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MG MGA - Redneck bushing puller

So, I'm in the process of overhauling the generator for my 1500 project, and it is pretty obvious that at some point in the past, the belt was run way too tight, since both mounting holes were deformed, and both the rear bushing and the ball bearing were a bit loose. Since everything else looks pretty good, and I know the generator was working fine the last time the car was driveable, I decided to put some effort into saving it, even though replacement units aren't necessarily all that expensive. I figure the sooner I get it refurbished, looking pretty, and packed in a box, the less likely I will be to spend real money on an "upgrade" that will probably work no better.

The first order of business was to repair the egged-out mounting holes, which I did by opening them up to 3/8" with a chucking reamer in my drill press, pressing in steel split bushings, which were then reamed to fit the 5/16" mounting bolts.

Next order of business was extracting the bronze bushing from the aft end frame, which is complicated by the fact that there is only access from one side. There is probably a special puller made that can do that, and if I were to guess, it probably costs as much as or more than a new generator. I was able to remove the bushing for all of about 15 minutes worth of labor and the cost of a 5/8" fine thread bolt and washer, and I thought that some of you might find my method potentially useful.

I used this same method when I replaced the pilot bushing in my crankshaft; the main thing is to pick a bolt size that will allow you to cut some reasonably deep threads in the bushing, but will not go beyond its outer diameter. In this case, a 5/8" fine thread bolt was ideal. Taking care to keep the tap straight, I simply run the tap down as far as it would go, without bottoming on the felt oil pad or its metal retainer. Then, using a spacer tube large enough for the bushing to pass, I simply ran the bolt down and tightened until the bushing started to pull out, and continued until I reached the bottom of the threads. I took it apart, and when I ran the tap back down to finish cutting the threads all the way through the bushing, it twisted out of the end frame without needing further use of the puller.

Here is a picture of the end frame, bushing, and puller apparatus:



Del Rawlins

A second picture, showing the tool in action. Sorry for the low quality, but it should be fairly self explanatory.



Del Rawlins

Nice job Del,

Do you think you could have used a nut instead of the bolt? After tapping the bushing, thread a nut on to the tap; assemble a shorter tube and thread the tap back into the bushing. Then run down the nut on the tap. This way the tapped threads wouldn't have to go as far into the bushing.

I don't know if it would work but just asking.
Chuck Schaefer

That would probably have worked too. Or, you could use a length of threaded rod instead of the bolt, with a nut on top. I used the bolt because it was far easier to find a fine threaded 5/8" bolt than it would have been to find threaded rod in that size. I like using fine threads for something like this because it gives more mechanical advantage for pulling.
Del Rawlins

For removing the crankshaft pilot bushing, I used the grease trick. Fill the blind hole with as much grease as you can. Get a round piece of solid steel (I think I used 1/2" dia) and tape it until it is a snug fit inside the bush. Insert the rod and whack it into the hole with a 2lb sledge. The resulting hydraulic pressure expels the bush.
Art Pearse

I find the grease method to be unnecessarily greasy...
Del Rawlins

Argh. Now I have to find another set of brush springs, because one of mine went "tink" when I barely flexed it tonight. The usual suspects don't appear to list them, but at least there is a vendor on Ebay UK that seems to have them. Guess it is always something.
Del Rawlins

Del

Most interesting. I am very keen on picking up all these engineering tips. A question though on reamers. Do you tend to use fixed size reamers, for which I presume you need to have a very large collection or do you use adjustable (expandable) reamers? The reason I ask is that I have a few of each and am looking to increase the range of sizes, so I am wondering which way I should go. As an example, I recently made a new bush for my clutch thrust bearing operating lever but did not have the correct size reamer. Fortunately, I was able to do the job in my lathe with an internal cutting tool. Not ideal I guess, but at least I got the job done.

Steve
Steve Gyles

I have a few sizes of chucking reamers that I bought for my airplane project, and the 2 I needed for this happened to be two that I had. I like to use a reamer for mounting holes and the like, because it results in a more uniform hole than a drill. I also have a set of adjustable reamers that I inherited from my father, which are extremely useful on occasion. The adjustable reamers are nice for gradually sneaking up on the fit you are after, like with the bushing you recently made. With the chucking reamers, what you have is what you have. I made some parts for my airplane that involved reaming tubes out to fit a series of rod end bearings, and with the adjustable reamer I was able to get it close enough that suction is created when pulling the rod end out of the tube. I don't have a lathe yet, unfortunately. Once I get a bigger shop to work in, that is going to be a priority. I'm not a machinist or anything; I'm just learning as I go like anyone else.
Del Rawlins

Hi Del. Out of curiosity what type of aircraft are you building/ My Uncle built a Jodel D11 from scratch a long time ago. I love aircraft almost as much as my MGA roadster. Cheers, Glenn
Glenn Hedrich

I was building a Barrows Bearhawk before I set it aside to work on the MGA. I occasionally still work on it when the opportunity presents itself, but for the most part it is in boxes and hanging from the rafters. I have fabricated almost all of the parts needed to assemble the wings, and have some other control hardware completed. At this point in my life, restoring my dad's MG is more important to me, not to mention less costly to work on.
Del Rawlins

This thread was discussed between 04/02/2010 and 05/02/2010

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