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| techtalk:ih:engmech02c [2020/08/25 01:41] – [Pining Bushings with a Set Screw] hippysmack | techtalk:ih:engmech02c [2025/08/01 18:26] (current) – [Selecting Bushings] hippysmack | ||
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| ====== Selecting Bushings ====== | ====== Selecting Bushings ====== | ||
| - | The factory machine work on 70< cam covers is stellar. ((Dr Dick of the XLFORUM | + | The factory machine work on 70< cam covers is stellar. ((Dr Dick of the XLFORUM |
| Reproducing it at home is nearly impossible. Even in a full machine shop its very time consuming. \\ | Reproducing it at home is nearly impossible. Even in a full machine shop its very time consuming. \\ | ||
| A good (at home) job is possible if you know what your doing. \\ | A good (at home) job is possible if you know what your doing. \\ | ||
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| * Length: The press fit area needs to be shorter than the bore depth in cover. | * Length: The press fit area needs to be shorter than the bore depth in cover. | ||
| * Flange Thickness: .060" / .065". | * Flange Thickness: .060" / .065". | ||
| + | * Pinion shaft bushings | ||
| + | * 1952-1976 bushing (25593-57) uses a .625" pinion bushing bore. ((Dr Dick of the XLFORUM https:// | ||
| + | * 1977-2020 bushing (25593-74) uses a .562" pinion bushing bore. \\ | ||
| ====== Removing Bushings ====== | ====== Removing Bushings ====== | ||
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| See also [[techtalk: | See also [[techtalk: | ||
| - | |Check local auto parts stores for a pilot bearing puller. ((photo by 62 Ironhead of the XLFORUM | + | |Check local auto parts stores for a pilot bearing puller. ((photo by 62 Ironhead of the XLFORUM |
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| ====== Installing Bushings ====== | ====== Installing Bushings ====== | ||
| - | * Bearing bronze into aluminum at room temp is a good matchup. There are no material shaving or galling problems associated with it. ((Dr Dick of the XLFORUM | + | * Bearing bronze into aluminum at room temp is a good matchup. There are no material shaving or galling problems associated with it. ((Dr Dick of the XLFORUM |
| * Just make sure there are no sharp edges on the bushing or cover bore. \\ You don't need to heat the case or freeze the bushing (unless you choose to). \\ The interference fit isn't great. One or both of the materials will flex under the interference. That adds up to the driving force never getting too great. \\ A note about heating aluminum; as temps rise, so does it's affinity for galling. | * Just make sure there are no sharp edges on the bushing or cover bore. \\ You don't need to heat the case or freeze the bushing (unless you choose to). \\ The interference fit isn't great. One or both of the materials will flex under the interference. That adds up to the driving force never getting too great. \\ A note about heating aluminum; as temps rise, so does it's affinity for galling. | ||
| * Bushing groove placement: | * Bushing groove placement: | ||
| - | * Compare the placement of the grooves in the bushings in the 68 and 78 cam covers below. It's the same. \\ Every factory cover is like this. So is the pin placement. | + | * Compare the placement of the grooves in the bushings in the 68 and 78 cam covers below. It's the same. \\ Every factory cover is like this. So is the pin placement. |
| + | * You have to look at the oiling. ((ryder rick of the XLFORUM https:// | ||
| + | * You don't want a slotted bushing on the pinion shaft, because that is what feeds oil to the crank. \\ The slot would allow oil to run from the cover into the gearcase, bypassing the pinion shaft hole and starve the crank. | ||
| + | * The intake with the big bushing gets an oil feed hole drilled in it. No need for the slot. | ||
| + | * The slots go at 9 or 3 O' | ||
| * Grind the flanges from the bushings as required. | * Grind the flanges from the bushings as required. | ||
| * With a die grinder, relieve the #1 & #3 flanges for gear tooth clearance. Grind until you match up with the cutouts in the cover. | * With a die grinder, relieve the #1 & #3 flanges for gear tooth clearance. Grind until you match up with the cutouts in the cover. | ||
| - | * Using general hand tools: ((doodah man of the XLFORUM | + | * Using general hand tools: ((doodah man of the XLFORUM |
| * You can put the bushings in the freezer for a few hours to shrink them some. \\ Then gently tap them in with an extension inserted the wrong way through a socket (smaller than the bushing flange). \\ It may not be the preferred method, but for someone with next to no tools, it does the trick. | * You can put the bushings in the freezer for a few hours to shrink them some. \\ Then gently tap them in with an extension inserted the wrong way through a socket (smaller than the bushing flange). \\ It may not be the preferred method, but for someone with next to no tools, it does the trick. | ||
| * Using a hammer and driver: | * Using a hammer and driver: | ||
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| Click on a pic to enlarge. \\ | Click on a pic to enlarge. \\ | ||
| - | | 1968 Cam Cover Bushings ((photo by Dr Dick of the XLFORUM | + | |
| + | | Bushings 1,3 and 4 ((photo by billeuze of the XLFORUM https:// | ||
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| + | | Rear intake bushing | ||
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| + | | 1968 Cam Cover Bushings ((photo by Dr Dick of the XLFORUM | ||
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| ====== Pining Bushings with Solid Pins ====== | ====== Pining Bushings with Solid Pins ====== | ||
| - | | + | The factory uses pins because they cost less to make and install. Their install procedure is tuned to the tight tolerances pinning requires. ((Dr Dick of the XLFORUM https:// |
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| * What the factory did: Holes are .1215" / .1220" | * What the factory did: Holes are .1215" / .1220" | ||
| * Now the FSM says to drill and install the pins. It never works out as well as the factory job. \\ Try to drill a hole in any material and hold .0005" | * Now the FSM says to drill and install the pins. It never works out as well as the factory job. \\ Try to drill a hole in any material and hold .0005" | ||
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| If you have access to a machine shop, it would be a simple guide to make. \\ | If you have access to a machine shop, it would be a simple guide to make. \\ | ||
| - | | Bushing Pining Jig ((photo by 62 Ironhead of the XLFORUM | + | | Bushing Pining Jig ((photo by 62 Ironhead of the XLFORUM |
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| ====== Pining Bushings with a Set Screw ====== | ====== Pining Bushings with a Set Screw ====== | ||
| + | * Instead of using only 1 set screw per bushing, 2 set screws in same hole works better. \\ (one on top of the other, top one locked down on the bottom one). | ||
| + | * You can use 2 set screws (#6-32 x 3/16" long) in each hole. \\ #6 is .138" O.D. (slightly bigger than the pins) \\ #8 is .164" (a bit on the large side for the die cast cover, cool on the pre-AMF cover though). | ||
| * Now, what if your solid pins are too tight for any reason? \\ Your pre-reamed bushing hole is now egg-shaped due to press fit distortions. \\ This also moves the beginning reamer cut position around, off concentric if you will. \\ So the results of the pin job effects the final position of the bushing bore. | * Now, what if your solid pins are too tight for any reason? \\ Your pre-reamed bushing hole is now egg-shaped due to press fit distortions. \\ This also moves the beginning reamer cut position around, off concentric if you will. \\ So the results of the pin job effects the final position of the bushing bore. | ||
| * Whats a guy to do at home? Forget the pins, drill and tap for 1/4" long #6-32 set screws instead. \\ This is way more user friendly. But it still needs special consideration due to the hole being half alum & half bronze. | * Whats a guy to do at home? Forget the pins, drill and tap for 1/4" long #6-32 set screws instead. \\ This is way more user friendly. But it still needs special consideration due to the hole being half alum & half bronze. | ||
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| * Use a good professional quality high speed steel (HSS), __plug chamfer__, hand tap. See [[techtalk: | * Use a good professional quality high speed steel (HSS), __plug chamfer__, hand tap. See [[techtalk: | ||
| * Also get a tee handle tap wrench. The centered tee makes for much less tap flexure when tapping. \\ It's flexing taps that break. Be it from misaligned wrench forces or too much twisting flex from high cutting forces. \\ HSS taps are much harder than their hardware store cousins. So they are less tolerant of flex. | * Also get a tee handle tap wrench. The centered tee makes for much less tap flexure when tapping. \\ It's flexing taps that break. Be it from misaligned wrench forces or too much twisting flex from high cutting forces. \\ HSS taps are much harder than their hardware store cousins. So they are less tolerant of flex. | ||
| - | * In order to avoid broken taps: | + | |
| - | * Drills and taps from the supply house aren't very expensive. \\ If you double up and practice the whole operation on some scrap, you will have a much more secure feeling on what your doing when you get to your cam cover. | + | |
| + | * Drills and taps from the supply house aren't very expensive. \\ If you double up and practice the whole operation on some scrap, you will have a much more secure feeling on what your doing when you get to your cam cover. | ||
| + | * Locate the holes to be tapped in the beefiest cover material area. ((Dr Dick of the XLFORUM https:// | ||
| + | * Your cutting tools need to be very sharp or you will have problems. Even slightly dull drills and taps will tend to bite into the aluminum and skid off the bronze. | ||
| + | * Drill and tap dry (oil makes this phenomenon of ' | ||
| + | * Drill .015" / .030" smaller 1st as a pilot hole. Then chase to size with a finish drill. A drill press makes drilling less artsy fartsy. | ||
| * Once the hole is drilled and tapped install set screws. If need be, you shorten the leading end of screw. \\ Then GENTLY peen the top of hole so they can't unscrew into the rotating cams. You may need to remove the screws in the future. | * Once the hole is drilled and tapped install set screws. If need be, you shorten the leading end of screw. \\ Then GENTLY peen the top of hole so they can't unscrew into the rotating cams. You may need to remove the screws in the future. | ||
| - | | Types of taps ((photo by Dr Dick, annotated by Hippysmack of the XLFORUM | + | | Types of taps ((photo by Dr Dick, annotated by Hippysmack of the XLFORUM |
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| ====== Reaming Bushings ====== | ====== Reaming Bushings ====== | ||
| - | Reaming a hole is no more than a hole sizing operation. If the drilled hole is not on location and square the reamed hole will not be either. ((~Grind~ of the XLFORUM | + | Reaming a hole is no more than a hole sizing operation. If the drilled hole is not on location and square the reamed hole will not be either. ((~Grind~ of the XLFORUM |
| Boring the hole with a milling machine is the best option if possible. \\ | Boring the hole with a milling machine is the best option if possible. \\ | ||
| - | For those guys who want the best job they can get, don't ream at all. Make your own bushes and in-position bore them in a mill just like the factory does. ((Dr Dick of the XLFORUM | + | For those guys who want the best job they can get, don't ream at all. Make your own bushes and in-position bore them in a mill just like the factory does. ((Dr Dick of the XLFORUM |
| * The reamer wants to 'walk off' instead of cutting. It will only cut if the walk is resisted. What resists the walk? | * The reamer wants to 'walk off' instead of cutting. It will only cut if the walk is resisted. What resists the walk? | ||
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| * Once the reamer is cutting, it's the O.D. of the reamer being held by the newly reamed I.D. that it has just created. | * Once the reamer is cutting, it's the O.D. of the reamer being held by the newly reamed I.D. that it has just created. | ||
| * So, what happens if the I.D. of the pre-reamed bushing is out of position (like if your bushes are not concentric)? | * So, what happens if the I.D. of the pre-reamed bushing is out of position (like if your bushes are not concentric)? | ||
| - | * Reamer sizes: \\ See also [[techtalk: | + | * Reamer sizes: \\ See also [[techtalk: |
| * 9/16" (.5625) for idler. | * 9/16" (.5625) for idler. | ||
| * 5/8" (.6250) for pinion. | * 5/8" (.6250) for pinion. | ||
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| * None of the #2 bushing options are gonna be cheap ($123 for a carbide tipped stub reamer) \\ That is cheap for solving this problem, if it does in fact solve it. \\ But there probably aren't many who agree that $123 is a cheap way out. | * None of the #2 bushing options are gonna be cheap ($123 for a carbide tipped stub reamer) \\ That is cheap for solving this problem, if it does in fact solve it. \\ But there probably aren't many who agree that $123 is a cheap way out. | ||
| - | |A reamer cuts along its chamfer angle, \\ not on its outside diameter. ((photo by Dr Dick of the XLFORUM | + | |A reamer cuts along its chamfer angle, \\ not on its outside diameter. ((photo by Dr Dick of the XLFORUM |
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