rustyshackleford426

Hi I'm new to working on cars and I just replaced my center section in my 8 3/4 rear end in my 1973 challenger. After driving it around and leaving the longest burnout I have ever done it started making a whine or supercharger noise from the rear diff. I am only 18 and this is my first Mopar and don't know much. I just need help finding out what the sound is and if I can drive it around for another day or do I have to stop driving it immediately and fix it. Thanks.

Drag Pak

Should not be any noise!

DDodger

I'm not going to mince words. Doing burnouts is stupid. If you have an "open" differential, that is not a sure grip (is not limited slip) you could have damaged the spider gears. If you only spin one tire, all the power is going through the spider gears, and that axle will be turning at twice normal speed.

Otherwise, hard to say "what you did." Does the rear axle actually have lubricant? Proper type? Enough of it?

Off hand I'd say pull it apart and inspect What ratio? higher numeric ("low" geared" ratios are going to be noisy at highway speeds, starting about 3.7 --3.9 or thereabouts. 4:10--4:11 almost always make at least a bit more whine than do 3.55--3.54 at the same speed

Not long ago, I had bought a Ford 9" center section "used." I ran it awhile, and at low speed I kept hearing noise. Put the rig on the hoist. "Seemed" like the INNER END of the axle wiggled, that is you could wiggle the tire, but it did not seem to be in the outer bearing. Sure enough!!! Finally tore it down, and this had either been a "mud rig" where one tire was spun a lot, or a "burnout queen." One spider side gear on one side had worn itself a "recess" in the casting, and was sloppy.

Archer

rusty -

If it's making noise the odds are the gears aren't meshing correctly or a bearing is shot.

If you did the work, how did you check the run-out and if some one else did it, bring it back. (If you just replaced the ham, how do you know the new one was in good working order?)

Burnouts should NOT adversely affect the drive train, if it's been built to match the motor.

Sorry, you didn't give a lot of info.

Archer

rustyshackleford426

Sorry for not having all the info. It is a 741 with 3.91 suregrip. I used to have a 2.94 open diff but I didn't like them not enough acceleration I noticed this when I got out accelerated by a Pontiac Montana van. The 3.91s came out of a friends super bee. He took them out because he just got 4.11s. I filled the rearend with lube and limited slip additive. The whine/howl starts at around 35 mph and gets louder as I drive until the exhaust over comes the sound. It's not super loud though. It only happens when I accelerate or have my foot on the gas. I replaced the whole center section when I put the 3.91s in.

Coronet 500

My first thoughts are:

#1- Does it have Green/Ball bearing axle bearings and if so has the thrust button been removed?

#2- Does it have OEM Tapered Bearings with a proper thrust button and have they been adjusted properly with proper end play?

This is critical and must be answered first before looking at pinion bearings and then side bearings and then backlash/wear pattern.

Don't forget to check U-joint tightness and alignment.

rustyshackleford426

It has the OEM bearings in it and I did not adjust end play.

Coronet 500

#2 must be done with thrust button contacting both axles.

rustyshackleford426

The problem was the backlash was not set right it had 6 thousandths too much so air was getting in there an causing the whine. Thanks for all the suggestions and and help guys!

RacerHog

Cool Beans..... So I take it she running around town pretty good now?