richmod

I'd like to keep this theoretical rather than pour over the details of my situation. Let me just say that I have stock gears/diff that whine on decel/coast only between 53 and 40 mph. Not horribly loud, but noticable and annoying. I plan on ckecking/changing fluid, etc etc, but would like to know this;

If the whine is due to improper backlash or pinion depth, can these things be adjusted without tearing the whole thing down and starting over? If it matters, I have about 12 k miles on it. So basically, can one silence the whine on used gears if it's due to backlash or pinion depth?

doctorstrobe

Hi,

If it's still in warranty you should probably bring it in to get it fixed.
If not then there's probably not much you can do without tearing the thing apart.
Pinion depth is only adjustable by pulling the pinion gear out and changing shims.
Backlash is done by pulling the differential out and changing shims.

Have you lowered it at all? I've heard other people complain about what sounds like gear noise and it was really that the pinion angle needed to be adjusted after lowering...

2007VistaBlueGT

I agree, also if you have aftermarket control arms you can get a whine on deccel or a flutter slowing down.

richmod

Not lowered, stock control arms. Basically, the original differential was replaced by Ford after numerous attempts to fix whines/vibrations/etc. I was told the new diff came already put together - you just remove the old one and put on the new one. However, the new diff/gears whine. So - when you install a new, sealed differential, do you still have to set backlash and/or pinion depth? I'm just trying to determine if it's a gear/setup problem from the factory or whether it was a install/setup problem at the time of the new diff installation.

GotMunchies?

Because the problem persisted when they swapped in a new differential, it could be a problem with balance in your drive shaft, especially if its most noticeable at certain velocities. Your drive shaft may be out of balance in such a way that it resonates at a rotational velocity achieved when the car is between 43 and 50 mph. Excessive vibration in the driveshaft could effect the internals of the differential. Likewise, it could be an issue with an axle, so have those checked out.

Riptide

The following is a general statement not necessarily aimed at the OP.

You know honestly. I totally sympathize about noises in cars bugging a person. I hate rattles, squeaks, hums, etc.. But it's just a reality of having a car. Just about any car especially as it gets older and in cold weather is going to be a rattletrap. You can really drive yourself insane trying to track down every little hum, whine, etc. in a car. Some people have spent hours if not days doing it. I guess if it's worth it to you go ahead. I just don't have the patience for that any more. If it isn't a performance or a safety issue then I don't spend much time trying to figure it out. If a cursory glance doesn't reveal the culprit and nothing is really wrong with the car then it's just an annoyance. And I learn to deal.

Just a random opinion courtesy me.

richmod

It disappears immediately when put in neutral. Since driveshaft and axles are still spinning, that rules them out. It is also independent of gear, which rules out tranny.

richmod

Gear noise is not comparable to rattles. Gear noise could indicate improper setup, which can reduce the life of the gears. Also, if this noise was there from day one, I would/could live with it. I have plenty of rattles, creaks, etc that don't bother me. But this is different. Since Fords repair attempts have caused my car to be noisier than before I took it in, why should I settle for that?

Riptide

Did you read the first sentence of my post?

doctorstrobe

It's not clear in your post, but if they replaced just the differential carrier and ring gear assembly and not the PINION gear also then that's not good. From what I've read the gear sets are lapped together and are a matched set. An old pinion gear with 12K miles on it won't mesh right with a new ring gear.

If they replaced both the ring and pinon at the same time then I'd hope they would have checked the pinion depth at least by doing the marking paint and checking the mesh pattern. Backlash is very easy to do so I'd figure they'd do that too.
I'm not sure how much the same ratio gear set varies from one to another...