The Hodaka Club Forum

Has any one used a 1/2 tap and bolt instead of a 14mm to pull the main shaft bushing out of the case ?
I can,t find a 14mm tap locally that has the same thread pitch as the locally found bolts so just looking at other options before I order one. I,m just a little worried that a 1/2 tap won’t cut deep enough threads to keep from stripping.
I did try the hydraulic method with no success.

I’ve used an EZ Out with a tap handle attached! Victor

I can't answer your question about bolts/taps . . . but will instead offer a couple of comments about the "hydraulic method" of mainshaft bushing removal:
1. HEAVY (thick) grease
2. Fill bushing completely full
3. Be absolutely SURE the backside of the bushing boss is resting on a solid support. (Failure to do this could result in hydraulically blowing out the bottom of the case bushing bore.)
4. Insert end of mainshaft in bushing, align the shaft and whack the end with a brass or dead-blow hammer. Check for bushing movement, refill cavity and repeat as necessary to get enough of the bushing out to be able to "grab" it for final removal.

I'm giving these comments because the hydraulic method as never failed for me. I suppose that an extremely worn bushing could allow enough grease leakage to limit the rise in hydraulic pressure. If that appears to be the case here, I wonder if a single wrap of masking tape (or better yet, that aluminum tape used on HVAC ducting) might fill the space and might survive the pressure pulse and help drive out the bushing?

Good luck!
Ed

Interesting. I’m curious about putting grease inside the bushing and plungering it the way you describe, works. Hydraulic Method? Tell me how this doesn’t cause the bushing to expand & fit toghter? I’m really curious about this! Victor

Maybe I will give the grease another try Ed. I did not have it completely full and only tried two good hits. I then chickened out for fear of wrecking the case. I did have it solidly supported on wood blocks.
Victor,I,m curious how you did it with an easy out. Did you heat the case and then pull up on the wedged easy out ?
Thanks for the help guys.

Yeah, it isn't immediately intuitive how the whole process works is it? Pressurizing the grease causes the grease to press everything it touches with the same pressure (psi). That pressure does indeed push against the inside wall of the bushing and (as mentioned) on the bottom end of the case bore . . . but it also flows beneath the bottom end of the bushing and pushes "up" on the full perimeter of the bushing. Since there is no pressure on the top end of the bushing, the very high and evenly applied hydraulic pressure on the bottom of the bushing causes the bushing to slide "up" in its bore. The "ring" shaped end of the bushing doesn't offer much area for the grease to push against, but the pressure is high (in terms of pounds per square inch) so it still results in significant "un-opposed" lifting force on the bushing . . . and the bushing then moves.

(thick grease, minimal or no bubbles in the grease, and a full cavity all help the process)

NOTE: When using this procedure, it is critical to NOT simply place the crankcase half on the bench top and whack away. In that situation, the bottom side of the mainshaft bushing boss will NOT be touching the bench . . . and it will almost certainly be blown out.

The bottom side of the mainshaft bushing boss MUST be resting on a solid support. Repeat, must.

Ed

Very good to point out that you cannot just put the case on the bench if using the hydraulic method. I did at first,but had a look before I started and that part of the case was not touching.
I did get it out,but I tried my 1/2 NF tap and it did work. I figured that if it didn’t I could then go to the grease. I kind of cheaped out because the only heavy grease I have is a heavy “tar” that I use to dampen air rifle springs and it,s pricey.
Thanks again for the help.

The 1/2" tap works fine. I did a Resonator article on this a few years back and we also discussed this method on the forum about the same time. No hammers or grease, a few turns on the tap and use a 1/2" bolt for the puller. Ah, here it is, Vol 2, #16.

I've done the hydraulic method with heavy oil with good results.