FXT issues diff. issues

hey all, on my 04 forester xt after about 60mph it feels like my diff is slipping and it kinda jumpy or skipping while accelerating. I have had the issue before due to off tire sizes (came like that when i bought it) and when i got new tires it was fixed and about 100x smoother. could this be an after effect now?

 

By "off tire sizes" I assume tires that were different size than each other, right? If that's the case, and the tires were different enough, and it was run like that for a while, that could have caused some permanent damage.

If the previous tires were just not stock size, but were all the same size as each other, that doesn't matter.

 

They were not crazy but one new tire and bald tires and in between. So I gope its not though. Any solutions?

 

Well, it's surprising the difference in circumference between new and bald tires. Especially if the manufacturer and/or model of tire are not the same. It can cause damage pretty quickly, in my understanding. Any idea how long it was run that way?

 

We just talked about this in another thread recently. If I remember, the overall circumference difference of your tires shouldn't be any more then either 1/4" or a 1/2", depending on who you ask. If I understand this correctly, having differences in your rolling circumference between tires causes your center diff to think your "slipping" that tire(s) and it starts trying to transfer power to other wheels, which will cause premature failure. If I'm way off, someone please correct me. But this is my understanding of it.

 

That's a pretty good explanation! I think my BIL said the limit was .25 inches (former Morrie's service writer)

 

it just kinda started agian. recently after new tires and the tires are no longer than 4 months old.

 

I see your also having turbo problems. Are you sure your not confusing the 2 problems? Also have you chained the fluid in your diff? Are the new tires wearing evenly?

 

Is this an manual or auto and what's the mileage?

 

If I remember right, I read in one of his other topics that its an auto, with less than 90k on it.

 

If that's the original tranny fluid then it's past due.

If the tires were run that way for a while then the damage may have already been done. Change the transmission fluid and front and rear diffs and see what happens.

If it's still wonky, then it may be a very expensive fix.

 

I find it a bit coincidental that it seems a couple times now, what he is thinking is a diff problem pops up at the same time he has a post about burning up another turbo.

 

True. Perhaps get that sorted out first.

 

haha sorry it just happen to happen all together and the car is automatic with 98k miles. and i would think two different things would cause these two issues.