1990 90 hp force..shaft play in lower unit input shaft.

[florida blue water]

hi,took apart lower unit to do impeller and found a couple of concerns,
1. have some side to side play on input shaft, and i dont have spanner socket to disassemble and check upper bearing.
is it common for that bearing to fail?
2. my drive shafts splines have nearly twisted one complete tooth yet it hasnt snapped. should i continue to run it or look for a new one? has anyone come across this?
thanks in advance. Mike

 

[eight tracker]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

Mike,there should not be any side to side play on any shaft in the lower unit!Sounds like the upper bearing is going bad usally caused by water getting in the unit or not enough oil when filled,when mine went bad it actually seized up so the motor wouldn't run.I used a punch and hammer to get it loose,check the prop shaft to see if you have any "in out play" that may indicate lower bearing issues also.
hope this helps.

tom

 

[Frank Acampora]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

Thrust on those gears in that lower unit is upward and there is no stop to prevent downward movement of the shaft when the engine is not running. To check play in the bearing, you must pull up on the shaft. However, the seal should stop side movement. Check the shaft seal for wear. You may be able to use a punch on the threaded retainer to loosen it. If it is salt water, soak it in penetrant for a couple of days if you have the time. Do NOT lose or damage the shims---they are no longer available and are absolutely necessary for correct gear mesh and backlash.

If the drive shaft splines have twisted it is probably because the engine was viciously stopped by locking the prop. I have seen this on smaller engines, twisted and others completely sheared off. It would be wise to look for a new shaft while you cautiously run the engine, BUT it would also be wise to drain the oil and look for metal chips from a broken gear tooth. Also spin the input shaft by hand with the water pump impeller out and feel for roughness--but again, be certain to pull up on the shaft or the gears will make noise.

The prop shaft should have about .010 run out. If you push it in then pull it out you will feel it and may also hear a click.

 

[florida blue water]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

awesome tips will do that tomorrow and report back. thanks for your time. gonna start soaking that spanner nut now..

 

[florida blue water]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

 

[jerryjerry05]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

Your very lucky that the drive shaft came out with that bad of a twist

 

[florida blue water]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

maybe it doesnt have as much play as i thought because i wasnt pulling up un it.
its at work and ill make sure in the am.

Thrust on those gears in that lower unit is upward and there is no stop to prevent downward movement of the shaft when the engine is not running. To check play in the bearing, you must pull up on the shaft. However, the seal should stop side movement. Check the shaft seal for wear. You may be able to use a punch on the threaded retainer to loosen it. If it is salt water, soak it in penetrant for a couple of days if you have the time. Do NOT lose or damage the shims---they are no longer available and are absolutely necessary for correct gear mesh and backlash.

If the drive shaft splines have twisted it is probably because the engine was viciously stopped by locking the prop. I have seen this on smaller engines, twisted and others completely sheared off. It would be wise to look for a new shaft while you cautiously run the engine, BUT it would also be wise to drain the oil and look for metal chips from a broken gear tooth. Also spin the input shaft by hand with the water pump impeller out and feel for roughness--but again, be certain to pull up on the shaft or the gears will make noise.

The prop shaft should have about .010 run out. If you push it in then pull it out you will feel it and may also hear a click.

 

[florida blue water]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

after checking the side to side runout while pulling up on the shaft, there is no play so i'm gonna buy some seals and a impeller, and a replacement driveshaft and let it ride for now. Thanks for the tips, you guys are great and knowledgeable..

 

[Nordin]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

Do you have the 2 piece driveshaft model? I have just rebuilt a 90Hp Force with 2 piece shaft.
On these gearcases there are no data for lowershaft endplay because the housing and shaft are coded from factory.
The housing is computer measured and you order new housing or shaft depending on the code stamped on the housing.

My lower shaft was snaped just above the rollerbearing. This because of low level of gearoil, I think. The bearing stuck and then the shaft snaped.
This bearing is mounted upside down compared with Chrysler design and there are shims between bearing/housingcast and the retainercup.
The shims make the endplay of the shaft and you need this play because of upward forces when the shaft turns.
Because of this shims you also have a side to side play.

I have talk to Franz at Franz Marine and he has measure endplay on two gearhouses and it is about 0.035-0.040.

I measured my endplay on the snaped shaft and it was about 0.026. So I think that about 0.025-0.040 will be ok.

The endplay for the propshaft should be 0.005-0.027.

 

[florida blue water]

Re: 1990 90 hp force..shaft play in lower unit input shaft.

Yes, I have the 2 piece shaft. I belive the twited splines are due to an old injury that the previous owners had and they just slapped it back together, but who knows. THE slpined shaft that has the damage on mine is where it goes into the bottom of the crankshaft. Just found one on ebay and waiting for it to arive.

Do you have the 2 piece driveshaft model? I have just rebuilt a 90Hp Force with 2 piece shaft.
On these gearcases there are no data for lowershaft endplay because the housing and shaft are coded from factory.
The housing is computer measured and you order new housing or shaft depending on the code stamped on the housing.

My lower shaft was snaped just above the rollerbearing. This because of low level of gearoil, I think. The bearing stuck and then the shaft snaped.
This bearing is mounted upside down compared with Chrysler design and there are shims between bearing/housingcast and the retainercup.
The shims make the endplay of the shaft and you need this play because of upward forces when the shaft turns.
Because of this shims you also have a side to side play.

I have talk to Franz at Franz Marine and he has measure endplay on two gearhouses and it is about 0.035-0.040.

I measured my endplay on the snaped shaft and it was about 0.026. So I think that about 0.025-0.040 will be ok.

The endplay for the propshaft should be 0.005-0.027.