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96 4eat can't get full awd lockup after installing switch

8K views 48 replies 9 participants last post by  bluedot 
#1 ·
so I just installed a duty c dummy resistor bank and a switch to select it or direct solenoid c control. everything electronically seems to work properly and I feel more rear wheel lock but I sill can't stop on a dirt hill and have my rear wheels spin with the front.
I know I have open diffs so at most my car spins 2 wheels at a time one front one rear... but uphill on loose ground I can't get rear wheel spin...

since I got the car I have known that I need a larger spacer ring for the clutch pack...

I recently had to use slightly different size tires on the front/rear because I had to, they were both 777 revs per mile tires but different manufacturers and worn more in the rear which caused a noticeable vibration over 50mph.

for the first few years of ownership I used dexron III this is a really bad idea! I wont go into it to much but subaru, j-spec, fluid is more viscous and has different properties... I found that out after regular dexIII reduced and left me with to little atf to operate the trans... around this time I freaked out and put some trans fix in a can and only after adding some did I read that it was not compatible with viscous clutches... from what I know this could have been bad for the over running gear clutch and my rear lock up clutch.?...
I have done one drain and fill with valvoline MaxLife full synth ATF which is compatible with subaru 4eat's.

I have taken apart my trans tail section many times and will post pics of this inspection. if anyone would like to put their two cents in about rear wheel spin and lockup it would be much appreciated!

as always thanks in advance!
 
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#33 ·
sorry for the laps in posting I did take pics of the replacement junk yard parts but my phone decided they weren't cool enough.....

its finally D day on my legoback I put it up on 4 stands last night and did some initial testing... to my horror I could not get the rear wheels do anything! 1st gear AWD lockup switch or not, totally limp.....

I'm guessing the clutch packs are worn and the teeth are likely slipping with more than average play between the housing.... will post pics and might even do a short video after its all blown apart.

I was googling and I found this
https://iptperformancetransmissions.wordpress.com/category/subaru/

so more clutch discs = more lockup?

on most of the drive hubs I see the grooving over the top like a slipping disc is only on the first two discs next to the drive hub, could one shuffle the discs to make up for the few that do have that damage?
 
#34 ·
So, I have a few questions. How does the AWD system work... one front wheel and one rear wheel are driving all the time and the power split is 50/50 or 60/40?

Then when one wheel slips/spins faster than the others, power is redirected the the other wheels?

Is this done through automatic lockers (electronic?) or just limited slip? I'm just curios and really wanna learn how my drivetrain works. Thanks!
 
#35 ·
There are several different systems. It depends on which transmission you have. Many threads about each of them, comparisons, virtues & vices etc.

All of the automatics have computer-regulated systems to control the F/R torque split on a second-by-second schedule.

Manual shift cars have a completely "dumb" system, everything is mechanically driven.

Some outbacks (not all) also have a limited slip rear diff. Newer outbacks do it virtually via rear brake control.

Tons of threads out there with all the details. If your '99 is an automatic, that transmission is known as the 4EAT or D-4AT, and you can use those as search terms.
 
#37 ·
my problem is in the valve body when I applied compressed air to the atf supply port on the tail section it spat out the top of the valve body and would not continue on to the clutch packs. I'm trying to source gaskets as i have an almost new valve body,,,


so after some tinkering I couldn't get the fluid to get past the valve body even with a nearly new valve body.... the gaskets were almost fully intact and leaked from points other than where broken. I saw the valve acctuate but no air pressure could be felt at the clutch pack port on the housing...

the first time I had this problem was because a mechanic left the backing plate out but no one has touched this but me and I never took the valve body off! any ideas as to how or why the valve body would still actuate but not allow pressure to the clutch packs? I have tested for blockages but can't find any each port works....
 
#38 ·
now that I have the ATF out of my ears here is a pic of one faulty valve body nothing special but I did circle where I got pressure seepage while mounted to the tailsection with its backing plate and gaskets in place... I tried two different valve bodys with the same result...


looks like I'm going to picknpull to get a new to me one I can verify works at the junk yard! have to pick up some canned air....


geez the FSM is non descript on this install! just reinstall I have been so careful mounting, nothing is broken,.,,,
 
#40 ·
junk yard tail section with untouched valve body and gaskets along with my known good duty c solenoid and a newer much tighter clutch pack had no effect still 0 rear wheel lock up... I didn't even get the standard atf oil temp light for a low fluid level which usually happens on a drain and fill at least for me...

so back to nearly square one... I'm positive this is lack of pressure problem I'll check the pressure port tomorrow but it looks like another tear down.... I hope the new gasket survives....

new gasket got mangled because a dowel stuck in the junk yard tail section.... going to stick it back together with import gasket maker to my dismay...

as it turns out my duty c solenoid failed mechanically ceasing in the drain off position or completely blown out internally. when I would apply air pressure to the failed solenoid it would spray out of the top and sides of the solenoid among other places... when I would apply air pressure to the junk yard solenoid it would resist and redirect the air pressure to the clutch pack.

anyone have any idea why the solenoid would fail like this? I don't think this is because of the switch I installed as I was suspicious of slippage before and installed the switch to test the rear wheels...

good news is that the junk yard solenoid has the same ohm resistance as the mechanically bad one so as long as its not stuck in the more common TB full lock position I should be good to go!
 
#41 ·
OH JOY! before I tore down the car I took a very close look (in daylight) at my original (came with the car) tail section, after reassembling the valve body with extreme care to align every part I was able to actuate the valve body with compressed air and feel it at the clutch pack supply port!

I think in my prior attempts I was letting the bottom of either the backing plate or valve body rotate down and outwards so that some of the fluid ports were misaligned hence the pressure release from the areas circled above.


after I get the car torn down I'm going to make a you tube video of the two side by side testing with air pressure. I should also get out my volt meter and include a duty c ohm test
 
#43 ·
no I couldn't find my oil pressure gauge.... but I can most certainly tell you that zero fluid pressure would have been read at the test port of the tail housing.

I'm positive that at least for me the best way to test a clutch pack is with compressed air, if seepage is seen at the solenoid or valve body something needs to be addressed before reassembly! both valves on the valve body should visually actuate and the clutch packs if properly seated with the driven hub should snap twords the transmission end of the tail housing.

80 or so psi yield a nice spray of ATF at any point of leak in the system indicating where attention needs to be paid.

air pressure is to be directed to the ATF supply port on the tail housing its the only open hole in the gasket that is not filled with a dowel or bolt and is mid way up the drivers side right next to a bolt.
 
#44 ·
JEEZ @#%$@$^$# ^$&^& CHRIST!!!!! so after testing the car on jack stands and being pleased with the result I tried to reverse and the car barely moved drive is the same... seems like the trans clutches are slipping really bad might just be over full on fluid any ideas?

this is my second drain and full with valvoline max life full synthetic ATF, their website indicates that the fluid is compatible with my car and many other 4eat transmissions...

any ideas?

thanks!

helps when you have the right amount if ATF... was over full but the dip stick read as not completely full top hole not filled with atf...

so drained a good amount out dip stick read low but car drove more normal with some slippage so I thought I drained to much but after adding half a quart the symptoms got worse again...
bogling my brain for the night....
 
#46 ·
if your dealing with brand new parts then yes they should be dipped in atf, the clutch packs are supposed to be soaked for some time. but generally no if the system works you don't need it full of atf to reinstall into the car. the pump should force enough fluid into the system to make it work.

I also believe the gaskets are supposed to be "hydrated" with atf prior to install if they go on dry they tend to stick and have to be scraped or buffed off before the new one is applied.

I always drip a good amount over everything when assembling but remember to much and its all going to drip down your arm when your reconnecting your duty c solenoid and watch that roller bearing!
 
#47 ·
did a drain and fill with dex3 no change added lucas stop slip no change yet car is idling now.... its very strange the trans seems to be doing nothing as if the only thing happening is me moving the shifter but the rpms do change.... going to swap in my spare tcu as I can drain the car completely while running without getting a code for low atf....

my only other thought is that I slightly pulled the reduction drive and driven gears away from whatever they seat into and didn't fully reseat them... but I would think that the tail housing wouldn't slide in place if that were the case, I was very carefull to have the clutch pack free spinning after torquing the tailsection on
 
#48 ·
looks like the atf pump has gone out X.x I don't have a gauge but while the car is in drive and at idle wheels wont move and I can't see any seepage from the test port on front drivers side of trans... ugg.... not looking forward to this replacement!
 
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