First off, thanks to everyone for their suggestions and feedback. I appreciate it.
I will remove the driveshaft to see if the diff works smoothly, but wanted to solicit advice before proceeding as the symptoms and timing is a bit baffling to me.
Some responses suggest that I should elaborate on some details. I’m not a newbie. I’m aware the car is full-time AWD (LSD front and center for this car) and that’s why I’m concerned about the differentials.
I bought this 1st-gen WRX new in November of 2001 and am the only person that’s driven it or worked on it outside of the dealership. The dealer did the first 3 years of maintenance as part of the warranty, but I’ve done all of the maintenance and repair to the car since 2004.
I am not a certified mechanic, but I’ve been working on cars and trucks for more than 30 years. I know what unibodies are and how they are made.
The car drove great before I did this master cylinder and brake pad/rotor change, but the brakes are not rubbing and the wheels will not turn by hand even with the brakes removed entirely.
The parking brake is not on and in fact both the disk and drum brakes are /removed/ on the rear of the car. It’s still difficult to turn the rear wheels and I cannot easily raise the front wheels to check them. Yes, the car is in neutral ;). There is oil in the rear differential and it appears clean.
Yes, the subframes are rusting, but I want to know what the rubbing/friction is about before giving up on a car that I cannot replace. I appreciate everyone’s input, but it’s not helpful to declare the car unsafe just because I said it has “lots of rust” :). I’m simply trying to disclose as much information as possible. I’m aware that cars lose structural integrity due to rust.
Unibody vehicles have very few jack points to begin with and that’s one reason there are front and rear points built into each side rail; there are few other places to securely put a jack. One of these standard jack points has failed and I was using the opposite-side jack point when I let the car topple the jack. It bent, but did not collapse.
The rear tire was a couple inches off the ground when the car rotated; the car pivoted horizontally around its front end and came to rest on its wheels. The jack is ruined, but there was no violent impact and I only mention this incident because the “friction” problem occurred after completing this service. Mechanics that I’ve asked don’t think the jack fall is related to the friction/noise, but I want readers to know about anything the might be relevant.
The car is not bent or misaligned to any observable degree. The half shafts and drive shaft appear straight and free. Nothing even touched these pieces during the jack incident. The front wheels may or may not have turned in opposition to one another during this fall or one may have skidded slightly.
I think that the car was mistakenly in neutral at the time, which contributed to the instability. In that case, the wheels were free to rotate with only the LSD center diff to resist it. That shouldn’t have harmed it, but I want to mention it.
The car isn’t coming apart, but rust will indeed end this car’s life sooner than I’d like. The engine has 85,000 miles, leaks no noticeable oil, and has new plugs and timing belt. The alternator may need replaced in a year or two, but the engine’s good to go for a long time. The clutch is great as I don’t abuse it and the interior is like new. Rust will render all that meaningless.
I will re-inspect everything around the driveline, but the left-rear wheel would spin normally when this all began, yet now it seems just as tight as the right-rear. The right-rear hub is now disassembled as I initially thought that the wheel bearing was the problem. I have a new wheel bearing in hand and the tools to install it, but the old one was pristine and obviously not the problem.
As with millions in the Rust Belt, our roads are covered with wet salt for much of each winter. I do my best and have long wanted an under body washing system that works each time I come in my driveway, but that’s not a practical solution due to cost, freezing, and water waste. A man can dream…
Thanks again for your time and feedback.