73 Dart Swinger Vibes and Solution?
All,
I own a 73 Dart Schwinger 360 cu in with a 727 and a 8 3/4 rear with a 489 hog head, also SS springs. It's is all new to include the drive shaft and the diff internals. The car has low low miles since completion. It's only been out on the freeway twice this year up to 70 or so mph.
I have noticed that I have the dreaded rythmic vibes/harmonics at freeway speed. I have spoken to some and have used this site for info and details, thanks! Before I press forward with any changes here is what I learned and pics of the associated drivetrain.
A local expert told me after seeing a pic of the yoke engagement into the trans, he indicated that this was the issue at least initially as it appears to be too far out.
So I measured the shaft and it came out to be 49" and 5/8" approx. Subtract 2" from pic see below.
I inserted the Yoke and pulled it out 1" and remeasured. The results are 50" as best as I can tell from the tape.
So the previous measurements I did not have the Yoke inserted properly before measuring when I had it made. It's appox 5/16 to 3/8 too short.
Sooooo, before I trot off and have my shaft lengthened I have some questions? Is this out of spec condition really enough to cause the vibes? I can see it being quite possible but I need some conformation/peace of mind.
Another issue that I looked into is the angles of the rear pinion and the trans.
From what I have read with the SS springs that the rear angle is supposed to be 7 deg? As you can see, the front output shaft is basically at Zero angle. It's not shimmed and the car did not have the vibe issues AFAIK before the rebuild of the car. Is this angle correct and an acceptable point to measure the shaft from?
Thanks for any input you have on this worn out subject, sorry but it's my turn in the barrel so to speak and don't want to waste and $$ and time.
Again, Thanks Marion
All,
I own a 73 Dart Schwinger 360 cu in with a 727 and a 8 3/4 rear with a 489 hog head, also SS springs. It's is all new to include the drive shaft and the diff internals. The car has low low miles since completion. It's only been out on the freeway twice this year up to 70 or so mph.
I have noticed that I have the dreaded rythmic vibes/harmonics at freeway speed. I have spoken to some and have used this site for info and details, thanks! Before I press forward with any changes here is what I learned and pics of the associated drivetrain.
A local expert told me after seeing a pic of the yoke engagement into the trans, he indicated that this was the issue at least initially as it appears to be too far out.
So I measured the shaft and it came out to be 49" and 5/8" approx. Subtract 2" from pic see below.
I inserted the Yoke and pulled it out 1" and remeasured. The results are 50" as best as I can tell from the tape.
So the previous measurements I did not have the Yoke inserted properly before measuring when I had it made. It's appox 5/16 to 3/8 too short.
Sooooo, before I trot off and have my shaft lengthened I have some questions? Is this out of spec condition really enough to cause the vibes? I can see it being quite possible but I need some conformation/peace of mind.
Another issue that I looked into is the angles of the rear pinion and the trans.
From what I have read with the SS springs that the rear angle is supposed to be 7 deg? As you can see, the front output shaft is basically at Zero angle. It's not shimmed and the car did not have the vibe issues AFAIK before the rebuild of the car. Is this angle correct and an acceptable point to measure the shaft from?
Thanks for any input you have on this worn out subject, sorry but it's my turn in the barrel so to speak and don't want to waste and $$ and time.
Again, Thanks Marion
