05 WRX drive train issue,grinding noise coming from center to back of car + rear wheel hop developping during tight slow turns

Question

I have a 05 WRX which has been producing grinding noise from somewhere between the center to the back of the car. The noise starts to happen once the car is warmed up and under power. It can also keep going when lifting the foot and coasting as well. The transmission is a 5MT and still shifts smoothly. The noise usually happens when driving over 50 kph.

I changed the fluid from the rear diff. The magnet on the plug didn't have any metal attached to it. The fluid was dark but no sign of metal shards. Putting new fluid in the rear differential didn't help solve the problem.

Now last weekend I started to notice rear wheel hop when performing tight low speed turns when parking the car.

Can this be the center diff getting worse? What is the best way to get to the root cause of this issue?

Thank you

Jean-Christophe Rodrigue · Accepted Answer

So the weird grinding noise was caused by the exhaust expanding due to heat. The expansion made an exhaust hanger touch the hitch that is installed on my car. Once these touched the engine vibration transmitted from the engine through the exhaust resonated with the hitch.
The noise problem had nothing to do with drive train components.
The wheel hop is unrelated to the noise but has been confirmed to be the center differential. A new center differential has fixed the problem.

Pᴀᴜʟsᴛᴇʀ2 · Answer

I'm not sure on the Subaru, but it sounds like your transfer case is having issues. When a transfer case is locked up, it can cause the wheel hop you're talking about. This is very common with vehicles which have a regular switchable transfer case (like my Chevy Silverado). On my truck, when in regular 4wd (not auto-4wd), if I go to turn the wheel while going around a corner it will ... er ... lope. I asked the Chevy dealer about this and he stated it's because the transfer case is loading up, which is not good for it. In your case, since yours is full time AWD, it sounds like the problem is in your transfer case and it is behaving like mind does in 4wd.

Answered by Pᴀᴜʟsᴛᴇʀ2 on September 26, 2021

05 WRX drive train issue,grinding noise coming from center to back of car + rear wheel hop developping during tight slow turns

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