I Donated broknindarkagain Posted July 26, 2011 I Donated Share Posted July 26, 2011 If I put a new transmission in that has a different final drive ration, can I pop in the FWD fuse and run with FWD until I found a matching rear diff? Will it hurt anything to use FWD for an extended amount of time. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
Zues Marine Posted July 26, 2011 Share Posted July 26, 2011 FWD fuse should really only be used for emergencies and towing, i wouldn't run it for more than 20 miles Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted July 26, 2011 Author I Donated Share Posted July 26, 2011 Yeah I know its an "emergency" thing...BUT, what will happen if you use it for a prolonged amount of time -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
Lojasmo Posted July 26, 2011 Share Posted July 26, 2011 Nothing. Lots of people do it in the summer for increased mileage. Link to comment Share on other sites More sharing options...
Zues Marine Posted July 26, 2011 Share Posted July 26, 2011 they shouldn't do that.. 4EAT's typically run a 90/10 f/r torque split in D anyway. If there was any benefit to using the FWD fuse, then the drivedrain already uses it during normal driving anyway. I've heard many different theories on how the FWD fuse works, one being that it allows the center diff to slip somehow...slippage=heat though. It's not something you're going to see a large gain off of, as your car is still moving the rest of the AWD parts, reguardless of if you're in FWD or AWD. Same theory as a truck going from 2wd to 4wd...the stuff is still spinning and moving whether it's in 4wd or not the only thing that'll end up happening is you damaging the center coupling clutch pack or dutyC. Link to comment Share on other sites More sharing options...
SBT Posted July 26, 2011 Share Posted July 26, 2011 The real question is why. Why not source a transmission to match your rear diff, or alternatively, a rear diff to match to match your new transmission at the same time? That's like saying that my car will run on two cylinders (poorly), but why not use all four. From everything I've read Subaru literature-wise, this fuse is only for 1 of 2 reasons. 1) Diagnostic - something's wrong in the AWD drive system and the fuse is installed to help isolate the issue to either the front-end, center or back-end of the sytem. Or, 2) Driving with the spare donut tire. Once the donut is removed and full-size tire reinstalled, the fuse is to be taken out. The center diff duty solenoid is designed to get a pulsed on/off signal voltage during normal operations. When you put in the fuse, you send 12v constant to the solenoid so it's open all the way, all of the time. Do you want to have that solenoid activated all of the time? And at some point, you're going to put undue strain on the car and chassis by driving it without the rear diff pushing. Things tend to fail when they're not operated the way that they were designed. Would expect greater internal pressures on the transmission as it copes with the loss of the rear power, and potential seal leaks or part failures. Depending on how many miles/much wear is already on the transmission, this could unduly wear your replacement transmission before you reconnect to the replacement rear diff. - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
johnegg Posted July 27, 2011 Share Posted July 27, 2011 you can run for an extended period with the FWD fuse in place. but the duty c is designed to get electricity on a ''duty cycle'', ie: 30 times a minute or 2 times a second....... putting the fuse in will power the duty c ALL the time. this means you run the risk of wearing it out. how soon is the question. some have done this for 2 years without problems. others have had the duty c fail in 2 months. but if you are swapping the trans any way, and planning on swapping the rear diff soon, just leave out the rear section of the drive shaft. the car will be happy driving with no rear power and when you swap in the rear diff, put the rear section of the drive shaft back in. the front section of drive shaft MUST be there or the fluid will spill out of the trans, but the rear section is not required until you want AWD. PS: putting in the fuse will not gain you any MPG. the car is still turning all the same mechanical parts, drive shaft and rear diff. they are just being turned by the wheels not the other way around. no problem. Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted July 27, 2011 Author I Donated Share Posted July 27, 2011 how do you separate the two halfs of the driveshaft? I like that idea better then the fuse. Thanks! Anyways, the reasoning behind it is because i can get a good deal on a trans...but i dont have enough money for a rear end yet. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
johnegg Posted July 27, 2011 Share Posted July 27, 2011 the rear section has a u-joint and a flat round plate on each end, i think ( i know the rear end does.). 4 bolts with nuts, 12 mm, on each end and you are done. the bolt heads are braced / wedged against the u-joint i think, so you really only need one wrench to undo it. i have a 95 lego that has been driving my son around at college for 5 years and 50k miles with no rear drive shaft. Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted July 27, 2011 Author I Donated Share Posted July 27, 2011 I know how to take it off the rear diff...I'm talking about the joint in the middle...how do i seperate the two halfs. there is no u-joint in the middle that Iremember seeing -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
johnegg Posted July 27, 2011 Share Posted July 27, 2011 4 12 mm bolts and nuts. one flange bolts to another flange. Link to comment Share on other sites More sharing options...
johnegg Posted July 27, 2011 Share Posted July 27, 2011 http://opposedforces.com/parts/legacy/us_b11/type_45/train/propeller_shaft/ http://static.opposedforces.com/epc_img/366494919901.png Link to comment Share on other sites More sharing options...
I Donated broknindarkagain Posted July 27, 2011 Author I Donated Share Posted July 27, 2011 Excellent thank you for the image. I thought you were talking about #3 in the image. -broknindarkagain My Current Project - Click Here COME AND TAKE IT "The only thing necessary for the triumph of evil is for good men to do nothing." Link to comment Share on other sites More sharing options...
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