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Drive Shaft Bearing Questions for 4.3 Cobra

T

theydrewa31

Regular Contributor
Hello All,

Trying to get this outdrive put back together after replacing bearings, O-rings and gaskets. I have one bearing left to install and have some questions. I am including a diagram below to clarify the bearing I am trying to install, the bearing is circled in RED.

driveshaft bearing.jpg



OMC calls for special tools to install this part, which ensures that the bearing is installed to the correct depth in the lower gear housing. The setup for the special tools are shown in the photo below.

Driveshaft Tools.jpg


The way it works is that the bearing is installed on the end of the tool assembly, then tapped into place with a soft mallet. The bearing will be seated to the correct height when the plate (labeled as part no. 391260 in the above photo) makes contact with the top of the lower gear housing as shown in the photo labeled "84" in the above image.

I think that on older models there was a lip on the bottom of that cavity that the bearing would bottom out on but that is not the case for my model. If it goes in too far it will simply fall out the bottom into the dog clutch area. I have no hesitation about buying any special tools needed, but some of these tools are impossible to find.

My questions for anyone out there who has done this or knows anything about this bearing:
  1. How crucial is the depth for this bearing? I did notice that there seems to be close to 1/4" of extra space on the bearing shoulder of the drive shaft when the bearing is seated onto the drive shaft. If I get it "close" and within the shoulder range of the drive shaft is that good enough? I feel like that's a bad idea, but I'm searching for a solution since the tools are so hard to find.
  2. Is there any other way to install this thing without the special tools? I have bearing/seal drivers, and I could tap it in with one of those, but again there is nothing to stop it on the bottom, and I don't want to install it to the wrong depth and have problems further down the road.
  3. If anyone out there has the tools, do you want to rent them to me? ;)

I am including additional information below, although it probably isn't necessary:

  • This is a 4.3L OMC cobra, the lower unit is a 1993.
  • The part numbers for the tools OMC lists for the job are below:
    • Spacer - 326584
    • centering plate - 391260
    • Rod - 326582
    • Driver - 326574
    • special washer - 326587
Thanks in advance for any help Gents!
 
I spent some time thinking about this today. From my understanding of the system the drive shaft this bearing serves is supported in its vertical position by the forward/reverse gears in the dog clutch area, and the intermediate driveshaft above it. There is over 1/4" of extra vertical mating surface for the bearing on the drive shaft.

My logic says that bearing is only there to control the horizontal movement of the shaft and keep it in line with the lower gears, and if the bearing slightly high or low in the lower gear casing it won't affect anything as there is a lot of extra mating surface on the drive shaft. I can easily see where the old bearing was seated, and I should be able to get it very close to the exact position the previous bearing was installed.

I am leaning towards simply installing this bearing in with a bearing/seal driver.

Please let me know if you think this is a bad idea. I'll take uninformed opinions at this point.

I'll try to post a photo of the driveshaft and bearing to show the additional mating surface as soon as I can.

Thanks in advance for any help gents!
 
As promised photo of the drive shaft and bearing included below. The bearing is seated all the way up against the upper edge of the mating surface in this picture to show that there is roughly an extra 3/8" of mating surface available on the drive shaft.

pinion bearing.jpg
 
If no one jumps in to stop me I'll share my results and update the thread if the outdrive explodes the first time I try to run it.
 
You might try calling those guys up in Canada who still rebuild these drives. The Tech’s name is Wayne Coll. Very knowledgeable on these units.
 
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