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4EAT Locking solenoid Q's


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71 replies to this topic

#1 86ruguy

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Posted 08 January 2007 - 06:18 PM

so i just read the write-up on what wires to fool around with to do this modification. however, i was curious as to if the TCU supplies power to this solenoid and the switch is supposed to interupt it or if the switch is supposed to let it have power.

i ask this because it was stated "NOT TO START CAR WITH SWITCH ON, or the a/t trans temp light will flash at you a lot"

i would like to do this to my "new to me" 92 wagon.

thanks,

Dave

#2 johnceggleston

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Posted 08 January 2007 - 06:48 PM

so i just read the write-up on what wires to fool around with to do this modification. however, i was curious as to if the TCU supplies power to this solenoid and the switch is supposed to interupt it or if the switch is supposed to let it have power.

i ask this because it was stated "NOT TO START CAR WITH SWITCH ON, or the a/t trans temp light will flash at you a lot"

i would like to do this to my "new to me" 92 wagon.

thanks,

Dave


look out, here it comes... all those responses for and against.

only a very few people have had success with this modification. it has caused ONE PERSON had trans damage, BECAUSE IT WAS LEFT ON ALL THE TIME, in the form of burned out AWD units = $850 - $950 repair, you have been warned.

see below.

#3 porcupine73

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Posted 08 January 2007 - 06:50 PM

Hi, as you stated, yes, "TCU supplies power to this solenoid and the switch is supposed to interupt it".

Just for reference, the TCU supplies a (I suspect square wave) signal at some frequency of variable duty cycle.

No power to duty c = basically 50/50 front/rear power split.

The secret to success with this modification is CAREFUL AND THOUGHTFUL use. It should never ever be used on dry or simply wet pavement. Mud, deep snow, sand, sheer ice would be cases where it might be useful, and even then probably just for starting from a standstill.

#4 Gloyale

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Posted 08 January 2007 - 07:07 PM

Hi, as you stated, yes, "TCU supplies power to this solenoid and the switch is supposed to interupt it".

Just for reference, the TCU supplies a (I suspect square wave) signal at some frequency of variable duty cycle.

No power to duty c = basically 50/50 front/rear power split.

The secret to success with this modification is CAREFUL AND THOUGHTFUL use. It should never ever be used on dry or simply wet pavement. Mud, deep snow, sand, sheer ice would be cases where it might be useful, and even then probably just for starting from a standstill.


I have done this mod and would agree with all of the above.
switch interupts, just when really needed.
BTW I've had codes set on first start up after using it.

#5 grossgary

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Posted 08 January 2007 - 07:09 PM

it doesn't matter if you start the car with the switch ON. yes, the trans light will blink...but so what, you know why it's blinking. if you really think you have a transmission code, just quit using the switch (you won't use it that often anyway)....sooooo...all that to say you'll know when it's a "real" code or not, it doesn't hurt anything, the light flashes at start up and then goes away, it doesn't even stay on. so other than 16 blips of light, there's really no reason to worry about a way of preventing it or how to use it and prevent that light from blinking. the light blinking is entirely benign. remember, you'll rarely use this switch in a daily driver, so you'll know if the light is blinking "for real" or not.

look out, here it comes... all those responses for and against only a very few people have had success with this modification. it has caused several peolple trans damage in the form of burned out AWD units = $850 - $950 repair, you have been warned.

can you edit that post? i posted numerous times asking for anyone that actually had a trans failure due to this switch. not one person responded to multiple requests, so this information is purely fabricated to this point (not accusing you, just stating a fact). Andy was the only one with issues and he LEFT IT ON. that doesn't count. if someone tows an AWD car on a dolly, you don't say subaru AWD transmissions are junk...it was a mistake. noone has damaged a trans with proper usage...or they haven't responded. please edit your post or provide a link to this information, this confuses people and will only start a repeat thread of the numerous threads already out there.

it should be mentioned...this mod isn't for everyone, but it is for me and is very useful. i've done it, years ago, used it many times and haven't had any issues. it's not a toy, shouldn't be used as a toy and should be done right. the switch should be hidden so that it can't be accidentally engaged and i suggest an indicator light in prominent view (i have one) that comes on with the switch, so you know it's on. it's a nice thought on an XT6 to use the DIFF LOCK switch from a manual trans..it'd look alll stock and sweet...but it's a bad idea because it's too easy to accidentally engage so i haven't done it.

#6 johnceggleston

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Posted 08 January 2007 - 08:37 PM

done

let me ask this, doesn't down shifting into 2 or 1 also transfer power equally to front and rear, 50/50? isn't that the factory provided 'switch'?

#7 grossgary

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Posted 08 January 2007 - 10:19 PM

just trying to stick to the facts before this turns into the other threads. i appologize if that was worded poorly. this is certainly a mod that should be done with caution but for those that may need it, which may be very few people, it is awesome.

i've seen the 1-2 shift mentoined before, none of the auto trans subaru's i've ever driven in do it. now, i'm not saying first and second gear do not change the shift characteristics...it may somehow, but it's nowhere near the no-slip traction control that the duty C mod provides. either it's available in other models that i haven't driven or this information is incorrect...or more likely it's interpretted incorrectly from the owners manual or FSM.

#8 nipper

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Posted 09 January 2007 - 11:53 AM

it doesn't matter if you start the car with the switch ON. yes, the trans light will blink...but so what, you know why it's blinking. if you really think you have a transmission code, just quit using the switch (you won't use it that often anyway)....sooooo...all that to say you'll know when it's a "real" code or not, it doesn't hurt anything, the light flashes at start up and then goes away, it doesn't even stay on. so other than 16 blips of light, there's really no reason to worry about a way of preventing it or how to use it and prevent that light from blinking. the light blinking is entirely benign. remember, you'll rarely use this switch in a daily driver, so you'll know if the light is blinking "for real" or not.

can you edit that post? i posted numerous times asking for anyone that actually had a trans failure due to this switch. not one person responded to multiple requests, so this information is purely fabricated to this point (not accusing you, just stating a fact). Andy was the only one with issues and he LEFT IT ON. that doesn't count. if someone tows an AWD car on a dolly, you don't say subaru AWD transmissions are junk...it was a mistake. noone has damaged a trans with proper usage...or they haven't responded. please edit your post or provide a link to this information, this confuses people and will only start a repeat thread of the numerous threads already out there.

it should be mentioned...this mod isn't for everyone, but it is for me and is very useful. i've done it, years ago, used it many times and haven't had any issues. it's not a toy, shouldn't be used as a toy and should be done right. the switch should be hidden so that it can't be accidentally engaged and i suggest an indicator light in prominent view (i have one) that comes on with the switch, so you know it's on. it's a nice thought on an XT6 to use the DIFF LOCK switch from a manual trans..it'd look alll stock and sweet...but it's a bad idea because it's too easy to accidentally engage so i haven't done it.


First off people have posted and responded when you have said prove the failure (three come to mind and i dont think one of them is still on the board) . Right now i dont think anyone wants to wade through the 100's of posts to find the exact posts. This is impossible since there is no set title for the post. This and HG posts are too numerous to wade thru.
Yes as I have said before you are the only one where it seems to work for, which should say something.
Also the "it's not a toy" comment should tell you why yours works and others dont, because it is a toy. For 98% of the people the TCU does a fine job of managing it. I suspect the other 1% are people trying to get the last legs out of thier AWD unit, and you are the last 1% (hehehe your special).
Now that said, the poster can do whatever he wants. I have taken a new philosphy, its not my money, i'm not loaning them my car, so they can do as they please as long as I feel they are warned of the possible outcome.
The one thing I would suggest is that the switch be wired into a dropout relay, so that when the car is shut off it resets itself to the normal position.

:horse:

Its not just a solenoid that controls the AWD, its a spol valve that is inside the tranny that also adjusts the pressure to the clutches. When you shut the solenoid off to get 50/50 split, you are dumping full pressure to the clutches (which rarely happens normally) and your odds of chewing up the clutches go up dramatically. The tcu applies just another pressure and duraiton thats needed to get the car going, and as soon as the car gets going it backs off. If you loose sight of how the system works, you will fry the unit.
The reason that our friend has a fully functioning long term system is that he respects this and understands how it works.

nipper

#9 Gloyale

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Posted 09 January 2007 - 12:01 PM

Nipper, Grossgary is not the only one. There are at least 2 of us who have done this mod!LOL

My 4EAT has the early "1st hold" switch. transfer clutch pressure is state to "increase" in the "1st hold" range. FSM also say's that in reverse, or upon wheel slip, that pressure is increased to the same as in "1st hold"

DOES NOT say that it is increased to "locked" The only time the FSM describes the pressure as "locked" is in reference to Duty solenoid C being inopperative. Which is what we do with the interupt switch.

Grossgary, I'm interested in how you wired your indicator light?

#10 porcupine73

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Posted 09 January 2007 - 12:06 PM

let me ask this, doesn't down shifting into 2 or 1 also transfer power equally to front and rear, 50/50?

I don't think so, because if you put the shifter in '1' and then make a turn, it doesn't bind up or anything like it would if making a turn with this switch cutting power to the duty c.

#11 nipper

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Posted 09 January 2007 - 12:06 PM

My 4EAT has the early "1st hold" switch. transfer clutch pressure is state to "increase" in the "1st hold" range. FSM also say's that in reverse, or upon wheel slip, that pressure is increased to the same as in "1st hold"

DOES NOT say that it is increased to "locked" The only time the FSM describes the pressure as "locked" is in reference to Duty solenoid C being inopperative. Which is what we do with the interupt switch.

Grossgary, I'm interested in how you wired your indicator light?


see :)

There was a thread here that somone was going to throw a scope on the Duty C Sircuit to see what happens, anyone knows what the outcome of that was?

nipper

#12 grossgary

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Posted 09 January 2007 - 12:27 PM

First off people have posted and responded when you have said prove the failure (three come to mind and i dont think one of them is still on the board) . Right now i dont think anyone wants to wade through the 100's of posts to find the exact posts.

i didn't want to turn this into another thread like all the rest, but since i'm being accused of lying.......i have yet to see a person mention any actual failures. i did a search for "duty solenoid" and the second thread that pops up (after this one), is the popular thread, that i was speaking of, with much exposure that i asked multiple times for one person that had issues and not one person responded with a non-mistake related issue:
http://www.ultimates...t=duty solenoid

the people that are most concerned with proving how terrible this modification is are the ones that have never done it. i'm all about getting both sides of the information out there, so long as it's accurate. there are a number of people at xt6.net that have done it as well...no failure yet, even on 20 year old auto trans with who knows how many miles, previous owners, lack of ATF changes, and sets of tires on them.

#13 grossgary

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Posted 09 January 2007 - 12:32 PM

Grossgary, I'm interested in how you wired your indicator light?

it's very simple. if you can wire a switch, you can wire an indicator light. i installed an LED and wired it on the same circuit, that's all. ground on one side, power on the other. make sure the switch that you buy has room for two circuits, that's all. wire the "duty solenoid" on one circuit, then the light on the other. that way when you turn it "On", it's completing both circuits...one for the solenoid, the other for the light. a radio shack or sound system place would likely be able to help you with it if you're having trouble picturing it.

#14 grossgary

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Posted 09 January 2007 - 12:36 PM

There are at least 2 of us who have done this mod!

there's at least three on the xt6.net board as well. one in NZ, one in WV and myself....and i think derrick as well, but i'm not sure. no problems and we had this done well before anyone on usmb attempted it, although i think one person did it, but either way, well before it was documented and publicized here.

#15 MountainBiker

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Posted 09 January 2007 - 12:49 PM

done

let me ask this, doesn't down shifting into 2 or 1 also transfer power equally to front and rear, 50/50? isn't that the factory provided 'switch'?

This comes from Subaru marketing speak. An OPEN differenttial has a 50/50 torque split. How do those work for you in low traction situations?

#16 grossgary

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Posted 09 January 2007 - 01:16 PM

the first and second gear issue is really an entirely different topic and it's been discussed before. the bottom line is that 1st and 2nd perform nothing like this duty C modification, so no matter the reasons they do not compare in function.

#17 MountainBiker

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Posted 09 January 2007 - 01:19 PM

Yes as I have said before you are the only one where it seems to work for, which should say something.

What about me? I've been using it for 3 years now, and I don't even get the flashing light! There are at least 3 other Foresters doing the same as I did (no flashing light) on SF.org. One of them has had the switch in place nearly as long as me.

Now that said, the poster can do whatever he wants. I have taken a new philosphy, its not my money, i'm not loaning them my car, so they can do as they please as long as I feel they are warned of the possible outcome.
The one thing I would suggest is that the switch be wired into a dropout relay, so that when the car is shut off it resets itself to the normal position.

That is very good advice! Don't come crying back to this message board if this mod doesn't work for you, or causes damage. I consider this mod to be "major" with some risk of damage to the vehicle. This isn't a "bolt-on" mod, and the organic control unit has to be functioning properly! ;)

I haven't installed the dropout relay yet, it is on my list of things to do.

#18 nipper

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Posted 09 January 2007 - 05:02 PM

I don't think so, because if you put the shifter in '1' and then make a turn, it doesn't bind up or anything like it would if making a turn with this switch cutting power to the duty c.


yes it does. your fogetting one thing. Not only is the split controlled by the on/off time of the solenoid, but the solenoid works in conjunction with the spool valve. We are talking two variables here. Also the tcu is still in control of the solenoid, so it can still give you a 50/50 split, but the transmission pump doesnt have to apply as much line pressure to the clutches to maintain that split.
Also in Low and Reverse the designers made a few safe assumptions about speed and steering angle, so they can design around that.

nipper

#19 Gloyale

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Posted 09 January 2007 - 07:40 PM

This isn't a "bolt-on" mod, and the organic control unit has to be functioning properly! ;)

I haven't installed the dropout relay yet, it is on my list of things to do.


organic. LOL "Excuse me,...but do you have organic control units?":lol:

#20 nipper

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Posted 09 January 2007 - 08:26 PM

organic. LOL "Excuse me,...but do you have organic control units?":lol:


i think he meant orgasmic, they cost extra

:lol: :lol: :lol:

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#21 86ruguy

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Posted 09 January 2007 - 09:55 PM

well gang, i was not trying to turn this into a ''FIGHT". i was just simply asking if it in fact controlled the power side of the circuit.
i appreciate all of the input for the yeah's and neah's but as a mechanically minded person i was just asking a simple Q.

i understand that if Subaru wanted me to have A FULL-TIME AWD AUTO TRANS they would not have made it with a duty cycle solenoid. the main reason for this mod to my car is so that if i decide to lift it and possibly go do so MILD off-roading, i will have a 50/50 split to work with instead of wheel slip.

again thank you for your inputs and i will now be unsubscribing from this thread as i do not want to be part of the "FIGHT".

Dave

#22 nipper

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Posted 09 January 2007 - 10:07 PM

Who's fighting, we arent fighting. :-p

you want to see fighting, go over to the old gen board and look at the syn vs dino oil discussion, now thats fighting

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#23 86ruguy

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Posted 10 January 2007 - 02:07 AM

Who's fighting, we arent fighting. :-p


well then you kids just play nice or no candy before bed:lol:

#24 nipper

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Posted 10 January 2007 - 10:11 AM

well then you kids just play nice or no candy before bed:lol:


oo no one mentioned candy before:rolleyes:

nipper

#25 86ruguy

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Posted 10 January 2007 - 09:50 PM

oo no one mentioned candy before:rolleyes:

nipper


YEAH!!!!! Really BIG pieces:lol:




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