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Thread: Question about tranny shift pressures

  1. #1

    Question about tranny shift pressures

    First, let me say that I know next to nothing about auto trannies. That said, I've read on some other forums where people claim higher shift pressures shorten the life of transmission components. I have the program that Dennis loaded for me onto my 9100 tuner. The shifts seem very firm, especially when I'm on the throttle fairly hard. Some of the shifts seem a little too firm at times. Does this mean that pressures inside my tranny are higher to achieve those head-snapping shifts? Am I risking early tranny failure? I like the shifts to be firmer than stock, but I would consider setting them back a bit if it would save some wear on my trans.

    I'm not in a hurry to make any changes right away, just curious what people's thoughts are on this. I thought I'd post in the Reinhart Automotive forum to see what Dennis' thoughts are on this, in particular. Thanks.
    2003 Mercury Marauder
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  2. #2
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    Hmmmm . . . good question, Fourth. Since my Jerry-tune/flash, my shifts are now neck-snapping as well. I would like to know the answer to this question as well.

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  3. #3
    TripleTransAm Guest
    Wear is a relative term...

    There are several ways to bring about firmer shifts and I'm not sure what exactly can be done through reprogramming.

    One way is to "torque manage". During the moment of upshifting, the engine can be 'throttled back' to reduce the amount of engine power during the interval in which the tranny parts are 'doing their thing' (bands applying pressure, clutches grabbing, etc.). This results in a loss of engine power during the upshift interval, so you obviously get more performance out of minimizing the 'throttling-back' duration. But the result is a harsher shift and obviously more shock to the driveline and increased wear on the bands and clutches, since they have more torque to deal with while trying to grab.

    Then there's the increase of line pressures which will change the amount of force with which the tranny components apply their grabbing forces. While the slippage is minimized in this case, since components are grabbing in a more harsh manner, there is more driveline shock to the solid components since the shifts are not soaked up by band or clutch slippage. So the friction surfaces should last longer, but there is more harshness transmitted to the driveline.

    I have no clue how much driveline shock the 4R70W can take. I also don't know how long the clutches and bands last while operating in stock slush-mode. I also don't know how long a 4R70W could last while getting the 4.6l DOHC's full power during upshifts without torque management.

  4. #4
    Thanks, TTA.

    Has anybody with the SCT 9100 programming software tried messing with trans settings at all? Shooter? I'm wondering how much control we have in the software and if it'd be worth it to me to buy the software and cable so that I could adjust trans shift settings.
    2003 Mercury Marauder
    2007 Lincoln Town Car
    1993 Crown Victoria LX

  5. #5
    valkyrie Guest
    Quote Originally Posted by Fourth Horseman
    Thanks, TTA.

    Has anybody with the SCT 9100 programming software tried messing with trans settings at all? Shooter? I'm wondering how much control we have in the software and if it'd be worth it to me to buy the software and cable so that I could adjust trans shift settings.

    I would be curious as well. I have the tuner customed by DR. I would actually like to mess around with the programming as I am not happy with the shifting points however I can't since it is customized.

    I would be willing to purchase the cable and software.

  6. #6
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    The stock programming limits engine torque to 80% of its potential during all upshifts. This is at full and almost full throttle.
    When the trans is upgraded, this torque management should be removed, mine is.

  7. #7
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    Fourth:

    No worries...the only time a transmission line pressure increase is detrimental is when it's done improperly, or for the wrong reasons. In the hands of a master programmer like Jerry from SCT, there should be no concern at all.

    The people who claim high pressures shorten the life of a transmission are probably referring to some of the less than optimum (I'm being polite here) shift kits sold for various trannies...check out this link for more info on line pressures and shift kits relative to the 4R70W, written by "The Man" himself...(it's down near the bottom)
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  8. #8
    Thanks, I'll check out that link. I actually read that about pressures and such over on the LS1 forums in regards to Chev tranmissions, but thought it might be relevant to our 4R70W / 4R75W trannies as well.

    Thanks for the feedback!
    2003 Mercury Marauder
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  9. #9
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    Quote Originally Posted by Fourth Horseman
    First, let me say that I know next to nothing about auto trannies. That said, I've read on some other forums where people claim higher shift pressures shorten the life of transmission components. I have the program that Dennis loaded for me onto my 9100 tuner. The shifts seem very firm, especially when I'm on the throttle fairly hard. Some of the shifts seem a little too firm at times. Does this mean that pressures inside my tranny are higher to achieve those head-snapping shifts? Am I risking early tranny failure? I like the shifts to be firmer than stock, but I would consider setting them back a bit if it would save some wear on my trans.
    I'm certainly no authority either, BUT it was explained to me in person, the basic fluid dynamics of the situation.

    There are two ways to increase Tq capacity, apply pressure, and friction elements. Since we cannot alter the elements from outside, all that's left is line pressure.

    The single most critical thing to an ATs life is cooling/lube. Here's where it gets messy....

    Increasing line pressure as some "shift kit" sellers and tooners would have you do, actually does three things, NONE are good.
    1) Raises the line pressure ALL the time. Unnecessary, hurts mileage, and is hard on the internals.
    2) REDUCES cooler flow. If you double the pressure, you cut the flow to 1/4, NOT good.
    3) Reduces lube flow. As above, PLUS the cooler return IS your mainshaft lube circuit.

    If the line pressure is high enough, long enough you WILL distort the apply pistons, causing leaks and/or blown seals. This is made exponentially worse because your cooler flow is reduced, so it will operate hotter.

    The ONLY correct way is to only raise line pressure with 1's & 0's just before, and during the upshift, then to return it to "normal".

    As I understand it, the line pressure is "adjusted" in the EEC to match the Tq capacity of the vehicle being modified. It is also tied to "load", to that at high loads it will shift quicker and with more pressure to prevent slipping and the resultant heat. The theory goes that if you are putting around, the shifts should be more firm (quicker) due to slightly closer solenoid timing, and increased line pressure, BUT at high power levels, the line pressure is raised to match the Tq production.

    Basically, you get more overall "during shift" line pressure than stock all the time, and better solenoid timing as well. And as the power comes on, you also get enough additional pressure to handle it.

  10. #10
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    Thumbs up Trans-Go Reprogramming Kit (Features-Gear Command)

    Quote Originally Posted by ModMech
    I'm certainly no authority either, BUT it was explained to me in person, the basic fluid dynamics of the situation.

    There are two ways to increase Tq capacity, apply pressure, and friction elements. Since we cannot alter the elements from outside, all that's left is line pressure.

    The single most critical thing to an ATs life is cooling/lube. Here's where it gets messy....

    Increasing line pressure as some "shift kit" sellers and tooners would have you do, actually does three things, NONE are good.
    1) Raises the line pressure ALL the time. Unnecessary, hurts mileage, and is hard on the internals.
    2) REDUCES cooler flow. If you double the pressure, you cut the flow to 1/4, NOT good.
    3) Reduces lube flow. As above, PLUS the cooler return IS your mainshaft lube circuit.

    If the line pressure is high enough, long enough you WILL distort the apply pistons, causing leaks and/or blown seals. This is made exponentially worse because your cooler flow is reduced, so it will operate hotter.

    The ONLY correct way is to only raise line pressure with 1's & 0's just before, and during the upshift, then to return it to "normal".

    As I understand it, the line pressure is "adjusted" in the EEC to match the Tq capacity of the vehicle being modified. It is also tied to "load", to that at high loads it will shift quicker and with more pressure to prevent slipping and the resultant heat. The theory goes that if you are putting around, the shifts should be more firm (quicker) due to slightly closer solenoid timing, and increased line pressure, BUT at high power levels, the line pressure is raised to match the Tq production.

    Basically, you get more overall "during shift" line pressure than stock all the time, and better solenoid timing as well. And as the power comes on, you also get enough additional pressure to handle it.
    Interesting that this thread comes up when today I just had a "Trans-Go Reprogramming kit" (series 3 May 99) .

    It features Gear Command which give you Complete Gear control whenever you want it . It states-Holds 1st - 2nd - 3rd to any RPM and you can backshift to any gear you want . It also give you short firm full throttle shifts . it involves changing internal springs , accumulator pistons and changing the plate hole size .

    This is stated from the instructions itself-"One of the goals of this kit is to reduce and cushion sudden inertial and torque loads against the driveline and internal parts during Kickdowns . Sudden loads distort the internal parts causing them to disassemble , break or wear . Kickdowns will be diffrent now , much shorter , to reduce engine/converter runup aganist sprags .

    The tech that installed this kit stated that this will also correct extreme line pressure due to electrial malfunction , stuck EPC valve , or crossleaks .

    Just my .02

    BTW-This is a small portion of a thread from " The 4R70W Transmission by Lidio " -I feel the MM’s needs a tried-and-true shift kit that alters main-line pressure as well as all the other little tricks in the valve-body.
    Last edited by 03SILVERSTREAK; 07-29-2004 at 06:55 PM.
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  11. #11
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    Hey Adrian,
    Very cool - I was looking at the Trans-go kit for a while. Some comments have kept me from taking the "leap". Keep us up to date on your latest mod!
    The link from RF Overlord is excellent! I started reading that from Dennis Reinhart's site last year but never finished. Many of the modifications look similar to the shift kits I have installed on older non OD transmissions (from the 60's & 70's).
    What are the chances of getting a copy of the install instructions from your kit so they can be compared to the instructions @ the above link?
    Good Luck and thanks again for posting!
    Paul
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    Edited for Content

    Quote Originally Posted by 03SILVERSTREAK
    Interesting that this thread comes up when today I just had a "Trans-Go Reprogramming kit" (series 3 May 99) .

    It features Gear Command which give you Complete Gear control whenever you want it . It states-Holds 1st - 2nd - 3rd to any RPM and you can backshift to any gear you want . It also give you short firm full throttle shifts . it involves changing internal springs , accumulator pistons and changing the plate hole size .

    This is stated from the instructions itself-"One of the goals of this kit is to reduce and cushion sudden inertial and torque loads against the driveline and internal parts during Kickdowns . Sudden loads distort the internal parts causing them to disassemble , break or wear . Kickdowns will be diffrent now , much shorter , to reduce engine/converter runup aganist sprags .

    The tech that installed this kit stated that this will also correct extreme line pressure due to electrial malfunction , stuck EPC valve , or crossleaks .

    Just my .02

    BTW-This is a small portion of a thread from " The 4R70W Transmission by Lidio " -I feel the MM’s needs a tried-and-true shift kit that alters main-line pressure as well as all the other little tricks in the valve-body.
    I'm sorry to hear about the Trans-Go, they know little if anything about how to properly engineer a kit for the AODE/4R70W. I've personally SEEN the results of their "kits", blown up A/Ts on the dyno. They've never been worth a damn, and until they get a clue, never will be.

    "Correct extreme line pressure due to a stuck EPC valve"?????? Right, what data do they have that suggests that would ever happen? If they have *any*, it's over 10 years old. The EPCs in the '95 up 4R70Ws won't "stick", there was an issue with a *few* between '93 and '94, but NONE since. Even FMC has never seen it in testing on a 4R70W, with the valve stuck!

    The only "shift kit" an 4R70W needs is a few accumulator springs pulled, correct accumulator pistons installed (if '96 or older), and the correct size holes drilled in the VB seperator, no more. Anyone who says different, is selling you stuff you don't need by scare tactics (like the EPC BS), or "good" salesmanship, but definately NOT out of necessity.

    BTW, the single MOST important "mod" on a MM A/T is the spilal retainer mod for the Mechanical Diode to keep it in place with those 6000 + RPM shifts, the seperator plate/accumulator spring stuff is second.
    Last edited by Logan; 12-18-2004 at 08:45 PM.

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    Question Trans-Go "engineered for performance, designed for durability."

    Well I went to the website above that is www.Tccoa.com and this is were I got the idea of a shift-kit in the first place - The TransGo kit runs a little bit more expensive than Bauman but it is referred more over the Baumann. It's a better shift kit and it has EPC (excess pressure control) valve that relieves high line pressure that can be harmful valve body and VB gasket. It also has 3 types of settings: firm-medium-hard. TransGo makes your shifts shorter and harder. It is "engineered for performance, designed for durability." It is no accident that the "mild street rod" setting on the Transgo kit is also referred to as taxi cab, and police cruisers.
    The best deal you can find on a Trans-Go is at the Transmission Exchange (800-776-1191).

    Don't forget:
    Reflash the PCM with the appropriate micro code while your at it.

    If your saying that they are crap then why would it be on there website ???
    Last edited by 03SILVERSTREAK; 07-30-2004 at 08:47 AM.
    I'll keep my Freedom, my Money, my Religion, my Guns & you can keep the " Change ".

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    Talking Reply, long!

    Triple post doh!
    Last edited by ModMech; 07-30-2004 at 12:14 PM. Reason: triple post

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    Talking Reply, long!

    triple post
    Last edited by ModMech; 07-30-2004 at 12:12 PM. Reason: triple post

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