Torque convertor balance questions

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72dart_swinger

72dart_swinger

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I know a guy trying to find a driveline vibration and he is running out of ideas. He has a new rear axle, new mounts, tci transmission and a new driveshaft but hasn't found the problem yet. So I was wondering how noticeable are the vibrations if you put a neutral balance converter behind an externally balanced engine? Or if you use an external balance convertor with a weighted flex plate? I was wondering if he may have some mismatched parts and if this could potentially be part of the problem/
 
An unbalance converter/ flexplate in a situation thats needs one or vice/versa creates a vibration so bad that you wouldn't want to take it down the street and quickly gets worse will a little rpm in neutral. Other vibrations could be many things from a tire with a seperated belt, wheel/axle runout, to pinion angle
 
If the converter has the wrong balance, it can shake quite badly for sure. He bought the transmission from TCI. Did he get a converter with it, and if not, where did the converter come from? Engine: cast or steel crank, engine displacement, Transmission: 904/727, year of engine/year of transmission.
More information please.
 
transman said:
If the converter has the wrong balance, it can shake quite badly for sure. He bought the transmission from TCI. Did he get a converter with it, and if not, where did the converter come from? Engine: cast or steel crank, engine displacement, Transmission: 904/727, year of engine/year of transmission.
More information please.
Click to expand...
The engine is a blueprint 408 I think, the transmission was a new tci 727 unit that came with a tci convertor. I think it was this one Street Rodder™ Transmission Pkg: '67-'79 Torqueflite 727 (318, 340, 360) - TCI® Auto He was never asked for the way the engine was balanced when ordering, and I think he is using a weighted flex plate.

I know it isn't the tires, they are like a week old and the wheels are not bent. The vibration appears at 45-50 ish under acceleration and goes away when he lets off of the gas. Pinion angle has been suggested to him as well as taking the driveshaft loose at the axle and turning the driveshaft 180 degrees.
 
72dart_swinger said:
The engine is a blueprint 408 I think, the transmission was a new tci 727 unit that came with a tci convertor. I think it was this one Street Rodder™ Transmission Pkg: '67-'79 Torqueflite 727 (318, 340, 360) - TCI® Auto He was never asked for the way the engine was balanced when ordering, and I think he is using a weighted flex plate.

I know it isn't the tires, they are like a week old and the wheels are not bent. The vibration appears at 45-50 ish under acceleration and goes away when he lets off of the gas. Pinion angle has been suggested to him as well as taking the driveshaft loose at the axle and turning the driveshaft 180 degrees.
Click to expand...

I don't know what converter TCI supplied, but from the factory and using the factory flex plate, the converter was weighted as follows:

318 engine: 1967 1977 No weights

340 engine: 2 weights size: .88" x .62" x .177"

360 engine: 1971-76 : 2 weights size:1.62" x .75" x.380"

The weights are welded to the front of the converter (engine side).

From my past experience these three converters must be applied to the appropriate engine., and are not interchangeable.

The fact that he was never asked the way the engine was balanced and could/will cause issues when ordering a converter was wrong on TCIs part. IMHO they dropped the ball.
All of the above should help your friend if the converter is causing the vibration.
 
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If "Torqueflite Patty" is still on Ebay, that vendor used to sell weld on weights,for standard 273/318/ 340 non counter weighted converters...
 
If it was a weighted imbalance it would vibrate all the time! At idle does it vibrate enough to feel the vibrations by simply placing your hand on the fender! It would be a harmonic vibration, and would be happening all the time!

If it is happening only between 40-50 mph, it is in the driveline! He needs to start by eliminating all of the driveline components one by one! Don't discount the rims and tires just because they are new, check everything! If it's possible, have the wheels and tires checked on the car, it could be a bearing in a wheel hub!
 
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