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By DANIEL TINDER - 16 Years Ago
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I apologize ahead of time for asking such trivial/fundamental questions, but still playing catch-up on a lot of mechanical basics.
Since I assume excessive banging on the crank nose is likely discouraged, after the key slot has been thoroughly cleaned out and de-burred/filed, how do you decide where to draw the line on filing down/fitting the woodruff key? While popping it in the freezer beforehand would likely allow some installation latitude, I don't want it to jam halfway in using a brass mallet, and then have to drag out a sledgehammer to seat it fully (or pry it out and start all over, for that matter). If it's TOO easy a press-fit, even though it's captured, would it then be more likely to break/fail or widen/damage the keyway?
Also, still wondering if anyone has ever come across a substitute for the OEM reinforced rubber valvecover-stud/valleypan-bolt seal that shreds debris when removed?
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By aussiebill - 16 Years Ago
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Daniel, theres not too much science in it, just put key in crank, replace if sloppy, i place light smear of oil on snout and draw crank pulley onto crank using long bolt, and remove with a puller! its definitly not advisable to drive on with mallet as i have had a pulley break through the 3 arms through the shockwave. The keyway fit to key is realistically about 002"-004" clearance, due to general wear etc. .000" would be good in a spaceship but not these engines, dont forget the pulley is about a size for size fit on crank. This is only my view and sure others can add to it one way or another. Regards bill.
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By John Mummert - 16 Years Ago
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Dan, it should take some effort to drive the woodruff key into the crank snout. It should not be loose. Support the under side of the snout for a little "feel good". The damper should be an interference fit on the snout. We shoot for -.0006" if we have control. Anything over -.001" will be a bear to get on and off the crankshaft.
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By DANIEL TINDER - 16 Years Ago
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Thanks John,
Good info. As I will be using a rebuilt NOS damper that was never installed, I should likely polish the bore and check it with a hole gauge until it's ID is .0006" under the crank OD?
While it would be simpler to polish the crank nose, the next damper MIGHT be larger. I noticed my original engine's crank/damper fit was not all that tight, so either the crank nose was polished in the past, of the fit became looser just from mileage/wear?
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By John Mummert - 16 Years Ago
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Dan, anything machined has a tolerance. Nothing is perfect. I have check Y-Block crank snouts @ anywhere from 1.2505" to 1.2515". The bore of the crank damper will have a tolerance also. So, some combinations might have as little as .0002" interferance fit while another factory combination might have as much as .0020". There will be a hugh difference in the amount of force needed to install or remove the damper. I have noticed that the steel replacement dampers for the T-Birds have very little interferance, not enough IMO. Some will slide on by hand. This can be very hard on the woodruff key unless the damper bolt is kept very tight. We have settled on the snout being .0006" larger than the bore of the damper as being a good balance. I always apply anti-sieze to the snout when installing the damper. I also put anti-sieze on the threads of the puller and installer to save the threads. Good tools will last a lifetime if you take care of them.
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By DANIEL TINDER - 15 Years Ago
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John Mummert (12/27/2009)
I have noticed that the steel replacement dampers for the T-Birds have very little interferance, not enough IMO. Some will slide on by hand. This can be very hard on the woodruff key unless the damper bolt is kept very tight.
John,
Can anything simple be done to improve a loose damper fit (knurling, Loctite, etc.), without making it near impossible to remove safely?
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By John Mummert - 15 Years Ago
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Dan, I suppose the crank could be knurled with a hand knurler. Look at the inside of the damper. It only contacts the snout over a short area. No point knurling where it doesn't hit. Is the damper an NOS Ford piece or one of the replacements? What kind of fit do you have? Some interference or does it slide on?
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By Ted - 15 Years Ago
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DANIEL TINDER (4/2/2010)
...Can anything simple be done to improve a loose damper fit (knurling, Loctite, etc.), without making it near impossible to remove safely?Permatex makes a product specifically ‘for relaxed’ hub clearances. Part #68040. I suspect Loctite makes a similar product.
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By DANIEL TINDER - 15 Years Ago
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John Mummert (4/2/2010)
Dan, I suppose the crank could be knurled with a hand knurler. Look at the inside of the damper. It only contacts the snout over a short area. No point knurling where it doesn't hit.
Is the damper an NOS Ford piece or one of the replacements? What kind of fit do you have? Some interference or does it slide on?
John,
NOS damper, over-honed (tale of woe follows), now slides on and even wobbles a bit (without key).
Originally measured ID with snap gauge and same ratchet micrometer used to measure crank snout. Since machine shop was nearly an hour away (thus periodic trial fitting didn't seem practical), and their dial inside mic. reading didn't agree with my snap gauge spec., I stood by while honing was done and made frequent checks using my tools, assuming relative measurement/technique would eliminate micrometer variation/error. BAD IDEA! Didn't consider heat expansion due to honing procedure, or whether I should have used the max., not min. ID as my guide.
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By DANIEL TINDER - 15 Years Ago
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It's official. I AM an idiot. Thorough examination of cheap chinese snap gauge reveals manufacturer forgot to grind a radius on one side. You'd think the measurement discrepancy would have inspired a closer examination. I obviously need a keeper.
Also, another example of the false economy of bargain tools. Remeasure with another gauge indicates I now have nearly .002" clearance.
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By Rono - 15 Years Ago
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John; Speaking of crankshafts, any word from the crank grinder about the stroker cranks? We are moving this Friday for new adventures in Maine. My temporary address will be P.O. Box 175, Pittsfield, ME 04967. Cell # 208-867-1176 Thanks, Rono
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By Y block Billy - 15 Years Ago
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Rono, Look me up and give me your number, you will only be about an hour from me. My cell is 207-333-8369. myrandci@fairpoint.net. I am in China at the moment but should be home within a week. As far as the damper being too big, I have shrunk couplings for machinery that was too big for their shafts. Anything heated, when it shrinks, it shrinks more than it ever expanded. Whereas the damper has a rubber in it this will be a hard feat to accomplish but if you kept cold rags around the part with the rubber while heating the center and then cooling a few times .002" shrinkage may be accomplishable. Just a thought, You then may want to use a blue loctite when installing damper, this is not the permanent and may only need a slight heating if you ever have tyo remove it.
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By DANIEL TINDER - 15 Years Ago
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Interesting. Didn't know heating caused permanent shrinkage. Since fresh honing has left a rough surface, I also wondered about the existence of some kind of low viscosity, super tough liquid metal that could be painted on?
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By DANIEL TINDER - 15 Years Ago
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I also wonder about additional honing to allow the installation of some kind of sleeve like ones used to repair the outer seal surface?
Expensive precision machining (that might still not totally eliminate a possible failure) could approach the cost of a new replacement though (?), negating any benefit.
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By John Mummert - 15 Years Ago
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I've never tried Bill's method of shrinking but if it works you can get the rubber replaced for a lot less than the cost of another damper. About $150 vs $500
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By Ted - 15 Years Ago
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DANIEL TINDER (4/7/2010)
I also wonder about additional honing to allow the installation of some kind of sleeve like ones used to repair the outer seal surface?Boring the damper and installing a bushing to restore the fit on the crankshaft is always an option.
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By DANIEL TINDER - 15 Years Ago
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Y block Billy (4/7/2010)
As far as the damper being too big, I have shrunk couplings for machinery that was too big for thier shafts. Anything heated, when it shrinks, it shrinks more than it ever expanded. Whereas the damper has a rubber in it this will be a hard feat to accomplish but if you kept cold rags around the part with the rubber while heating the center and then cooling a few times .002" shrinkage may be accomplishable.
Bill,
As soon as I obtain an accurate dial bore gauge to check progress, I will likely attempt your heat/shrink procedure. I assume applying a propane torch flame to the over-honed inside of the bore is what you had in mind? Any tips you could provide re: time/color change/cooling procedure, etc.? (plan: pack weight ring with cold/wet rags, get the bore red-hot, let it cool, check for shrinkage with bore gauge, repeat until target size achieved if progress noted?).
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By DANIEL TINDER - 15 Years Ago
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DANIEL TINDER (5/8/2010)
Y block Billy (4/7/2010)
As far as the damper being too big, I have shrunk couplings for machinery that was too big for thier shafts. Anything heated, when it shrinks, it shrinks more than it ever expanded. Whereas the damper has a rubber in it this will be a hard feat to accomplish but if you kept cold rags around the part with the rubber while heating the center and then cooling a few times .002" shrinkage may be accomplishable. Bill, As soon as I obtain an accurate dial bore gauge to check progress, I will likely attempt your heat/shrink procedure. I assume applying a propane torch flame to the over-honed inside of the bore is what you had in mind? Any tips you could provide re: time/color change/cooling procedure, etc.? (plan: pack weight ring with cold/wet rags, get the bore red-hot, let it cool, check for shrinkage with bore gauge, repeat until target size achieved if progress noted?).
Discussed this "heat shrink" topic with a local mechanic. He claimed (his experience) that torched-off frozen pulleys often have a looser fit when reinstalled. Might be due to other factors (metal type, clearance effects of cleaned corrosion, etc.), but with likely danger of compromised epoxy bond, I might just shelve this particular approach for now.
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By Ted - 15 Years Ago
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Y block Billy (4/7/2010)
....As far as the damper being too big, I have shrunk couplings for machinery that was too big for their shafts. Anything heated, when it shrinks, it shrinks more than it ever expanded.Billy. My experience with heat on connecting rod ends is a more relaxed fit or larger hole sizes with each heating of the rod small ends.
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By Speedbump - 15 Years Ago
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don't know if this fits the problem but Loc tite makes some stuff called Metal lock. It's a viscous green fluid designed to hold metal parts together when the press is lost. I've used it successfully in different applications but don't know about a balancer. The bottle says it's good up to .003. With hone marks, etc, might be a good fix. Guess it just depends on how much trouble it is to take apart again if it doesn't work.
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By DANIEL TINDER - 15 Years Ago
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Thanks Speedbump,
Been putting it off, but will eventually talk to both Loctite (Henkel) & Permatex tech. service about product details. Will likely go this route since damper feels quite tight when installed with key in place. If bolt is properly torqued and correct threadlocker products used on bolt & crank nose, I might get away with non-racing/mild street service without eventual keyway damage, driving only w. pump & gen.?
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By Speedbump - 15 Years Ago
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I know the stuff is crazy strong in round on round applications. I first learned of the stuff when it was sent to us as part of kits to upgrade weapons pylons on USAF jets. The only knock I've ever heard was that it can form a heat transfer barrier when used in things like exhaust hard seats. (but I've done it successfully) I've used it for replacement guides on heads where the machinework was done previously and the new guides didn't seem to have a good press.... and then had to remove one due to a mistake...guarantee that stuff holds. 
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By DANIEL TINDER - 15 Years Ago
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Wouldn't want too much hold when it came time to pull damper. Heat release like red Loctite?
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By John Mummert - 15 Years Ago
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I woudn't worry about getting the damper off. I'd only be concerned that you get it on the crank straight and it stays there. Maybe it will still be there 20 years from now.
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By DANIEL TINDER - 15 Years Ago
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John Mummert (6/2/2010)
I'd only be concerned that you get it on the crank straight and it stays there.
It did also occur to me that with .002" clearance, when jammed tight against the key it might be cockeyed enough to spin a bit funny. While the Loctite would take up the clearance and keep it tight (when torqued down), with the key pushing it askew, I could likely never get in on perfectly straight.
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By Ted - 15 Years Ago
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DANIEL TINDER (6/1/2010)
Wouldn't want too much hold when it came time to pull damper. Heat release like red Loctite?The Permatex Part #68040 product ‘for relaxed’ hub clearances comes back apart without any special considerations and appears to hold up fine over time. Like John mentions, insuring that the hub is perfectly centered is a concern but at 0.002” I wouldn't consider that being a show stopper as long as the hub itself remains tight.
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By aussiebill - 15 Years Ago
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Ted (6/3/2010)
DANIEL TINDER (6/1/2010)
Wouldn't want too much hold when it came time to pull damper. Heat release like red Loctite?The Permatex Part #68040 product ‘for relaxed’ hub clearances comes back apart without any special considerations and appears to hold up fine over time. Like John mentions, insuring that the hub is perfectly centered is a concern but at 0.002” I wouldn't consider that being a show stopper as long as the hub itself remains tight. Ted, as usual you add some logic to the situation.
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By marvh - 15 Years Ago
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If you are concerned about the hub not being centered I would install it then take a dial indicator and do a run-out check around the outer of the hub near the front seal, (not use the pulley as the rubber could be not trued). This would tell you if installed or not installed dead center.
2 thousand loose is what we used to use for machine matching a pin to a bored hole. The weight of the pin would slide slowly by its own weight through the bore. If you used the Permatex as Ted suggested that pulley will be there forever. Double checking by doing a run-out again would prove centered.
marv
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By DANIEL TINDER - 15 Years Ago
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marvh,
FYI: Measurement of outer hub surface of torqued-down NOS damper with test indicator (directly opposite threaded crank snout) revealed aprox. .007" runout, with bias not directly related to key position. So much for that idea. To satisfy curiosity, I will eventually install spare repro damper and take same reading, just to see if precision machining standards have improved in 50 years. Or, could installed torque stresses likely have distorted the outer hub surface?
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By marvh - 15 Years Ago
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Before you take off the damper to install the old damper mark the high spot somewhere say on the flywheel flange with another mark on the block for a comparison mark then do a run-out check on the crankshaft snout with the damper off. Maybe the crank snout has the same .007" run-out and giving as sense of not centered. Crank snout is bent not looseness in pulley.
marv
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By DANIEL TINDER - 15 Years Ago
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Thanks marv,
Anyone with half a brain would've thought of that.
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