2012 Legacy 2.5 CVT Front Differential Question

[colinmi]

Today I had the front end lifted working on the brakes.  When I rotated one wheel the other one turned the opposite direction -as expected.  There was about 5-10 degrees of backlash. The wheel will rotate that far before the other one starts to turn.  I am fairly new to Subaru and my question is if this in the normal range?  The car drives well but seems a little bit louder in front than my wife's 2012 Outback.  I know there are other things that could account for this but am looking to learn a little more about these machines.

[1 Lucky Texan]

sounds about right to me.

[lostinthe202]

I don't know the numbers for the diff backlash, but there def is some.  If you're gauging the backlash by how much the tire rotates, remember that the rotation of the axle at the axle's diameter of something like 1.25" inches and the tire at something like like 24" is going to look dramatically different.  Watch an analog clock that has a second hand.  The tip shows much more movement than a point on the hand close to the hub.  Add to that motion that when you rotate the tire, you're not only taking up the backlash for the side you're rotating, but also the backlash for the tire on the other side of the diff.

 

Do you have access to another vehicle?  Jack that one up and do the same thing, bet you see the same motion.

Edited February 26, 2017 by lostinthe202

[GeneralDisorder]

That would be spider gear backlash added to ring and pinion which is typically a pretty loose situation. You can't tell anything from that. Ring gear backlash alone would be in the .010" range but spider gears in the diff are often pretty loose.

 

GD

[idosubaru]

Practically speaking that's inconsequential as a diagnostic tool.

 

First step is to check the fluid

Second step is to look at mileage and fluid changes

Third is to sit in drivers and passengers seat and stand outside the vehicle while it's being driven past to determine if the noise is more left/right or central.

[colinmi]

Thank you for all the responses.  Because of them I learned a bit about the car. It's good to know this backlash isn't an indicator of something going bad.  I also did a little more practical diagnosis here and am reasonably sure that these tires are why things are slightly less quiet and smooth than I think they could be.  An alignment and some fresh tires are in my future I think.  Thanks again.