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Old 10-22-2017, 01:31 PM   #1
newshirt
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Default Knocking after installing new flywheel

I just installed a new stock flywheel, pressure plate, and clutch. Now I get a clicking sound when depressing the clutch petal. The clicking intensifies to a full knock when I press harder. Once it starts knocking, it continues even if I release the clutch petal. The click sounds like it is once per revolution.

The clicking does not occur when hand-cranking or cranking with the starter (with or without spark plugs). It only occurs when the engine is running, and the clutch petal is depressed.

What I have tried:
1. Used short starter bolts
2. Whacked the ring gear with a big hammer to make sure it was seated
3. Hand-turned the new throw-out bearing to make sure it was free

Any ideas what the click and knock might be?
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Old 10-22-2017, 01:52 PM   #2
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Default Re: Knocking after installing new flywheel

Don't think ring gear is even all around. crank and look all around. Just thinking...
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Old 10-22-2017, 01:55 PM   #3
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Default Re: Knocking after installing new flywheel

Quote:
Originally Posted by fastroadster View Post
Don't think ring gear is even all around. crank and look all around. Just thinking...
I looked for this. I hand-cranked and looked for ring-gear wobble. I could not see any.
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Old 10-22-2017, 02:37 PM   #4
Tom Endy
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Default Re: Knocking after installing new flywheel

If the clutch surface on the flywheel has been resurfaced a number of times it puts the surface closer to the flywheel mounting bolts. If excessive the springs in the clutch disk could be contacting the heads of the bolts.

It is also prudent to have the pressure plate mounting surface on the flywheel machined at the same time the clutch surface is machined to restore the factory distance specification which is 1.123".

Another possibility: if you had the starter off and was reinstalled with incorrect bolts (too long), the flywheel will contact them.

When you push the clutch in the flywheel can move forward slightly depending on the condition of the thrust washer on the crank.

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Old 10-22-2017, 03:11 PM   #5
Jim M
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Default Re: Knocking after installing new flywheel

Did you adjust the fingers on the pressure plate? That might be causing it?
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Old 10-22-2017, 03:14 PM   #6
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Default Re: Knocking after installing new flywheel

"When you push the clutch in the flywheel can move forward slightly depending on the condition of the thrust washer on the crank."
Tom may be on to something here.
Check the forward/rearward end play of the crank.
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Old 10-22-2017, 04:11 PM   #7
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Default Re: Knocking after installing new flywheel

Quote:
Originally Posted by Tom Endy View Post
If the clutch surface on the flywheel has been resurfaced a number of times it puts the surface closer to the flywheel mounting bolts. If excessive the springs in the clutch disk could be contacting the heads of the bolts.
Wouldn't I hear clicking when hand-cranking or turning the engine with the starter (with the clutch petal depressed)? It is completely clean. No bad sounds.
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Old 10-22-2017, 04:14 PM   #8
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Default Re: Knocking after installing new flywheel

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Originally Posted by Jim M View Post
Did you adjust the fingers on the pressure plate? That might be causing it?
No. I measured them to be 0.75" below the pressure plate surface, and thought that was okay. The clutch petal is adjusted to be 1" of free play before the throw-out bearing contacts the pressure plate fingers. They all contact simultaneously.
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Last edited by newshirt; 10-22-2017 at 04:28 PM.
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Old 10-22-2017, 04:58 PM   #9
Marshall V. Daut
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Default Re: Knocking after installing new flywheel

My #1 reply in such cases is that the ring gear has worked forward on the flywheel. But you seem confident that it is seated all the way around. Scratch that one off the list. Maybe.
My #2 suggestion, then, agrees with Tom Endy: flywheel bolt heads being clipped by the inner hub of the clutch disk. This actually happened to me 17 years ago with a freshly rebuilt engine. The flywheel had been resurfaced and when it came time to mount it to the crankshaft, where, o where were the four special bolts required to secure the flywheel to the crankshaft? The gremlins got 'em! I had four new repo bolts I was saving for a customer's engine, but it was the weekend and I needed my engine running by Sunday. HIS new repo bolts were installed and the drive train was finished up by Saturday evening, just in time for a quick start up and check. The engine started fine and seemed o.k. - until I pushed in the clutch pedal. "Clunk, clunk, clunk!" Release the clutch pedal and noise stopped. Push it in again: "Clunk, clunk, clunk!" I am anal about mounting the ring gear squarely on the flywheel and even staking it in place, so I knew that was not the problem. After checking everything else out and finding nothing askew, I resigned myself to removing the transmission/bellhousing and pulling apart the clutch area to find the problem. Cutting to the chase, sure enough! There were shiny scraping marks on the heads of those new repo crankshaft bolt heads. Apparently because the flywheel had been resurfaced (i.e., made the center section thinner), that moved the clutch disk just that much closer to the bolts. After more scrounging around in my garage, I was able to dredge up one original crankshaft bolt. Comparing the repo bolt head against the original one, the repo bolt head was almost 1/3 thicker. Teamed up with the clutch disk being moved closer to the crankshaft flange during resurfacing, that was all it took to put the disk in contact with the thicker bolt heads. Pushing in the clutch pedal made the clutch disk hub flex enough to do that. I ground down the four bolt heads enough to reduce their height, while saving enough "meat" for the safety wire holes. Putting the whole mess back together again resulted in NO knocking when the clutch pedal was pushed in. Dressing down the bolt heads was the ONLY thing I had done stop the knocking.
Long story just to suggest checking the bolt head thickness, but I was trying to document what I went through to solve the problem. ^%#%& reproduction parts! Why can't a simple thing like a bolt be manufactured correctly??? Jeez, Louise!!!
One other thing to consider that I discovered just this year. Not all clutch disks are created equal. Some have a thicker center hub area than others. I discovered this in a friend's Model A that clunked when the clutch pedal was depressed. It actually stopped the engine with a BANG!! Removing the clutch disk and comparing it to one purchased from a parts vendor, it became apparent that the one I had installed out of my "parts bin" had a thicker center hub than the Model A vendor's hub. And, no - I didn't install the disk backwards. It's almost impossible to do that because you won't be able to bolt the pressure plate cleanly in the flywheel recess. The disk I used was clearly meant for some other application, even though its dimensions otherwise were correct. When you pull your clutch to fix the problem, be sure to compare your disk's center hub thickness to a known good disk. Be concerned only with the side facing the crankshaft.
So, there you are! Two possibilities to solve your problem: crankshaft bolts and clutch hub thickness. If you are POSITIVE it's not the ring gear (and your symptoms do point in that direction), I'll bet it's one or both of those animals at fault.
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Old 10-22-2017, 05:02 PM   #10
Tom Endy
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Default Re: Knocking after installing new flywheel

An earlier post asked if you checked the adjustment of the fingers on the pressure plate. Attached is an article that addresses that subject. Pressure plates are supposed to come from the factory already adjusted, however, that is not always the case.

This adjustment should not be confused with the clutch pedal adjustment that controls the distance for the throw-out bearing.

When making the clutch finger adjustment of the pressure plate it is important that the mounting surface on the flywheel for the pressure plate be within spec at 1.123" as mentioned earlier.

Tom Endy
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Old 10-22-2017, 06:15 PM   #11
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Default Re: Knocking after installing new flywheel

Quote:
Originally Posted by Marshall V. Daut View Post
My #1 reply in such cases is that the ring gear has worked forward on the flywheel. But you seem confident that it is seated all the way around. Scratch that one off the list. Maybe.
My #2 suggestion, then, agrees with Tom Endy: flywheel bolt heads being clipped by the inner hub of the clutch disk.
I struck the ring gear about 100 times with a four pound hammer and jumbo punch (because of your earlier post from 2015). It never moved from the original measurement of 0.1400" from the edge. That measurement is uniform over all 360 degrees. So I'm hoping it's good.

Quote:
Originally Posted by Tom Endy View Post
An earlier post asked if you checked the adjustment of the fingers on the pressure plate. Attached is an article that addresses that subject.
I printed this document. I'll pull the bell housing and pressure plate tomorrow, and look for skinned heads on flywheel mounting bolts. I'm thinking you're right.

You guys are really great!
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Old 10-22-2017, 08:19 PM   #12
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Default Re: Knocking after installing new flywheel

If you had a reproduction flywheel starter ring gear installed this may be a problem for you. I have seen several that would not stay in place. They tend to walk forward. It would have been better if Henry had put the stop on the other side. Each time the starter engages it wants to pull the ring forward away from the stop. I had one that kept walking off, no matter how many times I hammered it back into place through the starter mounting boss. I final pulled the flywheel and had the ring pinned in place. I also discovered that the shop that had installed the ring had put in on backwards.

The attached article tells the story.

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Old 10-23-2017, 12:31 PM   #13
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Default Re: Knocking after installing new flywheel

I don't see any evidence of scraping on the flywheel bolts or clutch pad. (see attached)

The ring gear looks to be up against the flywheel stop, and appears free of obstructions.

Do you think the flywheel bolts could be contacting the rear main (behind the flywheel flange)? I used the Snyder's flywheel mounting bolts and dowel retainer, as shown in the original post.
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Last edited by newshirt; 10-23-2017 at 12:38 PM.
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Old 10-23-2017, 01:37 PM   #14
Marshall V. Daut
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Default Re: Knocking after installing new flywheel

Well, rats! 'Good thing I didn't bet a nickel on my own advice.
Hmmm. Yes, everything looks o.k. in that area. No signs of scraping or metal-to-metal contact. That's a good thing - and a bad thing. Good thing is, this is not the cause of the knocking. Bad news is - you still need to find the source of the knock.
So far, you have eliminated the most common causes of knocking when the clutch pedal is depressed: (1) cocked ring gear; (2) crankshaft bolt heads too tall; (3) clutch disk hub too thick. Let's look elsewhere for a moment.
You mentioned in your original post that the knocking continued even after releasing the clutch pedal, but there's no knocking when hand-cranking or using the starter. Is that still correct? If so, then we might be on the wrong track by suspecting the clutch area. I refer to the knock still being present even when the clutch pedal has been released. Are we correct that you for sure isolated the knocking sound as coming from the clutch area? Remember that noise emanating in the drive train telegraphs through the whole car so that a noise in the rear end can sound as if it's inside the transmission.
You also mentioned that this is a new engine. Was the engine block top decked and was it bored oversize, like to 0.100"? If so, it's possible that the top of the block has been decked before and now the tops of the pistons are slightly protruding above the surface of the block and are striking the edges of the head gasket, which in some gaskets overhangs slightly into the cylinders because the gasket holes are not large enough. This becomes more of a problem with the bigger bores, say 0.100" and 0.125" and is more commonly seen among older repo head gaskets than the newer ones. It might be that only one cylinder has this problem for some reason, which would explain why you hear the noise once per revolution. If the gasket is the problem, eventually the overhang into the cylinder will burn away and the knock will stop. Kind of unnerving in the meantime, though.
To re-assure yourself that the repo crankshaft bolt shanks are not too long and striking the rear main cap, remove one bolt and compare it to an original one, or post the measurement so that we can compare. I should think if the bolts were too long, it would lock up the crankshaft. Examine the tip of the bolt you remove for signs of it clipping the rear main cap.
Also, use a pry bar against the pulley to see if the crankshaft has fore and aft movement. This is only supposed to be about .005" endplay allowed. If radically more, the crankshaft could be moving forward and striking the back of the rear main cap, especially when the clutch pedal is depressed. That moves the crankshaft forward a bit anyway. Too much endplay slop would only make matters worse, especially if the bolts happen to be just a smidge too long. Hand cranking or even using the starter wouldn't re-create the knock. Try holding the clutch pedal all the way in and then use the starter. If you hear knocking then, the crankshaft is moving too far and/or the bolt shanks are too long.
Anyway, check these suggestions out next before we panic.
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Old 10-23-2017, 01:43 PM   #15
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Default Re: Knocking after installing new flywheel

A suggestion: Coat the flywheel mounting bolt heads with a liberal coating of chalk. Put the disk against the flywheel surface and rotate it back and forth to see if any chalk transfers onto the springs.

Excellent safety wire job. I have never been able to do that well.

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Old 10-23-2017, 01:47 PM   #16
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Default Re: Knocking after installing new flywheel

Quote:
Originally Posted by newshirt View Post
I don't see any evidence of scraping on the flywheel bolts or clutch pad. (see attached)

The ring gear looks to be up against the flywheel stop, and appears free of obstructions.

Do you think the flywheel bolts could be contacting the rear main (behind the flywheel flange)? I used the Snyder's flywheel mounting bolts and dowel retainer, as shown in the original post.
I never used any but original bolts, but it is real close. I would pull one out and look at the end of the bolt, that will tell you.
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Old 10-23-2017, 02:11 PM   #17
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Default Re: Knocking after installing new flywheel

I woukd have used the original flywheel bolts. I just measured an original for you and it is .808-.810 from the end to the bottom side of the head.
I have also head flywheel bolts loose and not tight causing obvious noise before

I agree as tom and Marshall said there can be various issues. Check your starter bolt length as well.
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Old 10-23-2017, 04:38 PM   #18
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Default Re: Knocking after installing new flywheel

I took some measurements:
1. Flywheel bolt length 0.820
2. Crank shaft end-play: 0.009
3. Old flywheel dowel retainer: 0.042
4. New flywheel dowel retainer: 0.035
5. Flywheel flange to bearing cap clearance: 0.049
6. Flywheel bolt extends beyond flywheel: .3750 (plus some extra when torqued down)
7. Flywheel flange width: .3950

Observations:
1. Ring gear is tight against flywheel, absolutely no gap
2. Two layers of masking tape on flywheel mounting bolt heads does not rub off on clutch disc springs
3. No scraping on ring gear
4. No scraping on flywheel housing
5. No scraping on bearing cap (but it may be too hard to see)
6. No scraping on bell housing


Do you think the big cotter pin at the bottom of the flywheel housing could cause it? It looked way too far away from the ring gear, and tight in the hole, but it did have a little scraping on the top which might have gotten there when I tried to remove the flywheel without first removing the cotter pin.
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Old 10-23-2017, 05:49 PM   #19
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Default Re: Knocking after installing new flywheel

If you installed a new throw-out bearing check to see if it has the word Aetna stamped on the side. This is a notoriously poor quality reproduction that flooded the hobby a few years back. They will fail coming out of the box. If it is, I would replace it. Bratton's carry a good quality Federal Mogul brand bearing, even though made in Mexico.

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Old 10-23-2017, 06:47 PM   #20
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Default Re: Knocking after installing new flywheel

Quote:
Originally Posted by Tom Endy View Post
If you installed a new throw-out bearing check to see if it has the word Aetna stamped on the side. This is a notoriously poor quality reproduction that flooded the hobby a few years back. They will fail coming out of the box. If it is, I would replace it. Bratton's carry a good quality Federal Mogul brand bearing, even though made in Mexico.

Tom Endy
I have the Federal Mogul throw-out bearing. I re-verified that it turns freely without clicks or drag. I also re-verified the pilot bearing.

BTW, the knock sounds like a little tack hammer on a granite countertop. Very distinct and sharp, like metal on metal. It starts as a click, then builds to a full knock if I keep pushing the clutch petal. Oddly, it remains after removing my foot from the clutch. Shutting the engine off is the only remedy.
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