Gear noise HELP 2005 Tahoe new 4.56 rear gears, .007 pinion shim, back lash .007, pinion preload 23nm, total preload 39nm.

[WFOALASKA]

 

[WFOALASKA]

View attachment 350660View attachment 350661

Slight whine, growl on deceleration on and off. Quiet hard acceleration, and slight whine at constant speed but on and off. Gears are Motive, non performance. First run was 1 mile and horrible growl on deceleration. Brought back to garage and checked them over. Found pinion preload loose. Removed shims on crush sleeve eliminater, reset to 24nm. Patter same carrier preload same. Back out 2nd run, now slight on and off growl whine on decel. Quiet acceleration. With this pattern, could the pinion depth be too deep or shallow?

 

[Bill 1960]

I don’t have the FSM available right now, so take this with a grain of salt. Pattern on the drive side looks a little close to the edge of the teeth?

I have had aftermarket gears that whined, even properly set up.

 

[WFOALASKA]

I don’t have the FSM available right now, so take this with a grain of salt. Pattern on the drive side looks a little close to the edge of the teeth?

I have had aftermarket gears that whined, even properly set up.

Ok, thinking mabey take .001 or. 002 out of pinion depth. Open lash to .008 or .009. I will post the paint pattern before the ones i have now. To show what it moved to.

 

[WFOALASKA]

Will gears be noisy if the pinion depth is a smidge off? Like .001 to .004?

 

[swathdiver]

First set of pics looks too tight. Second looks like they move off-center a little. The backlash on the 900s is .003 to .010 with the preferred numbers being .005 to .007. I'm far from an expert though. There's a few guys on here who have done it and posted pics about it.

@Matthew Jeschke @Erickk120 @asand @George B @ls1frc

 

[George B]

Sorry, I am not going to be of much help on this one.

 

[WFOALASKA]

Thanks guys. Have a game plan, bringing it back in garage. This is my first time doing a full, new gear set. Figured out what im doing wrong. Will show some pattern pictures after doing them correctly.

 

[swathdiver]

Thanks guys. Have a game plan, bringing it back in garage. This is my first time doing a full, new gear set. Figured out what im doing wrong. Will show some pattern pictures after doing them correctly.

Give this thread a bump around 9AM your time when these guys start waking up or get back from church. They'll be more people around to see this post.

 

[Erickk120]

First 2 pics assuming you didn't screw the preloads look pretty dang close, going from that, I would have pulled .002-.003 thou of pinion thickness at a time,check what the pattern looks like and then bring it back to original point if too shallow and add .002 thou and compare the difference between both patterns, it will tell you where to go. It seems most of the time you get whine on the coast but quiet on drive side means the pinion is slightly deep. What is the speed range you are getting whine or is it constant?

Now the last set of pics, the compound is way too thick, try to use less oil in the compound and when you roll a pattern only coat 4 teeth and also look at the negatives of other teeth painted, it will give you a better idea of the true pattern. The last 2 pics I cant tell if you added or removed, but it looks too deep to me, and the amount of compound doesn't help.

Also some gears the lower tend to have a little noise sometimes, not saying this is your case, but it happens sometimes. I noticed you are using newton meters to measure, did you mean that or is that actually 23 inch lbs of preload of rotation in the pinion, I believe spec is between 16-20 inchlbs according to the yukon manual, but I've seen ppl get away running in the higher end of 20-25 inchlbs just curious. Motives spec is 7-9 thou backlash and I assune the .007 pinion shim is the shim for preload with the spacer, and lastly your 39 nm preload I believe is your total rotational torque assuming that it is inchlbs and not nm to the carrier with pinion preload installed I believe its too high of a reading for the bearings.

If I math and read correctly 23 (inchlbs) pinion preload-39(inchlbs) pinion with carrier installed preload X 4.56 gear ration = 72.56 inchlbs of preload to the carrier which it would be too high. I know a lot of people say to just stack them til you cant pull the carrier by hard, and never have a problem but to each their own. I cant recall the specs for carrier preload but i believe 30/35 inchlbs is the middle ground for those. Dont quote me on that, I haven't touched an axle in a long time. I have those in my notes somewhere I will have to look around to be precise.

Anyways am just rambling on but its to get an idea of how things go wrong, setting these is simple but its the little details that get you.

 

[Erickk120]

Will gears be noisy if the pinion depth is a smidge off? Like .001 to .004?

depends how far off,I know the pinion for motive gear comes stamped with a pinion depth to check with a pinion depth tool, they are expensive and not worth it unless you want to do a lot of them and sometimes might still need adjustment after fact. I know the pinion head comes with a +-.002 thousands of variance from distance marked on the head. What was your factory pinion shim depth, I always start there and its usually pretty close most of the time, For me its usually always too shallow by a few thousands, but its a good starting point.

 

[Mudsport96]

Well, when you get to it let is know.
But, i have done gears before on an 8.8 ford crown vic (3.90 set) a 8.8 (4.56 & 4.88) and a 8.5 chevy (3.73). And no matter what i did even with a perfect pattern, the 3 90s always had some slight whine to them. I just figured maybe it was the way the were cut, maybe an imperfection in the face or something.

 

[Erickk120]

Well, when you get to it let is know.
But, i have done gears before on an 8.8 ford crown vic (3.90 set) a 8.8 (4.56 & 4.88) and a 8.5 chevy (3.73). And no matter what i did even with a perfect pattern, the 3 90s always had some slight whine to them. I just figured maybe it was the way the were cut, maybe an imperfection in the face or something.

For the ford 88 did those happened to be motive gear orange box? I did a set of those 390s and my god, I can feel the hardness of the material in the pedal to this day.

 

[Mudsport96]

Honestly i dont remember, pretty sure it was motive but not 100 percent. It's been the better part of 15 years ago.

 

[WFOALASKA]

Well, when you get to it let is know.
But, i have done gears before on an 8.8 ford crown vic (3.90 set) a 8.8 (4.56 & 4.88) and a 8.5 chevy (3.73). And no matter what i did even with a perfect pattern, the 3 90s always had some slight whine to them. I just figured maybe it was the way the were cut, maybe an imperfection in the face or something.

Definitely will. Its snowed 3 to 4 inches here in Alaska. Had to get outside projects put away. Bought all new berings and seals. Either tonight, or early tomorrow morning will tear it down and start over. Front diff has to be done too. But wanted to get the rear perfect, so the front will be easier. ( i hope ) Just rebuilt the transmission with a bunch of Sunnax goodies. So need to drain/ flush, and new filter it as well. Transfer Case is next for a full rebuild. Then the ole LM7. The wife and I bought this Tahoe, bran new in 2005. 3 sons, so it was the main family daily till 2 years ago. It has 188,920 miles on it now. Didn't even have to do a full brake job until 180,000. We live here in Alaska, interior, so no stop and go city life for it. Grocerie shopping is a 200 mile round trip..LoL ‐60 to 100 degrees and 3 feet of snow.. this Tahoe has never let us down. Its taken care of us.. now its time to take care of it. Die hard GM fan for sure. Will get some pictures up of it. Seriously, thanks for your help with these gears guys.

 

[Mudsport96]

Out of curiosity, why the 4.56s? Lift and tires?

 

[WFOALASKA]

Alright, brought it back in. This is the patterns from just a few min ago. This is how it was while driving.

 

[WFOALASKA]

Alright, brought it back in. This is the patterns from just a few min ago. This is how it was while driving.

The rotational toqure is in inch pounds. I checked it right before doing paint. It was 25 inch pounds. Total for ring and pinion together.

 

[WFOALASKA]

Drive is toe/middle. Coast is mid/heel. Picture is same no change, just after paint. Seem to show a bit better.

 

[WFOALASKA]

No change.. pulling apart.