Mysterious Violent Vibration

[mattsmithalamode]

So, I'm a new Corvair owner, and I'm trying to go through the car; it's a '63 Monza 900. The engine runs; it's a little hard to start, but it runs. One of my main concerns right now is the terrible vibration the engine causes when it's running. The vibration seems to increase with RPM's, and it rattles the whole car--very disconcerting. Normally, something like this is cause by a motor mount, but I've inspected the rear mount and it just doesn't look that bad to me. I could be wrong, but all of the rubber is still there. Is there a chance it could be a bent crankshaft pulley or possibly the fan pulley? I know I have to get a few Clark's belts, but the vibration seems to be causing the engine to throw belts at high RPM's.


Any help would be appreciated!!!!
Thanks


Matt

[Stinger Motorsports]

If the Car is a Manual transmission the problem is in the clutch assembly.. most likely the Flywheel to be exact. I have had a customer car that shook so badly that the shaking cracked the bell housing. Installed a new balanced flywheel along with a new pressure plate and a bell housing and it ran smooth as silk..

If it is an automatic maybe someone else can help cause I have no idea.!!

David Clemens
Owner
Stinger Motorsports

[Motornoggin]

I would suspect either a very bad miss (multiple cylinders), or the balancer ring has "walked" and is way out of balance. This could also explain the belt issue. Other than that, it might be a broken flywheel.

[mattsmithalamode]

Hey! Thanks for the quick responses! The car is a manual. Four speed to be exact. I guess my question is, if it were a broken flywheel, shouldn't I feel a strong pulse in the clutch pedal when I engage it? I've driven a fair amount of cars with clutch problems, and this is usually the case, but I'm just guessing. The vibration seems worst at idle, but it certainly doesn't go away with higher RPM. It doesn't seem to change, though, whether the clutch is engaged or not. As far as a miss is concerned, how would I check to see which cylinder? I've replaced four of the six plugs. (I've put off taking the carbs off to change the center two plugs till the weekend, but the old plugs didn't seem overly wet; wouldn't this indicate a miss?). And on the balancer ring, I'm unfamiliar. Is it on the crankshaft pulley? How do I balance it?

Thanks a lot! I'm really excited to be learning more!!!

[cvair4life]

Can you make a video and post it to YouTube then link it in here... I think it might help some of our e-Mechanics with this issue.

[mattsmithalamode]

Sure thing! After I get off work tomorrow, I will record a video of the engine and inside. The vibration is a little easier to hear and feel inside the car. The car is currently without a muffler, so it may be hard to hear with just the engine. Ha.


Thanks!

[Trip]

The Corvair flywheel is very unique.. and an interesting story behind it. Anyway the flywheel is actually three pieces riveted together. Over the years the rivets wear out and cause a nasty rattle. Since it's not broken you don't feel it in the clutch.

I don't know if that could cause a vibration as bad as you describe, but it's entirely possible.

Corvair motor/trans mounts have a sortof emergency backup plan. If the mount rubber stretches far enough you wind up with a metal on metal mount (on some it is concealed by the remaining rubber). This usually causes noise and vibration, but again not sure as severe as you describe.

Belt throwing can be caused by a number of things but properly adjusted on a good running engine it doesn't happen. Most people overtighten the Corvair belt trying to prevent a problem, and inadvertently cause one. The belt should be loose enough that you can turn the generator/alternator pulley with one finger without straining your finger.

A rough running engine (usually at idle) causes the belt to pick up a sort of pulse, you'll see it jumping around and it will probably be noisy.

Alternatively you could have a bad fan bearing but that wouldn't cause the vibration, or you could have a slipped harmonic balancer which could cause the vibration BUT a 63 Monza probably doesn't have a harmonic balancer but a solid pulley. The harmonic balancer didn't become necessary until they increased the stroke in 64 so I don't think any 63 or older cars have them... wouldn't swear to it though.

So there you have it...

The engine shouldn't vibrate nearly enough to cause that kind of vibration even if it was hard mounted, so that can't be it (at least not by itself).

You've either got a really bad flywheel or an engine problem. Start with the basics- Do a compression test before you start taking things apart. Next check your ignition system.... new points, plugs, wires, cap, rotor? Timing set correctly? (should be between 8 degrees and 13 degrees BTDC depending on engine but any should run ok anywhere in that range).

Once you are sure the engine itself is ok (it probably isn't), then yank it out and check the flywheel. Taking the drivetrain out of an early model Corvair is SUPER SIMPLE. My first time it only took an hour working alone. If your flywheel still has rivets you will want to bolt it while you have it exposed, even if it isn't the problem. I believe the procedure is available in the book "How to Keep your Corvair Alive" by Richard Finch. It's also almost certainly in the Corsa tech guide which is a must have resource. If you decide to buy one or the other I'll check my copies and make sure the info you need is there before you buy.. just let me know.

Anyone curious about the story behind the Corvair flywheel feel free to ask, I'm always up for talking Corvair history!

[miniman82]

Anyone curious about the story behind the Corvair flywheel feel free to ask

Because the engine was never intended to be mated to a manual transmission, so when it finally did get one they had to come up with a way to put a clutch in there. This was the solution.

[UNSAFE]

If the engine runs normally the vibration is likely the flywheel rivets. I had it happen once and it vibrated severely and rattled too. Often depressing the clutch pedal will change the vibration if it's the flywheel.

The fan belt problem is likely unrelated unless the vibration goes away when the belt comes off.

[fjp912]

This is not exactly on topic about the vibration but I'm curious why you weren't able to change the center plugs. On my '64 I didn't have to take the carbs off to change the center plugs. It helps to use a U-joint socket extender, and there's one piece of the linkage to unclip and move out of the way for a moment, but it's no big deal. Is there something different about '63 carbs that they interfere more?

[Trip]

Close but missing critical details Miniman =)

As you said GM designed the car as an automatic only, but very shortly before production started they decided to add a manual trans.

The problem they had was that the engine was destroying flywheels.... breaking them in two. Something about a certain frequency vibration or some such. The only obvious way to fix it was with serious reworking of the Corvair engine and they were WAY past the point where that was no longer an option. The solution they figured out was to make a special flywheel with the inner and outer parts connected by a "spun steel" part that acts sortof like a spring. The function of that center piece is to sortof absorb the vibration.

Also, it is pretty easy to change all the plugs on any Corvair engine as long as you have the air cleaner assembly removed. You do need a universal, or alternatively you can cheat and do it my way. I put the plug socket on the plug, then poke the fairly long extension down onto it. I just let the tip barely engage the socket and use the joint between the socket and extension as a universal joint. It does take a little dexterity but I do it all the time.

Anyone curious about the story behind the Corvair flywheel feel free to ask

Because the engine was never intended to be mated to a manual transmission, so when it finally did get one they had to come up with a way to put a clutch in there. This was the solution.

[mattsmithalamode]

Thanks so much for all of the responses, guys!

I apologize I've been silent on this thread. I've just been listening and working my butt of on the car every night. I'm fairly certain that I've narrowed the vibration down to a busted (or loose) flywheel, coupled with not-as-goog-as-it-could-be motor mount. Since I posted this, I've managed to get the engine to pur like a kitten (With the exception of some vapor lock, probably caused by the fact that I've yet to replace the carb spacers), but it still vibrates the same. I'm pulling the engine soon, so I'll know for sure.

As far as the question as to why I wasn't able to change the middle plugs, it's a relatively simple answer: I don't have a u-joint extension. Ha. I'm a young guy without a whole lot of tools, but this 'Vair will be done by March!

Thanks again!

[Gregory_Miller]

Where are you located, Matt?

[mattsmithalamode]

Hey! I live in Indianapolis, IN

[Trip]

LOL, I just noticed I replied about the flywheel thing twice... two long posts saying basically the same thing. I must have typed the first one when I was nearly asleep and then forgotten I did it!

Extra post deleted!