washer can be re-used.

Great advice, THANKS!

If I had to remove the pinion, will I have to do any backlash settings when I put it back on?

Just a thought. Have you thought of checking you spark timing.

Honestly, no. I had not even thought of that yet. I am waiting on the service manual to arrive so I can actually check all the motor systems and know what I am doing.

It could be related though.

More background: The pop/lurch was noticed once I started opening the throttle past the wake zone. I don't have a tach so I am estimating, but it started to happen at probably ~2000-2500 RPM. The motor purrs and runs smoothly, but out of no where - BAM!!! There is a pop/lurch that feels like the boat hit something submerged... and then it goes back to running smooth. This event lasts no more than a second and doesn't sound like the motor misses or sputters at all. The exhaust note never changes during the pop.

I did start counting at one point between the pops and got a pretty symmetric 10 second pause between each pop. If you raised the throttle more it would lessen to about 6 seconds between pops. I didn't try and push the throttle any more past this point (not even on plane). The rest of the outing was cruised at low throttle.

However, when at really low throttle (and speed), the pops would become way more intermittent with the time between pops as long as 15 minutes and as short as 20 seconds.

In my opinion it seemed to be load dependent. It does make me wonder if this is lower unit related, but with the hundreds of forum posts searched and read about this it seems to me it is the clutch dogs slipping.

I welcome all ideas though! Thanks again for your help guys.

 

[Frank Acampora]

Re: 1989 Force 125 Lower Unit R&R Questions

Backlash (.005) is set by the shims under the top bearing. Don't lose them and replace them when you re-install the driveshaft. Torque the pinion nut and nothing will have changed.

By the way: The manual recommends using a new pinion nut. The nut is a deformed thread nut. Personally, I reuse the old one. I either stake the nut with a sharp punch on three sides before installation or squeeze it a bit (no too much) in a vice. Either method will ensure that it deforms a bit and locks onto the threads.

And yes, that sure does sound like worn drive dogs.

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

Frank, thanks for the great info.

I went ahead and pulled off the lower unit and began dis-assembly. I am still waiting on a manual, however my roommate found one for an '85 Force 125HP. It seems (fairly) similar to what I am working with, with a few minute differences.

I did notice, when I pulled off the plate (under the water pump) it looks like the drive shaft is retained by a threaded nut that requires a special castle type socket to remove. The '85 manual makes it look like it all pulls out without any special tools however I am a bit skeptical. Any input on this?

Tomorrow I will go get some threaded rod or bolts to make a puller to pull the spool plate out (behind the prop). I am very curious to see how my clutch looks.

Thanks again to everybody for the immense amount of help this forum has been.

 

[Frank Acampora]

Re: 1989 Force 125 Lower Unit R&R Questions

UH! That's not a 1985. It is a two piece drive shaft model used in 1990-1994 engines. Probably a 1.92 ratio. Different gears, different shims, and different drive shaft bearings. Now don't hold me to the 1990 date--some MAY have been used on late model production runs of 1989, but certainly not before.

On this unit, yes, you must unscrew the internal nut to pull the driveshaft, but as I described above the pinion must be forced off. --ALSO--Good bit of luck on this one--An Evinrude prop (I think 15 spline) will fit over the splines so it is easier to remove the pinion nut. A force prop may fit also, but the Rude prop was trash so I pressed out the hub and used a 2 foot pipe wrench on it.

DO NOT lose or damage the shims. They are no longer available either in parts supplier sites or at bearing supply stores. Lower end of the shaft is supported with loose rollers--I forget how many, but don't lose them and if they do fall out, replace with grease to hold them while you are reinstalling the shaft. Driveshafts and gears are NOT swappable between this and earlier units, although if you change the seals, propshafts are. Dog clutch is the same.

This unit uses the mercury plastic water pump with stainless cup insets. This unit also needs a top drive shaft which is difficult to find, and a coupler. If you have them, hang on to them. if you don't, you will need to search for them in order to use the unit.

You have the one model (again, I think type "A") that was made with single exhaust and water inlets on the gearcase torpedo. Three other models were dual exhaust with exhaust exiting through the snout and prop. Water intakes for these were on the gearcase leg, below the anti-ventilation plate.

I have one of these that I spent 200 for because it looked in superb condition--Upon inspection I needed to replace the drive shaft seals, buy a water pump, and hunt up a threaded ring for the top. All in all, I invested another big piece of change and I like the older units better. I also have a dual exhaust version and I don't think it adds any performance. In fact, it seems to ventilate/cavitate easier on the same boat and engine combination.

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

Frank, thanks again.

The motor was complete and running. I have the driveshaft and coupler and don't plan to lose them.

As for the threaded nut that goes over the drive shaft, is there any easy way to remove it without a special tool?

I pray that with any luck my fwd drive dogs will be okay and then I won't have to worry about pulling the driveshaft....

 

[Frank Acampora]

Re: 1989 Force 125 Lower Unit R&R Questions

It should be put in right side up with an arrow that says "OFF" I simply put a long punch againts the tab or tabs and tap with a hammer. There is a danger of it being so tight that the tabs will break off though and then you will need to break it with a cold chisel.

If the engine was complete and running, why not just use the two piece drive shaft lower while you repair yours? It will swap right in unless the drive shaft is for a different length engine than yours. But, if, for example, you have a 20 inch engine and the lower came off a 20 inch engine, then there is no problem.

Looking back, in the photo I now see the coupler lying next to the lower unit.

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

If i have to break out the driveshaft retaining nut, do I need to replace it....?

 

[Frank Acampora]

Re: 1989 Force 125 Lower Unit R&R Questions

Yes! That nut is essential. On that lower unit, the gear thrust while running is up. Without it, the gears will rise too far, engage only at the ends, and grind themselves apart in no time.

Driveshaft goes in with narrow side of tapered roller bearing up, shims go in next, cone goes in wide opening down, then the nut retains it. That is why it is sintered steel. That is one of the reasons I do not particularly care for that unit. Gear thrust on the driveshaft is up towards the weaker part of the casting. The shims set the amount the pinion can rise, thus setting gear lash. It works, but I don't like it.

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

Well I made a puller and got all of the lower unit guts out. Dogs and both gears and clutch look pretty rounded off. I was able to get the pinion nut off, no problem. I then made a tool out of some 1" pipe to pull out the driveshaft retaining nut. I just made 4 cuts with the porta-band, bend out the tabs with a crescent wrench and filed the teeth until they fit. Funny thing is, my tool only fits one way into the nut, but worked like a champ. Pipe wrench on my home made tool and it spun right off.

The last thing I am struggling with is getting the friggin pinion off of the driveshaft. I don't have enough scrap metal to try the method you mentioned and wood isn't strong enough (I tried). The '85 manual I have says to clamp the driveshaft in a vise and then smack the l/u with a dead blow. Haven't tried that yet.

Thanks again Frank for all of your help! You have helped me more than you know.

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

Okay, so with the lower unit apart, I took the fwd/rev gears and dog clutch to the machine shop. The machinist ended up telling me that he didn't have small enough tooling to re-face them and said I might be better off using a dremel.

He also thought I might be okay if I just flipped it over and used the reverse dogs for forward.

Personally, I don't like to half-a** anything and don't want to have to pull the lower unit apart for a while after I re-assemble it. So I present a list of questions:

1) The first three pictures are views of the forward dogs, the last three are the reverse dogs. Do the reverse dogs look good enough to use as is?

2) What kind of bit do you guys use on a dremel for this job?

I'm would like to have the piece of mind with resurfaced dogs, but if I am going to have to go through 10 dremel bits to do it I might just say f- it and flip the dog clutch and be done with it.

I would love your input guys, especially from the ones who have resurfaced their own dogs....

Thanks in advance

FORWARD DOG:

FORWARD DOG:

FORWARD DOGS:

REVERSE DOGS:

REVERSE DOGS:

REVERSE DOGS:

 

[Smoofers]

Re: 1989 Force 125 Lower Unit R&R Questions

Just an update.

I flipped over the dog clutch and installed all new l/u seals as well as a new water pump. Took it out last weekend to test her out. SUCCESS!!!!

No more popping in and out of gear!

Thanks again to everybody for the help!

 

[hays]

Re: 1989 Force 125 Lower Unit R&R Questions

Hi, i want to know if anyone know's what the three plugs are for on the right side of the lower unit. Two are siDE by side, one positioned lower. I'm sure two are for changing the oil in the lower unit. What's the thrid for thank's hays