86 T4R mystery driveshaft vibration!!!
01-27-2013, 06:57 PM
#1
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86 T4R mystery driveshaft vibration!!!
Truck vibrates at 25-35 mph & 55-70 mph. majorities of vibrations is from the front end, meaning below me. ONLY happens when acceleration. STOPS when I let foot off gas.
I install new spring leaves in the rear and had to move my spring hangers 7.5 inches forward from stock and move my rear shackle mount 2 inches back. Everything looked right with a slight pinion angle issue. After reading 4Crawlers on “how to calculate degrees on pinion angles”, I calculated 23* off. I drove it like that for many weeks and it was horrible and annoying at all speeds. There was a bad vibration with foot ON the gas pedal. After getting new spring perches and correcting the pinion angle. All that went away except for the “25-35 mph & 55-70 mph” vibrations. My driveshaft is a custom made shaft measuring at 39" flange to flange.
after weeks of driving i took off the DS and discovered the double cardan cap that goes over the ball had a lot of play and also discovered that cap was broken.. i replace the entire double cardan, and re-grease all the u-joints and had it balance at a local DS shop.. after the install, the vibebration reduced 75% with a slight vibe at the same speeds. i check the TC flange nut and that was good. also check the motor mounts and that cleared too. so i decided to drop my TC 1/2 inch by adding washers. it helped a little. my wheels are /\, but never an issue before and never pulled to any side.
drive train info:
86 T4R, SAS, TG 5" lift f/r, 4.70 dual case, ARB locker w/ 5.29 f/r, 35x12.5x15 KM2, rear DS 39" double cardan, front DS 35 1/2" single cardan
i can get measurements again if needed..
What could be wrong? Need your expertice and advice. running out of ideas. Thanks.
I install new spring leaves in the rear and had to move my spring hangers 7.5 inches forward from stock and move my rear shackle mount 2 inches back. Everything looked right with a slight pinion angle issue. After reading 4Crawlers on “how to calculate degrees on pinion angles”, I calculated 23* off. I drove it like that for many weeks and it was horrible and annoying at all speeds. There was a bad vibration with foot ON the gas pedal. After getting new spring perches and correcting the pinion angle. All that went away except for the “25-35 mph & 55-70 mph” vibrations. My driveshaft is a custom made shaft measuring at 39" flange to flange.
after weeks of driving i took off the DS and discovered the double cardan cap that goes over the ball had a lot of play and also discovered that cap was broken.. i replace the entire double cardan, and re-grease all the u-joints and had it balance at a local DS shop.. after the install, the vibebration reduced 75% with a slight vibe at the same speeds. i check the TC flange nut and that was good. also check the motor mounts and that cleared too. so i decided to drop my TC 1/2 inch by adding washers. it helped a little. my wheels are /\, but never an issue before and never pulled to any side.
drive train info:
86 T4R, SAS, TG 5" lift f/r, 4.70 dual case, ARB locker w/ 5.29 f/r, 35x12.5x15 KM2, rear DS 39" double cardan, front DS 35 1/2" single cardan
i can get measurements again if needed..
What could be wrong? Need your expertice and advice. running out of ideas. Thanks.
Last edited by tyes; 01-27-2013 at 07:03 PM.
01-28-2013, 04:06 PM
#5
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01-28-2013, 04:18 PM
#6
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