I am having this problem with my axle. (I think its the axle or diff.) When I start driving about 35-50mph this really freakin loud whining noise starts coming from around the axle area, possibly the differential. I know its coming from back there cause I have no back seat, carpet, insultation etc. Its never done it until the last month or so, and its getting worse. Enough that I cant hear my flowmasters at that speed range. Goes away over 50. Any ideas?
its a '91 and has 170K miles
The gears were changed to 3.55 back in like 96. could it be low on fluid or something? Ive never dealt with axles so if I seem kinda dumbits cause I am.
Yeah, it could be low on fluid and that will be the easiest thing to check and/or fix.
There is a fill plug on the front driver's side. Take the plug out and then check the fluid level. The fluid should be right up to the bottom lip of the fill hole.
If your fluid is low and pouring more in solves your problem then you're set. However, I'm suspecting you have a bearing going south (even if the fluid is low). The only way to replace the bearings is to take the entire thing apart. I'd start with the outer axle bearings (out by the brakes) since they'll be the easiest to replace. After that, you've got the inner axle bearings which will require you to remove the carrier assembly. After that, there are the pinion shaft bearings.
Be sure to lube up that differential plug when you go to loosen it. It isnt half as easy as removing the plug on a transmission, especially if it hasnt been removed before
mine was doing the same thing so when I got my gears I put in a whole set of all new bearings. the one's that where the worst where my pinion bearings. Also it could just be the gears making some noise, but if it is as loud as you say it is then I'm going to agree with wagstdy that is probably one of the bearings. good luck
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Black 90lx Hatchback, Intake, headers,off-road H,40-series flows with dumps,Ford racing 3:73's with a richmond mini spool, Cobra racing wheels with 245zr17 yokamoto tires. Also ditched all smog and a.c. stuff, Black magic electric fan and aluminum water pump, Brand new world class t-5. Plenty more to come.
Checked the fluid level over the weekend. There was plenty in there, but it was blackish-grey? Thought it was supposed to be something else??? Anyway - the plug was magnetic and had ALOT of metal shards stuck to it.
I am guessing the bearings are probably wore down pretty significantly at this point.
Since Im opening it up might as well put 31 spline axles in the budget now. ... and I guess since I'll be putting new axles in might as well do a disc brake conversion.....which since Im doing that I might as well go 5 lug conversion and get new rims and tires.....
DOES IT EVER STOP!!!
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Sonic Blue 2003 Cobra - Autlogic chip, Magnaflow x-pipe, mufflers, 2.9 inch pulley, CAI
Black 1991 GT - 347 twin turbo 6-speed distributorless ignition - nothing stock
Loud whining noise coming from axle area 
