Vibration @ 3000 RPM. Converter??

[Josecuda]

My '68 cuda has a mild 440 backed up by a TF-727 using the stock torque converter. The car was finished two years ago and had no problem since. The thing is that last night I took the 'cuda for a ride and I noticed an annoying vibration that starts when the car hits 3000 RPM. If I lower the RPM's the vibration dissapears but if I go more than 3000 RPM it gets worst. I think the torque converter is guilty on this one but I'm not sure how to tell if it is. The 440 has a cast crank (external balance) and the torque converter that goes matched to it. Never had an issue like this before so any help will be highly appreciatted. Thanks!

 

[Josecuda]

Bump

 

[Robbie2734]

Just a question, do you have the vibration in neutral? If not maybe you lost a weight on one of the rear wheels?

 

[Josecuda]

Yes, I do have the vibration in neutral.

 

[Robbie2734]

Ouch, I think you're right about the TC. Maybe it threw a weight, you should be able to eyeball that.

 

[Mrmopartech]

Before you buy a new convertor,check the vibration dampener to see if it has twisted and moved on you,this will cause the problem.Your convertor,when you installed it,did it have weights on it,if so,are they still on there,mrmopartech

 

[Josecuda]

I've gotta check if the weights on the convertor are still there. I didn't even knew the convertor could "throw" them. Thanks for the help.

 

[fishy68]

I guess anything can happen but I've never seen a converter throw weights off. Somebody would have had to a really lousy job welding them on for them to come off. The balancer ring spinning like MrMopartech said is pretty common for an old balancer.

 

[Josecuda]

Just for a follow up on this old thread. The weights were in their place, the damper was doing its job fine. Changed the flex plate and used a B & M external balance adapter type flex plate to use an internal balance converter (neutral balance) I had laying around. Problem solved, being the convertor the faulty part. Thanks!

 

[fishy68]

Sounds like you have a neutral balance converter there. That's why the B&M plate fixed it.

BTW: All converters have balance weights on the outer ring. The converters made for externally balanced engines have an extra weight welded onto the face between 2 of the flexplate bolts. Sounds like yours must not have those weights. Glad to hear you got it fixed.

 

[haole]

I had the same problem. My flex plate bolts to the crankshaft loosen up. I re-torque them and used locktite red on the bolts.