Duster Driveshaft length causing Vibration?
All,
Looking for help in troubleshooting a driveline vibration on my 74 Duster w a 360/727.(car had a few problems when I bought it including a slipping trans. & a bad driveline vibration at ~55mph). The past few years of ownership have included: confirming proper driveshaft balance & U-joints, rebuilt 727, new engine(a stroked internally balanced 360), new tires(balance checked twice), & some shimming work to correct poor alignment btwn trans output and diff.(they are within 1/2-deg of parallel). CURRENTLY: vibration has been reduced but still starts to be an issue ~55mph & drives me nuts.
Car was originally a 6-cyl./904 car & was converted it to 360/727 with an 8-3/4 rear by P.O. My latest research is leaning me to think that the driveshaft is simply too short and/or trans. pinion is not the correct one for my set-up. I AM thinking that these shortcomings are resulting in my driveline vibration. (See pics included).
Details:
a) Distance between C.L. of U joints from the pinion (fully seated into trans.) & the differential input is 45-3/8"
b) Length of driveshaft btwn the centerline (C.L.) of U joints at each end is 44" (This results in sliding the pinion out 1-3/8" from its fully seated position to reach the driveshaft.
c) As the pics show, when installed, my pinion extends just over 3" out from the end of the trans. (I do not have the full length measurement of the pinion but understand that there are at least 2 different lengths commonly used)
So,...after reading about a hundred different posts here concerning driveshaft length and proper measurement procedures, here is what I am thinking:
1) My 44" driveshaft is too short. (as per various posts, the standard length for my set-up should be 44.99" and exact target length should be determined after a full set of specific measurements)
2) The fact that my pinion shaft has 3" of length showing is Way too much (As per various posts, optimum should be btwn 3/4" to 1-1/4"...additional length "could" result in vibrations...)
QUESTION: Does my reasoning seem solid? Has anyone experienced similar driveline/driveshaft vibrations as a result of my car's current set-up? What other troubleshooting steps can I take?
THX-Scott
All,
Looking for help in troubleshooting a driveline vibration on my 74 Duster w a 360/727.(car had a few problems when I bought it including a slipping trans. & a bad driveline vibration at ~55mph). The past few years of ownership have included: confirming proper driveshaft balance & U-joints, rebuilt 727, new engine(a stroked internally balanced 360), new tires(balance checked twice), & some shimming work to correct poor alignment btwn trans output and diff.(they are within 1/2-deg of parallel). CURRENTLY: vibration has been reduced but still starts to be an issue ~55mph & drives me nuts.
Car was originally a 6-cyl./904 car & was converted it to 360/727 with an 8-3/4 rear by P.O. My latest research is leaning me to think that the driveshaft is simply too short and/or trans. pinion is not the correct one for my set-up. I AM thinking that these shortcomings are resulting in my driveline vibration. (See pics included).
Details:
a) Distance between C.L. of U joints from the pinion (fully seated into trans.) & the differential input is 45-3/8"
b) Length of driveshaft btwn the centerline (C.L.) of U joints at each end is 44" (This results in sliding the pinion out 1-3/8" from its fully seated position to reach the driveshaft.
c) As the pics show, when installed, my pinion extends just over 3" out from the end of the trans. (I do not have the full length measurement of the pinion but understand that there are at least 2 different lengths commonly used)
So,...after reading about a hundred different posts here concerning driveshaft length and proper measurement procedures, here is what I am thinking:
1) My 44" driveshaft is too short. (as per various posts, the standard length for my set-up should be 44.99" and exact target length should be determined after a full set of specific measurements)
2) The fact that my pinion shaft has 3" of length showing is Way too much (As per various posts, optimum should be btwn 3/4" to 1-1/4"...additional length "could" result in vibrations...)
QUESTION: Does my reasoning seem solid? Has anyone experienced similar driveline/driveshaft vibrations as a result of my car's current set-up? What other troubleshooting steps can I take?
THX-Scott
