tdbrown75

Sure did, that's what they blamed it on the first time in so I got an Adjustable UCA and had the pinion set to -2 as recommended by most. Stock drive shaft to this point.

Tim

alkemist

IMO, that is all relative. Some people are just much more sensitive then others. Some can hear the slightest almost to nothing whine, feel vibrations, etc and then there are others that just can't hear/feel it at all.

I have minor vibrations along with minor decel whine. I knew the risks associated with gear swaps, and sometimes I do wonder what are normal characteristics. While some just claim that it shouldn't be, but again I go back to sensitivity of the person driving/riding in the vehicle.

tdbrown75

Yep, case in point with my friend's car. He's got the same humming sound I have and he's not at all concerned, I'm not even certain he can really hear it. I also called FRPP earlier today and went over everything with them as well. Thier take, more gear noise is perfectly normal with higher ratios. Noise that can only be heard by carefully listening with the radio off should be of no concern.

I've been to 2 dealerships and 2 speedshops, only 3 of the 6 mechanics that drove it could even hear it. 2 felt it was probably just the 4.10s and I should not be concerned. Only 1 was uncertain enough to investigate further and after an entire new gear set and axle also believes it is characteristic. The Ford dealer engineering hotline and FRPP say the same.

I think I've beat this horse enough at this stage. There's absolutely no performance impact and the car runs fine. Should something change dramatically down the road or something breaks then I can address it at that time.

tdbrown75

Update: I decided the 4.10s are a bit much for me on the highway so I'm dropping back to 3.73. I'm secretly hoping it fixes my vibe problem too, but I'm not overly optimistic about it. Car goes in Wednesday where I should have took it for gears the first time. I'll be back with an update once I get it back.

Tim

tdbrown75

I believe my vibration is fixed. During the gear install the mechanic noticed some casting left on the carrier where the ring gear seats. He says this would cause the ring not to lay perfectly flat against the carrier surface and could have produced the vibe. I took the car out on the highway and up to 90 MPH and it was smooth as butter.

The bad news is I had a small amount of whine on deceleration before, and now it’s about 30-40% louder and over a larger range. He’s going to tear back into it tomorrow to check the pattern and make adjustments to see if he can quiet it down.

I have an aftermarket adjustable panhard bar and UCA with firmer bushings so I don’t expect 100% silence. If he can just get it back where it was before I’ll be thrilled. Also the car felt plenty peppy with the 3.73s and the RPMs were MUCH better on the highway.

Tim

tdbrown75

I just spoke to my installer. He stayed late last night to make some additional adjustments. He adjusted the pinion depth and reduced the backlash from .12 to .10 to silence the whine. For any of you who might see this thread when researching your own whine/vibration issues, hang in there and know they are resolveable even if it takes a while.

Tim