Wheelspin in an *AWD*

Redlined · Post by **Redlined** » Tue Apr 12, 2005 7:25 am

First time poster here. Appritiate your time and patience,

Ive been ghosting your forums for a couple weeks. Stumbled across them while looking for a car to buy (Orriginaly inteded to bye a Impreza, but Legacys are much easier to find at a better price in my local)

Anyways. saw an add for a 90 legacy sedan AWD w ABS. Body is a touch rough. parking lot ding here or there, drove solid. no slip in in Auto trans. engine pulled strong no CV joint rattle when pulling around a courner.

Bartered a bit on the price. came to an agreement. and I bought the car.

On the ride home. I come out of a stopsign (Wet pavement, light rain) and the passenger side tire slips noticably. *scratches forehead* thougt AWD would grip better. come to another stopsign and give it a touch of gas(about 1/4 throttle purposely). Passenger tire slips again.

Take it the rest of the way home on the freeway and start to get an occasional Thump from the rear of the passenger side on medium bumps in the road (sounded like maybe I forgot to close the trunk lid or something).

Get home and start filing paper work, when I notice something I had missed before. a stamp "Totaled, reconstructed" on the title. Now im starting to freak.

Time to ask the experts.

1. Do AWD cars (on wet pavement) slip the front tires under acceleration Or is it likley/possible someone sliped in FWD parts durring the "Reconstruction"?

2. Could a bad strut on the rear passenger axle cause the thump I heard?

Thanks again

scottzg · Post by **scottzg** » Tue Apr 12, 2005 7:38 am

1 yes, they will slip the front passenger tire if you're driving alone and it slips. You gotta be throttling the beejezus out of it to get it to spin though, and even still you probably wouldnt notice it. Curious that you did. Someone else will have to chime in as far as the technical AT stuff, but if you stick your head under the car in the middle where a driveshaft would be you should see a driveshaft. If its there, then you have something else going on, im afraid.

2 my guess is that if you take off the back seat and look at the rubber doohickey in the little cubby under the rear quarter window (the top mount) you will find that one of the four nuts is loose. Tighten the bugger up and see if that fixes it. I haven't heard of a strut thumping, usually they just get really soft.

Fishy · Post by **Fishy** » Tue Apr 12, 2005 2:08 pm

I see you said you've got an automatic. I'm fairly sure this means that your car runs a 90/10 split of power to the front/rear UNTILL it detects slippage and then it locks up the centre diff to make it more like 50/50... I'm wondering if your centre diff might be slow to engage or not engaging correctly causing you to run as mostly FWD.

Of course most of the people here are way smarter about these cars than I am so I'll be corrected if/when I'm found wrong

but for now that's my 2 cents on it.

Post by **Legacy777** » Tue Apr 12, 2005 2:52 pm

THere is no center diff in the automatics. AWD is controlled by a duty solenoid, and in pretty much all cases will react faster to wheel slip then the manual transmission's viscous coupling.

Fishy · Post by **Fishy** » Tue Apr 12, 2005 3:20 pm

Legacy777 wrote:THere is no center diff in the automatics. AWD is controlled by a duty solenoid, and in pretty much all cases will react faster to wheel slip then the manual transmission's viscous coupling.

okay, I knew I'd get busted somehow on that one

in that case then can the duty solenoid get hosed and leave this guy with FWD?

vrg3 · Post by **vrg3** » Tue Apr 12, 2005 3:28 pm

I used to spin the wheels in my old 91 L AWD because the struts were all shot. The wheels bounced so easily that they couldn't maintain grip when I was doing anything remotely interesting.

dzx · Post by **dzx** » Tue Apr 12, 2005 3:38 pm

The fuse isn't in for fwd mode is it?

jake15 · Post by **jake15** » Tue Apr 12, 2005 4:44 pm

when you turn on the car does the power light flash on the dash? its right in the middle of the guage cluster on the bottom. if it does it means your AWD is not working for some reason.

Post by **Legacy777** » Tue Apr 12, 2005 6:08 pm

Fishy wrote:in that case then can the duty solenoid get hosed and leave this guy with FWD?

If the duty c solenoid totally fries, and is inoperable, you'll actually get 50/50 split all the time and get mucho torque bind.

The FWD fuse sends 12v to the duty c solenoid, and you are then operating in only FWD.

Post by **DLC** » Tue Apr 12, 2005 6:28 pm

The 4EAT in my wagon got so bad that it was indeed FWD, with no rear power at all. I'm blaming that on wear to the rear case, but i'm sure some of it was due to solenoids.

Redlined · Post by **Redlined** » Tue Apr 12, 2005 7:48 pm

ok.. Pulled the rear seat. no loose bolts but the little alcove had a bunch of powder resembling break dust in it.

Ive notice the "Power" light flash when I start the car but didnt notice it while driving... not that I was looking.

Gotta make a trip to the DMV to transfer the license so Ill look when I take the trip. Also see if I cant find an open field to... (sorry in advance) field test the AWD.

Also noticed a couple of the fuses where missing when I got home. (about gave myself an ulser) The driving lights being one of them. I replaced the fuse for the driving lights. Fuse didnt burn. Lights started working, no mysterious plumes of smoke from under the dash. Think someone might have jerked them for a differant car.

But Legacy777 says if the solenoid fries then I get 50/50.. same if the fuse is gone?

evolutionmovement · Post by **evolutionmovement** » Tue Apr 12, 2005 10:23 pm

You have a broken rear strut. That's the thumping. The shaft under the big nut in the center is snapped. It's happened to me before I went GR2. You may need to replace the top mount if the banging strut had enough time to wreck it.

Steve

Redlined · Post by **Redlined** » Wed Apr 13, 2005 12:20 am

Back from the DMV. Passenger tire will sometimes slip and when it does i seem to be stuck in FWD. possible that my Solenoid is "Sticky"?

Broken strut makes sence. the struts all seem soft so was planing on replacing them anyways. what makes a sensible (read: cheap, no Beilstien 13 point adjustible suspensions please) upgrade to the struts/springs while im doing the replacing? (Car will see 95% road duty, some "canyon carving" on ye ol' back roads)

As far as I can tell the Power light doesnt come on after the initial engine start up.

and thanks everyone for all the help!

scottzg · Post by **scottzg** » Wed Apr 13, 2005 12:31 am

kyb gr2 are 15% stiffer than stock and cheap at tirerack.com

Chef · Post by **Chef** » Wed Apr 13, 2005 2:38 am

"As far as I can tell the Power light doesnt come on after the initial engine start up. "

The power light will probably also come on when you hammer the gas - it basically indicates the AT is "power" mode, meaning it upshifts at higher points than during normal driving.

Check for the area under the engine bay near the front right strut for a 15 amp fuse in place. This is the place where introduciton of the fuse overrides the duty solenoid to fully energise it, turning the car into a FWD vehicle. If it's in place, there's the FWD problem.

91White-T · Post by **91White-T** » Wed Apr 13, 2005 3:48 am

My auto also takes a second or two of spin before it kicks in the rears. It might just be because of its age, and misc. crap wearing out.

Post by **Legacy777** » Wed Apr 13, 2005 7:04 pm

Redlined wrote:But Legacy777 says if the solenoid fries then I get 50/50.. same if the fuse is gone?

You talking about the FWD fuse correct? There is NOT supposed to be a fuse in there normally. If you put a fuse in there you get 100% FWD.

tris91ricer · Post by **tris91ricer** » Wed Apr 13, 2005 7:16 pm

I think he's asking if he can get a 50/50 split if the C solenoid goes out.. however, you already gave him an answer:

Legacy777 wrote:If the duty c solenoid totally fries, and is inoperable, you'll actually get 50/50 split all the time and get mucho torque bind.

FYI, torque bind is bad.

Redlined · Post by **Redlined** » Wed Apr 13, 2005 8:32 pm

Sleeper is right, thats what I was refering to and realized the answer after I made the post *Smacks forehead*

dzx · Post by **dzx** » Wed Apr 13, 2005 9:02 pm

*cough* double post

Redlined · Post by **Redlined** » Wed Apr 13, 2005 11:35 pm

Just an update. found the small box on the passenger side strut tower labled "FWD" opened it up, no fuse. So shes not set to FWD only...

So thinking maybe the Solenoid is bad/faulty/needs to be cleaned or replaced. Are these easily removable?

Oh yeah. sorry for the double post.

jake15 · Post by **jake15** » Thu Apr 14, 2005 12:40 am

the solenoid is in the back of the transmission. you have to take off the rear cover of the transmission where your driveshaft connects to the back of the tranny to replace the solenoid.

when mine broke the piston got stuck inside the solenoid making it FWD all the time.

Redlined · Post by **Redlined** » Thu Apr 14, 2005 1:58 am

So not a project to start on a weekday night when you have to goto work in said car in the morning. gotcha

93forestpearl · Post by **93forestpearl** » Thu Apr 14, 2005 7:47 pm

I thought the 4eat had an elctro-hyrdralic clutchpac in there to transer torque. Does the duty solenoid control the hydralic pressure?

Also, when I had my '90 with the 4eat, I did notice a slight wheel spin, about 10 degrees, if the front tires were on something loose, like gravel, before the rears hooked up. I could only really tell because I heard it. I've yet to notice anything like that with the viscous unit in my 5mt. And shes been abused heavily the last two years.

Post by **Legacy777** » Thu Apr 14, 2005 11:35 pm

93forestpearl wrote:I thought the 4eat had an elctro-hyrdralic clutchpac in there to transer torque. Does the duty solenoid control the hydralic pressure?

Yes, that's exactly what the duty c solenoid does.

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Wheelspin in an AWD

Wheelspin in an AWD