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Discussion Starter · #1 ·
I have a 98 cobra with 3.73 gears. This past spring the gears started whining and have been getting progressively louder, especially at 55, in all gears, it seems to be more speed related than anything to do with what gear it is in. In all gears the whine is the same. Its not the tires, they are not that old and have plenty of tread. They are Riken Raptors, 275/40-17's. I can hear it at speeds of 5mph on up. The rear has already been reshimmed by a good mechanic friend of mine. It was 6 months later that the whining started. It also doesnt change tone when turning left or right, braking or hard accelerating, or idling at neutral, so its not the fuel pump. Its just there when moving forward and loudest at 55mph. I changed the fluid when it was reshimmed, using the 80-90w (i think..) motorcraft gear oil, and half a quart of heavy duty lucas oil. Im about to change the fluid again to see if that helps any. Gonna use 75-140w mobile one syntec with a whole quart of the lucas this time. Any suggestions as to what this problem is, could be, stems from, how to fix, etc?
 

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lift the rear end of the car off the ground on some jack stands under the axle and not the body....out the car in first gear and let it idle. go back behind it and listen for the gear whine to make sure that its the gears.
if it is the gears the first thing i would do is change the oil. i am not too crazy about mixing ether. put 2 qts of 80w 90 lucas in (cheapest thing in case u have to pore it back out)
after refilling check it again to see if the noise went anywhere.

how long ago were the bearings changed in the diff housing?
how many miles on the car?

if the gears are fairly new and installed correctly then the noise is gonna be coming from the bearings.

if the bearings have been replaced then your gears were not installed correctly. most likely not enough backlash.

can i get a little more details on the gear installation, what was replaced and what was not?
 

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Dont forget to add some friction modifier additive. Or go with a synthetic gear oil that already has the friction modifier additive already mixed in. I know Royal Purple does.

Or just fill the rear with Lucas synthetic gear oil if you happen to like the Lucas stuff.
 

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Discussion Starter · #4 ·
110k on the car. the gears were in it when i bought it. i had them reshimmed cuz there was a clunk whenever i took off which turned out to be an upper control arm bad. not sure if the bearings have ever been changed in the housing. the one time i had it on a lift and in gear the wheels shook pretty bad like they were ou of balance with no weight on em. there was some slight play in the left rear wheel from side to side, but noone could hear the whining over the shaking of the wheels. the mechanics told me the bearings would be more like a squeal when they go bad, and would change tones under a load. this is not the case.. its the same. upon slowing down while in gear, the sound is similar to an airplane engine, only not as loud. the rear doesnt vibrate or shake while driving, and performs smoothly otherwise. i have replaced nothing in the rear except for the fluid when i had it reshimmed by a very good mechanic who specializes in that kind of work. sorry if i left out any details, not a regular poster in forums. anything else, ask and i will answer to the best of my knowledge. I am very mechanically inclined myself, but am short on the funds to just take apart the rear and replace stuff, and this is my only ride in cold weather. thanks
 

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Discussion Starter · #6 ·
lol mark. i do have a child that rides back there from time to time, and the whining from the rear drowns out her talking around 55mph. freakin annoying. hope i get some more feedback on this.
 

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this is what i would do......change the oil and take it for a drive, if it does not fix it than change the carrier bearings. and probably would not hurt to change the axle shaft bearings ether. while u have the dif cover off inspect the differential to make sure nothing is broken. the rear ends are somewhat simple man. let me know if u need any pics to help you out i have taken some when i rebuilt mine.
 

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Discussion Starter · #8 ·
Thanks oght6. Yeah that is what i plan on doing. I am really hoping a simple fluid change will do the trick. last time i checked it, the fluid level was good, but looked kinda murky like oil/antifreeze looks when mixed. thinkin maybe some bearings might have worn and put some metal into the fluid. i have an entire rear rebuild kit, but not the tools, time, or money to pay someone else to do it.
 

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Thanks oght6. Yeah that is what i plan on doing. I am really hoping a simple fluid change will do the trick. last time i checked it, the fluid level was good, but looked kinda murky like oil/antifreeze looks when mixed. thinkin maybe some bearings might have worn and put some metal into the fluid. i have an entire rear rebuild kit, but not the tools, time, or money to pay someone else to do it.
yeah man i would def change the oil then, and if you do decide to rebuild it let me knew i can help you out. its really not that big of a job. I did mine in the parking lot of my apartment complex. lol
 

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Discussion Starter · #10 ·
damn thats good news.. i might end up doing that. nothing i have had to work on has been an easy fix. now with cold weather setting in, my belt squeals against my alternator pulley. 3rd belt i have replaced, and have tried to reposition the alternator to no avail. one annoying noise after another with these things lol.. how do u manage?
 

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damn thats good news.. i might end up doing that. nothing i have had to work on has been an easy fix. now with cold weather setting in, my belt squeals against my alternator pulley. 3rd belt i have replaced, and have tried to reposition the alternator to no avail. one annoying noise after another with these things lol.. how do u manage?
dude there is a very easy fix. lol the whining of my Kenne Bell drowns out all of the other noises.
 

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Discussion Starter · #12 ·
lmao.. easy? wtf.. thats like $5000 for all that stuff. i could buy a new trans, rear, and get a half way decent new paint job for that lol
 

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lmao.. easy? wtf.. thats like $5000 for all that stuff. i could buy a new trans, rear, and get a half way decent new paint job for that lol
hahaha i didnt say it was cheap i said it was easy. lol
 

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Discussion Starter · #14 ·
if my motor was younger i would consider it. 111k is trying too much luck to add boost. besides, its a daily driver. i hardly ever race it.. need it to last with a crap economy and no money to buy another if this one goes
 

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if my motor was younger i would consider it. 111k is trying too much luck to add boost. besides, its a daily driver. i hardly ever race it.. need it to last with a crap economy and no money to buy another if this one goes
yeah i totally understand man.
 

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Discussion Starter · #16 ·
ill be changin the fluid tomorrow i think, hopefully everything goes well and i dont wring off or break anything. gonna do some other stuff too, maybe try and get rid of that belt squeal. ill dive under the hood of any friend or relative's car, but hate working on my own. lol
 

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ill be changin the fluid tomorrow i think, hopefully everything goes well and i dont wring off or break anything. gonna do some other stuff too, maybe try and get rid of that belt squeal. ill dive under the hood of any friend or relative's car, but hate working on my own. lol
i hear u man...to make things a little easier stop by ur local auto store and get a little hand pump that attaches to the oil jug. they are cheap and make everything so much easier.
 

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Discussion Starter · #19 ·
sweet, thanks for the tip! that lucas is a pain in the ass to put in anything that isnt anything but straight down
 

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yeah man, also i am not sure what u are planing to use for a gasket, but i used that gray silicone stuff.
 
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