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Old 04-19-2020, 07:47 PM   #1
JayJay
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Default 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.


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Old 04-19-2020, 08:07 PM   #2
Doug Linden
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Default 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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Old 04-20-2020, 04:55 AM   #3
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Default 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.
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Old 04-20-2020, 08:53 AM   #4
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Default 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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Old 04-20-2020, 10:16 AM   #5
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Default 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 .
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Old 04-20-2020, 10:24 AM   #6
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Default Re: Crankshaft pulley fitment

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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.
Good Day!
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Old 04-20-2020, 12:52 PM   #7
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Default Re: Crankshaft pulley fitment

Quote:
Originally Posted by john charlton View Post
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 .

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.


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Old 04-20-2020, 01:14 PM   #8
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Default Re: Crankshaft pulley fitment

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Originally Posted by Joe K View Post
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

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.


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Old 04-20-2020, 04:54 PM   #9
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Default 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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Old 04-20-2020, 05:13 PM   #10
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Default Re: Crankshaft pulley fitment

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Originally Posted by JayJay View Post
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
Unrelated to your pulley, but in your picture it appears you have a hex head nut where your front spring center bolt is?? Is that sitting in the front crossmember OK? The stock square head bolt sits flush with the crossmember.
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Old 04-20-2020, 05:54 PM   #11
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Default Re: Crankshaft pulley fitment

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Unrelated to your pulley, but in your picture it appears you have a hex head nut where your front spring center bolt is?? Is that sitting in the front crossmember OK? The stock square head bolt sits flush with the crossmember.
Well, I'll be damned. Thanks for the eagle eyes. I took a close look and that is in fact a hex head. But the head is depressed in the center. Either it's a hex bolt head with a depression in the center (which I've not seen) or else it's a length of all-thread with a nut on each end, and the top is not fully threaded to flush with the top of the nut. That's a kind of scary thought. It fits fine where it is, and there's clearance in the bottom of the crank guide casting for the head, but it's clearly not correct. The cross member ears look to be in good shape for the square head bolt so it should not be too difficult to put it right.

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.


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Old 04-20-2020, 06:01 PM   #12
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Quote:
Originally Posted by Dave in MN View Post
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.
Good Day!

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!


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