Tight prop shaft 120 hp chrysler

[icedogs66]

Had to replace bearing housing behind the prop was leaking oil removed prop and saw cracks. Bought new part installed it with old bearing race as per mechanic said it and bearing wear fine. After installing the housing it seems that the prop doe not turn very freely it has some resistance to it in neutral shifts into foward and revers fine but just seems really tight to turn by hand. I have not put the boat into the water yet or ran the engine am I just being paranoid or is the something else I should be looking for. Any help would be great.

 

[moparman]

Re: Tight prop shaft 120 hp chrysler

did you pull all the old shims off the old housing and transfer them to the new housing? ALso ,I don't think I would have taken a chance with the old race if it had to be driven out if the old housing,because sometimes the race can get warped,which disturbs the backlash settings. You might want to recheck your back lash if the housing has anything to do with the gear mesh,and make sure the old shims were swapped if any were on it . Hope this helps ,keep us posted on what you find. MOPARMAN

 

[Frank Acampora]

Re: Tight prop shaft 120 hp chrysler

What year? Is this a one piece or two piece lower unit? Does the prop have a 5/16 inch drive pin in front in the hub, or a thrust washer behind it?

 

[icedogs66]

Re: Tight prop shaft 120 hp chrysler

Didnt have any shims on the housing and appears to be the same size and shape. It is I beleive to be a 1978 it is a one piece lower unit and has the 5/16 pin

 

[Frank Acampora]

Re: Tight prop shaft 120 hp chrysler

If it has the drive pin, it is a two piece lower unit. The rear bearing is a tapered roller bearing and Usually has shims behind it. However, if you have replaced the bearing, then you MUST be certain that the cup (outer race) is fully seated in the carrier or it will squeeze the shaft down and pre-load both the front and rear bearing. You must also be certain that the bearing cone is fully seated on the shaft. You should have about .006 end play on the prop shaft after assembly. You need to also check the thrust washer inside the forward gear. If for some reason it is too thick, then again you will pre-load the shaft and it will turn with difficulty instead of freely.

Since you put in a new bearing carrier, and since tolerances are not held on machining the depth of the bearing pocket OR the land that holds the O-ring seal, it is quite possible that the bearing sits too far into the lower unit, requiring a thinner thrust washer.

 

[icedogs66]

Re: Tight prop shaft 120 hp chrysler

I guess that maybe I am not talking correctly the plate that I replaced goes dirrectly behind the prop it has 2 hex head bolts that hold it in. The centre has a black rubber seal and around that was cracked into the casing I didnt remove anything from inside the gear housing after putting the new one on it is tight.

 

[Frank Acampora]

Re: Tight prop shaft 120 hp chrysler

Yes! That is a two piece lower unit. If you did not replace anything other than the seal, then the new seal is tight. It may loosen up with use and it may stay tight. Did you lubricate it (the seal) with lower unit oil before putting the bearing carrier back in?