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Lower Unit Bearings

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sequimsailor

New member
Hey All,

I have a 1978 BF75 (7.5hp) that runs well, just have lots of water getting into the lower unit. I have taken everything apart and want to install new O-rings, bearings and seals, etc., just having a really tough time removing the drive shaft bearing and the shift linkage seal. I have used PB Blaster along with LOTS of heat, tapped with a hammer, used a slide hammer and still can't get either one to come out. Have no idea what tool to use to get the shift linkage seal out. It is comprised of a hollow metal (brass?) piece with a rubber bushing that is set into the housing with no way to brag it. Please see the attached pic and advise, thanks!
Honda BF75 Lower Unit1.jpg
 
The ball bearing is installed with an "interference press fit". Given that you wouldn't be wanting to save the bearing and focus more on not damaging the case or boss, I would give it the "Dremel Treatment". Meaning that I would use a carbide cutting wheel (several actually) and take it out in pieces. Even then, use plenty of the Blaster (I prefer Aero Kroil) to try and release the oxidized bond that has likely occurred. You need to protect that case as best as you can.

For the seal, you might try drilling some small holes in the seal face and screw in some small sheet metal screws with washers on them to pry against or use a slide hammer hook on.
It's either that or take the pins out of the shift rod "shoe" and the rod under the washer that is under the seal. Then you can remove the rod and the seal will be much easier to grab. But taking those pins out is going to be harder than it sounds.

That's my take on the subject. Hopefully you'll hear from someone that has some better tricks to share.

Good luck and let us know how it goes.

Oh, and Welcome Aboard the forum!
 
Excellent response JGMO! I never thought of the Dremel as a solution. I guess I could cut out the inner face, let the balls drop and then cut the outer face, trying not to score or damage the aluminum case in the process. Also, during the outer face cut it may relieve enough "interference" pressure that it might fall out before I damage the aluminum case.
Regarding the seal, I've heated and tried using the slide hammer on the upper threaded end of the shift rod, but to no avail. Good idea on the small screws. I can't imagine trying to remove the pins in the shoe deep inside the case. Thanks for your advice, I will let you know what happens.
 
Yeah, you need to be XTRA cautious cutting the outer race. When it gets to a place where you're having hold your tongue "just so" to keep control of the wheel, I would switch from the wheel to one of the many different shaped carbide bits I have for the Dremel. But then I have 4 of the rotary tools with an assortment of chucks and collets and bits. You may not be so well equipped. But, those little carbide bits are available at most decent hardware stores (although that doesn't necessarily mean Home Depot or Lowe's).

You're absolutely right about the cuts causing the race to "relax" enough to just "let go". If you make 3 or 4 partial cuts around the circumference, you might not even need to go all the way through or resort to the carbide bit.

Also, I've read about machinists swearing by a 50/50 mix of ATF and acetone being more effective at penetrating than PB Blaster OR Kano Aero Kroil. The ATF can even be used!

Standing by hoping for a success story.
 
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