Phillip Posted August 18, 2003 Share Posted August 18, 2003 Can anyone tell me what the FWD Fuse Holder located in the right rear corner of my engine compartment is for? I was told to install a fuse in it when towing the vehicle (1999 Outback) with the front wheels off the ground. Quote Link to comment Share on other sites More sharing options...
frag Posted August 18, 2003 Share Posted August 18, 2003 On cars with auto trans only. It disengages the rear wheels and make you car a fwd car. Quote Link to comment Share on other sites More sharing options...
Suzam Posted August 18, 2003 Share Posted August 18, 2003 Also NEVER tow a AWD Subaru...ALWAYS flatbed, serious damage to center differential WILL happen.:boohoo: The main reason to use the fuse would be with a spacesaver spare mounted on the car so the AWD mechanical parts don't get trashed because of the odd size (circumference) of the spare. REMEMBER...NO TOW...ONLY FLATBED!! Quote Link to comment Share on other sites More sharing options...
Phillip Posted August 18, 2003 Author Share Posted August 18, 2003 I'm confused; if installing the fuse makes the vehicle a FWD, why would damage occur if it were towed? The reason I ask is that I just purchased a 1999 Outback with a blown engine; it was towed with the front wheels off the ground (and the fuse installed) about 15-miles. I'm in the process of replacing the engine and hope the previous owner didn't damage the transfer case. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted August 18, 2003 Share Posted August 18, 2003 I highly suggest you read your owner's manual if you have it. It's a wealth of information for your car. Quote Link to comment Share on other sites More sharing options...
remarcable Posted August 19, 2003 Share Posted August 19, 2003 It doesn't really have a transfer case like a 4WD truck, but there is a good chance damage or excess wear has occured. An AWD subaru should never be towed unless on a flatbed or dolly. NONE of the cars wheels should touch the ground. The FWD fuse turns off power to the rear wheels but they are still connected to the drivetrain. Thus damage occurs when towed even with the FWD fuse in place. The FWD fuse is also only functional on models equipped with an automatic transmission. The fuse is there so you can use the donut-sized spare tire for short emergency trips under 50mph. I believe a manual tranny subaru can be towed with all four wheels on the ground for short distances at low speeds when in neutral. I've never owned one (MT subie) though so I may be incorrect. Quote Link to comment Share on other sites More sharing options...
incognito Posted August 19, 2003 Share Posted August 19, 2003 So let me get this straight... Towing with car off = bad Towing with car on = doesnt matter? (after all, i have done this, with a broken viscous coupler) Quote Link to comment Share on other sites More sharing options...
Suzam Posted August 19, 2003 Share Posted August 19, 2003 Under NO circumstance should an automatic be towed with any wheels on the ground, whether the power is supplied to the transfer case or not (car on or off). Manuals in neutral can be towed with 2 or all wheels on the ground (like behind a motor home). The only time I would think it would be OK would be by removing the rear driveshaft before towing with an automatic, not sure why you would go to that trouble though. Quote Link to comment Share on other sites More sharing options...
incognito Posted August 19, 2003 Share Posted August 19, 2003 Whoops, missed the part that his was automatic. Mines a 5 spd. Quote Link to comment Share on other sites More sharing options...
theotherskip Posted August 19, 2003 Share Posted August 19, 2003 Originally posted by Suzam Manuals in neutral can be towed with 2 or all wheels on the ground (like behind a motor home). manuals can NEVER be towed with 2 wheels on the ground - it will absolutely destroy the center diff, and possibly pull it self off the tow rig. you can either pull it with all 4 wheels on the ground (under 6 miles), or with all 4 wheels off the ground (either on a flatbed or dolly. the same goes for automatics, but for different reasons. when you tow an automatic with the engine off, the tranny fluid pump is not operational, so no fluid is being circulated, and it will burn the tranny up. Quote Link to comment Share on other sites More sharing options...
Tolerance02 Posted August 19, 2003 Share Posted August 19, 2003 I fully agree with Theotherskip. If a 4wd MT shouldn't be towed with 4 wheels on the ground wat's the difference with going down a long decent? Better with 4 wheels On the ground than 2 wheels Off the ground and unable to turn. OK, in case of AT the engine should run. Urban. Quote Link to comment Share on other sites More sharing options...
Suzam Posted August 19, 2003 Share Posted August 19, 2003 Whoops, my bust! My manual trans info came from a freind's neighbor who tows a Forester behind a motor home. I had a long dicussion with him about it at a BBQ and maybe I misunderstood him (or there may have been a beer factor). I agree about the 5-speed needs all wheels to turn. Thanks for the correction. Quote Link to comment Share on other sites More sharing options...
Dinero Posted August 19, 2003 Share Posted August 19, 2003 The center differential of the AT equipped Subarus is VERY prone to damage from having tires of unequal circumference on the car. The allowance for the difference in circumference is only 0.13" (1/8)!!!! So, I would suggest inserting the AWD fuse even when changing a flat tire. Several posters have reported AT damage from briefly using a mismatched spare. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 19, 2003 Share Posted August 19, 2003 OK - AT Subarus need the FWD fuse inserted if a spare (donut or significantly different size) is used right? Does it matter which corner gets the spare? Why aren't left/right diffs. damaged? Carl 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
theotherskip Posted August 19, 2003 Share Posted August 19, 2003 suzam - your neighbor probably had one of the tow rigs that tows off the front of the car's frame, leaving all 4 wheels on the ground. you can tow a 5mt all day long with this setup, as it will get all the lubrication it needs, and the center diff will have even inputs from the front and back... carl - the difference between the front/rear and center diffs is that the center diff is a limited slip. when either the front or rear turns when the other isn't, it will try to get the other one spinning. both the front & rear diffs are open, so they can have tires of different diameters without burning up like the center (limited-slip) diff would... When you install the fuse, it doesn't matter where the donut (spare) goes. Quote Link to comment Share on other sites More sharing options...
Martinjmpr Posted August 21, 2003 Share Posted August 21, 2003 I can see the info about unequal size tires damaging the t-case or transmission on an automatic. So, the other day, I got a flat, put the emergency spare on, and put the fuse in the FWD socket. They couldn't fix the tire (it was wearing out anyway - see my other post on tires) so they put a used tire on that was of a different make (although it is the same size: P205/70R15). (And yes, I know used tires aren't a good idea, but I'm in the middle of nowhere, there aren't any tire stores around, and I'm going to be in a big city in a few days and I'll be able to replace all the tires then. I just needed something to get me back on the road.) Just for the hell of it, I decided NOT to take out the fuse in the FWD well, basically to see if running my car in FWD only would yield any better mileage. But if this info on the damage to the t-case is correct, then it may be a good idea for me to leave the FWD fuse in place until I can replace all 4 tires, since we all know that different manufacturers can sometimes have different diameters in tires that are of the same nominal 'size'. Is that right? If so I guess I did the right thing for the wrong reason. Martin Quote Link to comment Share on other sites More sharing options...
Setright Posted August 21, 2003 Share Posted August 21, 2003 For sure it's a good idea to leave the fuse in ! Quote Link to comment Share on other sites More sharing options...
Commuter Posted August 22, 2003 Share Posted August 22, 2003 First of all, the "spec" that Subaru has on their website is no more than 1/4" variation on the circumference. Note - circumference... measuring around the tire. To translate this, that means a difference on tread depth of 1 millimeter (less than 1/16" inch). There can easily be this much difference with just a bit of wear on what are otherwise the same tires. I had to have one tire replaced when there was only about 20% of the tread "consumed" on the set. I jacked up the car and wrapped a tape measure around the tires. I was just at the limit. A tire of a different make, or model, or both, and wear... The odds are against you that it would fall within this tolerance. I recall a post by a member a couple of years ago. He got a flat on a trip, had it replaced with some used tire. 3 hours of highway driving to get home and his center diff was toast. The automatics are more susceptible than the VC's used in the manuals apparently. Both however can be damaged. I don't know if the FWD fuse does anything when the power is off. Even so, the plates in the clutch pack (auto) would still "brush" against each other I believe if one tows with 2 wheels on the ground. Friction, heat, damage... you get the picture. A question was asked about the front and rear differentials. Yes, they (the one with the donut spare) will be made to "work" due to the different sized tires, but they can take a fair bit of this. They were designed for it. The center diff is not as forgiving. The dunut spare is recommended to go on the back, since you can disable the rear axle (FWD fuse, auto) and if you have an open rear differential, it is no issue really. For those that have limited slip rear diffs, I'm not sure what Subaru recommends. I don't like the idea of a donut spare on the front with the turning, braking, powering etc that it takes. I think that the recommendation is still to put it on the back, but just don't drive too far or too fast. Perhaps someone can fill us in. Commuter Quote Link to comment Share on other sites More sharing options...
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