AAM 4.10 Gear Install, Noise, Moan from Rear End
05-23-2007, 07:04 PM
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AAM 4.10 Gear Install, Noise, Moan from Rear End I just finished upgrading my rear end. I purchased and installed an Eaton Posi Performance Differential, and a set of SLP/AAM 4.10 Gears. I re-used the stock pinion shim on the upgraded pinion. I also installed all new bearings and races. The first time I set up the diff the pinion pre-load was at spec, backlash was at .005" and the gear pattern was right in the middle of the teeth. I used GL-5 Gear Lube and Limited Slip additive like Eaton recommends. On my first road test I could immediately hear rear end noise above 10mph. Drive side little noise, coast side loud noise. Took everything apart adjusted backlash to .003" and tried again. Coast side got louder. Took everything apart for the third time adjusted backlash to .008" noise got quieter but still unacceptable. Any ideas what is wrong here?? Possible warped gears??
05-29-2007, 01:59 PM
#2
Originally Posted by jonm3456
I just finished upgrading my rear end. I purchased and installed an Eaton Posi Performance Differential, and a set of SLP/AAM 4.10 Gears. I re-used the stock pinion shim on the upgraded pinion. I also installed all new bearings and races. The first time I set up the diff the pinion pre-load was at spec, backlash was at .005" and the gear pattern was right in the middle of the teeth. I used GL-5 Gear Lube and Limited Slip additive like Eaton recommends. On my first road test I could immediately hear rear end noise above 10mph. Drive side little noise, coast side loud noise. Took everything apart adjusted backlash to .003" and tried again. Coast side got louder. Took everything apart for the third time adjusted backlash to .008" noise got quieter but still unacceptable. Any ideas what is wrong here?? Possible warped gears??
05-30-2007, 08:41 PM
#3
I bet your pinion shaft is TOO deep towards ring gear. My AAM 3.73 gears with stock.033 pinion shim was way off, the pinion shaft was too deep towards ring gear. Remove your cover and recheck contact pattern on the COAST SIDE of ring gear only. Memic a real coast situation by turning axle, tires, and ring gear forward about 5 revolutions (do not rotate gear by turning at driveshaft), you will get a much easier to read coast pattern that way.
Read this:
https://ls1tech.com/forums/gears-axles/706439-best-gear-install-writeup.html
...
Read this:
https://ls1tech.com/forums/gears-axles/706439-best-gear-install-writeup.html
...
Last edited by gollum; 05-31-2007 at 08:54 PM.
05-30-2007, 08:54 PM
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Centering the pattern high or low on the tooth is a pretty subtle thing. I learned that the hard way. It does sound like your pinion shim is too thick. Take some good photos and post them.
06-11-2007, 09:17 PM
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Are those shots all from the same set up? The coast side looks way too deep. The drive side looks better but offset to the outside, it looks like the back lash is a bit high for the pinion position. I think you need a thinner shim.
06-11-2007, 10:17 PM
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Your pinion depth is too short and shows you a picture of being "crossed up" in the first four pictures... but the fifth picture isnt too bad, if you were setting it up for a performance/drag race use only pattern.
Why do the pictures vary so much ?? I take it that you took pictures from different settings and have posted them. My advice would be to only show a series of pictures of each adjustment so they dont confuse or mislead those looking at them.
A rule of thumb for backlash is 0.001" for every inch of ring gear diameter... as a minimum.
Why do the pictures vary so much ?? I take it that you took pictures from different settings and have posted them. My advice would be to only show a series of pictures of each adjustment so they dont confuse or mislead those looking at them.
A rule of thumb for backlash is 0.001" for every inch of ring gear diameter... as a minimum.
