I did a nice right hand burnout the other night with some mild wheelhop and the next morning when I was driving I started to notice a HOWLING sound from the rear of my car. I notice it is only there when I have the car in gear and giving it gas (when I put the clutch in it goes away (new clutch too)). I just had some new differential fluid put in only a week ago. Is it time for a new set of gears or something? If I wanted 3.73's what brand do you guys recommend me getting (or what setup?). I was wondering what RPM to expect out of 3.73's with a 6 spd around 70mph? What is the stock gear ratio in a 96' z28 anyway? Thanks guys-

 

I've got whining from the rear to and the folks who put in my clutch said the pinion bearings needed to be replaced. I might just turn it into an excuse to put in a new set of gears

 

Whining happens when a set of new gears is not installed 100% correctly, weather it be shims, backlash or pinion depth. they are your stock gears? if your thinking about going with a new set of 3.73's i would say do it... my friend just put a set of 3.73's in his 95 A4 Camaro z28, they are NICE! chirps gears left and right... heh, and when i put ,y 4.10's in they woke the car up. i think you would enjoy a nice set of 3.73's brands.. Richmond are a little stronger due to their grind. but they tend to whine a lot more, which is why me and my friend went with Motive (genuine GM) and neither pair whine at all... best of luck to ya!

 

Maybe they did not put fluid in it. It happens. In any case, it sound like gear noise, so eventually you will want to replace the ring and pinion. Mine have been howling for quite some time. Just one of those things that is not a priority right now.

 

Just a guess, but if you got the wheel hop during your burnout, then it may have collapsed the crush spacer mounted on the pinion shaft. Unless you just want new gears, you may want to check for excessive pinion shaft end-play. If there is excessive play, take the driveshaft loose and remove the pinion nut, washer, joke, seal and front pinion bearing. In there you will find the spacer. A new spacer may cure your noise but the pinion nut will need to be re-torqued using a specific proceedure. If you are interested in trying this before buying new gears, I'll find a link to some directions on how to set-up that 'crush spacer' pre-load.

I bought Strange 3.73's for my car, installed them myself with all the right tools, and have about 20k miles {with lots of abuse} with no whine, or any other problem. I also use Redline oil. I would recommend Strange, although there are other good quality gear-sets avaiable. The main thing is proper install.

 

Oh, and your stock gear ratio should be listed on either the glovebox or drivers door facing RPO code sticker. Look for the code beginning with 'GU'.
GU2 = 2.73. GU5 = 3.23 with automatic and
with your manual GU6 for 3.42 {only ratio available in 96 for M6}

 

A heads up... there are different forums for various parts of the car. You're in LT1 Engine Tech. Moving to "Drivetrain".

 

Well it freaks me out that it only does it in gear so I am wondering if its the pinion bearings too?! Shoebox I am HONESTLY WORRIED they didnt put fluid in there , lol.....it was VALVOLINE (punk kids)!!! But I have put 400 miles on it since then and havent smelled any burning or anything since. Would I be able to notice if it was empty without pulling the drain plug?! THANKS EVERYONE FOR THE GEAR BRANDS TOO!!!!

 

The rearend / differential housing is a mostly {other than atmospheric vent} a sealed / isolated assembly. The vent hose serves the purpose of very little cubic ft / min volume of exchange between the vented atmosphere and the gear camber. It is located behind your driving position while going foward, which , if there is a smell to be detected, won't be while your driving down the road.
If there is no oil in the gearbox, {is the gearbox hot after driving a few miles, real hot?} and you smell it when stopped, then I would check the oil level via the filler plug {"drain plug"}.
If you have run it any time {<400 mi} at all with no oil, you will likely need to replace all the components of the rear end. {at the cost of the "VALVOLINE (punk kids)!!! " of course.

 

Did they put in the "additive" with the fluid? If M-6 go with 4,.10 OEMs and use Solid Spacers instead of crush sleeves.JMHO

 

The additive is designed to reduce / eliminate the noise produced by 'clutch friction bind' associated with 'clutch type' limited slip differentials. It has no affect on straight drive situations since the differential clutches are at idle in this situation.

 

I'm crawling under there tomorrow to check because I ONLY smell it when I am stopped, and its a HOT smell from the driver door area to the rear of the car, now I am worried for SURE!!! I also noticed my shifter **** shaft is HOT when I am shifting and the boot slips, and the metal part of the e. brake is hot too....hmmmm I hope they dont give me shizzzz about messing up my stuff and not trying to replace it ( ie putting fluid in while talking to me and then tell me its fine and has stuff in it!!! , how would I prove them wrong?! ) Thanks guys---

 

Sure your not low on transmission fluid?