merim123

iTrader: (11)

adding my experience to the thread, my 12 bolt built by strange with 4.11 gears did exactly the same with a spohn torque arm. The whine was unbearable and loud, it was in a 50-70mph spot. over 70mph silent. clutch in, silent. load, whine like no tomorrow. was a very annoying drive to the track and the last time i did it before I sold the rear end. I thought it was just how 12 bolts are.

cire0105

@98cherrySS

Ya, I was looking at those US gears exactly. What ratio did you go with? I've heard the numerically higher ratios are more prone to whine in general. I'll try shimming/bushing isolation before I swap gears on a new rear end, but if I'm still at this point next season it is a good option.

And sorry to hear about the fasteners backing out on the differential, I appreciate the heads up.

98cherrySS

iTrader: (2)

I went with their 4:10 gears. They are face hobbed which is a kind of radial milling (cuts while the gears spin) instead of the typical 5 axis milling used by most manufacturers. I have a couple of threads on here with photos of them. They are a superior product without a doubt. Also, consider this rod end as an option for the torque arm/pivot link. https://sealsit.com/product/sealflex-rod-end/. You will notice a substantial reduction in clunking from the torque arm.

cire0105

I would just like to report back that after installing bushed rod ends in place of the solid rod ends for the torque arm and watts link (using Competition Engineering 6152 Polyurethane Bushed Rod End for the 3/4 inch for the torque arm and sealsit 1/2 inch for the watts link) as well as a few hundred additional miles I have had no improvement in the gear whine. I have made my peace with the fact that this whine is at a frequency that is most irritating to me and not tolerable for a street/everything car. I hear it loudest at highway and freeway cruising speeds where the sound drills into my head. I'm left playing with the pinion shim-but more likely-changing the rear gear to a US Gear's Stealth series. After that I guess the 10 bolt is going back in...

Edit: I also changed my rear lower control arms to bushed UMI rather than the adjustable Bushed/Heim joint design I had on the car before. None of this helped with the rear end whine sadly.

pdxmotorhead

Ok so this is the way I recall the story ..

A few years back,, most of the gear manufacturers changed the tooth angle shallower on new gear sets, they did it to reduce rolling resistance, the older original 9" R&P sets had a steeper pitch to make them silky quiet..
The reason they changed was the Dana 44 and the 14 bolt, were whipping the 9" in road racing classes that had restricted power, the 9" uses more energy to turn under load than a 44 does. the new gears are also made on the same machinery as the 8.8 gears, so there is some fudging of the dimensions to save money.

cire0105

@pdxmotorhead

I did drop my quarter mile trap speed from 111-112 mph to 108-109 mph with the swap from the factory 10 bolt to the MWC 9" with the 3.89 gears. At the same time my wheel package went to 18 inch F14 foregestar wheels which somehow adds 10 pounds per corner over the stock 17s, so not quite apples to apples. My best time was identical between the two rear ends (13.1 on street tires) but I was somehow more consistent with the 10 bolt, not sure if that was just a bad day at the track though. I have not tried drag radials.

On a side note I ran my car at PIR and woodburn when I was in PDX a couple years back. Love the PNW.

merim123

iTrader: (11)

i see hawks selling the 8.8 housing by itself. if you're up for a challenge, maybe you can piece one together that way. At least it has 3" tube the whole way and all the brackets.

NEstyle

iTrader: (1)

Face hobbed (2 cut) gears are "supposed" to be weaker than 5 cut gears due to the reduced contact patch, though.

cire0105

@merim123

I don't know if an 8.8 is in my future if I can't quiet this MWC 9" down. Sinking time/money/effort into yet another rear end in hopes of a good outcome is something I'm not ready to do. Again this is a street/everything hobby car for me, with street being the first word. If I can't stand the drive to the race track then I don't care if my rear end can hold 1000 hp. God willing the gear change will quiet things down...

merim123

iTrader: (11)

I agree with you as well. I had the same disappointment with my 12 bolt strange. i still use a 10 bolt in my street cruiser. I just got frustrated with the whine on the highway.

cire0105

Everyone I just wanted to share this experience with you all who have been dealing with noisy rear ends with this "cruising speed light throttle" gear whine.

I had the opportunity last night to speak to a former ford engineer who worked in drivetrain NVH, he dealt specifically with gear noise such as ours. He said it has to do with the manufacturing process of the gears, that there is inconsistency -a waviness- in the meshing surface of the teeth if you really get down and inspect them with a micrometer. This leads to a slapping effect when the lows/highs of the teeth contact each other as they mesh, which results in the ringing/whining that we hear. It is an issue in the manufacturing process, apparently to manufacture every set of gears to exact tolerances is more expensive.

Essentially it comes down to luck if you get a good set from the assembly line you will have a quiet rear end. He said messing around with pinion shim will have little effect on this specific type of gear whine. He said back in the day he could mic a set of gears and know right away they would be loud as heck.

I ordered a set of US gears Stealth lightning series for my MWC 9", I will try to mic them before install, as well as the Motive gears when they come out. I paid a lot for this rear end, and I would have gladly paid a bit more if it had insured a quiet ride. I am disappointed that the aftermarket still pushes things through in a way to save a few extra bucks. At least give me the option to pay for guaranteed quiet gears, and don't set the expectation that it is normal/because race car.

Darth_V8r

iTrader: (4)

Try to put myself on the manufacturers shoes for a second ...

You make really tight tolerance gears and price goes up. Nobody buys because competition is cheaper. Then you advertise as quiet, but it is so setup depending that even ultra quiet gears can end up noisy, so you end up refunding.

I sent mine out to be rem polished and it helped substantially. But my car is so loud it could be drowned out.

cire0105

@Darth_V8r

I agree, I completely understand the "good enough" manufacturing philosophy. It is appropriate for the majority of customers.

My goal is simply to share information so that those who find themselves in a similar situation can make the best decision for themselves.

rem polishing sounds interesting after a quick google search, thank you for sharing that.

I hope this thread continues to be useful for people who are installing aftermarket rear ends in their street driven 4th gens.

LS1-IROC

iTrader: (4)

https://johnsindustries.com/quiet-zone.htm

Jimbo1367

I heard great things about these gears

merim123

iTrader: (11)

Checked out the video, lol, that first video, my 12bolt was probably 2x that whine. will have to give them a call.

Augie396

Having same wine quite up to 55 mph then get a wine under no load/ light load goes away above that speed.new 3
50 summit gears and bearings pinion depth set as per marking .007 back lash .have had 2 other gear sets in car all were noisy.orignal set were strange set up by them and were buy far the worst.starting to think its the gear set manufacturer tooling.

Kawboom

The quietest gear sets are for the Ford 9 are OEM, the Ford factory gears. If you care about the noise and you can use OEM gears you should consider it.

91 Z28

iTrader: (3)

I believe I've got us gear in my 9 inch and they are dead quiet

98cherrySS

iTrader: (2)

Old thread but 4 years later, still dead silent with US Gear, stealth, lighting treatment on my 4.10 gear set. This is after dozens of 1/4 mile passes and street shenanigans.