Technical follow up on 9 inch rear

I don't know if I should have continued my last post or start a new one. I guess someone will let me know if I screwed up. I checked gear pattern and backlash here are pics and the backlash is 0.022 thousand the rear had a whine on acceleration stopped when let off gas just a slight pressure on gas pedal comes back. clunk going from drive to reverse . how does gear pattern look what needs to be done, Thanks.Mike

 

Move the ring gear in deeper in to the pinion

 

Yes,,,,,backlash is way too loose .
Should be about 7 or so,,,,,no big deal,,,,,but it needs to be fixed !

Tommy

 

Pinion depth looks about right. Decrease the backlash.

 

i understand backlash causeing clunk can can i adjust pattern to decrease whine thanks mike

 

I think the best that you can do is get the drive side pattern where it needs to be and get the backlash within spec. Being a used gear set it may, or may not, still whine.

 

You definitely need to move the pinion in, that’ll move the pattern down on the tooth, right now on the drive side the pattern wipes off the edge of the tooth which is bad, moving it in will decrease backlash on its own as well. Ford spec for backlash on the 9” is 0.008-0.012”


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I would try moving the outer adjusting nut (ring gear case side) in one hole and rechecking backlash and tooth pattern. Do not move the inner adjusting nut (ring gear tooth side). Then recheck your tooth pattern.

I had previously commented that back in the 70's I did a lot of 9 in Fords for ring and pinion noise. It is my experience that changing the tooth contact pattern rarely cures a ring and pinion noise. It just changes the speed at which it come in. I'm ***uming that your noise is only in one speed range and goes away if you go faster or slower. If it is constant on a pull at all speeds, it is more likely to be a bearing noise probably one of the pinion bearings. I believe the outer pinion bearing is loaded more on a pull.

 

Changing backlash will move the pattern slightly horizontally across the pitch line of the tooth. I agree if it makes noise it’s likely going to always make noise.

How was case bearing preload set?


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Not sure if it was mentioned in the original post, but are these used gears? Is the ratio hunting or non-hunting? If non hunting and a used set that the timing was moved, the whine will stay. Decreasing the backlash will help the clunk.

 

Any chance non-hunting gears would happen to be marked as to original meshing?

 

What is that term, "hunting gears"?

 

What a great chart above. Putting that in my reference libary.

 

Let’s call one tooth on the pinion tooth one, on non hunting gear sets number one will contact the same teeth on the crown every revolution, on hunting gear sets number one will contact every tooth on the crown before it gets back to where it started, there are also partial hunting gear sets where it takes 2-5 revolutions to start over.

Typically non hunting gear sets are marked to be timed, although that is often paint marks.


Hopefully that sort of makes sense...

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To add to what Fargo said, in a non-hunting gear set the tooth count of one gear divides evenly into the tooth count of the other one.

There is a funny story of a salesman at a machine shop idly talking with the boss in the office when he saw some freshly cut gears on the desk. He was surprised when the boss said that they just made those.
The salesman asked, "You made those? I didn't think you [anyone] could make gears, I thought you had to buy them!"

 

I guess I too don't know what the term "non hunting" gears means.
But then again I have never called a third member a "hogs head".

 

I had not heard the term before either.

 

Think about it this way- the typical 3.00 ratio has 13 pinion teeth and 39 ring teeth. Tooth one as mentioned will mesh the ring gear at tooth 13, 26, and 39 each time. There is a good chart in Google land that has every 9" ratio and lists which ones that are non-hunting, hunting, and partial hunting.

 

I could devote an entire tech week thread to differentials...maybe next year!

 

"Hunting", "Non-hunting" and "Semi-Hunting" are actual terms used by gear manufacturers, they aren't slang like "pumpkin", "lump" etc.

 

I just glanced at the post . Be sure to load the gear set when checking patterns . Best as I can remember always tighten ring gear side last also .

 

The “ clunk” in a nine inch rear end is mostly the result of wear in spline area of the axles and axle gears. Plus clearance in the spider and axle gears. Plus engine speed. The change of a few thousands in the ring gear and pinion has little effect on the “ clunk”. Over the years I have seen nine inch rear ends that you could turn the pinion almost a 1/4 of a turn before all the slack was taken up. Usually a trackloc will help reduce some of the “ clunk”.








Bones