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04-19-2020, 07:47 PM | #1 |
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Crankshaft pulley fitment
So: new to me 1930 pickup, resto early 80's by the previous owner, less than 1000 miles since then. Maybe an opportunity, maybe a "uh-oh". Anyhow, there's a vibration in the engine I've been trying to track down before pulling it and doing a full rebuild. In the process I noticed the crankshaft pulley was wobbling, so I purchase a new one-piece to replace it. There was a big chunk broken out of one spoke on the old one, so I was thinking "yippee, I've found it!"
Well, got it back together and nope, the vibration is still there. But funny thing - the new crankshaft pulley is rubbing on the front motor mount. Worked a shallow groove in the pulley and took a corner off the motor mount. I think it would be fairly easy to relieve the motor mount a few tens of thousands to clear, but has anyone heard of this before? I was thinking maybe somewhere along the line a slinger washer was left out, but the pulley fits to the crankshaft just fine (slightly protruding past the end). Perplexed. Thanks. JayJay |
04-19-2020, 08:07 PM | #2 |
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Re: Crankshaft pulley fitment
A friend installed a rebuilt engine with a repro pulley and it also just slightly kissed the front mount when we started the engine. Not sure, but I suspect we found the high spot on the pulley and dressed it with a file. This was a number of years ago when some of the pulleys were less than prefect.
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04-20-2020, 04:55 AM | #3 |
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Re: Crankshaft pulley fitment
Run the engine without the belt to eliminate a few things.
I would not pull the engine until you have a reason to do it. These old cars age well. Good luck and enjoy it. |
04-20-2020, 08:53 AM | #4 |
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Re: Crankshaft pulley fitment
There are some um "defective" crankshaft pulleys out there.
I came across one directly from a vendor where the hole that fits over the crank was too small. Of course I got my money back. The vendor is now out of business. Perhaps this is an indication of cause & effect? Given that your new pulley seems to be of the "one piece" variety, is it possible the engine has "moved" during your "partial removal" necessary to put the pulley in place? It might even be something as simple as putting the front support in place "backwards" - which can be done inadvertently and covered up in the tensioning of the bolts. (or it might be backwards from time immemorial from a previous mistake.) If I recall correctly, the mount is actually bent in a slight "Z" which allows the hole in the cross-member to sit a little closer to the motor. Putting it in backwards WOULD create an interference point. The indication you give us ("protuding past the end") seems about right for the pulley. When fully bolted in place the pulley hub actually serves to "pin" the crank-gear in place and prevent front-back movement of this pressed on gear. Try a comparison of the old pulley (what remains) and the new. Joe K
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Shudda kept the horse. Last edited by Joe K; 04-20-2020 at 09:06 AM. |
04-20-2020, 01:14 PM | #5 | |
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Re: Crankshaft pulley fitment
Quote:
Joe - lots of things to think about. Here's what the situation is per your points: Fit on crankshaft: old pulley was two-piece, ID of the pulley and the spacer were about 0.007" - 0.011" larger than the OD on the crankshaft, so a pretty sloppy fit. Also very sloppy interface between the pulley and the spacer. New pulley ID is about 0.0015" larger than crankshaft OD, much nicer fit. The new one seems to be well machined as well. Imported undoubtedly, but nicely done. Engine moving front/back: When I jacked up the engine to remove/install the pulley, I kept one bolt each of the rear mounts in place. The only interference seems to be pulley-front mount, the rear bolts went right back in place well. Front mount backwards: I thought of that and checked. The tabs on the front mount that bolt to the engine are displaced from the centerline of the bottom bolt by a fair bit. Turning that mount around would move the tabs over an inch to the front, and I don't see how that would come close to working. Every diagram I could come up with shows those tabs aft of the centerline of the bottom bolt (see photo below). I'm happy to have anyone else chime in, I'm finding quite a few "issues" with the assembly 40 years ago so nothing is sacred. If the mount was in backwards that certainly would get rid of the interference, though. JayJay |
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04-20-2020, 05:13 PM | #6 | |
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Re: Crankshaft pulley fitment
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04-20-2020, 05:54 PM | #7 | |
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Re: Crankshaft pulley fitment
Quote:
One more thing to add to the list - get that replaced with correct. I'll have to think whether I can get some clamps on the leaves sufficient to do that while it's in the frame, or just leave it until I do a frame-off. If I do a frame-off. Sigh. Thanks for noticing that. I'd better check the rear too. My wife is philosophical - she says I got this to tinker with, and so far I've done gobs of tinkering and not much driving. I appreciate all the good advice, folks. Stay safe, isolated and masked. JayJay |
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04-20-2020, 10:16 AM | #8 |
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Re: Crankshaft pulley fitment
If you are saying the nose of the crankshaft is protruding past the the pulley then you need to put a suitable washer in between so you can tighten the dog hard up . Even with a slight gap the pulley can move ahead and astern and eventually wear in way of the crankshaft key not good . Also keeps the seal running true .
John in sunny Suffolk County England . |
04-20-2020, 12:52 PM | #9 | |
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Re: Crankshaft pulley fitment
Quote:
thanks, John. Guess I wasn't clear - the pulley protrudes forward of the crankshaft, the proper way to have the nut bear on the pulley not on the crank when tightened. JayJay |
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04-20-2020, 10:24 AM | #10 |
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Re: Crankshaft pulley fitment
I have seen this happen four times in the last 15 years of working on engines and installing them in cars. My solution was to remove material from the support yoke at the area of interference. So it is not that uncommon.
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04-20-2020, 06:01 PM | #11 | |
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Re: Crankshaft pulley fitment
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Thanks, Dave, good to know. Fixing it is straightforward, I think - clamp the mount in the mill and shave it a bit, it will look almost like it was made that way! JayJay |
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04-20-2020, 04:54 PM | #12 |
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Re: Crankshaft pulley fitment
I was going to post that the yoke could not be turned around but wanted to check first. Even if you could it would put everything else out alignment. BUT it could be bent.
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I know the voices aren't real but damn they have some good ideas! Last edited by redmodelt; 04-20-2020 at 06:45 PM. |
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