Topic: 1951 Johnson QD12 lower unit won’t drop – Page 2

This topic has 20 replies, 10 voices, and was last updated 6 years, 4 months ago by fleetwin.

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December 10, 2017 at 10:57 pm #68475
jeff-register
Participant
US Member - 2 Years
Have a KF5 that way, splines rusted.Wedged the cav plate, let sit & light tapping, spray the D-shaft & time
December 11, 2017 at 5:26 am #68485
bob-d
Participant
US Member
Thanks Jeff, so far have tried with the motor hanging upside down with the shaft in a vice, PB Blaster, Aero Kroll, heat from torch, tapping with a brass hammer on shaft,and a air hammer. No luck so far. I’m now going to put it over to the side of the shop (maybe if I don’t see it I won’t get annoyed!) and let it sit with liberal use of 50/50 ATF and acetone.
I guess the next step if the 50/50 doesn’t work would be to drill a hole in the center of the shaft and make a homemade puller arrangement.
The strange thing is that the motor is in nice shape, decals, paint etc. When I finally got the lower unit down, even the impeller looked good, and the lower unit oil was in decent shape.Not knowing the history of the motor I wanted to change the impeller just for safety sake, and that’s where the trouble started.
it only goes to show the problems that can occur when you take a shortcut,and don’t grease the top of the driveshaft whenever you drop a lower unit .
December 11, 2017 at 8:04 am #68487
Mumbles
Participant
A engine builder I know has a dowel puller for pulling dowels out of blocks before machining them. It comes with a variety of collets and works great for pulling stubborn driveshafts out to. It’s a big slide hammer thing and you might be able to find someone with one in your area.

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December 11, 2017 at 10:46 am #68488
chinewalker
Participant
US Member
Go carefully – the driveshaft isn’t hardened and it will mar, distort, twist if you hit it too hard. I’ve used vice grips on the shaft, tapping away from the driveshaft with a small hammer on the grips. Make sure grips are above the bearing surfaces so they don’t mar anything important.
December 11, 2017 at 3:08 pm #68492
fleetwin
Participant
US Member - 2 Years
quote Bob D:

Thanks Jeff, so far have tried with the motor hanging upside down with the shaft in a vice, PB Blaster, Aero Kroll, heat from torch, tapping with a brass hammer on shaft,and a air hammer. No luck so far. I’m now going to put it over to the side of the shop (maybe if I don’t see it I won’t get annoyed!) and let it sit with liberal use of 50/50 ATF and acetone.
I guess the next step if the 50/50 doesn’t work would be to drill a hole in the center of the shaft and make a homemade puller arrangement.
The strange thing is that the motor is in nice shape, decals, paint etc. When I finally got the lower unit down, even the impeller looked good, and the lower unit oil was in decent shape.Not knowing the history of the motor I wanted to change the impeller just for safety sake, and that’s where the trouble started.
it only goes to show the problems that can occur when you take a shortcut,and don’t grease the top of the driveshaft whenever you drop a lower unit .

The air hammer won’t be very effective using it at the bottom of the driveshaft. Pull the powerhead off so you can get at the driveshaft with the air hammer up next to the seized splines. Applying downward pressure on the powerhead (while hanging upside down in the vise) while using the air hammer on the upper driveshaft has worked for me a few times….
December 11, 2017 at 5:00 pm #68497
bob-d
Participant
US Member
Well it’s finally out……Using the ATF/acetone treatment last night along with vice grips and a hammer (thanks Chinewalker) which originally didn’t work with the PB Blaster etc… it finally came out. I’m now a firm believer in the 50/50 method.
Jim,I had a Snap On tool similar to the one your picture. Used it for getting the studs out of Porsche crankcase’s. I should look around for a collet that go over the splines for the future. Would have to make some sort of attachment to it for s slide hammer.
What’s interesting is that the drive shaft did not have the o ring or cutout for one on the shaft? It shows one in the parts breakdown. I know the earlier QD’s didn’t have one but with the QD 12 they changed it. Maybe the factory had a few of the earlier ones hanging around when they built my motor?
Next question, I know it’s not the space shuttle but should I be worried about the marring on the shaft causing stress cracks?
With the hundreds of pounds of torque this motor (ha) puts out I wouldn’t want it to crack out in the middle of the lake next summer.
Thanks again for all of the suggestions.

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December 12, 2017 at 12:29 pm #68522
Steve D
Participant
Hey Bob, Could you do me a favor and get a measurement on the length of that drive shaft. I just want to confirm something. Also sent you a PM.
December 12, 2017 at 3:45 pm #68528
bob-d
Participant
US Member
Hi Steve, the shaft is 25" X 1/2".
December 12, 2017 at 6:26 pm #68540
Steve D
Participant
Ok thanks Bob.
December 13, 2017 at 9:54 pm #68579
jerry-ahrens
Participant
US Member
I wouldn’t worry about the marring caused by the vice grips. As long as the impeller will slide down over them… if not you can clean it up with some emery paper.
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