pufferfish
Supporting Vendor
i have always had drivetrain noise. mostly gear whine after the steeda 3rd link, but some other faint clunking and whatnot. i installed an aluminum driveshaft and immediately noticed an issue. between the point of accellerating and decellerating, the drivetrain consistantly develops a horrible rattling sound you can feel. i don't have a vibration under load (tested to 160mph at VIR). i double-checked my driveline angles. to me, it sounded like excessive gear backlash causing the gears to bang from the front of the teeth to the back of the teeth. i steer clear of gears, so i took it to JPC. their first impression on the ride-along was exhaust hitting. it was all checked and nothing. they agreed the next logical source of the noise was the gearset. i decided to have the gearset replaced with a different ratio and add a torsen diff. going from 3.73 to 3.55 did quiet down the whine, but did nothing to kill the rattle. they changed out the driveshaft with 2 different aluminum pieces and checked my driveline angles, which were good, and the rattling persisted.they put a stock 2-piece in and the rattle is gone. i called dynotech (the mfg of my driveshaft) to ask if they had ever heard of this issue. nope. JPC installs many driveshafts and never saw this issue. the next thought was the transmission. i took it overto the ford dealer and had their shop foreman take a ride. i think he fully expected it to be normal NVH for a modified car, but quickly changed his tune when he heard it. he believes i should be looking at the trailing arms for a bushing that walked and allows the arm to touch another piece of metal. i disagree, but will look at it anyhow.
it makes the noise at highway speeds when i let off the throttle. once the engine starts braking, it goes away. if i push the clutch in at highway speeds, it rattles tremendously until i re-engage the clutch in gear. the likelyhood of a chassis metel to metal contact rattle only occurring under these conditions is really unlikely and i would still rattle with a 2-piece shaft in there.
since its not the rear gears/bearings or the driveshaft, the only place left for a drivetrain rattle is the trans, right?
i have scoured the internet and can't find another example of this issue, but figured i would post here to see if anyone else has heard of such an issue or has a suggestion to check as the possible culprit.
it makes the noise at highway speeds when i let off the throttle. once the engine starts braking, it goes away. if i push the clutch in at highway speeds, it rattles tremendously until i re-engage the clutch in gear. the likelyhood of a chassis metel to metal contact rattle only occurring under these conditions is really unlikely and i would still rattle with a 2-piece shaft in there.
since its not the rear gears/bearings or the driveshaft, the only place left for a drivetrain rattle is the trans, right?
i have scoured the internet and can't find another example of this issue, but figured i would post here to see if anyone else has heard of such an issue or has a suggestion to check as the possible culprit.