how much HP can 3400 handle

[Froggx]

Personally I know very little about the GM FWD auto trannies since I've always dealt with 5-spd's, but what I've heard from the GAGT guys is avoid the 40 series. I think the reason this is such a big argument though is that the two sides in this argument are arguing different virtues. One side is screaming "Throw a 45 behind a 300 hp engine and see how long it lasts." It won't, plain and simple. The other side seems to be shouting "The 45's in their stock application last longer than the 65's in their stock application." I do not know whether or not this is true but I will assume it to be at this time. The point I'm making is that these two sides are arguing completely different points which makes for the figurative argumentative equivalent of drag racing each other towards an immovable concrete barricade, even if you win, I'm gonna say "sucks to be you."

Personally I feel if people want to post about how much abuse the 3400 can take they should post here. If they want to argue trannies, there is an area on the board for that too, just need to start a new topic because this one has gone

[dbtk2]

"You guys like looking at the hp ratings so lets look at it this way... Why is it that when the 60/65 is run AT ITS HP RAITINGS it fails more often then a 4T40/45?? Show me real proof that this isn't true..."

How can you expect us to know of every single case of a failed tranny from being used at its hp ratings. You can't know any better than we can. I can tell you this though, the 4T60/65 have been around longer than the 4T40/45, so they are older trannies and most have a lot more miles than these newer trannies you are talking about. And, since they have been around longer, I would bet they are in a LOT more applications than the newer ones are. They are also in applications that are more likely to be modded. Why don't they use the 4T40/45 in the 8 second drag car, afterall they use the 4T65, since the 4T40/45 is stronger its obvious they should use that instead, right?

How many 4T40/45's do you know of that pull around 4000+lbs. all day long in a car making ~290hp/350ft.lbs and have done so for over 130k miles, and have had track runs on it? Find me one that does that, and I'll start to believe you. But until then, I'll just tell you my moms SSEi has the original 4T65E-HD in it, it is mildly modded making about 290hp and a very conservative 350ft.lbs of torque (and its been modded since it was nearly new), and it pulls around well over 4000lbs every day and has done so since it was new. The tranny is still very strong and shifts awesome. Never had any problems with it.

Shawn

[Froggx]

"You guys like looking at the hp ratings so lets look at it this way... Why is it that when the 60/65 is run AT ITS HP RAITINGS it fails more often then a 4T40/45?? Show me real proof that this isn't true..."

How can you expect us to know of every single case of a failed tranny from being used at its hp ratings. You can't know any better than we can. I can tell you this though, the 4T60/65 have been around longer than the 4T40/45, so they are older trannies and most have a lot more miles than these newer trannies you are talking about. And, since they have been around longer, I would bet they are in a LOT more applications than the newer ones are. They are also in applications that are more likely to be modded. Why don't they use the 4T40/45 in the 8 second drag car, afterall they use the 4T65, since the 4T40/45 is stronger its obvious they should use that instead, right?

How many 4T40/45's do you know of that pull around 4000+lbs. all day long in a car making ~290hp/350ft.lbs and have done so for over 130k miles, and have had track runs on it? Find me one that does that, and I'll start to believe you. But until then, I'll just tell you my moms SSEi has the original 4T65E-HD in it, it is mildly modded making about 290hp and a very conservative 350ft.lbs of torque (and its been modded since it was nearly new), and it pulls around well over 4000lbs every day and has done so since it was new. The tranny is still very strong and shifts awesome. Never had any problems with it.

Shawn

You've got one of the coolest moms I've ever heard of.

[tejohnson]

Not sure why Todd hasn't posted here (maybe because the thread name doesn't bring up trannies), but here are some pictures of your "strong" tranny...

http://groomlakelabs.com/gallery/transmission

LMAO Brad,

I have to go with the fact that the 4T4x-E is built for economy. Period. I was surprised to learn that there are plastic parts inside. I would assume that the pics in my gallery speak for themselves... This obviously was not a plastic part failure, but the differential. Friggin rod going through the center failed where where a pin holds it into the entire carrier assembly. When it broke, it slipped out one side, then cut off the passenger side of the case as it made a few revolutions. All of this happened in a matter of seconds. I have heard of many other failures related to severe slippage, to the typical issue of a failing selanoid (Either one of the pressure, shift, or TCC).

The modifications performed to my engine was just a port and polish. Expansion of the plumbing for air in and out, and this is the result. This has happened to others, probably just not this dramatic. Note to self: Don't turn the wheels and go WOT.

In order to support any higher HP with a 3400 bolted to a 4T4x-E, IMHO folks should really look at reinforcement. Otherwise, I look forward to seeing pictures of what happens to yours

[Quinky]

The slipping issue is not a transmission failure.. Its a problem with the computer controls.. The cars the 4T40e are in are designed to be your slush box economy cars... GM designed the transmission to shift as smooth as possible... They don't run high enough line pressure, so when you are driving at WOT the shifts are extreamly slimmy and slip a lot.. If you want the transmission to last you need to address this by boosting line pressure...

Thats not a transmission problem, Line pressure is computer controld through the EPC..

Diffs blowing up is also a commen failure in 60/65s not just the 40s... About the only fwd GM transmissions you don't see blowing up diffs are the 440T4's and the 125's...

[bszopi]

Ironically, many of the people on GAGT have boosted their line pressure and they are still getting the slipping. The line pressure has been boosted both externally on some and internally via PCM reprograms on others, and yet they still mention slipping.

[Quinky]

I see a lot of people on there have a slimmy 1-2 shift complaint... Even with the DHP PCM... Still sounds more like a computer problem or electronic EPC problem.. not an actual internalt transmission problem... There is one service bulliten I did forget about when it comes to the 40's.. It talked about the pumps should be replaced when rebuilding the transmission, this is because the pumps area a sealed unit and you can't pull them appart to check for wear... If the pump is worn out it can cause low line pressure and slimmy shifting as well after rebuild.. A lot of cheep rebuilds wont replace this part simply to cut down on cost..

1 persons complaint about slimmy shifting when cold only could be caused by low fluid level... The 40's don't have an external dispstick to check fluid level in a conventional way..

Besides diffs blowing up I don't see any other hard parts blowing up over there... Just looks like electrical problems..

Also seems that no one likes the Autotrans interceptor over there.. They seem to have some mis conceptions about high line pressure and how it affects/can harm the transmission..

[geoffinbc]

Diffs blow because of one tire fire burnouts. This causes the spider gears to spin around the side gears so fast they can turn red hot. Even if they get above 300*C you will ruin the hardness of the gears. If everyone had a limited slip or did not let the tires slip you would never see a diff problem unless it was a defective one.

My cousin blew out a Chevy 12 bolt with a mild 350 motor doing 1 tire fire burnouts. So if he can blow that then a small differential doesn't stand a chance.

Minimum line pressure is set by the relief valve in the tranny. Anything higher is done by the PCM. There is only so much line pressure can do before you need more clutches and bigger bands. Every car GM builds has a different clutch and band setup for the same tranny.

[TurboZ24]

Yeah, I shattered the differential pin on my muncie 5-speed going around 140 mph. Luckly it blew on the side without the retainer pin, so most of it stayed in place and I was able too still get home. Ruined the tranny, but still got it home.

[Quinky]

Anyone have a link to the info on the DHP PCM the gagt boys are running? I didn't see any when I was surfing their forum..

[tejohnson]

Anyone have a link to the info on the DHP PCM the gagt boys are running? I didn't see any when I was surfing their forum..

At pfyc.com:

http://www.pfyc.com/store/merchant.mv?Screen=PROD&Store_Code=PFYC&Product_Code=GA3010&Product_Count=17&Category_Code=GAUNDER

If you want more flexibility, I would suggest you spend a lil more and get the PowrTuner. That way you have the ability to change when you make changes to your vehicle.... Just another option

[tejohnson]

The slipping issue is not a transmission failure.. Its a problem with the computer controls.. The cars the 4T40e are in are designed to be your slush box economy cars... GM designed the transmission to shift as smooth as possible... They don't run high enough line pressure, so when you are driving at WOT the shifts are extreamly slimmy and slip a lot.. If you want the transmission to last you need to address this by boosting line pressure...

Thats not a transmission problem, Line pressure is computer controld through the EPC..

Diffs blowing up is also a commen failure in 60/65s not just the 40s... About the only fwd GM transmissions you don't see blowing up diffs are the 440T4's and the 125's...

To dive into this further (Sorry to stray or post off topic)....

In terms of what I am doing for a replacement... I bought a 2000 (or 2001) 45e with a 3.29 gear ratio (Picked it up ~$280 shipped from Boston, I am in WV). The limited slip I bought (and will eventually get) is built from a 65e diff core. I bought a transmission cooler I plan to run in series with the factory cooler in the radiator, attaching it in front of the condensor, and behind my intercooler. As for the internals, I am looking at Raesbestos Blue Plate Special clutches, and Koelene treated steels (the name of the company escapes me for the moment, but they make them for the 45e). Finally a new torque converter from Precision (Specs TBD, but no plans to raise the stall higher than stock, given I will be running a Turbo).

So the big question is, since you have a great knowledge of the 45e, are there any additional reinforcements I can look towards? For example, forged input shaft, output shaft, etc.?

[Quinky]

Nothing that I know off.. When you are getting yours rebuilt make sure they do change the pump... As for your diff make sure its the same gear ratio as your stock one, If its not you'll throw a gear ratio error and send the transmission into limp..

[imported_germ]

he has a programmer that will change his pcm around so he wont have a code pop up

so no worries there.

the tranny is being done by DP IIRC

[tejohnson]

the tranny is being done by DP IIRC

Oh hell no. I thought I mentioned to you that the transmission was being worked on by a local shop. I am not that much of an idiot to throw that much $ to DP. I am already highly agrivated about how long I have been forced to wait... I only bought the Limited Slip from EP, through DP.

As for the ratio, we have the ability to make the PCM conform to what ever ratio we wish to run