Driveshaft/pinion gear removal issues

[Pchrispy5]

Swapping my 68 merc 650 to short shaft and am currently having an issue getting the pinion gear off the driveshaft so I can swap the shaft and replace the bearings. Nut is already removed. I have tried applying heat, wedging under the driveshaft to pop it up, and is currently hanging by the driveshaft from a vise as I tried to use a hammer and wood to force the casing down. Still can’t get it to slide off tapers. Haven’t tried wedging while it’s been hanging yet, but looking for other ideas to get this loose. Also have been using penetrating fluid hoping it would help loosen it up. Would prefer not to have to spend almost $500 for another l/u case and all the components that I currently wouldn’t be able to remove. Thank you in advance for any help.

 

[harringtondav]

I've never worked on your O/B, but I had a similar problem with my previous Alpha 1 Gen II outdrive with a stuck pinion.
I put the lock nut back on with just a few threads engaged to protect the threads, but left clearance with the pinion.
I had the perfect long chisel that worked as a wedge. I put it between the prop shaft (can't remove it before the pinion is off). I gave the chisel several meaningful whacks with my 2" machinist hammer, and the taper broke free.
Assuming your prop shaft is out (?), shim up from the bottom of the bullet hsg with blocks under the loose pinion nut, find a wedge....maybe a tie rod end or ball joint separator, or chisel. Then swing away with a BFH.

 

[Pchrispy5]

I've never worked on your O/B, but I had a similar problem with my previous Alpha 1 Gen II outdrive with a stuck pinion.
I put the lock nut back on with just a few threads engaged to protect the threads, but left clearance with the pinion.
I had the perfect long chisel that worked as a wedge. I put it between the prop shaft (can't remove it before the pinion is off). I gave the chisel several meaningful whacks with my 2" machinist hammer, and the taper broke free.
Assuming your prop shaft is out (?), shim up from the bottom of the bullet hsg with blocks under the loose pinion nut, find a wedge....maybe a tie rod end or ball joint separator, or chisel. Then swing away with a BFH.

I have been letting it soak overnight with pb blaster as I just hung it in the vise yesterday. I did try that before, but that was on my stand sitting on the floor. Hoping the added weight of the lower unit strapped to the wooden stand will help.

 

[Pchrispy5]

I have been letting it soak overnight with pb blaster as I just hung it in the vise yesterday. I did try that before, but that was on my stand sitting on the floor. Hoping the added weight of the lower unit strapped to the wooden stand will help.

Still no luck. Broke 2 boards trying to knock it off from above, and tried using a large chisel. Will not budge. Even used a propane torch on the pinion gear for 2-3 minutes at a time. I can’t find anything online about stuck pinions this bad. May have corroded some due to a recent lower water pump seal going out which got replaced. Didn’t deal with water for long though.

 

[harringtondav]

This is a final Hail Mary: If you can find the below tie rod separator, and fit it into your bullet hsg, and drop the pinion/shaft to the bottom of the hsg. The notch would go around the shaft and over the pinion. The pusher lever on the end of the shaft. Don't know if you have the room.
The only other thing would be to pull the shaft pinion up as high as possible, and cut the shaft as low as possible with an angle grinder cut off wheel, or an oxy torch. If you're lucky the pinion/shaft stub will fall and pass out the hsg. Then you can work the stub out on a press or with some serious hammer action.

 

[racerone]

Water pump is removed ?----I can not see.------The issue may well the bearing under the water pump housing.-----I have had to pour boiling water on that area ( both sides) to heat the aluminum so the bearing slides out.----Heating the pinion is not the correct approach in my opnion.

 

[Pchrispy5]

The water pump is removed and the clip over the bearing is removed. Upper bearing spins loose. Does not use a locking cover. Pinion gear won’t drop far enough to slip anything behind, and there isn’t enough room in the gear case for the shaft to be pulled from the bottom after cutting. Still would be about 4-6 inches too long.
I did read about one trick I haven’t tried. A left/right thread coupler and 2 short studs. Create a spreader with a piece of wood and metal as a backer. Still thinking I may have to order a replacement lower. That’s what happens with older stuff. At least I already located the parts I need if that ends up the case.

 

[Pchrispy5]

Just to close this out, the pinion is possibly corroded onto the driveshaft, leaving it permanently stuck. May have never been removed since 1968 when it was built. I had to find a used lower housing and the gear and bearing components that were stuck behind the pinion. Found everything I needed for less than $500 and I’ll be switching all the movable parts over to the new one. Thank you to those that responded. I tried, but no luck with this one.

 

[merc850]

Check the gear lash - there are shims in there that set it.

 

[Pchrispy5]

I have tried that. I may have had it too tight on the rear gear, but have broken through several pieces of wood trying to knock the housing from the driveshaft. That pinion is on there good. Good amount of pb blaster
and wd40 have been used down through the bearing on top so it drains down through the roller bearing and to the pinion. It is currently attached with straps to the l/u stand I built, hanging from a vise by the driveshaft. Even after a week of spraying that down the driveshaft, still breaking boards. I have a new shim kit coming so I’ll make sure that lash is set properly on the new lower.

 

[harringtondav]

....likely too little, too late since you've purchased new parts.
This occurred to me this morning. Shown is an Alpha 1 Gen II drive shaft in a std. bearing separator. The separator had threaded holes that can be used to jack the shaft up against the housing, and hopefully off the pinion. Bite marks in your shaft shouldn't matter since you want to replace it.

 

[Pchrispy5]

....likely too little, too late since you've purchased new parts.
This occurred to me this morning. Shown is an Alpha 1 Gen II drive shaft in a std. bearing separator. The separator had threaded holes that can be used to jack the shaft up against the housing, and hopefully off the pinion. Bite marks in your shaft shouldn't matter since you want to replace it.View attachment 393693

I’ll try this out anyway. Wouldn’t hurt to have an extra lower housing since these are getting so hard to find. Thank you. The long shaft has a twist in the splines anyway, which is something I noticed the first time I ever dropped the lower. Never affected it at all, but they are twisted just a bit like they got a lot of torque applied when the driveshaft was only partway seated in the powerhead.