MustangGT711

I recently upgraded to a set of 3.73 gears. I was working with a friend installing them and could not acheieve the backlash based on a lack of variance in shims. For one week, I drove short distance to work at low speed to avoid damaging the gears. I had trouble finding a mechanic to take on the job after I had started basically... I had a mechanic go over the whole install, he has them set at .015 backlash, proper pinion depth and pre-load. I now have a whine/howl off throttle. They are Motive Gear and basically their only suggestion was "send us the gears." Does me no good with them installed so wondering if there's any suggestions/input. Is a whine normal during breakin with these gears? Any specifics I should look at? Thanks

djoneill

Yeah, I've read that gears settle down in the first few thousand miles, so you'll want to wait 'til after break in.

That said, however, you might want to do some research on Motive vs. Ford gears.

mfergel

Hard to say without knowing how much whine you have. I have different whine with the 3.73's. I think once you get used to how your car sounds when it starts sounding different you automatically think somethings wrong. I added aftermarket control arms top and bottom and it was really noticable.

lawrencecar1

FRPP FTW

Diabolical!

This has nothing to do with brand. I consider myself extremely car-competent, and the one job I will never, ever do at home is a gear install. That howling isn't ever going to go away. Even worse, now that a wear pattern has been established, it won't go away even if you have the gears reinstalled by a professional. You need to get a new set or learn to live with the noise.

Cobrakev

[QUOTE=Diabolical!;7914117]This has nothing to do with brand.QUOTE]

It has a lot to do with the brand of gear. Motive gears are well known to have gear whine. I hope you can get them to work for you, but it you can't live with the whine, get the FFRP.

MustangGT711

Thanks for all the info guys, It looks like I'll tough it out for a little bit and then swap gears. The gears feel great, just the whine during deceleration so I'm convinced its the ration I want. Next time I do a rear, it won't be in the car on my daily driver... Chalk it up to learning curve.

Ford-a-tude

I went with the Ford Racing 4.10 based on the general consensus that other brands may be a bit noisier. The backlash spec is .008"-.012", so at .015" you are pretty much out of spec. How did your gear pattern look? I did notice a slight howl on deceleration myself at first. I used regular non synthetic gear oil with no friction modifier for the break in. After about 350 miles of easy driving I switched to the Ford recommended fluid and friction modifier. The deceleration noise is noticeably better after break in, and unless I point it out no one even notices it.

Here's what my gear pattern looked like with a .009" backlash. In reality it's a number and what really matters is getting the best pattern you can. That's the part that takes time and why I did it myself. No one will do as good of a job on your ride as you will.

MustangGT711

The pattern is spot on dead center for pinion engagement and the gears came with the spec .008-.015 so it is at the high side for the gears according to installation. I am taking it easy with the break in, synthetic lube is being used.

157dB

Motoves whine hands down.
There is no 'breaking in' associated with whine when using good gears.