[g00fy]

I've read on other forums about people using FWD mode for various reasons (dyno/emissions testing, rear differential problems, drag racing, and of course flat tires).

I never thought about using the FWD fuse on the dyno, i just figured i would have to search far and wide for an AWD dyno when the time finally came. Anyways anyone have any experience/opinions on possibly using the FWD fuse for dyno runs?

 

[funkymonkey1002]

@g00fy I would be worried about the fuse blowing and suddenly being awd again in the middle of a pull. I've run on the street in FWD and I wouldn't recommend it.

 

[g00fy]

@funkymonkey1002 hahaha i didn't think about that... That would definatly make for an interesting situation.

 

[tallazzPilipino]

full-sized spare in both my parents' MY05 XT 4EAT and my MY01 S 5MT.

I would be worried about the fuse blowing and suddenly being awd again in the middle of a pull. I've run on the street in FWD and I wouldn't recommend it.

i was about to mention the same thing, if on a dyno. yikes!

_taF

 

[squash]

While it would be a Bad Thing for this fuse to blow, it is also extremely unlikely as it has a very low power draw. Its not like it flows more power based on throttle position or rpm or anything.

 

[BAC5.2]

I never thought about using the FWD fuse on the dyno, i just figured i would have to search far and wide for an AWD dyno when the time finally came. Anyways anyone have any experience/opinions on possibly using the FWD fuse for dyno runs?

You don't have AWD Dyno's out there? Wow. I'm spoiled. There must be a dozen AWD Dynos within 20 miles of my house, 3 within pushing distance of the shop.

 

[I Want Candy!]

Have had my XT auto on a front wheel dyno - in fact one of the most respected tuners in Oz does it all the time.

No issues at all

 

[NAEJ25]

The reason for the FWD fuse is for CA emissions, so they could 2 wheel dyno check the emissions .... I was told to never drive with it in FWD .... just looking to have to buy a new transmission .....

 

[pleiad7]

@NAEJ25 I dunno about that... Any AWD or 4WD vehicle in CA is automatically exempt from emissions testing on a dyno. Just ask any smog station owner - they would refuse to even put our FWD SVX on the dyno when it was due for testing.

 

[Graham]

The reason for the FWD fuse is for CA emissions, so they could 2 wheel dyno check the emissions

Er, no. They are exempt from the dyno check.

 

[voron999]

The procedure with the fuse also applies to Subarus with a full-size spare (to compensate for differences in rolling circumference if your tires are worn significantly more than your spare). Take a look at your owners manual, it should be outlined in there. I know it is in mine.

IF you do 5-tire rotation (like I do; I have two seasonal sets; 5 tires each), you do not have to worry about this hassle. Put the spare on and drive off as usually.

 

[pleiad7]

IF you do 5-tire rotation (like I do; I have two seasonal sets; 5 tires each), you do not have to worry about this hassle. Put the spare on and drive off as usually.

That works great only if you have non-directional tires, though.

 

[voron999]

@pleiad7 Yep. I forgot about that little detail. :icon_biggrin:

I carry non-directionals for my Sub. Kind of a bummer in that way, fewer tire choices. Oh well.

 

[NAEJ25]

Er, no. They are exempt from the dyno check.

My Subaru parts guy ( probably the most knowledgeable Subie guy I have met ) said they had to do that so when the cars were built they had to have some sort of way to dyno test them , even if they dont currently do that .... Something to do with when they first came out, CA emission testing was requiring dyno testing at that time ....

He said to NEVER run one in FWD ....

 

[The Rookie]

As far as I can make it from the transmission manual, fitting the FWD fuse puts the transfer duty solenoid at 0% so that no line pressure is supplied to the center clutch so leaving it fully open (no rear drive), so installing the fuse results in the lowest (none at all) wear of that solenoid.

EVEN IF it were at 100% then it would be on continuously with no movement, I'm pretty sure Subaru wouldn't supply a system for burning it out if it were likely to happen!

A little knowledge is a dangerous thing!

Simon

 

[Thermo1223]

In all honesty the tire rule only was crucial to early AWD systems(Halidex in particular I think).

I think now they evolved to certain point where it is unessecary to worry about it. Now I am not advocating running new tires on the back and bald ones up front. Not only completely stupid & defeating the purpose of AWD, it would just look funny

I'd imagine you would cause extra wear but on the scale of a few 100 miles worth over normal driving. So a trivial amount it would seem but that is my opinion not fact.

 

[Tuned200]

A solenoid isn't just a switch, which is a passive device and (assuming the switch contacts are in good condition) draws no power. A solenoid though is an electrically operated device, and that means it draws power to operate it. Drawing power means it will generate a certain amount of heat. If it isn't designed to be activated permanently, it may well overheat and burn out.

Having said that, surely Subaru must have designed it to operate for hundreds of miles in FWD mode. I've not seen any restriction on mileage while in FWD mode. (I'm not advocating leaving the car in FWD mode unnecessarily though.)

BTW, VDC equipped automatics don't have the FWD mode. It appears the VDC is supposed to take car of it itself, they do have an almost full-sized spare wheel which must help too.

I looked thru my owners manual and it does not mention a fuse either.

I also agree that subaru has built in a value for xxxx miles before it becomes a problem, as im sure we all know someone will do it. I remember seeing the same idiots driving on donut tires for months(not subaru owners, but you get the idea)

 

[BAC5.2]

As far as I can make it from the transmission manual, fitting the FWD fuse puts the transfer duty solenoid at 0% so that no line pressure is supplied to the center clutch so leaving it fully open (no rear drive), so installing the fuse results in the lowest (none at all) wear of that solenoid.

EVEN IF it were at 100% then it would be on continuously with no movement, I'm pretty sure Subaru wouldn't supply a system for burning it out if it were likely to happen!

A little knowledge is a dangerous thing!

Simon

Duty-C goes to 100% with the fuse inline, not 0%.

That means that the solenoid designed NOT to operate at 100% duty... is.

The solenoid isn't really the concern. What IS a concern is the additional heat generated with wheel spin within the clutchpack. You can weld the plates together from the added heat.

 

[Rvines5]

I bought my teenage son a '98 forester that was locked into FWD. The former owner who had owned it for several months said he never found the switch to turn on the AWD. My son found out about the fuse from the manual but we've never owned an AWD vehicle and assumed that FWD was the default. Since he's had it, it's been shifting progressively later. It got to the point of having to get up to 4000RPMs to shift into the higher gears. At that point he got onto Google and found this forum. He says it's much better in AWD, but I don't know if it's permanently damaged or what to do to fix it.

 

[adc]

I don't think there is a problem having it in FWD for a long period of time.. Its likely that there was a problem with the vehicle even before the other owner had it. Other possibility is that the auto tranny has been neglected and the ATF never changed. Check and see if the spin on AT fgilter is a genuine subaru one.

Welcome to the board.