1979 johnson v4 100hp

[dirtdriver11]

I am trying to rebuild the lower end on my motor. How do I get the upper and lower drive shafts out to replace the gears?

 

[Texasmark]

Re: 1979 johnson v4 100hp

Haven't been into an OMC lower unit since they quit putting the cap on the bottom with a dozen screws. But the newer design, implemented with the Triump 55 Rude in 1968 has to be something like the Merc had all along because in looking at the LU housing there is no other way to get to the innards.

Pull the prop and thrust washer and look up into the housing and there is some form of securing mechanism. It is probably a very large diameter (3 1/2" roughly) nut that is threaded into the ID of the housing. Unscrewing that nut should allow you to pull the prop shaft, carrier bearing, and R gear out. Some folks put the prop back on and beat on it with a hammer and block of wood; some put the prop nut only on and use a sliding hammer.

Once that's out, you should be able to look in and see the drive gear. The drive gear should be held on the drive shaft with a nut threaded to the end of the shaft. Take the nut off, and the gear, and pull the shaft out from the top.....probably want to remove the water pump prior to pulling the shaft.

I don't know anything about an upper and lower. Seems to me that one shaft would suffice and it would connect directly into the bottom of the crankshaft at the bottom of the engine block.

Someone will see this and come to my (our) rescue.

Good luck,

Mark

 

[Faztbullet]

Re: 1979 johnson v4 100hp

This unit uses a bolt in carrier which if you look in bottom of housing you will see. After removing it there a 2 large snap rings, you will need to borrow/rent or even pay a dealer or transmisson mechanic to remove.After these are removed you have access to gears, the foward gear,propshaft and front brg housing come out as a assembly after shift rod is removed and shifted into reverse. If replacing gears or driveshaft bearings you will need to have the shimming reset with a shim tool at a dealer or buy one...

 

[dirtdriver11]

Re: 1979 johnson v4 100hp

I am can see the clutch dog but i can not get the prop shaft to come out. also i took the nut of the end of the drive shaft but can't get that to come out either. any help

 

[Faztbullet]

Re: 1979 johnson v4 100hp

Remove the driveshaft brg housing under the water pump, while pulling up on driveshaft rap it with a hammer,the vibration will usually cause pinion gear to come loose. Remove the shaft and fish the pinon gear out with stiff wire, also the pinion brgs may fall out so dont loose any. After pinion and any brgs that may have fallen are out,shift unit into reverse by pressing down on shift lever and remove the shift rod, now grab the propshaft and yank it out, you will get the entire assembly propshaft,dog and foward brg housing.

 

[SparkieBoat]

Re: 1979 johnson v4 100hp

with the high cost of replacement gears, I usually just buy a used foot for around $150
I did go into on recently and change out the clutch dog...gears were ok and it was only worn on the reverse side.