Trans failures

[Redtruck-VA]

We often hear about trans failures and more than likely mulitiple failures with the guys making big horsepower. And we assume it is the horsepower burning them up. But I haven't heard about anyone actually breaking anything, just burning clutches leading to failure. So my question comes to this, is it possible that the problem isn't with the trans physically handling the power, but being the result of our tuning strategy? The trans line pressure (clutch pressure) is varied to reduce parasitic loss from the pump. The MAP and TPS provide critical signals to the PCM/TCM to determine "load" , The problem is we tune for the engine, often pulling fuel to make the engine run correctly. This modified signal I believe has a direct side effect of signalling that there is a lower load than is actually present reducing "line pressure" and the clutches slip causing failure. There is of course the Transgo and Sonnax line boosters that can be installed to modify the signal voltage (5v) a given percentage of the sensor's actual signal. I am thinking perhaps a better solution is to take control of the signal and fix it at constant voltage to maintain high line pressure to hold the clutches. This might even be something a window switch can control using rpm as the determining factor for line pressure rather the load calculations done by the TCM.
Your experiences and/or thoughts on this are welcomed.

 

[KGBIGCOUNTRY]

Also intrested to hear peoples thoughts. I have a line booster supplied in the transgo kit and wonder about trans failures. It does seem the issues are from the clutches and not shattering parts really. Greg on your AI does it show a Tans slip%.

 

[frostking]

Chrysler software engineers are absolutely terrible. If they used a mass air-flow sensor and constant line pressure transmission like GM our trucks would be perfect. I've considered using my old SMT-6 to map my own line pressure based on boost or to at least data log with it. The problem specific to boost on my truck is that I can make big torque at low RPM and less than 20% throttle on the highway and I can tell the line pressure stays too low and then starts slipping. Essentially I cannot downshift on the highway from 5th to 4th or 4th to 3rd under increasing throttle without it slipping. Turning off O/D and dropping it into 3rd then I can floor it no problem. My last upgrade should have seriously beefed up 4th gear, though, but haven't had a chance to test it.

I will likely be getting a 4l80e core from my '06 GMC 2500 HD to rebuild myself and may end up buying the flexplate adapter to use this tranny and GM converter on my Hemi. 4l80e standalone controllers are easy and plug-n-play.

 

[RubberFrog]

It's worth noting that SC is working on a line pressure option that could deal with this.

 

[frostking]

It's worth noting that SC is working on a line pressure option that could deal with this.

On a few model years, yes.

 

[Redtruck-VA]

Also intrested to hear peoples thoughts. I have a line booster supplied in the transgo kit and wonder about trans failures. It does seem the issues are from the clutches and not shattering parts really. Greg on your AI does it show a Tans slip%.

No, I don't have slip%. Do the newer truch show this?

Chrysler software engineers are absolutely terrible. If they used a mass air-flow sensor and constant line pressure transmission like GM our trucks would be perfect. I've considered using my old SMT-6 to map my own line pressure based on boost or to at least data log with it. The problem specific to boost on my truck is that I can make big torque at low RPM and less than 20% throttle on the highway and I can tell the line pressure stays too low and then starts slipping. Essentially I cannot downshift on the highway from 5th to 4th or 4th to 3rd under increasing throttle without it slipping. Turning off O/D and dropping it into 3rd then I can floor it no problem. My last upgrade should have seriously beefed up 4th gear, though, but haven't had a chance to test it.

I will likely be getting a 4l80e core from my '06 GMC 2500 HD to rebuild myself and may end up buying the flexplate adapter to use this tranny and GM converter on my Hemi. 4l80e standalone controllers are easy and plug-n-play.

The engineers in my book got a lot of things wrong, hell they couldn't even get the gearing right. I'd be interested in the the GM trans swap. I looked at them a little but didn't really research it. Pls let us know how that goes.

It's worth noting that SC is working on a line pressure option that could deal with this.

Yeah right, that will not be available on the 03 model.

And thanks for the replies. We need all the information we can get...

 

[truckin151]

The next couple mods I intend on doing will either be a new valve body or a trans from paramount performance
NAG 1 (722.6) Blueprinted, High Torque Capacity Transmission « Paramount Performance Products

that one is for the lx guys but they make one for the rams too

 

[truckin151]

I just like their throw what ever you want at it powerwise and they'll warranty it for the first year to make sure it works right

 

[RubberFrog]

On a few model years, yes.

04-11 is a few model years?

But yeah, 03 guys are still screwed.

 

[AF_Hemi]

last i checked, there are no more trans failures than there are with 04+. quite honestly, my money is on there being very few 03 trans failures simply because very few people mod the motors to the point the trannys break.

This shouldnt be an 03 specific thread. the trans issues include everyone --- 04+ even more so than 03. looking forward to seeing if we can get a solution to this

 

[SilsHemi]

Also intrested to hear peoples thoughts. I have a line booster supplied in the transgo kit and wonder about trans failures. It does seem the issues are from the clutches and not shattering parts really. Greg on your AI does it show a Tans slip%.

Here's the issue with any line booster. The booster tricks the the PCM into making a global change of 15-30 psi to all shift pressures. As an example, in reverse the stock line pressure is 220 psi. That is the highest psi setting of them all. Adding an increase there is unnecessary, yet a booster does that.

If we had an application that could fine tune line pressures via PT/WOT shifts, this would be the way to go for sure.


Sil

 

[SilsHemi]

It's worth noting that SC is working on a line pressure option that could deal with this.

Yes and IF it comes to fruition, you'll be able fine tune your line pressures via PT and WOT.


Sil

 

[Ramunit]

Yes and IF it comes to fruition, you'll be able fine tune your line pressures via PT and WOT.


Sil

Yeah, boosting LP an equal amount across the board is not doing any good when the LP is different with each shift point. Boosting LP blindly with a resistor can over do it on some gears and have little effect on others, sounds dangerous to the trans longevity to me. The need to fine tune LP for each gear is critical to finally get it right. Looking forward to some possible "fruition" from SC.

 

[Redtruck-VA]

Here is a thought, the max pressure is 250 psig and there is a mechcanical relief valve to make sure it can't go higher, we can assume the trans can handle that level of pressure. Using the diagnostic adaptor tool "Line Pressure Adapter 8259" will allow the installation of a 0-300 psig gauge. Monitoring the gage will let us know if there are any points where the LP is running low. We can either manipulate the LP signal voltage by clamping it or use a resistor to have it operate at a higher pressure. What I haven't heard of is anyone monitoring their LP or even knowing if it is running within spec IAW the manual.

 

[KGBIGCOUNTRY]

So Sil and Scott are yall both saying I should remove the resistor supplied in the Shift kit?? I agree an over all spike of pressure cant be good for it, but with the stiffer springs supplied to rebuild the valve body I would almost assume it was needed. Im courious about failures so i can try preventing them as long as I can, but that being said im sure all my 4lo racing in the dirt blowing through the gears is soon to catch up with it.

 

[KGBIGCOUNTRY]

Greg as far as the question about seeing trans slip on the AI im not sure yet if mine once its hooked up will show it or not. Just recieved part of the order and still waiting on the cable to arrive.

 

[Bad Habit]

hmmmm, very good info guys i likey this thread cause my mind is curious about this stuff too....

 

[SilsHemi]

So Sil and Scott are yall both saying I should remove the resistor supplied in the Shift kit?? I agree an over all spike of pressure cant be good for it, but with the stiffer springs supplied to rebuild the valve body I would almost assume it was needed. Im courious about failures so i can try preventing them as long as I can, but that being said im sure all my 4lo racing in the dirt blowing through the gears is soon to catch up with it.

Kenneth,


There are many factors that could cause transmission failure. If I were running Superchips, with reduced TM, I personally would not run the booster. But that's me. There are plenty that are running the booster without issue. I would rather have a solution that allows the user to tweak line pressures where needed, instead of making a global change. There's no solution like that at the moment, so folks use the resistors and boosters to increase pressure.


Sil

 

[KGBIGCOUNTRY]

Ok Sil thanks for clearing that up and I sure hope the stand alone tuning comes around. Im running to aggresive of a cam now to handel a canned 93 tune from Superchips and am not stacking currently with my SCT.

 

[truckin151]

Unless you have a sensor to monitor it, the ai wont read trans slip. I know it can read a lot on the 06+ but the 05's down are limited in what it will read.