Need help with vibration!!

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1972orangebeast

1972orangebeast

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Ok I'll start off by letting you know I have a 72 dart with a fresh built 360, 10.5:1 comp .484 comp cam, motor builder had the back half of crank internally balanced, and front half balanced with a 360 dampner so I could use my 340 flywheel and not have to get it balanced. I have a t56 six speed behind it with rms suspension , had the car running last year with no issues in with vibration , motor was pulled because not running good and found this 360. Just for reference I had drive shaft re balanced, have not messed with suspension angles or anything like so. The vibration starts at 2200 and gets worst, as the motor is still being broke in have not taken it over 3500 on the street, the weird thing is in the drive not moving you rev the motor and is fine, only when I have it in gear going down street. Also speed or mph does not matter happen at 5 mph or 50 mph just the same rpms.

If I balance flywheel and it doesn't need it balanced will that hurt anything? I'm lost and would like to get iron out as I'm trying to make the power tour this year! Thanks Gavin
 
Well it's "simple."

If it does not vibrate in gear, then it's right there in the engine.

Determine if having the clutch engaged or not makes a difference, you might have torn up the clutch disc (tore lining off one side)

If it shakes while moving, it's something in the drivetrain, yet to be determined.

I've never heard of "balancing the back half" of a crank. Personally, this sounds like BS to me
 
Sorry it does vibrate in gear going down the road, but not when in neutral sitting in the drive. That's the only thing I have changed since last yea r is the motor and I assume that's my problem. I had clutch out and checked its fine, but now if I have flywheel balanced could it effect anything else? Like is it possible it could get worst? It has a 360 dampner on the front and I saw and have my balancing sheet if that helps ? I don't know how to read it and I did see where crank had Mallory metal added in the rear of crank
 
its in the drive line.u joints would be a starting place.you said you had the d.s. balanced?i would look close at it,ask me how i know.chased a bad vibration for tears,turned out it was a badly done d.s.,and it was done by a well known company
 
Also, don't discount simple things like a broken engine mount. (Don't know why "we" call em motor mounts, LOL, it's not a Pree ***) but I digress

If you had something like a broken mount, etc, might be possible that the torque of the engine going down the road would pull it over and vibrate/ rattle against the frame/ body.
 
I watched the drive shaft get balanced, it was out by few grams , new u joints last year (less than 100 miles on everything) rms suspension frees up lot of space, no broken mount, I assume has to be something with that crank balancing and my flywheel. Also my 8 3/4 was just torn apart and checked and everything is good. Like I said last year with the 340 had no vibration at all, now I do. So for me that rules out the drivetrain besides motor for most part. I'm scared to try to bring motor up over 3500 to be honest.
 
if it does not vibrate in park,rev it up too,then its not in the engine...
 
I don't know why you "assume" it's the engine

You have said twice that it DOES NOT VIBRATE in neutral with the car stopped. This indicates OTHER than the engine and clutch.

DETERMINE that first!!!!

Get it in gear, clutch in, parking brake engaged, and block the tires for safety. Rev the engine at different RPMs until you are satisfied...........one way or the other..........that it does or does NOT vibrate

If it does NOT vibrate, put the gearbox in neutral, and take your foot off the clutch. Repeat the test. take your time. Rev quickly, rev slowly, hold it at different RPMs until you are SURE what you are hearing and feeling.

If there IS vibration the very FIRST thing to check is the belt(s). With the engine cold, you can run it long enough with the belts "off" to determine if they are the problem, could even be something wrong A/C, water pump, alternator, PS pump, etc.

Unless the engine (it is not a motor, unless you've converted it to battery power) has something serious wrong such as bent valves, whatever, 3500 is NOTHING.

Hell my Dart---before I tore it down for paint---has 3.7's in the rear----CRUISES at 70 at about 3300!!!


Make sure your tach is accurate, though. You can "figure that" online with the various calculators. You need to know your tire size, your rear axle ratio, and whether the 4 speed is an OD or "regular" 4 speed. Use a GPS if possible, and get a good solid reading at about 60 mph VS RPM in "high" gear.

Then feed that into an online calcuator.
 
he said it does not vibrate in the drive way,he said it is speed related.he can rev the engine and no vibes,that why i can say its not in the engine
 
Ok i guess I didn't ask that that if it was the motor it would vibrate in neutral correct? I'll try those couple of things to te verify that it doesn't vibrate in neutral with or without clutch engaged etc. I appreciate all the help, I'll update a little later when I try the couple things above.

Also it is not mph related, I've been running at 5 mph and 50 mph and it goes away if I up shift and rpms drop.

Also I haven't. Reved it higher than 3500 because I'm still seating the rings and motor doesn't have 10 miles on it yet
 
The power steering pump pulley is maybe 1/8" behind the crank pulley when your looking at the belts lining up, and is because 360 dampner is larger than the 340, would it really cause a vibration that bad? I can feel vibration in steering wheel, shifter, seat everything shakes!
Thanks agin
 
the motor wouldnt necessarily vibrate in neutral with a good cam and no load... You need to have the bottom end balanced properly ON HIS DIME...
 
Bingo...^^^^ A friend owns a speed shop & balanced. He has redone" balanced " rotating assemblies, both speed/machine shop & out of the box stroked kits. He just did a Chevy 350 long rod Scat kit. It was more ,than 20 grams off.
 
Are you sure it's not a misfire condition that is giving you the sensation of a vibration? Is it worse under load?
If I'm reading this correctly you're saying that it's RPM related & not MPH related. So that would suggest it may be engine related. I have to admit that your engine balancing combination sounds very odd to me. I certainly would have opted for a different way with that. I never heard of balancing an engine in 2 halves.
 
Yea I know the balancing sounded odd, started off that it was going to be balanced exactly like my 340, and I was ok with that, then when motor was done, my motor guy was trying to save me a few pennies I think and did the half and half thing, I'm still learning and just took it as it was ok, but now I'm not so sure, and if it is that would balancing the flywheel correct that now?
If that is the case, to balance a flywheel you need the whole motor to do so or can I just take flywheel somewhere to be balanced?
 
Pretty sure has to have whole rotating assembly to balance the flywheel correctly. As I have a 318 flywheel and I was wanting it balanced for a external 360.
Will be cheaper to just buy a 360 flywheel.
 
The whole thing has to be balanced together in the same manner. It's ALL one rotating assy & can't be separated into 2 halves. The flywhell is going to have an effect on the front part of the assembly as well as the back part. Same for the balancer. You can't mix an externally balanced damper with an internally balanced flywheel(un-modified) & rotating assembly.
I don't know what your machinist did in his balancing process, so it's hard to be able to tell you what to do now. If it were me I'd have it all redone & ditch the external balancer if you still intend on an internal balanced assembly. I'd probably use a different machinist for the job since his work so far has me skeptical of his knowledge.
I hope this helps. Good luck.
 
If I had to guess, like they mentioned - the external banace on thef ront of the crank, with the internal balance on the rear, could be creating some harmonics as rpms rise. Normally the weight offsetting the imbalance is either within the main caps (internal and best way to balance) or outside the caps(external and the cheap way). That gives each end of the crank the same "input" in terms of vibrations and torsional load. I think your problem lies there. It's not enough during a free rev, but is enough when the crank is loaded. I'd also look into aligning the bellhousing to the new engine.

If you're in gear driving in 3rd (figure around 30-40mph) and creaping up towards 3500 - so it's shaking - and you press in the clutch without taking your foot off the gas pedal entirely, what happens to the vibration?
 
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