I'm chasing a vibration problem. Every part of the drivetrain has been balanced or replaced from the tire/rim to the converter. Using a piston stop FIRMLY located in the spark plug hole with a jam nut, I've very carefully checked TDC and it comes to about 2.5 degrees away from the marked TDC on the balancer. It's a Ford Racing 28 ounce external, bolt on weight and looks to be in good condition. It is a common elastomer type with outer ring. Not a cheap balancer, but an SFI good quality. During a burn out, I can feel a slight amount of vibration at 5000 in first gear, shift to HIGH and repeat more vibration. Going down the track, it REALLY becomes harsh the closer to the stripe....about 6400 RPM. I'm out of places to look for the solution. Question, how many degrees off does it take for an external balancer to show a vibration? Thanks for your help.

you said drivetrain so the driveshaft was checked and rebalanced?

Is this a new engine?
If not, has it always vibrated?
28oz then it's a sbf.

To answer your original question I need to ask one. Was the crankshaft balance with that damper?

Sounds more like a driveline vibration from the way you describe it.....

Agree on the driveshaft. I chased a vibration for awhile once, finally decided to have the driveshaft checked from a friends suggestion and the guy called me from the driveshaft shop and said that he had to back away from the machine thinking it was going come off. If your driveshaft is a long 50"or more you could be reaching "critical speed". I had to go to a 4" dia. alum. and vibration gone. My old 3" steel at 55" long just wore out. Check 'driveshaft critical speed" and I think Strange and Morrison have charts to follow.

I'm trying to figure out what it is OP, your talking about with the balancer and TDC?

Thanks for the suggestions. The vibration started late last year in a different car. I sold that car and now have a new car with NOTHING from the old car except the balancer and flexplate......which were both visibly checked by the engine builder. I now have: new tires (balanced), new Weld Racing Pro Stars, new ring/pinion, new d'shaft in a 1988 Mustang (it has to be less than 50" long), Moser axles straight and true, a friends PG that worked fine in his car, new Gregg slack converter. D'shaft angles were checked and corrected from tailshaft to pinion angle. I'm just flat out of ideas and where to look. I'm going to remove D'shaft and have it checked again. Thanks for your help.

quote:

Originally posted by 62Galaxie:
Thanks for the suggestions. The vibration started late last year in a different car. I sold that car and now have a new car with NOTHING from the old car except the balancer and flexplate......which were both visibly checked by the engine builder. I now have: new tires (balanced), new Weld Racing Pro Stars, new ring/pinion, new d'shaft in a 1988 Mustang (it has to be less than 50" long), Moser axles straight and true, a friends PG that worked fine in his car, new Gregg slack converter. D'shaft angles were checked and corrected from tailshaft to pinion angle. I'm just flat out of ideas and where to look. I'm going to remove D'shaft and have it checked again. Thanks for your help.

Powerglide tailhousing with a bearing or bushing?

I chased a vibration for a month once back in the day, installed new bushing in tailhousing, did not fix it.

Bought and installed a roller tailhousing, MW yoke, did fix it.

Made no sense, but it fixed it.

I'm not familiar with a Ford engine, does the flywheel have a balance weight? Is it possible to install it wrong?

You say a new converter, it's possible that is the issue.

quote:

Originally posted by "The Bender":
I'm not familiar with a Ford engine, does the flywheel have a balance weight? Is it possible to install it wrong?

You say a new converter, it's possible that is the issue.

Yes...
Leave the car in park and sitting in the car slowly bring the RPM's up to as high an RPM as you have nerve. See if it vibrates. If it does obviously it's the engine.
If it's smooth, jack the rear wheels up and WITH JACK STANDS UNDER IT, get it in high gear and SLOWLY bring the RPM's up and see if you get vibration. If it vibrates then something is out of balance from the rear tires to the front u-joint.
Now your flexplate and damper both have counterweight built into them. Looking at them will NOT make them balance out your crankshaft. The crankshaft has to be balanced with both attached to the crankshaft during the balancing procedure.
As a matter of fact if your engine is a 5.0 it needs the 50oz flexplate and damper.


Hope this helps you find your issue(s)...

quote:

Originally posted by imakehp:

As a matter of fact if your engine is a 5.0 built before 1982 it needs the 50oz flexplate and damper.


Hope this helps you find your issue(s)...

FIFY

I ruined a engine that was doing the same thing. It was caused by a famous balancer builder sending a balancer for an internally balanced engine and my engine was externally balanced. Wrong ballancer

quote:

Originally posted by Mike Rietow:
I'm trying to figure out what it is OP, your talking about with the balancer and TDC?

I found TDC on the BALANCER by using a piston stop. Stop the engine about 20 degrees before TDC and make a mark on the balancer. Rotate the other way and when it stops, make another mark. Exactly half way between those two marks is true TDC on the balancer.

quote:

Originally posted by 62Galaxie:

quote:

Originally posted by Mike Rietow:
I'm trying to figure out what it is OP, your talking about with the balancer and TDC?

I found TDC on the BALANCER by using a piston stop. Stop the engine about 20 degrees before TDC and make a mark on the balancer. Rotate the other way and when it stops, make another mark. Exactly half way between those two marks is true TDC on the balancer.

Ok,move your TDC pointer to the correct position you've now established, it was incorrect.

That's not gonna affect the balance unless the crankshaft is twisted/bent. I'm sure this is what you're thinking, but it's not very likely at all unless the rear main seal is leaking (other symptoms).

Try a roller tailhousing on the powerglide, it might've tweaked the output shaft.

This message has been edited. Last edited by: Mike Rietow,