The motor in 398 is fantastic, I'm really happy with it right now. But I get terrible sounds on deceleration. From inside the car, it sounds like the sounds are coming from the front, but I wouldn't swear to it. Things are fine on acceleration, both leisure and aggressive. I have a slow grinding that doesn't go away with the ebrake on deceleration but does with the pedal. I also had a whorp whorp whorp that seems to be going away but still present with Redline Heavy Shockproof in the diff. And I get some contact with the exhaust on the carrier bearing, but this occasional. Clutch in doesn't seem to affect things at all. All these noises aren't present when the drive first starts, but drive for a few minutes, and it's undeniable.
I've taken the car to a few different shops, shop 1 said it was a bad bearing and diff, shop 2 said maybe the tranny? Shop 1 won't rebuild the diff because of age, which is no big loss because this shop hasn't exactly been stellar.
I've done some searching, and it sounds like some people are having success shimming the carrier bearing and installing a spacer (8mm is commonly called for) in between the driver jack shaft for the front wheels.
What is the best way to troubleshoot this? I realize that there are many causes for this, so I'm not looking for 1 answer solutions. I also realize that I may have a few different issues going on.
My plan so for is as follows:
Look at the driver's side axle with the wheel removed. Look and see if the angle from the axle to the jack shaft and see if a spacer seems appropriate. click
Stick a magnetic angle finder on the driveshaft and see how far off the different sections are. No one in the thread I read seemed to have a spec they were looking for, but a quarter an inch under the front carrier bearing seemed common. click
Lose the drive shaft all together. If the noise goes away, then it's likely the transfer case or the diff?
Stick Go Pros under the wheel wells of the front tires?
I have rebuilt the drive shaft about 1300 miles ago including the carrier bearing. I'd be surprised if they are bad, but it's certainly possible. Both front axles are new. I know front bearings are a b!tch to replace, so I'm hoping that's not it.
Suspects for this are (in this order): front bearings, driveshaft angle, jack shaft bearing or angle, diff, transfer case, drive shaft, tranny including center diff. Am I missing anything and how would you troubleshoot this? I am not willing to throw parts at this randomly and see what works.
Thanks for your help!