LSjunkie

Okay guys, I'm new to this forum but have just hit a brick wall with my car. Its a 99 Z28 A4. Has 4.11's and the tranny is all stock other than it being tuned with my ECU and a deep Derale pan. I JUST installed the deep pan and put a new filter in yesterday along with my pinion seal. My gears have whined since i bought the car but ever since i changed the seal and put the deep pan on yesterday it whines and grinds SO much more now. It slightly whines under acceleration but no matter what speed I am at it seems to be coming from the transmission now, especially under 40mph with no throttle, just coasting to a stop. I took the driveshaft out today and put it in drive and didnt hear anything, put the DS back in and it started again. I had the car on jackstands and with the car idling in drive the speedo read about 30mph, and the whine would come and go. Any ideas?

Danok72

My first suspect would be your pinion gear bearing, they are notorious for going out in these cars. Also your Gears/carrier may not be properly shimmed/set-up this would also cause the noise. Aftermarket gear sets (4.11s) are usually noisy even when installed correctly. Any or all of these could cause the noise.

LSjunkie

Okay I was thinking maybe the pinion bearing. Everything in the rear end is stock aside from the gears. How hard would it be to take the carrier out and gears to put new bearings in myself? The whining is so load when I slow down now I can't hear my exhaust and it's a dumped ORY with no muffler lol also, when I put it in reverse, it makes and metallic clunk/ting and whines when I back up.

Kevin Blown 95 TA

The pinion seal isn't easy to change - most people mess that up - not the seal, but the re-assembly. The pinion needs to be re-torqued to where it was previous to disassembly, and maybe slightly more. You use a recording torque wrench to check it so that it takes 15 or 20 in-lbs to turn the pinion without the carrier or axles in there. You can also do it by carefully marking the nut before disassembly and getting it back to where it was and like I said, maybe just slightly tighter, but that assumes it was right in the first place. There is also the issue of the tiny and weak crush sleeve maybe being too collapsed to hold tension on the bearing - that is a weakness of the stock 7.5" 10 bolt. You drive around with a loose pinion and it is going to grind up bearings and gears.

If that isn't your problem or only part of it, I'd also check the c-clip that holds the axles in. Those have a sharp side and a rounded side to them and depending how they are installed, they can eat away at the carrier and develop play that lets the axle move in and out and grind on the caliper. You might notice that more on turns.

LSjunkie

Yeah when I turn sometimes and it's mainly left turns, I can hear kind of a faint whine noise as if it was pulsating and then when I straighten back up it goes away. The grinding noise just seems so amplified now that I changed that seal so I probably crushed the crush sleeve and the way the pinion gear moves around, it seems like that bearing is shot.

LSjunkie

Also, I used and impact gun to take it off and to put it on. I know, prolly a newbie mistake but at least it happened with the stock 10 bolt and not an aftermarket one. Learning experience I suppose. How much you think it would be to make the 10 bolt pretty stout? I don't have $2,300 bucks for a moser 12 bolt

Kevin Blown 95 TA

Depends on what is wrecked in it. You could spend $1000 - on it just for gears, install kit & bearings, reinforcing cover, maybe more for some better axles, and solid spacer to replace the crush sleeve, it will still be weak, but way better than it is now and fine for a mildly modified car, and labor can be a few hundred unless you are going to do it yourself. At a minimum, you should do the solid spacer (relatively cheap part from Ratech) and the reinforcing aluminum cover in addition to whatever else it needs for repair. The solid spacer & shims is a pain to set up, but it is worth it to get the super weak crush sleeve out of there.