Driveline vibration

[Royce]

Joe  the car vin says 352. When I had the motor out I checked and it is a 390 now.. It looks like a recent engine rebuild was done.. C1 block and heads  original style mounts.. 57 Lima Bean has me convinced it is a torque converter..How can anyone question Jay Brown's "riding mechanic" diagnosis.

[e philpott]

Royce I would send that converter to these guys http://www.dynamicconverters.com/aboutus.htm and have them check balance , if you like the Converter they can repair and not re-engineer the Converter , I have sent quite a few to them for repair , they can also tweak the stall up or down if want , the performance repair side is a great small group of guys that easy to work with for such a huge company

[Royce]

This is a Hughes street performance converter 2000 rpm stall it is about perfect for this application  . Relatively inexpensive so replace might be a better option than repair

[gt350hr]

  Royce if the vibration happens in neutral , you nailed it being the converter.

[shady]

I had a converter vibration that happened intermittently under load, never in neutral. ran hot too.

[gt350hr]

  That's a new one on me. Must have been the stator and turbine out of sync.

[shady]

It was a lock up converter, now that I think about it.

[57 lima bean]

I had a converter vibration that happened intermittently under load, never in neutral. ran hot too.

   This is what I had asked Royce to do on jackstands floating the load with the brakes.Hope this is the cause and not some zany,madcap idea coming from listening to too much Beaker Street when younger.

[Pentroof]

I had a vibration in a new build that I absolutely had pinned down to a converter...or so I thought. Every other possibility in the driveline was eliminated with the 1700rpm vibration still happening in park with all the accessories off.

Well, it turns out my cam and my tri-Y headers generate a natural resonance and the passenger side pipe was barely touching the tranny crossmember. One large crowbar persuasion and 90% of the accentuation was gone.

Problem was, I had to replace the converter to convince myself to look at the exhaust. I may weld some large weights to the exhaust to kill the rest of it.

[Royce]

Well an epic fail on diagnosis so far. Replaced flex plate and converter and no change.  Unhooked all the accessories and no better. I think I have eliminated any problems from the engine back.. idling in neutral engine runs perfect. Makes plenty of power and no nasty mechanical noises,, Front damper has no run out.. Rev it up to about 2000 and it starts to vibrate and gets worse as you add rpm..I am suspecting internal engine problem   but what?

[338Raptor]

Are you 100% sure you have the right damper? (Weighted vs non-weighted)

[Royce]

Yep  Early type damper..

[GerryP]

A misfire can cause a vibration.  Just because you don't have it at idle doesn't mean it's not there.  Any chance you can get your hands on an ignition scope?

[machoneman]

Well....I'll tell as quick as I can an now old story. Uncle Bill had a brand new '57 Ford Fairlane V-8 that had a weird and similar vib at highway speeds. The dealership looked everywhere. They gave up and called in a factory repr. He also came up empty handed...until he told the mechanics to pull the engine.

On teardown. he found one rod end, the big end IIRC, had not been machined at all and was therefore way out of balance. One new rod, checked for balance, and all was well.

Moral? If you're sure the balancer and 'wheel are o.k, a teardown may be in your future.

[Joe-JDC]

Do a quick stroke check to see if it is a 3.784 or 3.984".  I have a sneaky suspicion that the flexplate does not match the crankshaft.  I had a '69 R Code mustang that I bought with 4 speed, and it had the N heads, CJ cast iron intake, carb., exhaust manifolds, flywheel, four speed, etc., etc., and on the drive home it vibrated above 2000 rpm and just got worse the faster I drove.  Upon teardown, it was a 390 flywheel.  Looked perfect, looked correct, until you turn it over and see the weighted side was smooth.  The other scenario with imbalance(different car) that I experienced was a piston stuck and when I tried to start the CJ after it had sat for over a year, it would not turn over.  I thought it was just a weak battery, so I put a new battery in, and jumper cables to a running vehicle with the new battery.  It moved an inch or so, and then popped, and started running.  I drove the car for three years with a miss and vibration.  No amount of tuning would get that miss to go away.   When it finally broke, on teardown, there was a rod broken in three places.  The small end was still attached to the piston stuck almost at TDC, and the big end was still spinning on the crankshaft.  Had oil pressure, and felt strong, but vibrated.  I really have had three CJs that gave me problems since they first came out in 1968.  I like FEs, but the CJs have bit me several times.  Joe-JDC