monstaru Posted June 9, 2010 Share Posted June 9, 2010 on an auto?who's done it?cheers,brian Quote Link to comment Share on other sites More sharing options...
Uberoo Posted June 9, 2010 Share Posted June 9, 2010 didn't mudrat weld the center diff on that one divorced transfer case vehicle he made that went to the rubicon? Correct me if I wrong but it may have also been an ej engine and 4eat. Quote Link to comment Share on other sites More sharing options...
monstaru Posted June 9, 2010 Author Share Posted June 9, 2010 did you weld your center diff?no , you didn't. Quote Link to comment Share on other sites More sharing options...
Ratty2Austin Posted June 9, 2010 Share Posted June 9, 2010 If you are talking about "welding" a center diff on a 4EAT for an EJ, you might just do the simple thing, and flip the duty solenoid "c" around, and keep the wires hot to it? (I think that is what you do, but check with those who have done it) Anyway, it's not a center diff in the autos anyway- its a clutch, just like the rest of the auto's gear sets... you just have to tell the computer/ or solenoid to "enable" that clutch pack 100% of the time, giving you a lock between front/rear.... (or is it just all power to the rear only?) Anyway, the answer to weld center diff on an AT is no, cause there isn't one as far as I know..... (but I could be mistaken) Quote Link to comment Share on other sites More sharing options...
eulogious Posted June 9, 2010 Share Posted June 9, 2010 What type of auto are we talking about? If it's the 4EAT, then what Austin said. I will just speak a little of the 4EAT here, if it doesn't apply sorry The 4EAT has a MPT (Multi Pressure Transfer) clutch that transfers power to the rear wheels when needed via the duty c solenoid. The duty c solenoid is then controlled by the TCU, which I am sure you knew all this already. So there are a couple of ways that you can lock it up. If you ground the solenoid out, it closes the solenoid, therefore providing as much power as it can via the clutches to the rear wheels. Here's a quote from chux about how the transfer works... where did you read that? it's a common misconception. but the front gets full power, all the time, regardless of what the rear is doing. it's really like 100/10, and then as the TCU puts more pressure on the transfer clutch, it varies up to about 100/80 (only reason it isn't 100/100, is the solenoid/clutch will still slip unless mechanically modified, they will not hold all the power). if your transfer clutch burns out entirely, you loose the rear drive, but you can still drive around fine. it's FWD, and you might not even notice it until it snows and you're stuck and I am talking about the 4EAT. 3ATs are not full-time. so they're 100/0, push the button and they're 100/80. torque splits really can't be boiled down to just a number ratio. as so many AWD systems have so many variables to how they react. with a mechanical center diff, like in a subaru 5MT AWD or FT4WD system, it really needs to be out of 200, as if one end is stopped, the other spins twice as fast. so a FT4WD system, unlocked, is 100/100, unless one end sees more resistance, and then it changes, all the way to 200/0, with almost no restriction. a VLSD center (EJ AWD 5MT) changes the amount of resistance depending on how much slip has already occurred. so 100/100, one end loose traction, and it goes to 150/50, then the VLSD heats up, and transfers power to the side with more traction, and it goes back towards 100/100. So he states it best how it transfers power via the MPT clutch. But there are downsides to grounding out the solenoid. It might wear out quicker, you can damage it by leaving the switch on and burning out the clutches, etc. There is also another route, and that is to modify the actually TCU like I did, and then you can control the MPT clutch to your liking. This way is the "safer" way, because it uses the code developed by subaru to control the MPT clutch, so you are not hurting the MPT clutch at all. Other than those two options, I really don't think that there is a way to "weld" the center diff in an auto, mainly because you can't really "weld" a clutch AFAIK. But really, what do I know I say this of course without ever actually opening a trans myself so there might be a way to do that, but from what I have read in all my research when modding my TCU, there is no way to get a 100/100 all the time out of a 4EAT, it all depends on the condition of the clutches, and even then you won't get 100%, and not all the time... The switch would be the easiest way to accomplish this. You just need to cut into one wire. If you want more info on the switch, let me know. I did it in my car and can give you the location of all the wire and what not. I hope that helps a little Quote Link to comment Share on other sites More sharing options...
monstaru Posted June 9, 2010 Author Share Posted June 9, 2010 (edited) umm, yeah, i have read all of that before.... i have had about 4 4EAT's apart. there are a set of housings involved with a clutch.they could be welded together i think.hence why i asked , "if anyone had done it" excuse me for using the wrong wording.the "viscous coupler" as it were , is what i want to conjoin....... and , since noone has just welded the damn thing together, i guess i'll do that. cheers, brian Edited June 9, 2010 by monstaru Quote Link to comment Share on other sites More sharing options...
eulogious Posted June 9, 2010 Share Posted June 9, 2010 I gotcha. So since I have not done it, I will just be standing by watching your progress If you need any help from the peanut gallery, you know where to find me If you do it, take some pics! It would be interesting to "see" how it could be done. Good luck man! What's your end goal with this? "True" 4wd with an auto? Quote Link to comment Share on other sites More sharing options...
monstaru Posted June 9, 2010 Author Share Posted June 9, 2010 really, i am just being lazy. if i could weld them together to achieve full lock up at the rear, i would be getting equal power to the rear, or almost equal power as the front.... then i would not have to put in a D/R. and i have wanted to try an auto for wheeling.the reduction of a torque converter mathematically works out to about 2:1, so it would be like using a low range.....cheers, brian Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted June 9, 2010 Share Posted June 9, 2010 (edited) After some thinking, I should point a weak point in the auto, especially after welding the rear clutchpaks, is going to be the flexplate, which is already weak to begin with. More recently Subaru has updated to a thicker flexplate on some applications. I myself, have cracked, then broken off a flexplate completely just with normal driving, in a turbo's ej22t. I may or may not have current crack on the one in my SVX. Having mentioned this, a must would be to go to the newer beefier flexplate before you find out how weak it is. Should be a nice low gear though for crawling i would think, those 4eats are pretty stout, and not something to just carry around, they have some beef in them. I dont think the way to go is thru the duty C solenoid, those things are not manufactured to be on 100% of the time, they will burn out after solid use, so welding would the most effective approach, i am sure it can be done i have been torn into the tailshafts a few times...seems to be possibles Also, maybe just add a few more clutch rings to the clutch pack, bring it out of spec so it locks wihtout any added pressure in the transfer seal. that would almost be the same as welding it. The FSM shows how to take them apart, and there is room for at least a few more spacers, and friction disks in there the what the factory put in, tighten that sucker up some.... Edited June 9, 2010 by bheinen74 Quote Link to comment Share on other sites More sharing options...
eulogious Posted June 9, 2010 Share Posted June 9, 2010 I have read the same thing with the torque converter giving more power on the low end. I plan on wheeling my 4EAT, I just need to replace my CV joint, and then get my lift and tires, which should happen here at some point :-\ That was part of the motivation to try to figure out my paddle shifters, was to get better control of the AWD as well, to make it a better wheeler/toy/DD. The 4EAT is a stout trans, so it should be able to take some abuse! I believe gloyale has wheeled his 4EAT and hasn't had any issues, but I don't know if he modded it in anyway or not... I am curious on what you come up with man! I love my 4EAT, and you can get them for fairly cheap out of a JY, so being able to lock it up into 4wd all the time might make for a fun offroad toy drive terrain in the future... Quote Link to comment Share on other sites More sharing options...
Gloyale Posted June 9, 2010 Share Posted June 9, 2010 I dont think the way to go is thru the duty C solenoid, those things are not manufactured to be on 100% of the time, they will burn out after solid use, OK, just to clarify a few things. First.....NEVER ground out the duty solenoid. Doing this while it's connected to the ECU basically shorts out the transitor that runs that circuit. It does drive the voltage low.....which cause the Duty C to stop draining pressure and engages the clutches. But the price is burning up the TCU or the Solenoid or both. Simply interupting the circuit....I.E. a switch inline on the wire.....is the "right":rolleyes: way to do this "locking" mod. And yes I've done it on many rigs so this isn;t speculation. Also, maybe just add a few more clutch rings to the clutch pack, bring it out of spec so it locks wihtout any added pressure in the transfer seal. that would almost be the same as welding it. The FSM shows how to take them apart, and there is room for at least a few more spacers, and friction disks in there the what the factory put in, tighten that sucker up some.... I have thought about this too. Problem is that the 4eat already has a history of shearing off the hub where it's welded to the end of the output shaft. But it likely would work well for a bit. It's worth noting, the Phase II 4eats have a WAAAAAY more solid transfer output. Also they are almost 3 inches shorter......almost identical length to the EA D/R boxes. So if you where gonna try this, the later trans may be a better option, although the more complex TCU could be tough to install in a non OE setup. Quote Link to comment Share on other sites More sharing options...
eulogious Posted June 9, 2010 Share Posted June 9, 2010 First.....NEVER ground out the duty solenoid. Doing this while it's connected to the ECU basically shorts out the transitor that runs that circuit. It does drive the voltage low.....which cause the Duty C to stop draining pressure and engages the clutches. But the price is burning up the TCU or the Solenoid or both. Simply interupting the circuit....I.E. a switch inline on the wire.....is the "right":rolleyes: way to do this "locking" mod. For the record, yes you are correct. I was summarizing, because I figured the OP already knew about this mod, so no point in running through a mod that he knows about. My TCU is modded, AND I have a switch that is interrupting the circuit, just like you said. If anyone wants any info on this mod, SEARCH FOR IT, its been covered before... Oh, and it's not even the "right" way to do it. The TCU only send a 95% duty cycle to the duty c when it's fully locked "normally", so by adding in the switch, you are applying 100% duty cycle to the solenoid, which WILL fry it over time. The ONLY true "correct" way to do this mod is to modify your TCU firmware, so there for even when it's locked up, the solenoid is only seeing 95% duty cycle just like subaru intended Just wanted to state that for the record Quote Link to comment Share on other sites More sharing options...
idosubaru Posted June 9, 2010 Share Posted June 9, 2010 go weld one up brain, that's awesome! i've never heard of anyone on any of the boards messing with the 4EAT, so you'll have the excitement of covering new ground. you don't need any extra parts to play with do you? you are applying 100% duty cycle to the solenoid, which WILL fry it over time. most (if not all) of us that have been doing it for years have never had it happen so not a real world stat worth worrying about for most of us. i like the probability of no work over the requirement of restructuring firmware. what you did is awesome, but that's beyond most folks. i wish i had the time to dig into that stuff, there's great opportunity there, but it's easy to swap a DC. hmmm...tangent time - did you ever finish that thread up with pictures of how you control it - knobs and doohickey's, i don't recall seeing that but would love to. Quote Link to comment Share on other sites More sharing options...
monstaru Posted June 9, 2010 Author Share Posted June 9, 2010 (edited) well, for the record.not a damn one of you has welded the diff, visc, coulper,ie ************ing tailshaft on these trans. yet , you all seem to want to add an opinion about it. did i ask for opinions?NO.i asked for experience welding the sum *************** up..... i don't want your thoughts on how i should accomplish it.i don't need advice.i'm gonna do it anyway.just wanted to have an intelligent convo with someone that HAS done it......... and gary, we posted the same time.no i do not need any extras at this point.thanks cheers, or not, brian Edited June 9, 2010 by monstaru didna see gary in here...... Quote Link to comment Share on other sites More sharing options...
Gloyale Posted June 9, 2010 Share Posted June 9, 2010 (edited) Oh, and it's not even the "right" way to do it. The TCU only send a 95% duty cycle to the duty c when it's fully locked "normally", so by adding in the switch, you are applying 100% duty cycle to the solenoid, which WILL fry it over time. The ONLY true "correct" way to do this mod is to modify your TCU firmware, so there for even when it's locked up, the solenoid is only seeing 95% duty cycle just like subaru intended 95% duty cycle is FWD from the TCU (this is what the TCU does when put in FWD mode) 05% duty cycle would "locked" or maximum output 4wd from the TCU. Sorry, but you got it backwards. When running in "locked" mode with this mod the Duty C get's ZERO.....that's right ZERO power. Totally de-energized. When switched to "locked", the thing sits like a rock in the trans not hooked to any voltage. How could it "fry"? Sorry Mostaru for the tangent.......I just don't like to see misinformation posted about how TCU controls the transfer. Edited June 10, 2010 by Gloyale Quote Link to comment Share on other sites More sharing options...
eulogious Posted June 9, 2010 Share Posted June 9, 2010 (edited) Sorry I was merely summarizing and I got it backwards because I have been up for 27 hours straight, my bad. Sorry for cluttering your thread Brian, you won't hear from me again about this, eulogious out! Edited June 11, 2010 by eulogious Quote Link to comment Share on other sites More sharing options...
Markus56 Posted June 9, 2010 Share Posted June 9, 2010 (edited) you can put the 4EAT in a 50/50 split by shifting into 3rd and pressing the button under the shift lock. Just wanted to throw that out there, I dont know if you knew that not. Edit: and now that i've read the whole thread, i'll shut up. sounds interesting! Edited June 9, 2010 by Markus56 Quote Link to comment Share on other sites More sharing options...
frogstar7055 Posted June 10, 2010 Share Posted June 10, 2010 I've got the 4eat lock mod on mine and my opinion whether you want it or not is if you weld it and drive on pavement at all it will break. Switch engaged on pavement causes a horrible binding in any direction but a straight line. Just saying. Quote Link to comment Share on other sites More sharing options...
monstaru Posted June 10, 2010 Author Share Posted June 10, 2010 noone asked if this was a fulltime4wd trans either:).....so , i doubt it will "bind" like you seem to think it will their frogboy..... Quote Link to comment Share on other sites More sharing options...
frogstar7055 Posted June 10, 2010 Share Posted June 10, 2010 noone asked if this was a fulltime4wd trans either:).....so , i doubt it will "bind" like you seem to think it will their frogboy..... Lets see if I got this right, you want to weld up the transfer clutch on a 4eat? That pretty much makes it full time 4wd don't it? Just saying. Quote Link to comment Share on other sites More sharing options...
frogstar7055 Posted June 10, 2010 Share Posted June 10, 2010 (edited) excuse me for using the wrong wording.the "viscous coupler" as it were , is what i want to conjoin....... cheers, brian Do it on a spare trans,one you won't care about when it grenades. Just saying. Edited June 10, 2010 by frogstar7055 Quote Link to comment Share on other sites More sharing options...
monstaru Posted June 10, 2010 Author Share Posted June 10, 2010 Do it on a spare trans,one you won't care about when it grenades. Just saying. i never said ANYTHING about drivin on the road:)......cheers, brian Quote Link to comment Share on other sites More sharing options...
Yo'J Posted June 10, 2010 Share Posted June 10, 2010 I wont sound like a nike ad or anything but I would love to see new things and cool pics! This is why I love this site! Suspense, drama, action! Ya'll r fun. Quote Link to comment Share on other sites More sharing options...
frogstar7055 Posted June 10, 2010 Share Posted June 10, 2010 It actually might work great if it's kept on the dirt. Just saying. Quote Link to comment Share on other sites More sharing options...
Mugs Posted June 10, 2010 Share Posted June 10, 2010 Trust me, what he is building will never see pavement. Except to maybe off load it from the trailer. Quote Link to comment Share on other sites More sharing options...
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