Anyone here an expert with gear setup in 9 in rear ends?

[Zachalanche]

I know others have had occasional luck with 9" setups that run "quiet", but I never have. I've spoken and corresponded with many others over the years, including some of the manufacturers, and I've concluded that it's just not part of the engineering criteria for the aftermarket. Factory gears are "triple-lapped" whereas most aftermarket sets are "single-lapped". I admit I've not used any of the new "double-lapped" sets coming on the market in the past couple of years, so they might be better.

In any case, if you want OEM noise levels, I'd use a Ford 8.8 setup. It's nearly as strong, has less parasitic loss, and can be had with 3" axle tubes, 31 spline axles, and any differential you can name. The best bit is that Ford Motorsports still manufactures and sells R&P kits. You can even find new housings if you look for them.

Thanks for the info. If I had to do this over again I would probably go with the 8.8 for the weight savings and decrease in parasitic loss, although I have a 2012 boss 302 with an 8.8 that has a little whine to it as well. The dealer replaced the ring gear and pinion and all bearings under warranty twice, and there was no improvement. Its not terrible, but it is in a car that has a ton of rubber isolation, I would imagine it would be a bit worse if the rear suspension was all heim joints (like my mach 1). I could go to the effort of swapping the axle, which would require a bit of fabrication work and a different torque arm and watts link mount making it relatively expensive, but it seems to me that there is risk that there won't be an improvement in noise.

This build has sacrificed most comforts for the sake of performance, so, some noise is tolerable.....actually a lot of noise is tolerable, but the volume and frequency of this gear whine i currently have is enough that I can't stand to drive the car at all.

I had this on order with Summit:

https://www.summitracing.com/parts/ugr-s007

The order was cancelled and now it shows as unavailable. I don't know if US Gear decided not to make these, but supposedly they were going to use a different manufacturing process that made the gears quiet.

My Cougar had a OEM 4.30 gear set in it and it was dead quiet.

Andrew

Its starting to sound like I should give the old oem gears a try.