45 Cam Bushings - Reaming

[skidshoe]

I pressed and pinned some new cam bushings into some good cases/gear cover I got as a basket case. I need to line ream the bushings but I have no reamer bits. Any suggestions on where to purchase these or advice on doing this myself? Should I take it to a machine shop and let them fit the cams to the bushings? I've rebuilt numerous Harley engines but never had to touch the cam bushings. Thanks!

[chuckthebeatertruck]

Several questions to help guide you:

1) Was the basket case motor ever together (ie the cam cover fit the right side case and run in)
2) Why did you replace all the bushes -- were they out of spec, etc.
3) Have you measured your cams -- are they brand new, slightly worn, etc. Is any more than a thou different from the others?
4) Is the motor apart so you can pilot off the right case from the inside?
5) What about the pinion?
6) Did you do the case bushes as well as the cover bushes?
7) Do you have access to a sunnen hone with mandrels covering .5 - .8 inches (your own, a buddies, or a near by machine shop)
8) How did you install the bushes? Press is the method, but did you heat the cover first, freeze the bush, etc. Did they drop in handily or did you have to truly press them?
9) Did you press fit the pins and pein them?


There's several different ways to skin this cat and the above questions will help narrow down an approach that fits your budget, knowledge, and comfort level.

[skidshoe]

chuckthebeatertruck,

1. Motor was together at some point, matching cases and cam cover.
2. No bushings in the cases, but old bushings were in a bag. I deciphered what bushings went where and they were sloppy, like .005-.008 sloppy, why not press in new?
3. Cams are measuring about .682 to .685
4. Motor is apart and would absolutely line ream with the cam cover on.
5. Pinion bushing is new also, will fit with some emory paper work.
6. Did all new bushings since nearly all were removed, made the most sense.
7. Have access to a buddy's sunnen hone but no mandrels this small.
8. Bushings were in the freezer, slight heat on cases and pressed in with my arbor press. I would consider an ideal fit, not too tight, not loose.
9. Pressed the pins but did not pein them, I've never noticed any other 45's with peined pins, should be no way for them to back out with the cams installed.
10. Kind of at a loss..aside from this it would be a simple rebuild and I'd have it in the bike as we speak..I live super rural and local shops don't get the Harley thing...I suspect some may have the tooling to do it but don't want to touch it.

[chuckthebeatertruck]

Ok, this helps quite a bit. Long story made short, there are at least four different ways to do this; and reaming is one of them.

First, let's get a few things out of the way. I'm going to start by giving you more "precise" ways to do this. Precise doesn't always mean "necessary" but it does mean closer to what the ideal state of the motor is by design. Getting a motor running and getting the most out of it are two related, but different things.

Priority one is making sure the case and cover align regardless of reaming. Rather than type out how to do this; here's a thread from another forum that lays it out:
http://www.caimag.com/forum/archive/...p/t-19089.html

Second priority is dealing with your camshaft journals. In my view, .682-.685 is way too much spread unless you plan to bore and fit each bushing individually. This will be hard as commercial bushes only shrink down to about .685. So while you can fit some of your cams, you will have a hard time fitting the others to a good spec. This is because your case side journals started out life a touch over .686 and the ream is .6875 -- giving just over a thou clearance. Personally, if you have cams with replaceable shafts replace them with standard size. Or, get new cams. Or prepare to buy a foot of SAE660 bronze and make your own bushes.

Third priority is determining your budget, your machine accessibility, and how much you want to do yourself. If you have a lathe and a mill and know how to use them -- this is easy peasy. Second easiest is a sunnen. Third easiest is the HD ream set. Fourth easiest is buying commercial reams and making your own pilots or shells. And Fifth easiest is the shade tree method -- make sure the case bushes align and then use a ball hone to fit each bush. If the case and cover align -- then you're just talking fit. The problem is that it is very easy to bell mouth a bush when using a brush hone for anything more than surface finish.

Now, let's get into this very quickly. Commercial bushes, such as the ones Eastern sells, are sized to fit a standard cam journal -- in other words, they are usually right at .687 on the case side before you press them in. BUT, when you press them in, they shrink up a bit -- and then pressing in the dowel creates even more distortion (By the way -- peen the bushing flange over the pin -- they can and will work loose eventually). So, we've got to deal with that distortion to get a correct fit and eliminate binding. That's really what we are doing when you "line ream" or otherwise deal with the fit.

A lot of folks don't want to believe this; but Harley did not fit each cover to each case. They were all standard and fit on the line. Reaming is a "field repair." If you think about this for a few minutes, it makes a ton of sense. The bush center lines must be close to one another to begin with. Otherwise, the ream would wind up trying to create a new hole to align the center lines giving an eccentric hole -- which isn't a good thing for shaft support! So, the cases and covers had to be precisely made to begin with :-)

So, we now can agree on three points:
1) HD didn't line ream -- they fit the center lines with precision when the cases/covers were machined and sized each bush using a standard pilot.
2) We can duplicate this precision using a mill if we have access to the machine and know how to use it and then precisely and squarely bore each bush to a perfect fit. It's a lot easier to type this than to do it and a little jig making is in order.
3) If the cover is in alignment with the case, we can simply size the bushes one to one and then use a hand scraper to deal with minor variations that may/may not cause bind.

Let's get down to it :-)

I start from the pinion out. We can adjust the cams, but it's a lot harder to adjust the pinion as it must align with the crank to ensure we have good oil pressure. Sloppy = crap pressure and premature wear. This is the one bush where I truly do aim for a thou of clearance. On other bushes, I don't get as concerned with super close -- .001-.002 is good if a little noisy as we creep up to .002.

This is where we start making decisions. The best way to accomplish all this is to index on a mill and use a boring head to achieve a perfect fit. If you have the access to such machines and understand what you're going to have to do/make to get this right. But, let's say you don't have this and need to make sure that pinion fits correctly. First thing to do is to make up a tight fitting pilot for your ream. I'm digging deep into my brain, but I recall the necessary sizing for a pinon on a 45 is .625 or 5/8ths. Most reams in that size will have a shaft around 1/2 inch. So, you make up a pilot (bronze or aluminum prefered) to center the reamer shaft dead in the main bearing race. Assemble the cover and push the ream through the bush. One full revolution and STOP. Remove the cover, remove the ream and pilot. Check the sizing. If close; good. Grab a pinion shaft and bearing/cage assembly. Slip it in; put on the cover and gently rotate. No bind, good. Slight drag -- pull the cover off, and here's where we choose again. Some guys will run the ream again; others will use a ball hone; others will use a bearing scraper. I prefer the scraper as it's usually only a tiny amount of material. Mark the bush (sharpie/dykem/thin acrylic paint) test the pinon again and revolve it a few times. Examine the witness marks on the bush and use the scraper to reduce the high spot. Try to avoid emery as you mention -- the particles tend to stay embedded in the bronze and cause premature wear. Once we have the pinion sized up, I move to case bushes second.

For case bushes, we want to make sure they are square and true. Again, a mill is great for this; but a reasonably good drill press will work as well with a chucking reamer. The idea is to square the case bores with spindle. while a ream "should" follow the bore -- it is possible to bell mouth them by hand if you're not practiced with a hand ream. When we use a chucking reamer, I do not power it. Instead we rotate the spindle by hand. Push the ream through the bush, one revolution. Withdraw and check.

If you don't have all this stuff, again, you can make up a type of pilot or just say screw it and go for it by hand. Remember, .686 and a bit is the standard journal size. .6875 (11/16ths) reams are widely available. Most will put you at just over a thou of clearance . . .or pretty darn good. The other sizes for the timer and the oil pump I can't recall off the top of my head.

Again, if you reasonably believe the cover and case are in alignment and are a are the good enough is good enough type; then you can use a ball hone. It isn't terribly precise but you can get a motor run.

Keep in mind this is just one way to do this. There are others.

[Paps]

Dave Gamlin of Wayback Wheels had brand new reamer sets which line ream those bushings. Give Dave a call.

[skidshoe]

chuckthebeatertruck, thanks for the thorough feedback. What you're saying about the factory fitting each based on center line makes perfect sense. I thought about this based on the pins that guide the cover in place...I figured the factory would not have to deal with line reaming if the cases and covers were precisely machined.

My experience and availability to a good mill or lathes is minimal(you can only ask a buddy so many times before you feel they're sick of you "using" their tools) and that's why I was seeking a simple solution for my shade tree mechanics in my "speed shop". I'm not building a bike to ride to California, just another to putt putt around on, therefore I think I'll find an 11/16ths and 5/8ths reamers and bug my buddy one more time to make a pilot.

The cams are the good enough type, again not taking off to California with this. They are .684s and .685s, why one is mic'd at .682 on the cover side I'm confused, but I know it's close to acceptable in its respective bushing. I will be pertinent with respect to fitting the pinion shaft as I understand the importance of it. Thanks again for your input and not pouncing on my aptitude, haha.

[T. Cotten]

Fitting bushings must be a "lost art", Folks,...

If nobody knows how to use a triangular scraper.

....Cotten