4EAT Locking solenoid Q's

[idosubaru]

i'm not being hostile, i'm stating facts and posting links. i requested people who have had failed transmissions and there were no responses..except andjo who 'left it on, on the highway', a mistake, we all know that..it's been said a billion times. we at xt6.net have had this mod in place (without near the fanfare) since 2003, there are a number of users there as well that are not members or frequent here. no failures on transmissions nearing 20 years old over there.

 

if people screw up alot of things it's a 1,000 dollar repair (changing oil, changing coolant, rotating or replacing tires, replacing thermostats...etc), it seems you stand in opposition to this modification on principle and keep quoting all of these transmissions that have failed....but i don't recall seeing them. not saying it isn't there, but i can't find it and noone is speaking up.

 

andyjo admitted to leaving it on, on the highway...that doesn't qualify for "what came first the chicken or the egg?". again this seems like a biased oppinion. here is my situation.....i come from a board where this mod has been in place for years. there haven't been any failures. then the topic explodes over here on usmb recently, and all of the commentators are people that haven't done it. it seems to me this information is best presented in a factual manner, and for those of us that have done it properly and need it, it is well worth it.

 

there's no hostility at all, but i'd like to see this topic remain factual for the minority that can use it, because it is awesome. this will not hose your trans, many have done it at xt6.net for years. there is a risk, yes. if anyone does toast a trans, it's because they did something wrong.

[MountainBiker]

grossgary i never said that.

i also have applauded you for having the only one that works, so thats just plain not fair.

 

 

nipper

Nipper keeps forgetting about me and my 3 years of successful use! He must have me on ignore!

 

Look at post 17 of this thread, and a few other threads where I posted my results. I don't recall if I posted in Andyjo's long thread, because I wasn't on the board at that time, and I had already done the mod.

[johnceggleston]

i concluded last week that the difference between the mod switch which locks the AWD unit and shifting into 1 or 2 (and obviously there is a difference since, as someone pointed out , there is not torque bind) the only doifference is that when in 1 or 2 the computer is still involved and allows for slipping and the bleed-off of pressure to avoid clutch pack damage.

 

this begs the question, how fast do you want to go while the car in a 50/50 split? when the conditions require more rear end power, instead of turning on a swicth, just shift to 1 or 2. unless you'er going 45 mph, you'll get the power you need and youy'll avoid the possibility of damage.

 

if conditions warrant more power to the rear end, i don't think you should be going fast enough to be in thrid.

 

on the other hand however, there will be a rear end power benefit at slow speeds with the AWD unit locked; there is also the possibility of damage if abused or not monitored correctly.

 

just think of it as locked hubs on a standard 4WD truck. you have more power, buy you don't want it or need it at higher speeds.

[Gloyale]

 

this begs the question, how fast do you want to go while the car in a 50/50 split? when the conditions require more rear end power, instead of turning on a swicth, just shift to 1 or 2. unless you'er going 45 mph, you'll get the power you need and youy'll avoid the possibility of damage.

 

It doesn't work like that. especially in the older 4eats found in GL's,GL-10s, XTs and XT-6.

First of all you only get the increased transfer in 1st on these old ones. BUT there is no 1st on the select lever. You must push in the 1 hold button when the shifter is in 2nd position. Then you get 1st gear. so you'd be limited to about 20-30mph tops.

Second of all, The increase from being in 1st is not nearly as much as when you lock it with the switch. It just isn't. If you haven't done it you don't know.

Third and maybe most importantly, The older computers just aren't as good as the new ones. It takes way too long once the front slips to kick in and send power. Even then it is not smooth and isn't even enough power to the back end when it's really deep snow. I have a 93 Legacy, with 80,000 more miles than my GL, and it transfers beautifully. It just bites and goes no matter what. No front wheel slip. even in the deepest snow. I don't need the switch in that car. But my GL just doesn't transfer power real well(unless I use the switch).

Also, If EITHER of the speed sensors fail, or if the AT temp sensor fails or becomes grounded, the computer control won't send any power to the rear wheels. So this switch gives you a way to get out of bad conditions even if one of these fails by overriding the computer and lockin em up.

[johnceggleston]

Second of all, The increase from being in 1st is not nearly as much as when you lock it with the switch. It just isn't. If you haven't done it you don't know.

 

the one exception being that if your duty c has failed, and mine did. i know what locked feels like.

 

what i haven't ever experienced is the need for 4WD. i i've never ben in an old gen subaru, much less driven one, so i have no knowledge there, nor did i even consider those cars. and i'm not faulting any one who needs the mod.

 

the point i was trying to make is this, as designed the system does a pretty good job, FWD mostly, 50/50 when you need it while protecting the trans from being damaged. and if you're traveling 45 or 50, you are either going too fast for the conditions or the codtions do not require more power.

 

putting mods on your car to compensate for an aging car, trans, computer, system, whatever ..... is fine. but as you point out, it's not necesary on the legacy mid 90's with 80k miles.

 

did i get it right?

[Gloyale]

everything except the milage of the mid 90's Legacy. It has 290,000 miles! I said it has 80,000 more miles on it than my GL which is at 210,000!

 

I wouldn't use the "lock" at more than about 30-35 mph. Even if the inceased transfer of the 1st hold range worked (which it doesn't, not in my car) I would be way wound out in rpms by about 20-25. and even at 20, once I am movin I would want to be in second.

[MountainBiker]

the point i was trying to make is this, as designed the system does a pretty good job, FWD mostly, 50/50 when you need it while protecting the trans from being damaged. and if you're traveling 45 or 50, you are either going too fast for the conditions or the codtions do not require more power.

Yeah, 50/50 torque distribution always gets you unstuck. Open diffs give you 50/50 torque split...

 

If you don't feel the need for the mod, then you don't need the mod, it's that simple. Seems that most of those that have used it enjoy the benefits.

[86ruguy]

OMFG!!!!!!! :mad: will you guys either do the friggin mod and leave it alone and BE IN FEAR OF RIPPIN' up your trannyand leave the 5%duty crap to the engineers at SUBARU. you guys are getting way deeper then you need to.

 

obviously, the switch cannot be left on at anything more than say20 mph or your already weak (from the factory) 4EAT transmission is going to EXPLODE IN YOUR FACE.

 

i just don't get it, those of you that don't want to do the mod to your car, FGS don't do it.

 

those of you that have done it and have not had any problems, apparently know not to leave it on.

 

thank you for all of the wonderful input, but it is done to my car and the only time i have used it so far is to do DONUTS in a vacant snow covered parking lot.

 

i will also prob use it to do some rallyXing.

 

PEACE:cool:

[Gloyale]

OMFG!!!!!!! :mad: will you guys either do the friggin mod and leave it alone and BE IN FEAR OF RIPPIN' up your trannyand leave the 5%duty crap to the engineers at SUBARU. you guys are getting way deeper then you need to.

 

 

I am working on design for a duty cycle controller right now. I may end up with a variable control using a potentiometer. I have already done the switch the simple way. It works. I just think the idea of forcing lock without completely shutting of the duty solenoid is great. I will start a new thread once I build and test it.

 

BTW, many people have stated that "an open diff is 50/50". This is only true UNTIL ONE WHEEL SLIPS! then torque transfer is limited to no more than can be applied to the wheel with the least traction. Which doesn't help at all when the tires get to slipping

[idosubaru]

the point i was trying to make is this, as designed the system does a pretty good job

it does a decent job, but that doesn't mean it can't serve my personal uses better. i drive off road in snow, mud and ice. there are times when the TCU is not sufficient for what i'm trying to do. but most people don't encounter those situations.

[MountainBiker]

I am working on design for a duty cycle controller right now. I may end up with a variable control using a potentiometer. I have already done the switch the simple way. It works. I just think the idea of forcing lock without completely shutting of the duty solenoid is great. I will start a new thread once I build and test it.

Excellent! I look forward to seem your results.

 

BTW, many people have stated that "an open diff is 50/50". This is only true UNTIL ONE WHEEL SLIPS! then torque transfer is limited to no more than can be applied to the wheel with the least traction. Which doesn't help at all when the tires get to slipping

Which is exactly my point! After one wheel slips, torque is still evenly distributed 50/50, and you are still stuck. That is why I always mention open diffs when somebody claims the 50/50 torque distribution is actually a good thing in poor traction conditions.

 

I think we need a tongue in cheek smilie, which would help to show why I always bring up the open diff!

[PopsicleMud]

I am working on design for a duty cycle controller right now. I may end up with a variable control using a potentiometer.

That's what I want to do. Someone over at XT6.net used a Kenworth light dimmer to generate the PWM signal, but he posted that he had done it and didn't give any details. I've started researching LED dimmer designs as a way of doing it.

[idosubaru]

we also have another member (in addition to the one you're speaking of), that designed a duty C controller. but he basically developed an entire stand alone TCU to do it and was very tight lipped about the entire deal. no information offered.

[Gloyale]

Which is exactly my point! After one wheel slips, torque is still evenly distributed 50/50, and you are still stuck. That is why I always mention open diffs when somebody claims the 50/50 torque distribution is actually a good thing in poor traction conditions.

QUOTE]

 

What are you talking about? A locked 50/50 transfer will still send power to each axle. Be it a hydraulic lock like the automatics, or a mechanical diff lock or the selective 4wd like the old ones. One wheel slips and you lose torque at other wheel on that axle(unless you have a LSD diff on that axle) but not at the other axle.

 

An open center diff goes from being 50/50 to practically 0/0 when there no traction at one wheel. Subies with the Viscous center diff will still transfer some torque. But that is not an open diff, it is limited slip. Mountainbiker please read up on differential types and theory. open center diffs will leave you with no torque. a locked 50/50 will give you torque to both axles no matter what.

[MountainBiker]

Which is exactly my point! After one wheel slips, torque is still evenly distributed 50/50, and you are still stuck. That is why I always mention open diffs when somebody claims the 50/50 torque distribution is actually a good thing in poor traction conditions.

 

What are you talking about? A locked 50/50 transfer will still send power to each axle. Be it a hydraulic lock like the automatics, or a mechanical diff lock or the selective 4wd like the old ones. One wheel slips and you lose torque at other wheel on that axle(unless you have a LSD diff on that axle) but not at the other axle.

 

An open center diff goes from being 50/50 to practically 0/0 when there no traction at one wheel. Subies with the Viscous center diff will still transfer some torque. But that is not an open diff, it is limited slip. Mountainbiker please read up on differential types and theory. open center diffs will leave you with no torque. a locked 50/50 will give you torque to both axles no matter what.

The key word in what you say above is TRANSFER. When the VLSD engages, it transfers torque, which is no longer a 50/50 torque distribution.

 

An open diff never goes to 0/0, it is always 50/50. So when one wheel spins or is in the air, it has equal torque applied to it as the other the other wheel, and both will have near zero torque. This is what you get with 50/50 TORQUE distribution.

[Gloyale]

An open diff never goes to 0/0, it is always 50/50. So when one wheel spins or is in the air, it has equal torque applied to it as the other the other wheel, and both will have near zero torque. This is what you get with 50/50 TORQUE distribution.

 

You say right there that "both will have near zero" !! yet you still say 50/50???

50% of zero is Zero!

Try this. Put a 2wd car or truck up on jackstands. Start the car and put it in gear and let the tires spin. You can grab one side and stop it by hand. the other side will keep spinning. Now imagine that the stopped wheel is the one on the ground with traction. It won't get any power cause the other one is in the air. I guess really it goes to a 100/0 torque transfer. with the 100% going to the spinning wheel!! A true 50/50 split would make the wheel with traction spin and move the car even if the other was off the ground. in other words you would not be able to stop it by hand. we may be splitting hairs about terms. You obviously know that an open diff will leave you stuck.

[98obster]

it does a decent job, but that doesn't mean it can't serve my personal uses better. i drive off road in snow, mud and ice. there are times when the TCU is not sufficient for what i'm trying to do. but most people don't encounter those situations.

 

Wow, haven't been here for a while and the "snow switch" discussion is still going strong. I did this mod probably back in September (warm then) on my OBS pretty much like Andyjo explained. As his pictures matched my situation exactly, I had no probs at all-definitely solder the connections. I think the picture of my switch is in here somewhere. I made it pretty simple (DPST), basically an on off switch where the off is the ON (up) position for our purposes. I modified a red hinged cover (radioshack). You lift the cover and flip the switch and when the cover is closed the circuit closes. The biggest problems with this mod will definitely be when and if you forget it is "on"-so whatever it takes to foolproof the switch.

In the Colorado front range we've had over 50 inches of snow since x-mas and I used it a half dozen times to get going and to get and keep unstuck and occasionally also to plow through the deep stuff though I probably didn't need it at that point. I definitely do not have an indication of any problem by engaging the switch. I don't know how I would recognize any pending problem with the clutch pack or Duty C solenoid as a result and I have not perceived anything out of the ordinary. I've even had the switch on while in reverse-no problems. I have 118k+ on my 4eat. the fluid probably has 15k on it. the worst thing I did was do a few tight circles on dry pavement when I first installed it to "test" it. I do not think you would need to test it-just triple check your work and definitely test continuity and solder and heat shrink connections. Also Peach and Good Luck.

Jon

[nipper]

I am working on design for a duty cycle controller right now. I may end up with a variable control using a potentiometer. I have already done the switch the simple way. It works. I just think the idea of forcing lock without completely shutting of the duty solenoid is great. I will start a new thread once I build and test it.

 

BTW, many people have stated that "an open diff is 50/50". This is only true UNTIL ONE WHEEL SLIPS! then torque transfer is limited to no more than can be applied to the wheel with the least traction. Which doesn't help at all when the tires get to slipping

 

Torque like electricity likes the path of least resistance (none of us like to work harder then we need too).

 

If you can get the controller to work, i would suggest a circuit taht unlocks the AWD after 20mph. But either way keep me informed, as i am interested in a more reasonable controller

 

nipper

[MountainBiker]

You say right there that "both will have near zero" !! yet you still say 50/50???

50% of zero is Zero!

Try this. Put a 2wd car or truck up on jackstands. Start the car and put it in gear and let the tires spin. You can grab one side and stop it by hand. the other side will keep spinning. Now imagine that the stopped wheel is the one on the ground with traction. It won't get any power cause the other one is in the air. I guess really it goes to a 100/0 torque transfer. with the 100% going to the spinning wheel!! A true 50/50 split would make the wheel with traction spin and move the car even if the other was off the ground. in other words you would not be able to stop it by hand. we may be splitting hairs about terms. You obviously know that an open diff will leave you stuck.

I don't think anyone is splitting hairs here in this side discussion, which is about the definition or torque and torque split. It matters in this context because Subaru claims a 50/50 Torque split, or 60/40 or 90/10 in various situations.

 

A 50/50 torque split means that both wheels have equal torque applied to them. So if one is zero, the other is zero. BTW, torque has no direct relation to wheel speed, so equal torque can be applied if one wheel is spinning and the other wheel is stationary. In this case, whatever torque is needed to spin the wheel (say 30 ft-lbs just for discussion), then the stationary wheel also has 30 ft-lbs applied to it. This 30 ft-lbs may or may not be enough to actually turn that wheel or move the vehicle.

 

A true 50/50 TORQUE split can (and often does) make one wheel spin and the other remain motionless (and the car remains motionless).

[98obster]

I don't think anyone is splitting hairs here in this side discussion, which is about the definition or torque and torque split. It matters in this context because Subaru claims a 50/50 Torque split, or 60/40 or 90/10 in various situations.

 

A 50/50 torque split means that both wheels have equal torque applied to them. So if one is zero, the other is zero. BTW, torque has no direct relation to wheel speed, so equal torque can be applied if one wheel is spinning and the other wheel is stationary. In this case, whatever torque is needed to spin the wheel (say 30 ft-lbs just for discussion), then the stationary wheel also has 30 ft-lbs applied to it. This 30 ft-lbs may or may not be enough to actually move the vehicle.

 

A true 50/50 TORQUE split can (and often does) make one wheel spin and the other remain motionless (and the car remains motionless).

 

 

I think that is a good explanation. So, if my rear wheels were stuck and spinning only one tire, could I apply the e-brake to increase the torque enough to get the other wheel moving? jon

[MountainBiker]

I think that is a good explanation. So, if my rear wheels were stuck and spinning only one tire, could I apply the e-brake to increase the torque enough to get the other wheel moving? jon

Yes, this sometimes works. It definitely increases the torque delivered to the spinning wheel, which in turn increase the torque delivered to the stationary wheel. Unfortunately, the parking brake is also applied to the other wheel, so this doesn't always get you unstuck.

[nipper]

I think that is a good explanation. So, if my rear wheels were stuck and spinning only one tire, could I apply the e-brake to increase the torque enough to get the other wheel moving? jon

 

if its a manual you can slowly apply the ebrake. if its a automatic you can slowly apply the service break.

 

If its a manual and your really stuck, you can apply the service brake (or grow a third foot)

 

VW (beetle based) bajas beetles (and dune buggy)had a directional ebrake, where you could apply just one brake for the same reason.

 

nipper