Question about tranny shift pressures

[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 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.

[studio460]

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.

[TripleTransAm]

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.

[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.

[valkyrie]

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.

[Zack]

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.

[RF Overlord]

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 (http://www.tccoa.com/articles/tranny/transmission/page5.shtml) for more info on line pressures and shift kits relative to the 4R70W, written by "The Man" himself...(it's down near the bottom)

[Fourth Horseman]

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!

[ModMech]

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.

[03SILVERSTREAK]

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.

[Krytin]

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

[ModMech]

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.

[03SILVERSTREAK]

Well I went to the website above that is www.Tccoa.com (http://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 ???

[ModMech]

Triple post doh!

[ModMech]

triple post

[ModMech]

Well, it's not I that says the Trans-Go and Baumann kits are not the BEST thing, but one of the fellas that was on the Engineering Team for the 4R70W. You see, he knows better than ANY aftermarket firm what REALLY makes it tick, and he has nothing to gain by attempting to "sell" this or that, he only wants the right info to get into the hands of the masses, not marketing hype.

EPC stuff about 1/2 way down


From one ofhis posts on the "V6 power board"

""First I’ll cover the seperator plate changes in the transgo shift kit.

Hole #1 and 1A
Hole #1 is a damping orifice for the converter clutch control valve. This hole damps the output of the converter clutch solenoid. That solenoid is only an On/Off solenoid, it controls pressure output by tuning on and off very fast. The more on time, the more pressure, the more off time the less pressure. This is called pulse width modulated, or PWM. They recommend opening this hole to .067” from it’s current size of .050”.

I do not recommend any change to this hole. As I said, this solenoid turns on and off very fast and the output goes from 0 psi to 55 psi. This hole dampens the peaks and valleys from the output of the solenoid to provide a smooth signal to the converter clutch control valve. If this hole is too big, then the valve will start to respond to the on/off pulsations, giving an unstable system.

Hole #1A is the feed to the solenoid. Currently it’s .100” in production, so there is no need to change this (this hole was recently added).

Hole #2
This is the intermediate clutch feed orifice. I go over this in my article. I recommend .081”, .100” and .125” for low, medium and high power applications. They recommend .067”, .094”, and .125”. For the most part we are pretty close. The low setting, .067”, isn’t much different than production. Starting in 1996 this orifice went to .063”, I doubt there is much noticeable difference in .004”.

Hole #3
They recommend not changing this hole. This is the direct clutch feed orifice. They recommend no change because they want you to remove the check ball. I’ll cover this later.

Hole #4
This is the OD servo feed. It should already be at .150” in production, and they recommend no change and either do I.

Hole #5
This is the forward clutch exhaust. They recommend not changing this as well. I disagree. You guys with 1994/95 cars want to open this orifice to get rid of the sag, or hesitation, at the 3-4 shift.

Hole #6


Hole BR
This is the feed for the OD servo release. They recommend at least an 1/8” or a slot OK. Most all of your cars will already be a slot. This is not a problem.

Hole A,B,C
These are recommend to be .093”. Holes A and B in any 4R70W will already be this big or bigger. The early AODE’s (1992-1993) have some smaller holes. So these do nothing for our cars. Hole C is the power off forward clutch feed. I recommend different sizes based on power, but .093” is OK.

Hole AC1,2,3
AC1 is the backpressure feed for the 2-3 accumulator. This is used on 3-2 downshifts. Most all should be .125” already, and they recommend .125”
AC2 is the 1-2 accumulator feed and it’s never been smaller than .160” so I don’t know why they even mention it.
AC3 is the bottom of the 2-3 accumulator. This is also used on 3-2 downshifts. Again, most of your cars should be at least .200”, they recommend at least .125”, and I agree.

Hole R
I think they meant this to be the reverse clutch feed, but it’s not. It’s a feed to the reverse clutch, but has never been less than .125”. They recommend .093”


EPC Relief Valve (Page 3)
They say this valve corrects (extreme line pressure due to electrical malfunction, stuck EPC valve, or crossleaks.” I would under no circumstances EVER do this. We have never seen any pressure spikes that have caused any damage. That’s not exactly true, in 1995 there were less than 50 failures from pressure spikes, but we fixed the problem. This valve would not have prevented damage in those cases.

The reason I don’t recommend this is that if that valve ever gets anything stuck in it and opens, you will fail the trans. It will cause a large line pressure leak. It doesn’t solve a problem, but creates the potential for disaster. Again, I have never seen pressure spikes that this would prevent damaged caused by them.

Valves (page 4)
Step 1 and Step 2
All these changes allow the trans not to upshift out of manual low into second and allow you to get every manual gear.

This is much better accomplished electronicly than with these mods. First off, if you pull the lever into 2 at 120 mph it will go into 2. This is a bad thing. There are values in the EEC that allow this and those should be used.

In addition to this, the pressure coming out of the solenoid pressure regulator valve is raised (Step 1) to a higher pressure. This pressure should not exceed the 55 psi from the factory. The shift solenoids, which this valve supplies fluid too, do not work the way you would think. There is always fluid flowing through the solenoids and the solenoids must exhaust the fluid that goes to them when the solenoid is off. When the solenoid is turned on, the exhaust path is stopped. If you provide too much pressure to the solenoids, they will not be able to fully exhaust, especially cold. This could cause the shift valves to start to drift one way or the other. I realize they change the 1-2/2-3 shift valve spring, but they don’t change the 3-4. Both shift solenoids supply pressure to the 3-4 shift valve. Each solenoid alone doesn’t have enough pressure to move the valve, in production. But since the pressure is raised, the 3-4 shift valve could move.

Step 3
This is the converter clutch control valve. This is a very sensitive control system and requires a very fine balance between all it’s parts. I doubt they have done the development we have to make a good control system. I wouldn’t mess with the valve at all. I do recommend the stiffer spring for 1995 and older cars. (I didn’t put this in the Thesis because springs aren’t serviced seperatly)

Step 4
The main regulator valve has the land removed that regulates the flow/priority system. If you go to my article, I don’t recommend this for the reasons mentioned in the article.

More Valves (page 5)
I haven’t actually seen the new manual valve so I don’t know what it does.

The Taper spring (step 3) is a further mod to override the EEC and give you the gear you select. See above for my opinion.

Step 1
The 3-4 capacity modulator valve spring. They include a stiffer spring. This will make the 3-4 shift softer. In production starting in 1996, we actually lowered the load of this valve.

Low Valve. This is a higher spring load than production. This won’t really accomplish too much other than making the manual 2-1 firmer. It will still have the delay (or neutral feeling), but will be firmer when it comes on. This change is not a problem.

ACCUMLATORS
I’ll only address the new style piston. I don’t know the spring loads so I can’t really comment on much, but I’ll give it a shot.

As you add spring load to the bottom spring, the start pressure of the accumulator lowers, making a softer shift. They have you put a washer in the bottom, in my opinion the wrong way. The solid spring is similar to taking the spring out. I suspect that the solid springs limits the accumulator stroke (or travel). This is something that I do not recommend. Your better off with a light spring load or no spring.


The ball removal
This ball removal makes the direct clutch feed orifice .160”, the size of the ball hole. Like I said in the thesis, leave all the balls in. Taking this out will give you firm 2-3 shifts, maybe too firm for some (I’m getting older) but the backout or partial backout shifts will be very harsh. This harshness could result in driveline damage (U-Joints)

For firmer 2-3 shifts your better removing the spring and drilling the hole.


Overall
Overall I think the kit has some good things and some bad things. I don’t like the major reworking of the shift valve/solenoid pressure regulator stuff to give you every gear manually. I’d much rather do this in the EEC, you can still have protection from over-reving and not have the compromises. And, every once in a while, I see a car with this kit that just does not work due to all the valve replacement.

I don’t like the main regulator valve, again gets back to the priority circuit.

Most of the holes are OK but if you have a 1996 or newer trans, you won’t be changing many of them anyway.

If you’ve put one in your car, I’d like to see the production main regulator valve put back in, the ball put back in and the feed orifice opened. You don’t have to remove the manual shift stuff as long as you don’t move the lever when you are too high of a speed, sometimes that lever is tempting. I’d also like to see the EPC relief valve removed, but that requires a whole new valve body to fix.""


Those are the facts, and now you have the same info I have on the subject.

[Krytin]

Thanks! Thats the info I was looking for! I guess I'll just follow the instructions in the article - I think I'll buy the book/tranny manual as well!

[03SILVERSTREAK]

Thanks! Thats the info I was looking for! I guess I'll just follow the instructions in the article - I think I'll buy the book/tranny manual as well!On thursday morning I called Dennis and asked him if he can help me in providing a modified program from his own MM since we have the same EEC in our cars .

The new modified program consisted with lowering the line pressure back to normal so as to prevent the trans from shifting as hard as it was . I also asked to adjust the idle to compensate for the U/D pulleys producing a 12.9 voltage reading from the Alternator while in Drive .

With the use of the cable , I downloaded the new program that Dennis E-mailed into the Tuner and installed it into the EEC in the car .

Well not only did the Idle go up to about 850RPM , but the harsh shift points calmed down to a nice short quick shift . The trans Tec that installed the shift kit set it to mild street Rod/Police cruiser and so far it works well . hope this helps . BTW-anyone that has the tuner should buy the cable from Dennis so as you don,t have to send the tuner back and forth through the mail for reprograming . it will save you money in the long run ...

OBTW-I understand that shift kits are not perfect things and that there are Pro,s and con,s to them and trust me I did research on a lot of them . many claim they are the best and some are complete crap but I felt this one works well for me (for now) , so for those that want to consider this venture do a little homework , ask questions from your local trans shop and friends that have them , then pick your kit and a good trans shop and go for it .

And a Special Thank-You to Dennis Reinhart for the New Tunning . Your are the Big Kahunna . :burnout::burn: