Electric Assist Project: E-charger (2000 Subaru Outback)

[brucey]

Drilled holes this morning, spent a good hour tapping them because aluminum galls up so easy. Kerosene helped some at least.

Went to use a pulley puller and it doesent work. Even with the impact gun (dumb, I know.)

I am now sanding the leading edge of the motor shaft in hopes that rounding it off will help get the pulley on and off.

Currently though, I set my oven to 'atomic' and set the whole assembly on top of the oven to radiate it, hoping the heat will help it move off.

[Patrick]

Propane torch.

[brucey]

After letting it set for an hour over the oven, I put the pulley puller in and gave it some light use with the impact gun.

Didn't strip the threads, but I did bend the bolts of the pulley puller. I'm going to try to get stronger, shorter bolts for this and hope it works. At least the threads didn't strip this time.

[Frank Lee]

Maybe, if it looks like it's going to get to the point of wrecking stuff, bring it to a machine shop and see if their bearing plates + press can take care of it. The few $$ they charge will more than make up for the aggravation.

Then have it sized PROPERLY before re-install. It may have to come off again some day.

[brucey]

Yup yup. Looks like machine shop only at this point. I just tried it with grade 8 bolts attached to the pulley puller and it was a no go It had been on the oven for 3 hours at this point and was way too hot too touch. This thing will not budge, I don't get it.

It went on without much trouble, a slap or two from a mallet and it went right on..

If it does come off it's getting trimmed so I can slide it on and off with a little work, and not anything specialized. This is ridiculous.

[ShadeTreeMech]

Here's a tidbit of info that I was suspicious of but uncertain about from this site

Aluminum and steel will always react and corrode when put together.

My suggestion is once (maybe if?) you get the pulley off, have the pulley hole oversized and get a steel insert pressed into the aluminum. It is possible there is a better choice of metals, just make sure whatever metal is in contact with the motor shaft, that there won't be a reaction between them.

I wonder the price difference (and less total aggravation) if you have a new pulley made from steel? It's sounding possible the aluminum pulley is going to have to be cut off.

For what it's worth, when aluminum is cast in a die cast machine, steel is used for the die, but extremes are taken to make sure the aluminum doesn't bond with the steel; namely after EVERY CAST the die is sprayed with a solution of water and oil. The oil apparently slows down the tendency of the molten aluminum to bond with the steel, but yet it still occasionally happens. When this does happen, the aluminum has to be manually carved out of the die.

[ShadeTreeMech]

Here's a table of metal reactivity sorted from most reactive to least reactive. On this list, the further away from each other on the list 2 metals are, the more likely they will react with one another.

There are 92 metals listed.

The aluminum alloys are #s 6-9 and 12-22, meaning they are very reactive.

The likely iron alloys used in the motor shaft are #s 30 and 31, which tells me there is a slight reaction. Unless there is a stainless steel in use on the shaft, and the most likely to react to aluminum is #78, which indicates a nearly instantaneous reaction.

Another useful quote from the above page.

Galvanic series relationships are useful as a guide for selecting metals to be joined, will help the selection of metals having minimal tendency to interact galvanically, or will indicate the need or degree of protection to be applied to lessen the expected potential interactions. Generally, the closer one metal is to another in the series, the more compatible they will be, i.e., the galvanic effects will be minimal. Conversely, the farther one metal is from another, the greater the corrosion will be.

[dcb]

you might put the whole assembly in the freezer for hours, then quickly get it out and set up the puller, then try to heat the pully with a torch but not the shaft so much, and pull.

[brucey]

I drilled/tapped some new holes on the face of the pulley, bringing them just 3/4" from the center and used a file to grind some of the shaft down just slightly, hoping maybe the top of it had ballooned out somehow from forcing it. Still a no go. Grade 8 3/8" bolts and an impact gun on a puller does nothing at all but make a bunch of noise. Going to the machine shop tomorrow morning, if they can't get it out then I'll have to cut the pulley sadly ): Such a beautiful piece too. Once I get everything aligned and operable, I do plan to re-do the front bracket. Yes, I know I need to focus on one problem at a time, but that bracket has had too many 'oops' at this point for my tastes to leave it on there permanently. On the bright side though, I seem to have invented a new way of welding. Just stick two pieces of metal together and it instantly corrodes into one solid piece!

Shadetree: Good info to know, and hopefully can help someone out one day. I didn't realize it could corrode on something that tight. Pulley is 6061 aluminum, but shaft is steel, what kind I am not sure. Buh. Learning experience eh?

[Frank Lee]

It didn't corrode on there in under a week so something else ain't right either.

Dissimilar metals are assembled together all the time. They just need a barrier of some sort be it paint or grease or anti-seize compound or ?.