91 SS AWD troubleshooting

[FrozennorthLGT]

So since I bought my 91 SS I have been skeptical about the rear wheels actually being driven. Its had a tranny and rear diff swap in its past, and I couldnt get the rear end to step out in the snow at all. Not a scientific way to tell I know, but I was mostly just playing around after I bought it. So tonight I did a rear diff fluid change because I have no idea when it was last done, and while I had it up in the air I did a test. My question is how much force should it take to stop the rear wheels spinning when the car is in the air, in drive? I could stop them with my foot, but it seemed to take a fair amount of force. Less than it took to stop the fronts in the same manner though.

[kimokalihi]

It's not a 50/50 split. I've never tried doing what you're doing but it's considerably more front bias. I don't know the numbers off the top of my head but I want to say something like 70/30. Sounds to me like your AWD is functioning properly.

[Florin1]

I think the split is actually 90/10 Haha. Autos ftl

[Legacy777]

Try putting the gear selector in 1 and see if it requires more force to stop.

The normal torque split is 90/10. The thing that makes this difficult to test like what you're doing is that the differential will send power to the other wheel. A roller or dyno setup would really be the way to test it. You can also try putting the front wheels on ice and the rear wheels on pavement (obviously during the winter) and see if the rear wheels will propel you.

[FrozennorthLGT]

Ill have to wait till we get some snow/ice, but Ill try that. I was also going to try the same test with the car up in the air and put the FWD fuse in, since I assume that cuts ALL power to the rear, but it was late last night and I forgot before I put the car back down.

[Alphius]

The multiplate transfer clutch in the 4EAT dynamically alters the front/rear bias based on throttle position, gear selected and wheel slip feedback.

The normal, shifter in D, driving around torque split is 90f/10r. Based on front wheel slippage and throttle position, this is dynamically altered up to 50f/50r as necessary. (For example under hard acceleration)

In R or 1, the torque split is constant 50f/50r. In manual mode 2nd (for winter driving) I believe it is also 50f/50r, but of this I am not sure.

Were you stopping only 1 rear wheel? If so, the open differential was simply making the other rear wheel spin faster. This does take a small bit of effort, but not a lot. A better test in my experience would be to simply drop the hammer from a stop. If the front tires spin, you've got something wrong. If the car takes off with no slippage, you're probably good.

When you start your car, does the "Power" light on the dash blink 16 times very quicly? If not, then your transmission and AWD system are most likely still functioning fine. If you do see 16 quick flashes on the Power light when you start the car, then your transmission is trying to tell you something (a trouble code) and you need to search this site to find out how to pull your trouble codes.

[FrozennorthLGT]

Yes I was only stopping one wheel. My assistant wasnt interested in trying that...something about safety concerns...lol. And the power light lights up on startup, and I believe stays on, but doesnt flash 16 times I dont think, Ill have to check. One of the two, either power or manual, stays on all the time...not sure what that could mean if anything...

[kimokalihi]

Probably manual. You said you were using the manual button.

[Legacy777]

Is the light green or orange?

Green is for the power light, and orange is the manual light.

Read this regarding the manual button, power light, and how to read the codes from the TCU.

http://surrealmirage.com/subaru/trans.html#manualbutton

[FrozennorthLGT]

Sorry Josh I was mistaken. Neither light stays on. The power light comes on for a few seconds, green, and then goes out. Tomorrow I will mess with seeing if the manual light works.