Harmonic balancer/damper - How to remove and install
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===Without threaded damper bolt hole in crank=== | ===Without threaded damper bolt hole in crank=== | ||
| − | Some SBC engines from 1968 | + | Some SBC engines from 1968-back came with the damper installed at the factory with no drilled and tapped hole in the crankshaft snout for a retainer bolt. Removal isn't affected by this, however installation IS. |
| − | ====Drilling the snout==== | + | ====Drilling the crank snout==== |
The ideal solution is to drill and tap the snout with 7/16-20 threads. This must be done correctly, with the hole drilled and tapped concentric to the crank c/l. If there's any question about this, let a machine shop handle the job. | The ideal solution is to drill and tap the snout with 7/16-20 threads. This must be done correctly, with the hole drilled and tapped concentric to the crank c/l. If there's any question about this, let a machine shop handle the job. | ||
====Hardware==== | ====Hardware==== | ||
| − | + | An ARP damper bolt and washer may be used. Torque it to their specs, or to 60 ft/lbs if using an OEM bolt/washer with clean oiled threads. If there is access to good quality grade 8 hardware, a 7/16-20 x 2.25" long bolt with a 1/4" thick washer can be used. | |
====Proceed without drilling the snout==== | ====Proceed without drilling the snout==== | ||
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*Use a sturdy block of wood like a 4-5" thick slice of a wooden fence post or 4x4, use it grain-on, not across grain to help keep it from splitting- you'll be hitting it fairly hard in most cases, especially if no heat/cold is used. The wood is used to insulate the damper inner hub from the hammer blows. | *Use a sturdy block of wood like a 4-5" thick slice of a wooden fence post or 4x4, use it grain-on, not across grain to help keep it from splitting- you'll be hitting it fairly hard in most cases, especially if no heat/cold is used. The wood is used to insulate the damper inner hub from the hammer blows. | ||
{{warning|NEVER hit the damper on the outer ring- this can break the bond between the rubber and steel, making the damper useless. NEVER hit the damper metal to metal with a hammer. A damaged damper could fail, possibly causing personal injury and damage to the vehicle or even bystanders. Use gloves and '''[[Health and safety in the shop or garage#Eye protection|eye protection]]''' at a minimum.}} | {{warning|NEVER hit the damper on the outer ring- this can break the bond between the rubber and steel, making the damper useless. NEVER hit the damper metal to metal with a hammer. A damaged damper could fail, possibly causing personal injury and damage to the vehicle or even bystanders. Use gloves and '''[[Health and safety in the shop or garage#Eye protection|eye protection]]''' at a minimum.}} | ||
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| + | Below is how the factory recommended installing a SBC 265 cid engine damper without a threaded crank snout: | ||
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| + | [[File:Sbc damper install non threaded crank.jpg]] <br style="clear:both"/> | ||
| + | '''NOTE:''' The reference to threading capscrews to hold the hub and "flywheel" in place is for a 265 cid SBC that used a pulley and hub riveted to the flywheel. These were not actually dampers per se- they contained no rubber or other means of absorbing/dissipating harmonics. | ||
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| + | ==Honing to fit== | ||
| + | (This was previously a separate article by Techinspector1. It has now been added to this article.) | ||
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| + | The question arose the other day when someone suggested honing a damper hub in order to get it to press onto the crank snout of a SBC a little easier. Another contributor said there was no way he would hone a damper. The following is my reply: | ||
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| + | Normally, I wouldn't hone one either, knowing that the intended purpose of the damper is to transfer harmonics from the crankshaft to the inertia ring on the damper and also knowing that if the fit on the crank snout is too loose, that these harmonics will not be transferred and could result in a cracked crankshaft. | ||
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| + | I think what the contributor is saying is that most of these aftermarket offshore dampers are bored about one and a half thousandths (0.0015") too tight, making the press fit dimension about 0.003" interference when it should actually be about 0.0010" (one thousandth) to 0.0015" (one and a half thousandths) interference. Visually inspect the crank snout closely for burrs or nicks that might interfere with the smooth installation of the damper. Use a fine file and/or emery cloth to smooth the surface. Check how far the key sits proud of the crank surface and measure the depth of the keyway in the damper. You want to make sure the key is short enough off the crank surface to not interfere with the roof of the keyway in the damper to prevent the damper from being installed at all. | ||
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| + | Measure the snout of the crank about halfway back (the crank snout is tapered) with a known accurate micrometer that reads to the fourth place (ten thousandths of an inch). The snout should measure within one thousandth from low to high tolerance of the specified diameter from the factory (1.2460" / 1.2470"). Let's say for grins that it measured 1.2467". Take that measurement and the damper to your local machine shop and tell them to hone the damper hub to 1.2452" /1.2457". The 1.2452" hole would give you a 0.0015" interference fit. The 1.2457" hole would give you a 0.0010" interference fit. Either one will work and will give the machine shop a half thousandth to play with. If they can't hold a half thousandth tolerance, you have chosen the wrong shop to do the work. Don't try to do this with a brake hone at home. You'll just egg shape the hub and FUBAR the whole mess. | ||
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| + | Now, on your way home from having the machine shop hone the hub of your damper, stop by and pick up some dry ice. Once you get home, break up the dry ice into a one gallon baggie and wrap it loosely around the crank snout. Put the damper in a pan of water and bring it to a boil on the kitchen stove. Remove the pot from the stove and carry the whole thing to the garage. Remove the dry ice baggie from the crank snout. Spray the crank snout with WD40. With gloves on to prevent burning your hands, place the damper onto the end of the crank and engage your install tool. | ||
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