How to tell if your diff is going bad

[94Jettameowpsst]

I have a 1990 talon tsi w/ 96k miles on everything. I was just wondering ( i know 90 trannies are weaker) how do you know if your diff or something in ur transmission is going bad? I was just driving, it didnt pull to either side, but it sounds like a squeaky belt coming from the passeger side of the car and cant figure it out. I dont have an inspection plate on the bottom, kinda got tore up and bent to hell, and its the first time i drove the car in the rain. I couldnt tell you if it was makin any sounds before because i was runnin the exaust straight from the dp...kinda loud. I just got it fixed and noticed this sound. Im not saying its LOUD, but audible under part throttle enough for me to worry. Also, when i pull out, actually inany gear, it sounds like "road noise" from tires, but it inclines with acceleration, i shift, then its the exact same pitch. Any help appreciated. Btw, i used regular gear lube, cant remember weight, but it doesnt leak from anywhere either.

 

[94Jettameowpsst]

Update: The squeaking sound i have it narrowed down to a wheel bearing, although i've never heard one sound like this because its gotten a lil louder, or its the mechanics wire holding my downpipe up. BUT, on the other hand, it does it when im stopped at a light, not a lot or loud, but the squeaking still happens. Heres the shitty part. I noticed a distinct whine my VW had when my diff blew the gears out the bottom of the tranny but not to the same extent. I have a funny feeling my diff is goin or somethin in my tranny is gonna let go soon. When i decel there is no whine, but as soon as i touch the gas it sounds like the turbo spoolin but not as loud, and not the same (if you follow me here ) I dont know what to do cause i heard you cant get a closed diff for the 90 tranny and i just freakin got this car. If the diff is gonna go soon, could it be welded to make it "locked"? Any input on ANY of this would be great.

 

[94Jettameowpsst]

Has noone had a bad transmission. This is my daily driver and i just wanted some opinions if anyone had some similar symptoms

 

[94Jettameowpsst]

Well i kinda ruled out the diff being bad, i heard from a couple people that i took for a ride in my car that the input or output bearings are going bad. Now i changed my 80-90 lube to pennzoil synchromesh and the whine is minimal but i still have a squeak from the front right side of my car. Anyone have experience changing or having bad shaft bearings?

 

[94Jettameowpsst]

Since nobody can troubleshoot or has any idea about my transmission, heres a question someone may know the awnser to. I just noticed this: How much play side to side should there be while your in gear?

 

[lov4godgst]

Since nobody can troubleshoot or has any idea about my transmission, heres a question someone may know the awnser to. I just noticed this: How much play side to side should there be while your in gear?

When my tranny was replaced, my mechanic asked me if I had movements in any gears, so he could replace that bearing. I know that in my other DSM my 4th gear has had movement for as long as I can remember....several years, so that alone may not be a big deal. However, you said its whining and stuff, so I cannot comment as to whether it needs rebuilt.
Oh, and don't weld your diff if its a daily driver.