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Old 02-18-2011, 10:25 AM
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Yukon 3.75 gears for Ford 9 inch....noise

Make a long story short, I built my own housing to put a Ford 9 in a 1999 Camaro SS. The car is a stick and the stock rear was making noise, so after two gear changes in the stock 7.5 and all them making noise I decided to build a 9. Everything turned out real nice except now the 9 is making noise. I started with Richmond Excels, which I know the reputation Richmonds have for making noise. Of course they made noise as low 10 mph. So, I bought a set of Yukons. I have a set in the 8.5 10 bolt in my truck and they are silent. Anyway they are 1000 times better than the Richmonds but I still have a small whine on acel and decel. I started out with the same .019 pinion shim I had with the Richmonds and the pattern was too deep. So I started to bring the pinion out. I went to .021 all I had was a .010 and a .011 to add together, back lash at .006. It still looked too deep to me but I was out of shims and the next jump I could make would be .025 and it was to far out. I loaded up the center section and took it to a local machine shop. Jimmy Mattingly’s Machine Shop. He builds pulling tractor engines and is a major Ford guy. Anyway Jimmy told me to open the backlash up and that my pinion shim looks OK. He gave me a couple more shims a .012 and a .014. This time I opened the lash up to about .008 and put the .010 and the .012 in to give me .022. It looked pretty good to me but it seemed like the drive side was staying too deep and the coast was coming out more than the drive. So I went on and tried .011 and .012 to give me .023 and it looked like the coast was too far out and the drive was good. I put it together with .022 and about .008 back lash and it has a small whine. I am thinking about just unbolting the pinion and replacing the .010 with the .011 put it back .023. I figure the lash will open up a little more but should still be in spec. looking for some opinions on where to go. I am about done with rear ends.... I only put about 5 miles on the car for a test drive. I want to fix the noise so I don’t mess the gears up.

If you would like to see the 9 I built here is a link to it on LS1 tech

http://www.ls1tech.com/forums/gears-...d-8-8-a-4.html

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Old 02-18-2011, 12:06 PM
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Many of the Yukon gears require more backlash than other gears. If this is a 3.70 gear then you may be having the same problem that I have had with them. I've had a few of the 3.70 Yukon 9 inch gears that had some noise in them.
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Old 02-18-2011, 12:13 PM
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Quote:
Originally Posted by big gear head
Many of the Yukon gears require more backlash than other gears. If this is a 3.70 gear then you may be having the same problem that I have had with them. I've had a few of the 3.70 Yukon 9 inch gears that had some noise in them.

Ok, then I should be ok just shimming the pinion out another .001. The back lash should still be good.

This is thier 3.75 gear. It was a little higher priced then the 3.70. The Richmond I had was a 3.70.

http://www.yukongear.com/ProductDeta...px?ProdID=2156
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Old 02-18-2011, 06:58 PM
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I don't have any experience with the 3.75 gear. Why did you choose it over the 3.70?
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Old 02-18-2011, 07:00 PM
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Quote:
Originally Posted by big gear head
I don't have any experience with the 3.75 gear. Why did you choose it over the 3.70?

I had a 3.73 in the 10 bolt and liked it. I figured it was a little lower so why not.
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Old 02-20-2011, 09:25 AM
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Would you guys mind to take a look at these patterns? I have moved this thing around every which way and can not get a good pattern. It doesnt help now that they have been driven on. The coast side is staying heavy toe. I have opened the lash all the way up to .015 and cant hardly make it move. I can bring the coast up the tooth but the drive seems to get to one point then stop moving. Would you guys run any of these patterns? I am begining to wonder if its this aluminum Yukon case. I may try to set them up in the factory cast case just to see if it helps.















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Old 02-20-2011, 03:05 PM
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Are you changing the pinion depth too or only the backlash?
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Old 02-20-2011, 08:23 PM
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Quote:
Originally Posted by big gear head
Are you changing the pinion depth too or only the backlash?

I spent the whole day moving that sucker every which way you could think. Changing pinion shims and back lash at least 50 times. I set it up in the old center section today and I think I have it. I have a pretty good pattern. The only problem is I have to change out the bearings on my trac loc to the smaller ones now. I had to put the ring gear on the open carrier that was the original to set it up.

No that I know that the gears can be set up I may try the aluminum center section one more time.
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Old 02-21-2011, 08:07 PM
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Well this is where I am going to run it. I took it all back apart, started over, and put it back together in the aluminum case. I think my problem before was that I wasnt tightening the caps tight enough before check my pattern. I put it back in the car and ran it on jack stand and I didnt hear a peep out of it. Before I could hear the noise running the car on jack stands. I havent drove it yet so we shall see...

This is with .025 pinion shim and .010 back lash.



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Old 02-21-2011, 09:07 PM
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Looks aceptable for a 9 inch Ford gear. If it's quiet then you did good.
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Old 02-22-2011, 04:18 PM
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Well I didn't do good if you know what I mean. I don't know what else to do to it. I am bound and determined to get a quiet gear in this car. Any recommendations? What about US Gear?

It just seems weird that the coast would not come off the toe with back lash changes.
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Old 02-22-2011, 04:23 PM
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I have more trouble with 9 inch gears than any others. I don't know why. I think I would have used the 3.70 gear instead of the 3.75 because the 3.70 is a more popular ratio and produced in higher numbers. They usually work harder to get things right on the high production gears than they do with the low production stuff.
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Old 02-22-2011, 06:06 PM
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Quote:
Originally Posted by big gear head
I have more trouble with 9 inch gears than any others. I don't know why. I think I would have used the 3.70 gear instead of the 3.75 because the 3.70 is a more popular ratio and produced in higher numbers. They usually work harder to get things right on the high production gears than they do with the low production stuff.

Thats nice to know. Thats the reason I got rid of the 7.5 10 bolt. I couldnt get the gears to setup in them for anything and not make noise. Plus they are weak. I thought with the simpleness of setting up the 9 I could get this thing done and in the car. Looks like I might be buying another ring and pinion. Do you just mainly use Yukon? Should I try to find an original Ford ring and pinion.
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Old 02-22-2011, 07:17 PM
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Many of the "odd-er" in-between ratio Ford 9" gears(of which your 3.75 ratio set is, the 3.70 is the common set) are targeted primarily at circle track racing use, to taylor engine rpm at the end of a straight to exactly what they need...and so tend to be noisier because no one cares how loud they are in a racecar as long as they do the job and last the race or the season.

The difference between the 3.70 and 3.75 ratio is something you would never even feel on a street or strip application...if you ran each set back to back you would have an extremely hard time telling the difference by how the car acts...if you could even tell, because the difference is sooo small.

I think the common 3.70 set would be your best choice for a quiet gear.
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Old 02-22-2011, 07:22 PM
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Yea, I've just been using Yukon gears for the last few years. I do some Richmond or US Gear when there isn't a Yukon available, or if a customer brings his own gears. I've got to do a US Gear 3.31 for a 12 bolt soon, which is going to be interesting because they only made 200 of these. I've also got to do a Richmond 4.30 12 bolt gear soon, which is another low production gear. The 3.70 might be a better choice for you. I think you could probably get rid of the 3.75 if you wanted to. There are people who don't care about a little gear noise and would like a good deal on a set of barely used gears.
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