Driveshaft Wobble on 2004 DF225 Johnson (VIDEO)

[hanksboat]

How much is acceptable?
Backstory:
I accidentally bumped the starter before the water was over the inlets, starting in a bucket. It just turned over not fired. When I did a proper start, I heard a light ringing and started to see a little smoke coming from midsection. I realized the motor was not peeing. I pulled the lower and found a destroyed driveshaft bushing and hairline crack in the impeller casing. The Bushing well on my midsection is pretty corroded and I plan to JB Weld the corrosion divets before replacing the driveshaft bushing. I ordered the bushing and pump parts.

I decided to shift the lower unit in drive/reverse and rotate the prop to observe the driveshaft. I noticed a decent wobble. To the eye it looks like runout, but I'm not so sure it's not alignment sourced in the lower gear box. We've put several straight edges on it and can't really make out a bend, but a few thousandths could be there and not seen. Certainly, the driveshaft bushing is meant to reference that shaft, removing stress on the ring/pinion assembly. I just don't have a good sense of acceptability since this is the first driveshaft I've observed.

What do you think?
https://www.youtube.com/watch?v=ejVETyEUk3I

[redlowrey]

The only way you could check your drive shaft properly would be to dismantle it and put it between two live centers and check with a dial indicator. If the main shaft has any end float at all, it will wobble when you spin it.
I think your problem has been brewing tor a while.

[hanksboat]

The only way you could check your drive shaft properly would be to dismantle it and put it between two live centers and check with a dial indicator. If the main shaft has any end float at all, it will wobble when you spin it.
I think your problem has been brewing tor a while.

As far as checking the driveshaft, I generally agree that's ideal and I may do that. I have clamped it to a table with drive shaft facing straight down and I get the same runout on a single side of the shaft. It's very consistently seen on one side, 0.050"-0.060" (50-60 thousandths) at the tip. Same thing when I put the lower on it's side, and in neutral, I can freespin the shaft and observe the same runout. Could this be a mis-alignment in the lower bushing/pinion gear set? I've seen a straightening method of using a torch to spot heat the shaft to remove runout, but I'm not sure it's truly bent or misaligned in the bottom. Since I trashed the drivehsaft bushing, could it be that the lower bushing/bearings are jacked up? It sounds fine hand spinning for what it's worth.

The service manual runs through removing everything in the lower when removing the driveshaft. Is there a way just to remove the drive shaft without doing the full lower gear set?

[hanksboat]

To update - I got the new drive shaft bushing and clamped it with a bench vice on the splined end. It was tight enough to have no wobble, but rotate freely. That removed virtually all the runout all the way down the shaft. Obviously, there was none at the clamped end, but in the middle and base there was 1-2 thousandths max. It must be just the magnification of the wobble from an unsupported driveshaft. I'm just going to put it back together and run it.

[redlowrey]

That is why I asked how much end float did you have, If you didn't notice any vibration before, just run it and see, if you have to pull it down so b it. The hardest part of removing the drive shaft is getting the pinion off the end of the main shaft before you can remove it.

[hanksboat]

That is why I asked how much end float did you have, If you didn't notice any vibration before, just run it and see, if you have to pull it down so b it. The hardest part of removing the drive shaft is getting the pinion off the end of the main shaft before you can remove it.

Yep - I appreciated that incite. I will check for vibration - I hope there is none!

Tell me if I'm nuts, but this is what I think happened: When I bumped the starter dry, the rubber impeller stuck and got off track when rotating. Evidenced by a hairline crack I found in the metal sleeve of the impeller housing. It wasn't able to pump water effectively, which is why the tell-tale wasn't peeing. The off track impeller caused the driveshaft to rotate off track, destroying the driveshaft bushing, which was probably already in poor shape being a 16 year old boat. The bushing was only loosely held in the midsection due to corrosion in the mid-section driveshaft hole and broke loose.