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Duty C replacement


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39 replies to this topic

#1 SubaruFred

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Posted 04 July 2011 - 01:18 PM

I've known for some time that my duty C is failing and it's time to replace it. Sometimes it works, sometimes it doesn't work. What I need first is a parts list and some suggestions on where to buy them.

This is for a 93 Legacy LS with 177k miles. I figure I should replace the clutch pack while I have it apart. Anything else I'll need besides the following:

clutch pack
duty C solenoid
rear trans case gasket (or RTV)
exhaust manifold gaskets (2)
4 qts ATF

Thanks in advance!

#2 lmdew

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Posted 05 July 2011 - 05:22 AM

Have you flushed the trans?

Does the FWD light come on when you put the fuse in?

If the light comes on the C-Duty coil is good, but it could be a plugged valve. New fluid may take care of the problem.

There is a gasket for the C-Duty and I'd get 3 gallons of fluid so you can flush the trans when you put it back together.

#3 jboymechanic

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Posted 05 July 2011 - 08:54 AM

Don't be surprised to find you transfer clutch drum is notched, may be a good idea to have a spare shaft/drum assembly ready just in case. I learned this the hard way when I went to replace my, my hub was actually sheared off the shaft and I had to leave the car on my friend's lift for a week while I sourced the parts.

You may want to check you rear speed sensor and try a trans fluid flush first, but at 177,000 miles you're probably ready for a new solenoid either way.

#4 SubaruFred

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Posted 06 July 2011 - 02:46 AM

Have you flushed the trans?

No, I drained and replaced 4 qts and added 1 qt of Trans-X. I drove a few thousand miles and drained and replaced 5 qts. The old ATF looked very good both times.

Does the FWD light come on when you put the fuse in?

Yes

If the light comes on the C-Duty coil is good, but it could be a plugged valve. New fluid may take care of the problem.

The duty C functions correctly about 90% of the time but tends to fail after long drives.

There is a gasket for the C-Duty and I'd get 3 gallons of fluid so you can flush the trans when you put it back together.


I'll be sure to get that gasket, thanks.


Don't be surprised to find you transfer clutch drum is notched, may be a good idea to have a spare shaft/drum assembly ready just in case. I learned this the hard way when I went to replace my, my hub was actually sheared off the shaft and I had to leave the car on my friend's lift for a week while I sourced the parts.

I'm hoping that the drum is okay since there is no torque bind when the duty C is working. When it fails there is TB and a flashing power light that typically goes away with the next re-start.

You may want to check you rear speed sensor and try a trans fluid flush first, but at 177,000 miles you're probably ready for a new solenoid either way.


I think the key symptom here is that the duty C works fine 90% of the time but fails both with and without the FWD fuse installed. If it was dirty ATF, a clogged valve or a notched drum I would expect to have TB all the time, not just when the TCU indicates a failed duty C.

Thanks for your help and I'll be sure to post the results of changing the duty C and clutch pack.

#5 SubaruFred

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Posted 14 July 2011 - 02:51 PM

Any suggestions on where to get the parts?

#6 95legwagon

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Posted 14 July 2011 - 07:36 PM

hey get them right from subaru .... im goin through this currently and im gunna make a post about it. with pics and parts list and prices. i went to the dealer and got the duty c which was hard for them to locate cuz its not called that. the part # is 31942aa061 ( this was for a 95 legacy wagon) i got that the 2 small gaskets for it and the tailshaft housing gasket for $150. FROM THE DEALER! i think thats a good price considering usually u get screwed @ the dealer :lol: oh i have the problem and i only have 109,000...... i got the car with the problem @ 98,000 miles and didnt know what it was til i read it on here. well good luck!! :cool:

#7 SubaruFred

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Posted 14 July 2011 - 08:44 PM

Thanks! I had a hard time locating the part numbers on-line and finally had to call a dealer to confirm which part # I needed. After a lot of searching I found the duty C solenoid that Subaru calls a "VLV ASSY - TRF CCH" at Rock Auto for only $50. The stealer wanted $100+ for it. I ordered the plate and gaskets from an on-line dealer for $16 shipped.

These are the part #'s for my 93 Legacy:

31942AA070 - DUTY C
31954AA030 - PLATE
31954AA070 - GASKET (2)
31337AA120 - CASE GASKET

FWIW, if anyone needs a AA061 duty C, Rock Auto has a few left for $50 ea and there's also one on ebay for about $50 shipped. The thing with Rock Auto is that they don't list the part but if you do a part # search, they come up. They don't carry any of the gaskets.


Below are some great resources I found today while searching for parts:

http://www.main.expe...ext._blowup.jpg

http://www.main.expe...._partlist1.jpg

http://www.main.expe...._partlist2.jpg

http://opposedforces.com/parts/

http://www.subarupartsdepot.com/

Edited by SubaruFred, 14 July 2011 - 08:47 PM.


#8 DevC

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Posted 14 July 2011 - 08:51 PM

Subaru dealer parts are pretty reasonable when it comes to pricing.

#9 SubaruFred

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Posted 14 July 2011 - 11:59 PM

I'm not so sure about that. 95Legwagon paid $150 at his local dealer for the same parts I got on-line for $77 incl shipping. Now this is contigent upon me receiving a genuine Subaru duty C from Rock. If it's an aftermarket part, I'd still call it a better deal. If they simply mixed up part #'s and I have to return it for a refund and order another, I'll still save a few bucks but it won't be worth the wait or hassle. We'll see...

#10 johnceggleston

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Posted 15 July 2011 - 03:06 PM

di you get both gaskets and the valve body? which subaru calls a ''valve assembly'' and it includes the duty c.

for reasons that i do not understand the duty c , from the online dealers, for the 95 lego is about 25 cheaper than the duty c for the later 90s cars. i thought they were all the same part but apparently not, not exactly.

at least this is what i remember from the last time i looked in to it several years ago.

#11 95legwagon

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Posted 15 July 2011 - 04:45 PM

di you get both gaskets and the valve body? which subaru calls a ''valve assembly'' and it includes the duty c.

for reasons that i do not understand the duty c , from the online dealers, for the 95 lego is about 25 cheaper than the duty c for the later 90s cars. i thought they were all the same part but apparently not, not exactly.

at least this is what i remember from the last time i looked in to it several years ago.


i got everything but the plate because i shouldnt need to replace that....it was special order but i got it yesterday (3 days after i ordered) n i liked that it was genuine. cant beat that! and yes you are correct it is a valve assembly..... thats why they had a hard time finding it in their computer.....i told them it was a duty c solenoid lol....the guy was like huh? but if that part is genuine good job on finding it online! i had a hard time finding anything.....and i didnt want to wait a week or two for it and possibly shear off that tailshaft......:-\

#12 SubaruFred

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Posted 16 July 2011 - 01:36 AM

di you get both gaskets and the valve body? which subaru calls a ''valve assembly'' and it includes the duty c.

for reasons that i do not understand the duty c , from the online dealers, for the 95 lego is about 25 cheaper than the duty c for the later 90s cars. i thought they were all the same part but apparently not, not exactly.

at least this is what i remember from the last time i looked in to it several years ago.


Yes, I got 2 valve assy gaskets, the plate, duty C solenoid and a ext housing gasket. The only question/concern is whether Rock Auto actually ships the correct duty C. It's not listed under transaxle parts for my car but it came up when I searched for the Subaru part #. If I receive a genuine Subaru solenoid for $50, I'll be very happy. Either way I'll post about it when it arrives, good or bad.

FWIW, there is some overlap between duty C part #'s but in general, 90-93 use 31942AA070, 94-95 use 31942AA061 and 95-98 use 31942AA090. For whatever reason the AA061 is easier to find and cheaper than the others.

#13 SubaruFred

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Posted 16 July 2011 - 02:59 AM

No option to delete duplicate post? Okay...

Edited by SubaruFred, 16 July 2011 - 03:02 AM.


#14 95legwagon

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Posted 16 July 2011 - 06:57 AM

lol i dont see a duplicate post....... yea ill be interested to see if thats 1: the right one you need and 2: a genuine part..... cuz if i got mine for 150 and you got yours for 50....i know where ill be shopping from now on :lol:

#15 SubaruFred

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Posted 16 July 2011 - 11:25 AM

Post #13 was a duplicate of #12 until I edited it.

I'm anxious to see what Rock sends me. For the price I don't care if it's genuine Subaru, as long as it works.

Did you see this?

http://cgi.ebay.com/...=item27b45a9373

Any chance you could return the one you got from the dealer? I also found the AA061 at several online suby dealers for ~$75.

#16 95legwagon

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Posted 17 July 2011 - 07:14 AM

lol i wish i had found that yesterday .....i did the duty c replacement yesterday......8 hours later! the tailshaft housing was stuck bad. but all is fixed now. i can post pics if u want them and if u wanna know the order everything has to come off ill tell ya. :)


you can check out the guide i made for doing this @ http://www.ultimates...t=duty solenoid with pics!

Edited by 95legwagon, 17 July 2011 - 10:19 AM.
including link to guide


#17 SubaruFred

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Posted 17 July 2011 - 11:15 AM

Oh well, you still saved a lot by doing the work yourself. Thanks for writing that guide. I'm sure it will come in handy when I finally tackle mine.

#18 95legwagon

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Posted 17 July 2011 - 01:40 PM

no problem! i did it for people that havnt done it and want to tackle it! good luck on yours when you do it! it took me 9 hours (about) to get everything done....so prepare for a whole day spent!

#19 jboymechanic

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Posted 19 July 2011 - 04:27 PM

It's really not a hard job. My car has been in WI for its whole life and has 230,000 on it and everything came apart without breaking or having any issues. I had access to air tools and a lift, so that made the job easy.

#20 SubaruFred

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Posted 21 July 2011 - 05:47 PM

Look what I got today! Less than $60 shipped from Rock Auto and they have more in stock.

Posted Image

Now all I need is some <90F weather so I can install it.

#21 95legwagon

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Posted 21 July 2011 - 06:35 PM

Nice find! good luck on the install!

#22 SubaruFred

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Posted 21 July 2011 - 06:58 PM

Thanks. I feel pretty lucky to find this deal.

#23 SubaruFred

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Posted 29 August 2011 - 10:40 PM

Well, I'm glad I didn't pay dealer prices for my duty C and related parts since they made no difference. I still have the same intermittent TB I had before changing the duty C. When the TCU accepts the duty C as good, there is no TB at all. When the TCU decides that the duty C has failed, I have full TB until I shut the engine off and restart. This leads me to 2 options:

1) Try a new/used TCU
2) Install a duty C switch for manual AWD control

I prefer option #2 at this point which leads me to ask if I can take manual control of the duty C? If so, how? If not, I guess a FWD fuse switch on the dash is the next best thing. I would prefer to re-wire the duty C so that it is in FWD mode normally and 50/50 split when selected. I know it's possible, just don't know how to wire it. Schematic links would be invaluable.

BTW, I finally figured out how to read the TCU codes and the old ones are 23, 24 and 33. Engine speed sensor, duty C and vehicle speed sensor #2. The current code (when present) is 24 only. The wiring to the duty C looks fine but I didn't ohm test it when I had the trans apart.

Edited by SubaruFred, 29 August 2011 - 10:43 PM.


#24 johnceggleston

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Posted 30 August 2011 - 07:17 AM

BTW, I finally figured out how to read the TCU codes and the old ones are 23, 24 and 33. Engine speed sensor, duty C and vehicle speed sensor #2. The current code (when present) is 24 only. The wiring to the duty C looks fine but I didn't ohm test it when I had the trans apart.


which code is #24?

i'd try the used TCU first. much easier.

if the duty c is bad, (probably not since it is new) or a wire / connection is bad, a switch shouldn't make much difference. you can switch it but if the signal doesn't get to the duty c .....

plus, if you ''dis-connect'' power to the duty c you get ''locked'' 4wd, and TB. power it all the time , put the fuse in, you get FWD. how does a switch help if the duty c is not operating correctly, ie: not getting the proper amount of power at the proper time?

#25 SubaruFred

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Posted 30 August 2011 - 11:03 AM

which code is #24?

i'd try the used TCU first. much easier.

if the duty c is bad, (probably not since it is new) or a wire / connection is bad, a switch shouldn't make much difference. you can switch it but if the signal doesn't get to the duty c .....

plus, if you ''dis-connect'' power to the duty c you get ''locked'' 4wd, and TB. power it all the time , put the fuse in, you get FWD. how does a switch help if the duty c is not operating correctly, ie: not getting the proper amount of power at the proper time?


Code 24 is for the duty C. I wish I knew how the TCU determines that the duty C is bad. I'm guessing that it might be blaming the duty C for mechanical issues. I rented a lift by the hour to change the duty C and didn't have time to address the grooves in the clutch basket and hub. I gambled that the grooves could be left alone.

Anyway, since I really don't care about having full time AWD but want AWD on demand I'm thinking of removing duty C control from the TCU and using a simple switch to control it. As I understand things the TCU sends a varying voltage to the duty C to control the torque bias. What if I only send full voltage or no voltage to the duty C? It would either be open or closed. Much like installing the FWD fuse except that the torque bias would either be 90/10 or 50/50. I'd only use AWD off-road or in snow/sleet, etc.

I'm assuming that the wiring is still good but if not, I'll have to address that whether I install a switch, fwd fuse or new TCU. I'm not very optimistic that a new TCU will solve this issue without addressing the 178k wear in the MPT clutch assy. Do you know what voltage is sent to the duty C to open it fully? 5v or 12v? I also need some guidance on the wiring. I'm sure this has been done before but it could take a lot of searching to find it. Thanks for your help.




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