How far on FWD?

[ensteele]

I need to buy a set of tires for one of my SVXi. It has a set of new tires on the front and worn tires on the back. I would like to put a different brand of new ones on this car, but I don't want to drive it home this way. The total miles from where it is to home is 600 miles. I could put the fuse in and drive it in FWD, but would that be too far to drive it that way? I could put 2 more new ones on, but it will cost me more to do that than buy a new set of 4. I would like to have it aligned while I have it in the shop at home. I don't like to have work done on a car when I don't really know the shop.

Would 600 miles be to far? Any other precautions that I should take. Thanks.

[huck369]

Earl...
I'm sure some will dissagree with me, but I have run Subarus for months in FWD to no ill effects....so driving it home will be no problem...But that is only my opinion which is a result of my own actual experience...

[NikFu S.]

I on the other hand have run for mere minutes in FWD and destroyed my tranny.
I think the trick is to keep the wheels from slipping.

Again, on my other other hand, after my tranny was rebuilt it was in FWD due to a mechanical defect, and ran fine for +2 years even through abuse, until the center diff popped, which is a result of 3 years of wheelspin (icy winter and "spirited" summer driving).

I think you'll be ok.

[SomethingElse]

Ran 2 months on FWD ran fine for 1500 miles or so...till i finally fixed it.

[ensteele]

Thanks for the quick response. I go over to ID on Friday and Chris T will pick me up at the airport. I will spend the night and then drive home on Sat. It is only 550 miles or so. There should not be any slipping of my tires because there is no snow or ice yet. I want to get it aligned before I put the new tires on and I can get a much better price here at home. Thanks again. If any one else has a response, I will listen to those as well.

[subarufamily]

the previous owner had the fwd fuse in for 9 mths all spring to fall with no ill effects it ws after they put the fuse in it for the winter and drove it for the snow that they shelled the tranny you should be fine in my opinion anyway

[Myxalplyx]

Originally Posted by subarufamily

the previous owner had the fwd fuse in for 9 mths all spring to fall with no ill effects it ws after they put the fuse in it for the winter and drove it for the snow that they shelled the tranny you should be fine in my opinion anyway

I need a little more education in this matter. Why does driving in the snow pose a problem with the FWD fuse in? How is that different than driving in the dry if power is only being applied to the front wheels? Is it because you get in a situation where the front wheels are turning faster than the rear wheels? What if the rear wheels are stationary and the front wheels are spinning at a high rate of speed? Does that pose a problem?

[ensteele]

Originally Posted by subarufamily

the previous owner had the fwd fuse in for 9 mths all spring to fall with no ill effects it ws after they put the fuse in it for the winter and drove it for the snow that they shelled the tranny you should be fine in my opinion anyway

Do you mean that they took it out for the winter instead of put it in? If you put the fuse in, it puts it into FWD. If you take it out, it puts it into AWD.

[NikFu S.]

It is my understanding excessive or violent wheels spin like what you get in FWD will shatter the front diff. It is an open diff and in a no traction situation one wheel will spin radically while 3 others do nothing. It's just is not designed to handle that stress. A failure of the C Sol will give a similar condition, but also depending how it fails, bind the center transfer clutch, eventually causing that to fail. This is what happened in my car. The trans was rebuilt but the C Sol was not replaced resulting in transfer clutch failure within days. I am not sure how my front diff survived all that time. It could have been the almost complete lack of friction on ice. Spinning the wheels (or wheel) on dry pavement no doubt puts far more stress on the front diff, and to note, my diff failed on dry pavement under what probably would have been a traction loss situation had it gotten that far.
One more thing to note, the previous years I had been using bald tires. I had yet to spin them with the new grippy tires I had just bought this summer. I would like to say this is evidence of the greater the traction/surface friction you have when you let the fronts loose, the geater the risk of destroying the front diff.

[ensteele]

I am not planning on spinning the wheels. I will drive it home carefully and that should be fine.

[dcarrb]

FWIW, I drove my silver SVX in FWD for many weeks of routine commuting and grocery gettin' without any (apparent) ill effect.

dcb

[Myxalplyx]

Originally Posted by NikFu S.

It is my understanding excessive or violent wheels spin like what you get in FWD will shatter the front diff. It is an open diff and in a no traction situation one wheel will spin radically while 3 others do nothing. It's just is not designed to handle that stress.

Ok, so spinning only one wheel can cause damage. Spinning the two front wheels (Like on a dyno) should not pose a problem since the two wheels are spinning at the same time, same speed. Ok....thanks!

[Mr. Pockets]

Originally Posted by huck369

Earl...
I'm sure some will dissagree with me, but I have run Subarus for months in FWD to no ill effects....so driving it home will be no problem...But that is only my opinion which is a result of my own actual experience...

I'm going to agree with Huck; I think driving it home with the FWD fuse in should be fine. It's better than the alternative, not putting the fuse in and driving it home.

When duty solenoid C went bad on my wife's Legacy, a dealer mechanic told me that I could either fix the solenoid or drive around with the FWD fuse in 'as long as I want.' I think I left it for about three months before I fixed the clutch. What happened after that was entirely my fault and not related to the prolonged use of that fuse.

[Mr. Pockets]

Originally Posted by Myxalplyx

Ok, so spinning only one wheel can cause damage. Spinning the two front wheels (Like on a dyno) should not pose a problem since the two wheels are spinning at the same time, same speed. Ok....thanks!

I don't think that's the case. If you have both front wheels spinning for an extended period, with the rear wheels stopped, I think you could do permanent damage to the transfer clutch.

The transfer clutch is multiple plates stacked on top of each other. One half of that clutch (every other plate) is geared directly to the transmission. The other half of the plates are geared to the rear wheels. Without pressure applied to the clutch pack, the two halves are free to spin in between each other, for the most part. Duty solenoid C applies pressure to that clutch, sending torque to the rear wheels.

Without that solenoid working, and without the rear wheels spinning, half of the clutch plates are standing still and the others are spinning furiously between them. I think you'd burn the fluid in short order and do damage to the clutch pack as well.

Putting the fuse in and driving around normally (without causing the 'violent wheelspin' nikfu apparently causes on a drive home ) doesn't cause the same sort of stress on the fluid or the clutch. Yes, there will be differences in speed between the two halves of the clutch, but not nearly as big a difference as one half being stopped entirely and the other spinning away.

[subarufamily]

OK OK OK I CAN'T TYPE they drove it all spring , summer , and fall no problems ( that i know of ) and why they put it in i dont know . but when they took it out drove it for the winter time in the snow they shelled the tranny , i would assume they got stuck and overheated the tranny , i dont know , i just know , PER the dealership, they did this. So good news I have a tranny with only 11000 miles on it, new I believe(possibiliy rebuilt or reman)