On the dyno....but no AWD!!
 

Well, I finally got my SVX over to AlteredAtmosphere up in Gaithersburg, MD to do some baseline dyno pulls on their AWD dyno. All tied down and ready to go...the rear wheels didn't budge! #*!!^
The car has been running fine and nothing on the dash is blinking during start up.
Went ahead and had the tech do two quick pulls (158.7 hp/169.2 ft-lbs of torque) and then drove to work-- no apparent ill effects.
Suggestions as to what might be going on? I'm guessing something is going on with the transfer case (okay, the car has 184k on the odo), but the lack of any blinking lights or "weirdness" during normal driving seems strange...
Thanks in advance for everyone's help.
-Bill

Fuse?
 

You didn't happen to pop in the FWD fuse did you?

My awd worked intermittantly after I bought my car and has now permanently stopped. Had my dealer run the code and it's my Duty Solenoid C or the 'transfer clutch solenoid' that's malfunctioned.

I have an OBDII '96 and my CE light comes on every so often b/c of it. Since yours is a '92, I wonder if Solenoid C doesn't trip the CE light in your MY?

When the awd is gone the car doesn't feel markedly different, so unless you floored it during the rain, it would've been difficult to notice before.

I only realized mine wasn't working when I had it up on four stands at Harry's (newsvx) place in June.

-Chike

P.S. Good baseline. That's very similar (if not slightly higher) to what 4EAT WRX's put down on the dyno. :)

There are lots of threads on this subject now. I had the same problem. No blinking lights and no RWD. I got a gauge and measured the tranfers pressure, port on top of the housing and no pressure. Checked out the electirc end by adding a switch to the solenoid "C". Turning off the switch puts it in full time AWD except this didin't happen at first. After a few days it freed up but then with one flip of the switch it stuck good. Replaced the "C" assembly and all was well. :)

The original "C" was updated after 92.

Other people have had the clutch basket come loose. The pressure test will tell you this.

Thanks for all the responses! I'll post the dyno plots in my locker as soon as I get them scanned. What does it run - $ wise - to replace the C solenoid? I'm thinking I might go Chike's route and just take this as a sign that I should go the 4:11 path and replace the trans/transfer case/rear diff (thank God for backup cars!!:D )
-Bill
p.s. nope, I didn't put the FWD fuse in -- believe me, my first thought was the previous owner had put it in for some reason and forgot to remove it. Then I realized that the FWD symbol in the dash is supposed to light up when the fuse is in (right?)

FWD will light up on the dash when the fuse is in.

Can the AWD dyno be locked so the front and rear wheels turn at the same rate?

Re: On the dyno....but no AWD!!
 

Yes, your transfer clutch is worn out. When they wear out, they don't transfer torque to the rear wheels any more - but there are no electrical faults so no warning lights pop up.

If you're mechanically inclined (and very careful), you can replace it yourself or pay between $500 and $900.

I think there is little else that would cause your loss of AWD without a warning from the TCU of some kind.

The dyno operator showed me that the rollers were operating correctly, as my first thought was that the rear roller was somehow locked up. The rear tires didn't even start to move...
-Bill

Re: Re: On the dyno....but no AWD!!
 

Sounds like it's time to get my hands dirty!:D
Let's hope the SVX community responds to my 4:11 Thread.
-Bill

If you search for it, Bill, I know you can find my comments about replacing the transfer clutch on my Legacy. If you can't find it, or would like some further advice, feel free to call me. I'll PM you my phone number.

Bill,

If it's just your Duty Solenoid C, the part runs a tad over $60. If it's your transfer clutch then it'll be in the $500-1K range easily.

However, going my route has it advantages. 4.11 or 4.44 gears will improve your acceleration a ton while reducing fuel economy only slightly (aprrox 1-2mpg on the highway).

Go for it! :D

-Chike

Re: Re: On the dyno....but no AWD!!
 

I disagree on two points. First, it's highly improbable that the transfer clutch would be worn out unless it was abused in a very specific way, namely by towing the car improperly or running it on a 2WD dynamometer, and I strongly doubt even that would cause any significant wear. Under all [normal] conditions, there should be virtually no speed differential in the clutch, thus no wear. (Much like an LSD.)

The second point is that if you noticed a loss of AWD, i.e., the front wheels spin while the rear wheels do not, you should get a code for speed sensor two because it detects an extreme speed differential which should not exist under any [normal] condition. The exception to this is that you will not get the code if you never do anything that would cause the front wheels to spin significantly faster than the rear wheels.

Re: Re: Re: On the dyno....but no AWD!!
 

Isn't it possible that one of the previous owners abused this car? For all we know this car could have been driven around on 4 mis-matched tires for 20,000 miles at some point in it's life. That would cause problems down the road....if not sooner. We get Legacy's in here about twice a month with transfer case problems. The first thing we notice is that at least one of the tires is wrong.




Dave

I'm going to get her up on jacks this weekend and start with running the TCU to see what codes - if any - pop up. Then I'll move underneath to see if the "C" solenoid is getting a signal, see if there is pressure getting to the transfer case, and pulling the speed sensor to see if there are metal shaving evident. I've been checking out old threads and it looks like a "basket" break could have taken things out of commission (?).
Question - should I be running with the FWD fuse in place in the mean time (emergency use of the car only - I plan on not driving it until I've got the problem isolated and corrected)

Chike -- is the price you quoted for parts only, or the total repair if I took it to a shop? I checked out Pocket's write up and it looks like something I can handle at home.

-Bill

$60 for the solenoid is just the part alone when ordered from red95svx with his great discount! :D

If your clutch basket is messed up, the entire assembly could run in the $700-800 range for parts alone. However, from your description, I seriously doubt that's the problem - and here's why...

First, check out UberRoo's locker which shows a clutch basket repair he undertook. When I PM'd UberRoo about it, he mentioned that when the clutch basket goes out, there's some serious metallic grinding noises you'll hear along with trans fluid leaking from the rear of the trans (where the driveshaft comes out from the transfer clutch).

If your ATF level is fine and if you've heard no metallic grinding noises, then I'm sure it's just the electrical solenoid that's messed up.

-Chike