Gearcase driveshaft tolerance / runout question How much is acceptable?

[TrickyRicky]

I bought a used gearcase. From the input shaft number it is from a 89 45hp commercial.
The drivehaft is bent. How much runout can there be and what is the best way to check it? Dial indicator?

 

[TrickyRicky]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

when you spin the prop by hand and look at the driveshaft it has an obvious wobble at the spline end.

 

[riptide09]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

If you can see the wobble then the shaft is junk and needs to be replaced. If it was run that way there is a good possibility that other parts will need to be replaced. I just redid the lower end on mine, 115 HP, and a new driveshaft from the local dealer was $470. I got a brand new one off eBay for $190. Seal kit from dealer was $95. The pinion gear lock nut is one time use and then run around $10. If you need the pinion gear they are sold in matched sets only and also run around $500 from a dealer.

 

[boobie]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

Check your post on the " other site".

 

[TrickyRicky]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

What in the world are you talking about. It is almost impossible to bend a driveshaft, even if you put it in a large vise and try to hit it with a sledge hammer!! I have about 15 pic's of that unit from all directions, and can see no bends. Did you install it? and have a problem with it? Did it not work? I have sold about 700 in the last few years, and never have seen a "bent" driveshaft. I would have noticed it long before I put it up for sale!! However, even though I do not except returns, If you send me, or fax,the professional infomation from your licensed marina, I will call and speak to him, than I will accept it. It must be packed exactally as it was when you received it, and if it is damaged on the return , UPS will make note of it when it is delivered and we will not accept it and YOU will have to file a claim with them, I can't! [only the shipper can] You must pay the return shipping.

This is the response I get from the seller I bought this from. I am an honest person. It seems by the answer that this seller knew exactly what he had to me.

 

[orbanp]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

Hi TrikyRicky,

You could try straightening the drive shaft. Hopefully the wobbling is not that bad. Chances are that the guy who disassembled it, bent it when removing, he probably did not really know what he was doing.
Checking with a dial indicator should be fine. Find a machined smooth circumference at the end of the drive shaft, below the splines, and measure with the dial indicator there. The run out should not be more than to one thou (0.001") when correct.
It is probably bent just above the upper bearing, where the water pump is. I would try to straighten with a pipe put over the shaft, in-situ. I would not disassemble the gear case at first. Remove the water pump and see if the bend is where the key is for the impeller, that would be the weakest point on the shaft.

Good luck, Peter

 

[TrickyRicky]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

Thanks for the advice. Wobble is pretty bad. I would say without measuring with indicator about 3/16" (by eye) I am 100 % sure I will never get the shaft runout .001, even if I did remove it (myself that is) . A local marine shop owner looked at it for me. He encouraged me to take it apart myself and try to straighten the shaft. If not he said he would do it for $200 plus parts.

 

[orbanp]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

Hi TrikyRicky,

Thinking about it, you probably do not need the one thou accuracy. That would be for areas of the shaft where the bearings are located. That part of the shaft is probably OK, bending the free end of the shaft would not bend the shaft inside, between the bearings.
The spline end of the drive shaft does go into the crankshaft. The splines itself have some clearance. The crankshaft will hold the shaft in a straight position when assembled. So just straighten it to the best, and I think you should be fine.

Good luck, Peter

 

[TrickyRicky]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

The local marine mechanic I had look at it said something about vibration. If end up keeping the unit it I will disassemble it and first try to get the shaft reasonable straight. I have a friend that has a huge lathe and maybe I can use it to mark the highspots.Tweak it and recheck in the lathe until I get it a reasonable result.

 

[boobie]

Re: Gearcase driveshaft tolerance / runout question How much is acceptable?

Now that sounds like a good idea