95 Subaru Legacy Wagon --4WD Question

[rainman19154]

1)No 4WD button or lever. Rear emblem says AWD.

There was no owner's manual with the car... I've ordered one off ebay but for now, can someone give a thumbnail explanation of the system?

FYI, I don't anticipate off road use; just whatever ice and snow Philly streets throw my way.

However, I'm accustomed to there being some sort of on/off feature for the 4WD... whether a lever or an electrical switch.

[Rooster2]

AWD means full time all wheel drive. There is nothing to shift in or out of four wheel drive. If there are decent tires on the car, it will pull you through the nastiest snow and ice that Philly has to offer. You will be impresssed.

[lmdew]

Auto or manual Transmission?

 

Make sure the tires all match and are properly inflated.

 

If you have an auto transmission, you will find a little black fuse holder on the passenger side firewall just behind the front strut tower. If you put a fuse in it, the c-duty selonid will be energized all the time and make it a FWD car.

 

Manual transmissions have a viscous coupler in the trans.

[rainman19154]

It is an automatic.

 

As it stands... w/o the C duty engaged, I'm basically in 4 wheel mode all the time? Sounds like a loss of economy, not to mention extra drivetrain wear.

What is the required rating on that fuse? 20 amp adequate?

 

 

And BTW... thx for the rapid replies. I'll be here lots as I get used to the new ride.

[lmdew]

Not much drain on the fuel, if you see a 1 mpg drop in AWD I'd be supprised.

 

The draw is not much, 10-15 amp should be fine. Some folks run around this way, but the AWD system was not designed that way. The C-duty soleniod may go out ahead of time, as it is only energized in a hard turn so you don't have torque bind.

[Suzam]

This system isn't like a 4 wheel system with the locking hubs. With those there is a fuel savings when you unlock the hubs and keep the front components from spinning and causing drag on the driveline.

 

Subaru's alway have a minimum 90/10 front to rear power split that can vary up to 50/50 so the system is always energized. Most all the loss of economy is from the weight of the components themselves not from any drag.

 

You could save move with good driving habits than you would gain from driving with the fuse installed for FWD. The fuse is there for temporary use with a smaller diameter spare tire, not as a permanent installation. You will see an explanation in your manual when you get it.

[johnceggleston]

1)No 4WD button or lever. Rear emblem says AWD.

There was no owner's manual with the car... I've ordered one off ebay but for now, can someone give a thumbnail explanation of the system?

FYI, I don't anticipate off road use; just whatever ice and snow Philly streets throw my way.

However, I'm accustomed to there being some sort of on/off feature for the 4WD... whether a lever or an electrical switch.

 

this AWD system is a computer controlled integrated part of the 4eat auto trans. it is not a 4WD system as you have know in the past. the system always monitors the speed differential between the front and rear wheels and it adjust the power output to the rear wheels as needed. on flat dry pavement, you have a 90 / 10 split favoring the front. ( it is not simply a front wheel drive car, if you put in the already mentioned FWD fuse and test drive the car you will feel a difference from the AWD driving conditions.) when the front wheels slip due to slick conditions like mud, snow or rain, the computer will send more power to the rear, if it is working correctly.

 

so if all 4 tires are the same circumference (within 1/4 inch) and properly inflated, drive it and forget it.

 

 

 

.

Edited October 25, 2009 by johnceggleston

[rainman19154]

This thread has told me what I need to know to get by for a day or two.

Read my intro ... I just bought the car and it does have one off sized tire - (much to my disappointment). The oddball is on the right front.

 

For now, I will get two matching on the front and install the fuse.

 

Thx

[zyewdall]

This thread has told me what I need to know to get by for a day or two.

Read my intro ... I just bought the car and it does have one off sized tire - (much to my disappointment).

 

How long has it had the off-size tire on it? Have you tried driving it in tight circles on pavement... how does it behave? a common problem with the automatic transmissions if they are driven with different sized tires, is to start hopping around turns as if it was in 4wd with a locked center, like 4wd trucks.

[rainman19154]

I can't guess how long the odd tire has been on there. I've put about 15 miles on the car since picking it up.

I will be swapping that tire to the rear first thing tomorrow, and installing a duty c fuse. I do have to drive it tomorrow but hopefully it will be less than 20 miles round trip. I'll have time to get this 'conversion' done before I go.

 

I have felt some binding, assumed it was associated with the off size tire and am currently hoping no permanent damage has been done.

The binding occurs in tight cornering and does free up once I'm rolling straight again. It seems to not be an issue as long as I keep the turns wide.

 

All things being equal, I could have changed those tires today but I brought the car home and attended to other duties. In the little bit I did drive I could tell that I had an issue to be addressed but other demands pulled me away.

 

The info here has given me a clearer picture of what is going on.

[johnceggleston]

I can't guess how long the odd tire has been on there. I've put about 15 miles on the car since picking it up.

I will be swapping that tire to the rear first thing tomorrow, and installing a duty c fuse. I do have to drive it tomorrow but hopefully it will be less than 20 miles round trip. I'll have time to get this 'conversion' done before I go.

 

I have felt some binding, assumed it was associated with the off size tire and am currently hoping no permanent damage has been done.

The binding occurs in tight cornering and does free up once I'm rolling straight again. It seems to not be an issue as long as I keep the turns wide.

 

All things being equal, I could have changed those tires today but I brought the car home and attended to other duties. In the little bit I did drive I could tell that I had an issue to be addressed but other demands pulled me away.

 

The info here has given me a clearer picture of what is going on.

 

there is lots of info here on torque bind if you search for it.

 

with 2 new and 2 old tires you are better off running both new ones one

on the same side of the car.

 

long term use of the FWD fuse may cause the duty solenoid to wear out early.

 

good luck.

[rainman19154]

I have to say, keeping the mismatched to one side vs both on one end - is an insight. I do understand the reasoning but dunno that I'd have thought of doing it that way.

 

For now, I have one oddball and I think it'd be less of an issue on the rear.

 

Should I not put the fuse in? I;m hoping I can get a better tire on there tomorrow... probably not a perfect match but one that is closer in size.

(The current odd tire is a differant tread and I'd say closer to 1/2" differance in size)

[Bucky92]

you would have to find a tire that is within 1/4 inch in diameter ( total circumference of the tire) to the rest..which is extremely small honestly.

 

Good luck with it... I picked up my 95 legacy LS wagon for $250 with a bad tranny..swapped in a used tranny and its been dependable now for 12K miles.

 

If the seller ..you dont trust..I would suggest doing the timing belt change very soon..probably wasnt done since most people dont know how to do them themselves and the thought of a $600-$800 repair bill keeps them from doing it.

[rainman19154]

Hahaha I asked, and the fellow said it had been done. He said they'd done the water pump, too - even though it didn't need it.

Allegedly, the car was his father's. I honestly don't know what to believe from this guy. He says he'll be able to dig up some service records in the next couple days. IF that happens, it might give me a clearer picture.

 

I've swapped the tires now and it seems a bit better. I will know better once I've driven it further than around the block.

 

I know finding a tire that is basically an exact match is going to be tough.

Sadly, I can't immediately afford to go out and spend 400+ for a new set of four.

 

And as a further rub, the three matching tires are in really good shape with deep tread. They are reasonably new.

 

 

Thanks for all the support. I'll keep ya posted.

Edited October 26, 2009 by rainman19154

[johnceggleston]

if you have only one odd size tire you are better off putting in the fuse to prevent trans / transfer clutch damage. but i wouldn't plan on driving that way until you wear out the 3 good tires, the duty c probably will make it that long but it may not. if you have 2 pairs of matching tires, they match each other but not the other pair, then put them on different sides of the car and leave the fuse out. you'll have 4wd and you will be able to determine if the binding you feel is internal or caused by the odd tire.

 

the open diffs will allow for the different size tires side to side, but noting will allow for different size front to rear except the fuse.

 

if it has been run with an odd size for very long it may have caused some damage.

 

usually torque bind is caused by not changing the ATF or from the duty-c solenoid failing or by mis-matched tires.

 

if you have to, you can pull the rear section of the drive shaft, but then it's only front wheel drive.

 

put the fuse in until you buy a pair of tires, and buy them before it snows.

[rainman19154]

I've put in the fuse, after moving the oddball to the rear.

Indeed, it does seem to have solved the problem for the time being. I understand this is not a repair but a stop gap to prevent further damage.

 

I don't know that I can get a set of tires this week but hopefully in about ten days I can get a set of four. In the mean time, I can keep my driving to a minimum.

 

Thanks for your patience and generous advice on this.

And may I add, compared to some other forums I've been on over the last few years, this one doesn't seem to have many self important wiseguys. That's certainly a plus.

[zyewdall]

 

And as a further rub, the three matching tires are in really good shape with deep tread. They are reasonably new.

 

If they are close to new, can you just find someone who carries the same size/brand of tire and get a new one to match? Some places will also shave a tire down to be the same tread depth as the old ones.

 

This isn't a problem unique to the newer subarus, as more and more cars have all wheel drive. Most tire shops should know about it and understand why you need it to match exactly.

 

Z

[CNY_Dave]

Hahaha I asked, and the fellow said it had been done. He said they'd done the water pump, too - even though it didn't need it.

Allegedly, the car was his father's. I honestly don't know what to believe from this guy. He says he'll be able to dig up some service records in the next couple days. IF that happens, it might give me a clearer picture.

 

I've swapped the tires now and it seems a bit better. I will know better once I've driven it further than around the block.

 

I know finding a tire that is basically an exact match is going to be tough.

Sadly, I can't immediately afford to go out and spend 400+ for a new set of four.

 

And as a further rub, the three matching tires are in really good shape with deep tread. They are reasonably new.

 

 

Thanks for all the support. I'll keep ya posted.

 

 

Tirerack will shave a tire before shipping it to you.

 

Dave

[Fairtax4me]

AWD vs 4WD is the difference of basically a center differential.

With 4WD the front and rear drive shafts are locked together and can not turn independently. This is why using 4WD on dry pavement is not recommended, because it leads to torque bind of the drive line and can damage the suspension and tires.

 

AWD systems make use of a center differential or clutch or coupler which will allow the front and rear drive axles to spin independently of each other if the need arises, such as when making a turn. As long as the system is working properly there will be no noticeable effects or difference between driving on dry pavement or muddy/wet ground.

[rainman19154]

If they are close to new, can you just find someone who carries the same size/brand of tire and get a new one to match? Some places will also shave a tire down to be the same tread depth as the old ones.

 

This isn't a problem unique to the newer subarus, as more and more cars have all wheel drive. Most tire shops should know about it and understand why you need it to match exactly.

 

Z

 

I can picture what you're describing but I've never heard of such a service.

 

I'm in Philly... I'd think that just about anything like that ought to be available in a town this size.

[johnceggleston]

I can picture what you're describing but I've never heard of such a service.

 

I'm in Philly... I'd think that just about anything like that ought to be available in a town this size.

 

the last time i was at merchant tire and mentioned this subject, the mgr responded that they did not do it because they were very hard if not impossible to balance and align. i just assumed that they did not have the needed equipment to do the job and were justifying their inability with a lame excuse. besides, sell and shave one tire versus selling 4, what would a sales manager recommend.

 

call around, you may find what you need.

[CNY_Dave]

I can picture what you're describing but I've never heard of such a service.

 

I'm in Philly... I'd think that just about anything like that ought to be available in a town this size.

 

Tirerack will do it on a new tire from them and ship it to you, or to a garage.

 

 

Dave