There is a problem with almost EVERY 2004R on the road.

[chris718]

In second gear the intermediate servo applies and the second oil pressure remains there after the trans shifts into 3rd and 4th.In third and forth the inner cavity of the servo is fed third gear oil which has a larger diameter than the 2nd apply piston so the oil pushes off the piston.Here is the problem.The servo pin(unless it is a 200 3 speed )is not attached to the piston.2nd gear oil will continue to apply enough pressure to apply the pin even after the shift if you arte using any boost valve over the largest one ever installed at the factory and any of the 3 original servo inner springs.Here is why.The 3rd spring is calibrated to have enough force to hold off the pin against a given servo diameter and given line pressure when both cavities are chargedAny time you either remove the inner springinstall or install a boost valve bigger than .471 " you have upset the balance of the servo pin that was mathematically calculated to work with given pressures.The factory used the floating pin as a way to remove unwanted 2/3 AND 3/2 characteristics inherent in the original design of the trans.The pin was actually designed to introduce drag to improve function.Without the correct spring or one designed to hold off even the largest servo designed(CK 3.005")every car will have the band dragging the drum.Every single one,no questions asked ,at 3/4 and wot.The only fix is to attach the pin to the servo or use a spring that has been the real correction for this.Take it as fact or fictional .Much testing has been done to procve this.Study the servo for yourself and see.Guidance and support for this project was provided by Joel Rabe who I am extremely grateful to for pointing this out to me while I made the necessary corrections.Here is the solution.

 

[WH1_T-Type]

So what does this boil down to for us, the consumers? I haven't heard of anyone listing that pin as the cause of failure before...but maybe it has been and it had been blamed on something else ?
i'm assuming you are offering that spring for sale, if so, how much?

 

[chris718]

The servo pin is dragging the band a certain amount on every one,the more time you spend at hi throttle the worst it is.Overadjusted tv cable in a transplant is just another example of how the increased pressure on the pin will drag the band.

 

[TurboBuRick]

Interesting.

" Dragging on every one???" Every gear?

Is this taking power away from the wheels?

What are the effect of this?

Rick

 

[chris718]

It will drag in 3rd 4th.EVERY SINGLE ONE.As soon as the pressure fed to the second piston is high enough that when it works on the .500" end of the band pin and becomes greater than return spring pressure.GM made the springs stiffer incrementally with relation to boost valve size.I calculated this mathematically with each combo of spring and boost valve and there is a pattern.They made the spring stiff enough to overcome full line pressure (model dependant)working on the pin diameter.Every one computes out to explain the theory.The pin moves independant of the servo.The minute we raise max line,use no spring on the end of the pin,or install a softer one in a odel with a larger factory boost valve the band drag starts.The amount of drag depends on max line and spring pressure.Gm designed some drag in for a reson,however when we play with this circuit we dont reaalize how sensitive it really is.Just like the 3rd control valve,everyone laughed up there sleeve in the beginning and most are now doing the mod.As I move ahead power loss is becoming a big concern of mine.The drag causes power loss.THIS IS FOR REAL.

 

[TurboBuRick]

You are onto something here Chris. I called Jimmy not long ago and asked a very similar question. After the last upgrade a few years ago the car has never felt the same. 1 and 2 seem fine but something is holding back 3 and 4 for sure. I can feel it. I asked Jimmy if there was any way 2nd gear was not releasing all the way when in 3rd and 4th. As bizarre at it sounds, I can feel it.

So where do we go from here? Do you have the springs for sale? How hard to do the fix? Keep in mind I'm not a trans guy. Allot of your terms go over my head but I am trying to understand.

Rick

 

[chris718]

Remove the servo cover snap ring and servo and install the spring.10.00 spring.I have worked with a few people that built these things and had band failures over and over with no loss of pressure during the shift and THIS WAS THE REAL CAUSE OF THE PROBLEM.They either left out the spring or used the wimpy pink spring w/250 plus punds of line.It just doesnt work.As Istarted looking into it a good friend of mine pointed out that the band was dragging and this is what we found.No guess work.

 

[TurboBuRick]

I could not tell you if there is a spring in mine or not but none the less It needs to be done. How do we get the spring?

Rick

 

[chris718]

Send me your email address.

 

[chris718]

This can be done in 10 minutes or less on the lift.There is a huge improvement in the shift quality at all throttle angles,downstairs it takes car of bang boom shifts and upstairs the shifts actually got better as well.

 

[TurboBuRick]

turboburick@sbcglobal.net

Do you think this will also help with 2-3 hunting?

 

[CGASTON]

It will drag in 3rd 4th.EVERY SINGLE ONE.As soon as the pressure fed to the second piston is high enough that when it works on the .500" end of the band pin and becomes greater than return spring pressure.GM made the springs stiffer incrementally with relation to boost valve size.I calculated this mathematically with each combo of spring and boost valve and there is a pattern.They made the spring stiff enough to overcome full line pressure (model dependant)working on the pin diameter.Every one computes out to explain the theory.The pin moves independant of the servo.The minute we raise max line,use no spring on the end of the pin,or install a softer one in a odel with a larger factory boost valve the band drag starts.The amount of drag depends on max line and spring pressure.Gm designed some drag in for a reson,however when we play with this circuit we dont reaalize how sensitive it really is.Just like the 3rd control valve,everyone laughed up there sleeve in the beginning and most are now doing the mod.As I move ahead power loss is becoming a big concern of mine.The drag causes power loss.THIS IS FOR REAL.

Chris,

Now what will this do or how will this help someone that has a stock trans w/ lonnie diers BRF valve body and bigger servo?

'87 Turbo T w/E85, 224/224, ported iron heads and intake, 80 lbs injector, TE45A, GEN II, TT and EXTENDER EXTREME G, XP Double pumper and something secret, 86 T-TYPE (Kenne Bell test car) and '11 Tundra Limited Sent from my iPhone using Turbobuick

 

[chris718]

Hunting is a shift timing issue.As for what it will do on other transmissions,it will stop the band dragging.The only time this wont help is if the servo pin is attached to the servo like on a 200 3 speed servo,however the bad thing about the 200 one piece servo that is now apparent is there is nothing to kick it off completely on a 2/1 when it is designed w/out a knock off spring.

 

[TurboBuRick]

Does the dual feed mod play any role? Can it magnify the situation?

RL

 

[chris718]

Does the dual feed mod play any role? Can it magnify the situation?

RL

I dont see anything bad about dual feeding however the original return springs in the drum were designed to exhaust an area almost 1/3 of what is used when dual feeding for 3rd gear.Also the oil exhaust out a small hole when the valve backshifts,unlike in reverse where the manual valve when moved creates a huge opening.I have felt major improvements all around with the new springs.Im still polishing the product,I enjoy finding solutions when problems arise.That is my purpose.

 

[chris718]

Chris,

Now what will this do or how will this help someone that has a stock trans w/ lonnie diers BRF valve body and bigger servo?

'87 Turbo T w/E85, 224/224, ported iron heads and intake, 80 lbs injector, TE45A, GEN II, TT and EXTENDER EXTREME G, XP Double pumper and something secret, 86 T-TYPE (Kenne Bell test car) and '11 Tundra Limited Sent from my iPhone using Turbobuick

If your trans has the original boost valve .471 and the original return spring ,it will do nothing.However the trans has trouble with the line pressure that boost valve makes so most have been updated to generate increased line pressure by changing out the boost valve.

 

[KingLouis]

i'll deal with it when and if it starts acting up.

 

[chris718]

i'll deal with it when and if it starts acting up.

Modst of the time you never know ,but I can guarantee you one thing,if it is a stock pin with a .500 boost valve IT IS DRAGGING THE BAND.

 

[TurboBuRick]

Good job bro!

Let me know when you have some ready for sale. Also any tips on the 2-3 hunting thing would be much appreciated.

Rick

 

[dand]

X2 on job well done!
Will want one of these once they are avail