bmx045 Posted January 25, 2012 Share Posted January 25, 2012 it would be amusing to see how much a stock 5eat can handle power wise while in gear....just for shits and more shits. Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 25, 2012 Author Share Posted January 25, 2012 (edited) Depends, different from trans to trans, since they are all a little different. One of my clients on stock trans is doing around 400whp, which 400/.7=571bhp. But that's with WOT shifting as well. Lots of torque via E85. My worn trans at 30k ish miles would let go in middle of 3rd at 300whp, which at that point was a 100% replacement candidate. The limit is so high it's just silly. The problem is you wear out clutch packs quickly when shifting at a super high power level, even if you do all the right trans mods. So you don't get to enjoy stock-like longevity. But with any super high powered car, you best accept that you're going to pay a lot more to keep it on the road than the stock counterpart, so no big surprise there. I hear about guys who open up their modified 4L80Es after every drag weekend. They're also pretty fast... Edited January 25, 2012 by ClimberD@HexMods [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
bmx045 Posted January 25, 2012 Share Posted January 25, 2012 perhaps colder climate states have a prolonger tranny life? you and sprank seem to have the problems. Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 25, 2012 Author Share Posted January 25, 2012 perhaps colder climate states have a prolonger tranny life? you and sprank seem to have the problems. Nope I wish, you could just overcool the TCU and call it a day. Trouble is I have a collection of worn 5eats shipped in from cold places. My Texas transmission holds like super glue. Holy hell you may be on to something! TCU raises line pressure as temps go down (it reads ATF temp at two points). If you put a variable resistor on both of those, or any reasonable resistor, you could basically turn up line pressure. I have the sensor scaling if you want to play with it. Downside is you would lose 5th gear and TCC lockup. Upside is it would hold gears for longer, so more power at medium throttle. That combined with Sport mode may be good for autocross racing, but would be bad for the highway. If you did this with an F1, you would probably break the trans, since adding any more line pressure would be a bad idea. It's already as high as you would ever want to go, when warmed up. Another idea, just switch the temp sensors to ground, aka tell the TCU trans is overheating. There is a chance line pressure would be raised in an over-heat situation, to reduce friction. TCC would lock up, and 5th would work. Not sure if the TCC would respond to it as you would want though. Might end up being a waste of time. It's a real hack... [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
lieutenantcolumbo Posted January 25, 2012 Share Posted January 25, 2012 Holy hell you may be on to something! TCU raises line pressure as temps go down (it reads ATF temp at two points). If you put a variable resistor on both of those, or any reasonable resistor, you could basically turn up line pressure. Didn't IPT just throw a resistor in Msprank's '08.........the one that failed? Link to comment Share on other sites More sharing options...
bmx045 Posted January 25, 2012 Share Posted January 25, 2012 How can I play with tcu sensor scales? I don't see why the tcu doesn't use the coolant temp as a guideline....would seems easier as the coolant temp should remain parellel with aft temp Link to comment Share on other sites More sharing options...
Mega Users seabass07 Posted January 25, 2012 Mega Users Share Posted January 25, 2012 Atf does not stay parallel with coolant in all situations though. I wouldnt trick it into thinking it was overheating. At some point it triggers a fuel cut. It happened to me with the coolant gauge just over half way, so i dont think it was from the coolant temp. Link to comment Share on other sites More sharing options...
bmx045 Posted January 25, 2012 Share Posted January 25, 2012 i figured a resistor would bump line pressure..... Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 25, 2012 Author Share Posted January 25, 2012 oh boy... it's one of those things where if you have to ask, don't do it. All these hack electrical fixes won't actually get your car anywhere near where it needs to be in terms of trans performance. I was just posting for the hell of it. [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
bmx045 Posted January 25, 2012 Share Posted January 25, 2012 Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 25, 2012 Author Share Posted January 25, 2012 i figured a resistor would bump line pressure..... I misread this. Thought you meant a resistor how it's typically used, on the LP solenoid. I don't know why my mind made that jump. That way has proven to work miserably via to IPT/MSprank experiment. TCU will just learn around it and neutralize the effect. Either way, if you are the type to read the FSM and figure out the way to do temp mods, go for it. I don't recommend it. It won't be the slam dunk you're after. [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
bmx045 Posted January 25, 2012 Share Posted January 25, 2012 literally, my slam dunk would be to just have the tranny hold together WHILE in gear, that's all i ask for. I let off and manual shift as is anyway....when i'm feeling sporty... Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 25, 2012 Author Share Posted January 25, 2012 literally, my slam dunk would be to just have the tranny hold together WHILE in gear, that's all i ask for. I let off and manual shift as is anyway....when i'm feeling sporty... then you should be fine [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
bmx045 Posted January 25, 2012 Share Posted January 25, 2012 it would be cool to see a 35r'ed stock 5eat hold the gear. Like i said, a beat up old 05 LGT (dont think fluid was ever changed) with a 20g/td05 was holding up on the dyno hot lapping 3rd gear pulls.... Link to comment Share on other sites More sharing options...
frkkevin Posted January 25, 2012 Share Posted January 25, 2012 it would be amusing to see how much a stock 5eat can handle power wise while in gear....just for shits and more shits. Mine failed at 400whp with an "IPT" modded vb and trans cooler 512whp/465ftlb 2005 5EAT Legacy (Build Log) Videos - - Link to comment Share on other sites More sharing options...
doccrowley Posted January 26, 2012 Share Posted January 26, 2012 Atf does not stay parallel with coolant in all situations though. I wouldnt trick it into thinking it was overheating. At some point it triggers a fuel cut. It happened to me with the coolant gauge just over half way, so i dont think it was from the coolant temp. I too had the tranny overheat and car hit fuel cut off and shut the car down. Roadtrip from CA to UT, 4 bikes on the roof rack, 4 people in the car, luggage for 10 days and had just passed through Death Valley, CA at 120f 1 hour prior. Car shut down and needed 45minutes to cool down before it would start again. Didn' help that I was pushing the car to 120mph frequently as well. (was StgII @ 57K miles when ATF temp light came on and car shut down). Link to comment Share on other sites More sharing options...
frank_ster Posted January 26, 2012 Share Posted January 26, 2012 what was the temp of the coolant when the atf light came on ? ^ Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
Mortal2None Posted January 26, 2012 Share Posted January 26, 2012 Don't over analyze it. For a healthy transmission (no burned clutch packs, no case hardened steels, all tolerances in good spec), you're going to do all the damage during a shift. It is the exact same rule for MT cars' single clutch @ flywheel. If you never shift, then the static bind is very strong, and will last forever. I think too much torque (T/S VF's will do that) down low is even too much for the "static bind". I'm thinking its either the TCC or the clutch packs but sometimes giving it gas in D and very low RPM's I'm betting a bad shudder out of the tranny. I'm 90% sure its the lock up clutch in the TC though. it's never happened when the converter was at stall speed. (The motor boat effect) I'm also wondering if the line pressure is insufficient at under 2200 RPM. (I don't know what RPM the 5EAT pump is supplying max pressure) The other possibility is my tranny is no longer healthy but I have a feeling I'm going to find out in the very near future. I'm going to look into getting a modded torque converter with a HD lock up clutch. (Hopefully its an option and maybe the Nissan one will swap over) Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 26, 2012 Author Share Posted January 26, 2012 It can be done, but normally the TC is not a problem. It doesn't try to lockup very often, never in 1st or 2nd, only manual mode in 3rd. [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
bmx045 Posted January 26, 2012 Share Posted January 26, 2012 It can be done, but normally the TC is not a problem. It doesn't try to lockup very often, never in 1st or 2nd, only manual mode in 3rd. 08+ it locks in 2nd. Link to comment Share on other sites More sharing options...
frank_ster Posted January 26, 2012 Share Posted January 26, 2012 and hot tranny will lock up in 3rd.. the lock up shudder is common on older gm's. its lugging the engine and is also there when the engine is a bit to lean Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
Mortal2None Posted January 26, 2012 Share Posted January 26, 2012 Hmm, I don't think it's the engine shuddering but that's something to look into. It feels like it's coming from the transmission. (and only when the converter is locked and the RPM's are under 2400) I'll see if I can get it to replicate the issue with the car locked in 3rd gear. (Happened to me twice in traffic rolling along at 25-30MPH) The whole car shakes violently. It scared the crap out of me the first time it happened. Link to comment Share on other sites More sharing options...
doccrowley Posted January 27, 2012 Share Posted January 27, 2012 what was the temp of the coolant when the atf light came on ? ^ Just slightly over the typical needle position. Alot of 5>4thgear passing in 2 lane highway traffic. Thought maybe I had a fuel vapor lock as I was close to being out of gas, but if ATF overheat can cause fuel cut????? I was 30 miles left to go in the tank of gas, 6 miles from the highway exit for fuel. Link to comment Share on other sites More sharing options...
ClimberDHexMods Posted January 27, 2012 Author Share Posted January 27, 2012 When my clutch packs were letting go in 3rd at peak torque, it was evidenced by chatter, shaking the whole car until I let up on the gas enough to let the clutches grab solid hold. By the time the trans is doing that, your trans is cooked. It took me a long time for it to wear that point, but eventually it reached its end, and the chatter was the notice to quit and find a different transmission, or to rebuild the existing one. Solution to overheating: bigger ATF cooler. I have only heard a few instances in which ATF lights came on, and all are under extended severe duty. Never heard of fuel cut though... different safety mapping sure. [CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER] Link to comment Share on other sites More sharing options...
frkkevin Posted January 30, 2012 Share Posted January 30, 2012 I've never seen my ATF light come on even when my trans failed. However I got the joyful flashing cruise and sport light and it allowed only 1-3rd 512whp/465ftlb 2005 5EAT Legacy (Build Log) Videos - - Link to comment Share on other sites More sharing options...
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