New 4.10 were quiet, but now noisy
08-04-2012, 06:31 AM
#1
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New 4.10 were quiet, but now noisy Stock 10 bolt. M6. Project down a year and a half. Had a friend well experienced with gear set up install new 4.10 (AAM) with solid spacer, stud kit, and finished with a T/A cover. All bolts torqued to spec, welded axle tubes also. Installed at the same time: UMI Adj torque arm (full length), UMI TA relocation crossmember, UMI non adj LCA, new u-joints. Car has 7500 miles, stock springs and shocks, and stock Goodyear F1 tires. Went through 6 heat cycles on the gears, once running through them spiritedly. Drive #7: made a pinion angle adjustment, test drove. Turned around on 4 lane hwy, not a complete stop, but very slow. Grabbed 1st with a wheels spinning powerslide, grabbed 2nd with a chirp, then full acceleration through 2nd and 3rd. Backed off in 4th, then hit 6th. Noticed a pronounced whine at speed, and stays there all the way down to about 20mph. Can't hear so much on accel due to exhaust, and maybe loading the rear? The shim packs were very tight, pinion was tight also. I don't understand what could have happened/moved. The were silent until then. I didn't even launch "hard". I didn't hit second really hard, as I didn't spin through it. Any thoughts?
08-04-2012, 03:19 PM
#2
I installed the same AAM gears with the Ratech solid spacer. There are two things I noted with these parts:
1) the Ratech solid spacers ID is quite a bit larger than the pinion shaft and if left to it's own devices it will not center on the shaft when installed. I wrapped some aluminum tape around the pinion shaft where the solid spacer sits to hold it concentric with the pinion shaft until it's tightened down.
2) I used a Richmond install kit and the pinion shims in the kit had the ID too small and they would sit on the fillet of the pinion gear. If installed this way you'd get a false setup on the pinion depth. Open the ID of these shims up so they sit flat on the pinion.
It's good to set the carrier bearing preload tight like you did and everything else in your build sounds good. I'm thinking when you hit it the pinion setup might have changed under load because of the reasons I listed above. With the carrier nice and tight that for sure didn't move from the original setup.
My AAM 4.10s are quiet.
1) the Ratech solid spacers ID is quite a bit larger than the pinion shaft and if left to it's own devices it will not center on the shaft when installed. I wrapped some aluminum tape around the pinion shaft where the solid spacer sits to hold it concentric with the pinion shaft until it's tightened down.
2) I used a Richmond install kit and the pinion shims in the kit had the ID too small and they would sit on the fillet of the pinion gear. If installed this way you'd get a false setup on the pinion depth. Open the ID of these shims up so they sit flat on the pinion.
It's good to set the carrier bearing preload tight like you did and everything else in your build sounds good. I'm thinking when you hit it the pinion setup might have changed under load because of the reasons I listed above. With the carrier nice and tight that for sure didn't move from the original setup.
My AAM 4.10s are quiet.
Last edited by guppymech; 08-04-2012 at 03:39 PM.
08-04-2012, 03:47 PM
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Im also assuming its the pinion that moved. I haven't checked anything yet. Thinking I might beat on it a little to see if it "moves" anymore. And yes, the spacer was really loose on the pinion and I would think it would cause a vibration if not centered properly. I had incorporated two small A/C orings between the pinion and the spacer, but my installer forgot or didn't understand what the reasoning was. I'll be sure they are in there this go around.
08-04-2012, 04:02 PM
#5
The purpose of the solid spacer is to keep the bearings preloaded. It's job is not to ensure the pinion is turning true. That is the job of the pinion bearings and the housing itself.
My guess is your pinion nut came loose(lost preload) which can cause gears to whine.
My guess is your pinion nut came loose(lost preload) which can cause gears to whine.
08-04-2012, 04:23 PM
#6
Im also assuming its the pinion that moved. I haven't checked anything yet. Thinking I might beat on it a little to see if it "moves" anymore. And yes, the spacer was really loose on the pinion and I would think it would cause a vibration if not centered properly. I had incorporated two small A/C orings between the pinion and the spacer, but my installer forgot or didn't understand what the reasoning was. I'll be sure they are in there this go around.
Last edited by guppymech; 08-04-2012 at 04:29 PM.
