I have two, 1990 Legacy's and am thinking of puting in the fuse under the hood to turn them from 4wd to 2wd for the summer. My question is will this save any fuel, but would it hurt the automatic transmission. Has anyone tried this over a longer peiod of time? Thanks for reading this.

This subject has been debated a number of times. The consensus view:

1. There will very little, or no, gas savings

2. You may potentially damage the transmission, specifically the duty solenoid

 

So, there is no upside to installing the fuse, and it might cause trouble for you.

The duty Solenoid was not designed for full voltage all the time. You could harm it. And you won't save any gas as the autos are 90% front wheel drive anyway unless the wheels spin.

 

GD

no gains when i've done it. i've run 2wd with auto's and manuals, no difference.

 

never hurt the auto trans when i've done it either. not worth the risk for the average person though.

 

you're still carrying all the additional weight of 4WD as well as the driveshaft, rear differential, 2 rear axles, larger and different hubs/bearings are all spinning too.

I've tried it also, no noticed improvement in fuel mileage.

I did wonder though if there would be a noticeable difference with removing the driveshaft and rear axles.

 

A side note to this though, I live on a hill with a gravel driveway, I really didn't like the wheel spin with my outback in FWD only mode. Main reason I didn't go further in experimentation. Still curious though.

What they all said

Sorry to say but it is the so many-thhh question about the 2wd fuse! It is to drive home with a space saver spare tire.

 

Why would you want to drive FWD if you have a AWD car. Actually the automatic is 90% FWD on a normal road (straight line). AWD will be always a winner. Imagine turning into a corner where there is sand on the road or a sudden moose-test like maneuver the AWD will allow more control and response.

 

no worries Zoltan be happy you got an AWD car

Edited April 12, 201114 yr by rverdoold

I've tried it also, no noticed improvement in fuel mileage.

I did wonder though if there would be a noticeable difference with removing the driveshaft and rear axles.

 

A side note to this though, I live on a hill with a gravel driveway, I really didn't like the wheel spin with my outback in FWD only mode. Main reason I didn't go further in experimentation. Still curious though.

 

I thought I read somewhere that it is likely to damage the wheelbearings when no driveshaft is present and having the weight of the car on the bearings.

I thought I read somewhere that it is likely to damage the wheelbearings when no driveshaft is present and having the weight of the car on the bearings.

no damage.

 

by driveshaft he means the driven shaft between the transmission and rear diff. no way for that to impact the bearings, nearly unrelated.

 

if you're referring to axles, that's not the case either. you can't drive a 4WD without the axles as the bearings are completely exposed. but you can disassemble the axle and install the outer joint into the hub thereby retaining the seal, bearing, etc. i have a car like that, did it a couple years and 50,000 miles ago.

no damage.

 

by driveshaft he means the driven shaft between the transmission and rear diff. no way for that to impact the bearings, nearly unrelated.

 

if you're referring to axles, that's not the case either. you can't drive a 4WD without the axles as the bearings are completely exposed. but you can disassemble the axle and install the outer joint into the hub thereby retaining the seal, bearing, etc. i have a car like that, did it a couple years and 50,000 miles ago.

However, without the pressure of the driveshaft, all the ATF would just leak out the tail housing.

However, without the pressure of the driveshaft, all the ATF would just leak out the tail housing.

rear driveshaft is two pieces, so you remove the rear half (the longest) part of the driveshaft and leave the front in place to hold the fluid.