sorry folks but the search option is disabled right now i must start this fresh...i have been to DTT's forum and have read the articles on tranny longetivity and line pressures...i realize that too high pressures can and will blow seals and lead to leaks..

but i also noticed that pre 2000 trucks or whatever had on average lower line pressures than post 2000...

my question is for anyone who has doen the research or has talked to Bill over at DTT..what pressures will lead to blown seals??...what do the tests show?...i have a stock setup and would like to bump pressures up to a nice safe yet productive number....a smooth comfy shifting type of ride is not important to me

thanx guys

Andrew

 

whether it be ATS, DTT, Goerend, BD, etc, etc, etc. They all argue about line pressures. I'll tell you what mine is and you can go from there. Though it is aftermarket and has valve body mods that make a difference, My pressures ar as follows...

Stall Test: Idle 75 psi, WOT 120 psi

Test #1: Accumulator port @ 1000 rpm manual first gear
no TV opening 75 psi
full TV opening 120 psi
Rear servo port @1000 rpm "L"ow range
no TV opening 75 psi
full TV opening 120 psi

Test #2: Accumulator port @ 1000 rpm manual 2nd gear
no TV opening 75 psi
full TV opening 120 psi

Test #3 Accumulator port @1600 rpm "D"rive gear OD locked out
no TV opening 85 psi
TV opening at downshift threshold 130 psi
full TV opening 140 psi
Front servo port @ 1600 rpm "D"rive gear OD locked out
no TV opening 85 psi
TV opening at downshift threshold 130 psi
Test #4 Rear servo port @ 1600 rpm "R"everse gear
no TV opening 200 psi
half TV opening 300 psi
full TV opening 350 psi

Test #5 Governor test port "D"rive OD locked out variable speeds
25 mph 35 psi
30 mph 50 psi
35 mph 65 psi
40 mph 75 psi
50 mph 80 psi
55 mph 80 psi

As to what pressures lead to blown seals? Factory seals I don't know. When doing pressure tests, look for DIFFERENCES between accumulator port readings and the various other ports as in tests 1,2, and 3. This will indicate seal leaks internally, which will need immediate attention. Any more than about 2-3 psi difference is cause for concern.

The next thing to be careful about is operating in OD or locked up 3rd at less than 1600 rpm. Low pump rpm can lead to lower pressures and clutch slippage, especially if you're loaded. Light loads aren't a big deal.....but be careful towing in OD. Light throttle in those gears also dictate a closed TV valve, and when "nailed", and the low rpm high torque of a CTD will slip clutches as well, because of a lower line pressures at that lower rpm, before line pressure can be raised with the TV advancement.

Someone else might know just how high you can turn up a factory valve body, I however am not sure, therefor will not offer advice on that one.

GL, hoped I helped a little.

 

thanx "got...DIESEL?" totally appreciate it....

my tranny is shifting great and lockup is nice...its a daily driver and power is stock...no towing and no racing... factory pressures i have come to understand are lower for "comfort" shifts or whatever....id like to turn it up slightly but i wanna know how much i can go....i am NOT gonna play a guessing game with my tranny pressures ...

this brings me to an interesting point as well...i have read that the stock clutch packs and internals have been shown to stand 800hp (DTT i believe i read it)...but its the low line pressures that lead to failures .....if too high pressures blow STOCK seals...why then during a rebuild dont we put in proper seals and then raise the pressure and have a longer lastign stock tranny?

 

If you just turn the line pressure up your trans will throw codes, shift at wrong rpm and go into limp mode. You need a valve body and resistors to get it right. The replacement seals are basically stock performance parts.

You won't blow any seals with the stock trans. it will go into limp mode way before that. Just turn the pressure up 5 psi at a time till you get problems and then back it off 5 psi. If you want firmer shifts you can tighten your throttle valve cable.

 

RickCJ....i have a 95..its a47RH there are no trouble codes to my knowledge....everything is mechanical and hydraulic....i can turn up the light throttle pressure and line pressure with the turn of a screw with the pan off....i simply havent found the info on what the stock seals can take in terms of pressure.

 

i know however what numbers to expect during my initial measurements....i know ur tranny has approx 58/100 psi mine starts with a little less from factory like 50/80...guys have turned theirs up to 70/120 approx when running 10 plate with gsk's...

 

OK I see it's a 95, just turn the pressure screw as far as you can with out falling apart, it won't blow the seals. You'll be lucky to get 100 psi.

 

they say 1 turn equals 3psi....no idea how accurate THAT is though. Might save a little trial and error, and pan removals.

FYI, turning up that line pressure can also cause later shifting.....which in a '95 can make one hell of a 1-2 hang up at 2550......trust me, I was fightin that for a while.

 

later shifting ? really....well im changing the fluid on the tranny soon and im gonna take some measurements down there to see what the pressures are like and then i'll see what i can do...summertime would be nice with a 10 plate and 3kgsk's but im not gonna dish out money for a tranny just cause the idea has been well marketed here ....the trannies can hold alot of power.....before the allison came around dodge had the best tranny behind a diesel IMHO...they're just set for comfort from the factory which is counterproductive....

i slight increase cant hurt things but i dont wanna do anything without some concrete numbers...anyone have links to sites about our tranny???

thanx

Andrew

 

mr T, The best information on these transmissions for the non-technical guys is what DTT puts together for the public on their site. www.dieseltrans.com

If you want a useful technical manual and decent build instructions, contact the folks at www.txchange.com.

You are correct that it is pretty hard to hurt the mechanical versions of these transmissions if you do not turn up the power, and they are dirt cheap to rebuild if you are careful and use quality parts.

Lastly, you are way wrong on the quality of the T1000 Allison. I see three or four a month with the clutches burned out from guys running over 370 horses. They are a consumer transmission being sold to folks that do not know the right questions to ask, and sooner or later they all have to dig up about $5 grand to have them fixed right if they turn the power up in their engines. Even after you spend $5k, they will not last very long if you go over 550 horses, and we do that all the time on the Dodges.

 

thanx for the help RCW i wasnt praising the allison in any way dont worry....i know the prices of treason.. just messin around...yep the allison is very expensice to begin with and repair bills and replacement parts are very expensive....its a fully electronic tranny with lots of bugs in it and is actually rated for a max 590 lbs of torque in its stock form which is pretty lame...it is however heavier and has beefier parts so i consider it an upgrade behind a diesel in comparison to years past....i'll check on DTT and ask some questions on there about this ...was hoping someone had beaten me to it is all