Driving with bad wheel alignment

[justdeserts]

On my 1993 Subaru Legaxy. I’ve  had a really messed up left rear steering knuckle where the control arm bushing is bent out of shape. I’ve been wondering if this is going to contribute to premature transmission failure as I’ve heard it’s bad to even drive with mismatched tires on Subaru AWD platform. 
Car drives okay till I get to around 55mpg where it starts shaking a lot and it will generally shake if I have it at the lower RPM range of any given gear. 
I’ve already driven it an awful lot all over my state. I want to know if I might be OK to make this road trip I’m thinking of making or take it back home and get it all fixed up completely ASAP. Thanks guys!

[doublechaz]

If your alignment is bad enough to give different wheel speeds and burn up your center diff, then you will blow one or more tires pretty darn quick.  Probably before it has time to hurt the center.  Running a matched set of tires is correct.  Which makes roadtrip 'just grab a used odd one' at the tire shop not an option.  Then there is the thing where literally every single time I've ever been to a tire shop over the last 40 years they tell me, "Oh, that's a really rare tire size, we'll have to order that.  It'll be about a week."  Even though I can look in their lot and literally 50% of the cars in the lot have that same tire size on them.  It's just a lie they tell so they don't have to admit that "just in time" inventory has down sides.

It's hard to say through the internet if you are clear to take a road trip.  How far, what speeds, etc.  If you have uneven tire wear I would consider not doing it.  If the tire wear is alright, then perhaps that specific repair item won't wreck your road trip.  Sounds like it is time to check and replace bushings all around.  Seems like the sheet metal warrants that level of repair if you can do a lot of it yourself.  I did all of mine at 250K.  AZ allows cars to live that long, unlike MI.

[justdeserts]

Hey thanks! I’ve driven it hundreds of miles by now so I think I’m gonna make one more extended trip before finishing up the rest of repairs. Also good tip on the bushings I’ll get around to them if I’m still driving it 40k from now

[doublechaz]

To be fair, mine turned out not to need most of the bushings at 250k.  I assumed based on other cars, so, you know.  But I'm not sorry I did it as I did poly all around so it is a little sportier than OE.  But there are lots of variables about bushing wear so nothing beats getting under there and inspecting.

Have fun with your trip.