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Discussion Starter · #1 ·
Hello, I installed my first set of 4.10 gears on my 03 f150 and experience loud whining during hard deceleration and slight whining while cruising 40 then disappears after 55 mph but still will whine under deceleration. I have a dial indicator and a torque dial wrench measuring in inch lbs. This is my pattern after 250 miles.
Automotive tire Automotive lighting Hood Tread Rim

Automotive tire Wheel Tire Alloy wheel Rim
 

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Termi Powered 427 Cobra, & M850
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Unless you have considerable experience setting up ring and pinions by reading the mesh patterns on the drive and coast sides of the gears, you will most likely not be successful. OEMs use the Master Housing Depth (MHD) method of setting up ring and pinions because it is better suited to a mass production environment where you have to be right the first time, everytime.

The MHD for an 8.8 Ford is 4.415". That dimension reflects the distance from the center of the Ring gear to the backside of the pinion where the tapered pinion support bearing seats.
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Although the pic above references a 9" Ford, the MHD reference is correct for all rear ends. The only dimension that changes for different style rear ends is the MHD.

In the FWIW bucket, once you have installed a ring and pinion incorrectly, they are permanently damaged and can not be reinstalled so as not to whine. That means your current ring and pinion is toast and you need to buy a new ring and pinion to replace your current ring and pinion.

If this sort of work is a bridge too far for you, you should have the next R&P installed by a shop that specializes in this sort of work. If they are wishy-washy about being able to install a R&P without the attendant whine like you are currently experiencing, then you have the wrong shop. Pick another candidate to do the job. Remember each time you install a R&P incorrectly and it whines you are damaging the tooth mating surfaces on both gears and rendering them useless, meaning you are in the market to buy another set of gears — again.

When you set your ring gear backlash, check it every 90˚ of ring gear rotation for four rotations, don't forget to set the preload on the ring gear carrier bearings. Improper preload (and therefore backlash) will also cause whining and damage the tooth mating surface of the new R&P, meaning you get to buy a new R&P one more time.

When you select your replacement R&P you want to select a 'hunting tooth gear set' if at all possible. A hunting tooth gear set is a gear set whose tooth counts are prime or relatively prime. In other words they will have no common factors between them. This is the best configuration for R&P gears, since any tooth on either gear will contact every tooth on the other gear before encountering the same tooth again.

Prime numbers are always odd with the exception of the number 2. The only prime number with a 5 in it, is 5. No other prime number greater than 5 will end with a 5. The prime numbers between zero and 50 are; 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47.

For example a hunting gear set with a 3.91 ratio would use an 11 tooth pinion and a 43 tooth ring gear. Both numbers are prime and in operation the pinion would hunt on the ring gear contacting every tooth one time before contacting the original tooth it had started on. An example of a non hunting gear set would be a 3.50 ratio using a ten tooth pinion and a 35 tooth ring gear. Any single gear tooth will always contact its corresponding gears’ teeth in the same place every time. Hunting tooth gear sets are the best configuration for ring and pinion gears, since any tooth on either gear will contact every tooth on the other gear before encountering the same tooth again, producing the most uniform wear patterns, lowest noise and highest service factors.

Final thoughts, smalll pinions are bad, big pinions are good. Small tooth count pinions are not as strong as their larger tooth count brothers. For a drag race application large diameter pinions provide longer life. A coarse gear tooth provides stronger roots than a fine gear tooth. Always build for strength.
 
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Discussion Starter · #6 ·
Well thank you for the through explanation and providing information I was having difficulty getting.
Ok another question related, even though it would be temporary till I get another set of gears could I try adjusting the gears to the factory pinion shim on the old pinion and see if that will do for the meantime? Or just better off looking at what I got in there as unfortunately trash?
 

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Well thank you for the through explanation and providing information I was having difficulty getting.
Ok another question related, even though it would be temporary till I get another set of gears could I try adjusting the gears to the factory pinion shim on the old pinion and see if that will do for the meantime? Or just better off looking at what I got in there as unfortunately trash?
That does absolutely no good whatsoever.

The dimension from the center of the ring gear to the backside of the pinion, where the first conical bearing registers, is different on every pinion — which is why the pinion needs to be shimmed in the first place. Putting the old shim back in place, at the very best, is a kiss and a promise. Most likely it is a complete waste of time because you don't know where either pinion is vs where it is supposed to be.
 

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When installing new gears they need to be installed with precision that you're not going to get just by using parts on hand.

In order to have them installed correctly it's better to have someone with the proper measuring equipment and that knows how to read gear tooth patterns do it.

ks
 

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Discussion Starter · #9 ·
Hello everyone.
I wanted to post an update with the 2nd set of 4.10 gears I ordered. I remained with Ford performance but I went through the website American trucks for a bearing and shim kit that came with everything this time.

Unfortunately my previous set only came with 3 bearings and no gasket and the shims were terrible. I purchased this set from a Ford dealership in town (Mel Hamilton) as it turns out my source of all of my problems from my very first install was the big pinion bearing. Did not even come with gear marking compound so I was silly enough to use silver antiseize in place of it.

I do thank you guys for the information I needed for future installs, my new set is as quiet if not quieter than my stock gears at 240,000 miles. Even my neighbor was shocked on the condition of the bearing. It was even made in the USA.
 

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