93 Legacy 4wd slipping

Flywheel, Clutch, Transmission, Axles, etc...

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Scotty
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93 Legacy 4wd slipping

Post by Scotty »

Anyone know why my 4wd drive is slipping in the snow. I hit a slick spot and the tires will start to spin like they never did before, then something seems to kick in and I will suddenly gain traction like normal and the car will go again. I don't really know how this system works so I thought I'd ask if anyone has an idea what might be happening?

Thanks!

Scotty
Legacy777
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Re: 93 Legacy 4wd slipping

Post by Legacy777 »

Welcome to the BBS Scotty.

Can you provide some additional information about you Legacy. Is a manual or automatic transmission, how many miles are on the car, is the check engine or power lights on/flashing?
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Scotty
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Re: 93 Legacy 4wd slipping

Post by Scotty »

Its an automatic, 200,000. No check engine light on, ABS light is on.
wtdash
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Re: 93 Legacy 4wd slipping

Post by wtdash »

Hi,
Sounds just like when my rear transfer clutch(es) pack was worn....or it's the Duty C solenoid.

Put a fuse in the FWD fuse holder on the passenger side strut tower to verify if the car stays in FWD mode. This confirms whether it's mechanical (clutches) or electrical (Duty C).

Search on here or over on the http://www.ultimatesubaru.org/forum/ site for a How To on fixing the rear clutch. It doesnt' require removing the trans, but does require some work.

You can also wire in a switch to effectively 'lock' the rear transfer clutch so you'll have 50/50, but this should NEVER be used on dry pavement as it'll trash your center diff. This would be a temporary fix 'til you can fix the rear.

ABS or POWER light is on? Does the POWER light blink when turning on the car?

GL,
TD
Turbo Subies:
'87 GL-10 Turbo - SOLD
'90 BJ EJ22T/DOHC & 5speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX -SOLD
'96 BD-turbo'd-SOLD
'98 SF - NA-T
Scotty
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Re: 93 Legacy 4wd slipping

Post by Scotty »

Hi,
Thanks for the info. Exactly what I was hoping someone could help me with. I really know next to nothing about how these work, but I'm hoping to learn! So the Duty C solenoid is what engages the rear clutch for more power to the rear? Where does the electronic signal for the Duty C come from? and how does the system determine when the wheels are slipping? Could the ABS system cause the problem? ABS light is on but no POWER light. NO blinking when starting up.

I found the FWD fuse holder on the inner fender. Just so I'm sure I understand, when I put a fuse in there does it basically lock the car into FWD and prevent it from going AWD?

Thanks!
Scotty
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Re: 93 Legacy 4wd slipping

Post by Scotty »

Found this detailed explanation of Subaru AWD systems.

http://www.phdarch.net/awd.htm
Legacy777
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Re: 93 Legacy 4wd slipping

Post by Legacy777 »

Scotty,

I don't think the ABS light being on would affect the transmission. The duty C solenoid gets its signal from the TCU. The TCU determines the amount of lock by measuring the speed difference between the front speed sensor (gauge cluster) and the speed sensor in the rear section of the transmission. If there is a speed difference it will apply more lock to the rear wheels.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
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