LX Forums Forum banner

The Facts about Blue Top Solenoids....

50K views 57 replies 29 participants last post by  Luke81Roberts 
#1 · (Edited)
The difference between blue top and brown top solenoids is their orifice I.D. and possibly internal windings / closing spring rate (at zero duty cycle the pintle valve is held closed by the spring), that's it. What controls both is the duty cycle commanded by the PCM / TCM. Duty cycle is the percentage of ON time versus OFF time that moves the pintle valves off their seats, for how long and how far. On our rides, that duty cycle is tailored to match the OEM brown tops.

What this means is during part throttle operation, the applied duty cycles which are dynamic and change based on a number of inputs (for example throttle position, rpm, which gear) offers less ON time to affect shift events that are relatively long in duration. At wide open throttle (WOT) they are near 100% duty cycle.

When blue tops are installed, and those same duty cycle requests meant for brown tops is commanded during part throttle operation the pintle valves open to a different position. This along with the higher fluid flow results in higher pressure that produces shorter shift events during part throttle operation, which is interpreted by the driver as firm or hard shifting.

On AMG vehicles that utilize the 722.x, the commanded duty cycle properly matches the blue tops, thereby allowing for normal comfortable / acceptable shifting events at part throttle settings (they can toggle between different transmission settings).

Finally, maximum line pressure (actual pump pressure) does not change with either blue tops or brown tops; NAG1 pump pressures are on the order of ~280psi (the version FCA builds is a WA-580). To increase line pressure the valve body can be modified. Actual available pressure can be upwards of 800psi pre-regulation, but in excess of say 400psi internal pistons / rams are being distorted and eventually damaged due to pressure distortion. The most robust of NAG1's are no more than say 380psi.

In a nutshell, at WOT where it really matters there is not a lot of difference between blue tops and brown tops. Also the aftermarket Tranzformer does not alter pump pressure, as this requires physical alteration of the valve body.
 
See less See more
#44 ·
So are blue tops like a snake oil? Do they really help or not help anything .
 
#45 ·
Red Tops FTW!
 
#48 ·
Blue tops for me with stock TCM is not that much, just tightened things up. With the MTCM, it's a harder shift event-especially on downshifts. I did them because I felt it was a "hardware" upgrade vs a "software" upgrade with tranzformer. I'm not pushing 500+hp, but stock Browns were sluggish in shift event which I felt were like dragging the clutch packs and thus more wear.
Anyway, the blues make drives so much more fun and that's my bottom line [emoji12]

Sent from my iPhone using Tapatalk
 
#50 ·
Not trying to step on anybodies toes here but I wanted to correct a few things and maybe clear up a some stuff as well. For those of you that do not know of me I do transmission tuning and have run this valve body very extensively on a flow machine with pressure sensors at all sorts of different duty cycles.
So 1st thing about the solenoids. One is what is called modulator pressure control and the 2nd is the shift pressure control. Modulator pressure controls the working pressure or what most would call line pressure. It has no effect on the shift firmness. Modulator pressure is in play during a gear change but it controls the overlap of the clutches. Or in reality how fast the off going clutch drains.
Shift pressure controls the pressure being applied to the on coming clutch or what you feel as how firm a shift is. It is only active during a gear change. Unless modulator pressure is run so low that the total working pressure is reduced below 100-115psi then other pressures start to be effected as well.
Now I have never seen a factory tcu run anywhere near 0% duty cycle on these. Shift pressure will finish out at 0% but this is typically when the shift has ended already. Now in addition to this I have run the same car with and without a standalone tcm that has full control and there really is not any comparison to what the shifts are like at very low duty cycles.
Also the valves are naturally in a closed state with no current. There is a lot more I could go into but it starts to get blurry.

Now for do the bluetops do anything at wot. The answer is yes but it is fairly marginal. I would have to go back and log the pressures at 0% duty cycle as I have not done that. But at what are typically very aggressive duty cycle pressures around 15-20% duty cycle there is about a 10psi difference. If the brown top is at 0% it has 100 psi of shift pressure. Bottom line is that the % difference gets smaller as the pressures increase and this is true.

Now a little disclaimer on this as well I have not datalogged every tuners tcm tune out there but I have done a few both in Mopar and Mercedes and like I said have switched cars from the factory tcm to a standalone and the shift firmness is not really in the same ballpark. And this does not matter if it is brown or blue solenoids. And I do not run 0% duty cycle on any shifts. Typically around 15% is about max. For instance with no tq management I was running a Mercedes CL65 the other day and if you do not know it has a v12 TT that makes somewhere around 730lb/ft of torque but probably a little closer to 500 at redline and I was running 20% duty cycle on it for a fairly quick shift but not abusive. It was a completely stock vehicle.
 
#51 ·
Not trying to step on anybodies toes here but I wanted to correct a few things and maybe clear up a some stuff as well. For those of you that do not know of me I do transmission tuning and have run this valve body very extensively on a flow machine with pressure sensors at all sorts of different duty cycles.
So 1st thing about the solenoids. One is what is called modulator pressure control and the 2nd is the shift pressure control. Modulator pressure controls the working pressure or what most would call line pressure. It has no effect on the shift firmness. Modulator pressure is in play during a gear change but it controls the overlap of the clutches. Or in reality how fast the off going clutch drains.
Shift pressure controls the pressure being applied to the on coming clutch or what you feel as how firm a shift is. It is only active during a gear change. Unless modulator pressure is run so low that the total working pressure is reduced below 100-115psi then other pressures start to be effected as well.
Now I have never seen a factory tcu run anywhere near 0% duty cycle on these. Shift pressure will finish out at 0% but this is typically when the shift has ended already. Now in addition to this I have run the same car with and without a standalone tcm that has full control and there really is not any comparison to what the shifts are like at very low duty cycles.
Also the valves are naturally in a closed state with no current. There is a lot more I could go into but it starts to get blurry.

Now for do the bluetops do anything at wot. The answer is yes but it is fairly marginal. I would have to go back and log the pressures at 0% duty cycle as I have not done that. But at what are typically very aggressive duty cycle pressures around 15-20% duty cycle there is about a 10psi difference. If the brown top is at 0% it has 100 psi of shift pressure. Bottom line is that the % difference gets smaller as the pressures increase and this is true.

Now a little disclaimer on this as well I have not datalogged every tuners tcm tune out there but I have done a few both in Mopar and Mercedes and like I said have switched cars from the factory tcm to a standalone and the shift firmness is not really in the same ballpark. And this does not matter if it is brown or blue solenoids. And I do not run 0% duty cycle on any shifts. Typically around 15% is about max. For instance with no tq management I was running a Mercedes CL65 the other day and if you do not know it has a v12 TT that makes somewhere around 730lb/ft of torque but probably a little closer to 500 at redline and I was running 20% duty cycle on it for a fairly quick shift but not abusive. It was a completely stock vehicle.
Thanks; what I read basically confirms what I've wrote. I elected not to elaborate on modulation or shift pressure for simplicity. You have gone down that (information) path a small distance. A whole lot more education would need to occur to ensure everyone understands what both functions achieve as it relates directly to either the brown or blue top solenoids (the service manuals we have access to do a great job actually, but boy is it dry).

You and I agree shift pressure eventually reaches zero duty cycle, as you state near end of the shift event

In the transmission section of the service manual it states with no duty cycle being applied, the solenoids are in an open position. Are you saying the same thing when referring to "valves are naturally in a closed state with no current"

Can you elaborate further how blue tops and brown tops differ when subject to the very same duty cycle request at WOT

 
#52 ·
So the solenoids are bleed valves. They release pressure. So when they are off they are closed and supply no pressure reduction. The higher the duty cycle the more they open. This reduces the respective pressure for each function. Basically modulator and shift pressure have the same max pressure of around 100-110 psi. This is dedicated by another valve in the valve body and of course total working pressure. They simply control pressure on a side of another valve so they are extremely low volume.
As far as reaching 0% duty at the end of the shift this is actually after the shift is over. There are actually many stages to a shift and several different targets for this. You will see the shift pressure solenoid drop to 0 before the shift solenoid turns off. This is to make sure the valves in the valve body complete there movement after the shift is over. Actually until the shift solenoid turns off you are still running the new clutch in shift pressure with a max of 100psi, Then it returns to working pressure when the shift solenoid turns off.
My hunch is that the spring pressure in the blue tops is higher. I would think that the inductance was different but that would change the htz you would run on the solenoids. I see a pretty much straight 10-20psi difference throughout the entire duty cycle range. Like I said I have not run blue tops to 0% to see but I have run them to 19%. Below 15% there is little to no difference in pressure. The valves are near or are closed. Same for above 55% duty cycle, the pressure is as low as it will go. Also you have to look at how much current it takes to open and keep the valve open. It is just that at a regulated pressure of 40 psi adding blue tops adds the same total psi as it does if you were at a regulated 80 psi.
Next time I have a set on the valve body machine I will do a full sweep.
 
#53 ·
Great thanks, I'll rewrite the pertinent sections in my posts to correspond.
 
#54 ·
don't really want to get into this conversation but i'm just gonna drop this here:

from FSM

DESCRIPTION

The typical electrical solenoid used in automotive applications is a linear actuator. It is a device that produces motion in a straight line. This straight line motion can be either forward or backward in direction, and short or long distance.
A solenoid is an electromechanical device that uses a magnetic force to perform work. It consists of a coil of wire, wrapped around a magnetic core made from steel or iron, and a spring loaded, movable plunger, which performs the work, or straight line motion. The shift valves (solenoids) are On-Off solenoids and are powered up by the TCM with a 12-volt power source and are internally grounded in the transmission. The Torque Converter Clutch (TCC) and Pressure Control (PC) solenoids are also powered up by the TCM and internally grounded in the transmission but are pulse with modulated (PWM) . PWM measurable voltage varies depending on percentage of modulation requested by the TCM.
The solenoids used in transmission applications are attached to valves which can be classified as normally open or normally closed. The normally open solenoid valve is defined as a valve which allows hydraulic flow when no current or voltage is applied to the solenoid. The normally closed solenoid valve is defined as a valve which does not allow hydraulic flow when no current or voltage is applied to the solenoid. These valves perform hydraulic control functions for the transmission and must therefore be durable and tolerant of dirt particles. For these reasons, the valves have hardened steel poppets and ball valves. The solenoids operate the valves directly, which means that the solenoids must have very high outputs to close the valves against the sizable flow areas and line pressures found in current transmissions. Fast response time is also necessary to ensure accurate control of the transmission.
The strength of the magnetic field is the primary force that determines the speed of operation in a particular solenoid design. A stronger magnetic field will cause the plunger to move at a greater speed than a weaker one. There are basically two ways to increase the force of the magnetic field:

  1. Increase the amount of current applied to the coil or
  2. Increase the number of turns of wire in the coil.
The most common practice is to increase the number of turns by using thin wire that can completely fill the available space within the solenoid housing. The strength of the spring and the length of the plunger also contribute to the response speed possible by a particular solenoid design.
A solenoid can also be described by the method by which it is controlled. Some of the possibilities include variable force, pulse-width modulated, constant ON, or duty cycle. The variable force and pulse-width modulated versions utilize similar methods to control the current flow through the solenoid to position the solenoid plunger at a desired position somewhere between full ON and full OFF. The constant ON and duty cycled versions control the voltage across the solenoid to allow either full flow or no flow through the solenoid's valve.


UPSHIFT/DOWNSHIFT SOLENOID VALVES

The solenoid valves (1) initiate the upshift and downshift procedures in the shift plate.The solenoid valves (1) for upshifts and downshifts are located in the shell of the electric control unit and pressed against the shift plate with a spring.
The solenoid valves (1) are sealed off from the valve housing of the shift plate (5) by two O-rings (4, 6). The contact springs (8) at the solenoid valve engage in a slot in the conductor tracks (7). The force of the contact spring (8) ensures safe contacts.




MODULATING PRESSURE CONTROL SOLENOID VALVE


The modulating pressure control solenoid valve (1) is located in the shell of the electric valve control unit and pressed against the shift plate by a spring.
Its purpose is control the modulating pressure depending on the continuously changing operating conditions, such as load and gear change.
The modulating pressure regulating solenoid valve (1) has an interference fit and is sealed off to the valve body of the shift plate (4) by a seal (arrow). The contact springs (2) at the solenoid valve engage in a slot in the conductor tracks (3). The force of the contact springs (2) ensures secure contacts.



TORQUE CONVERTER LOCKUP CLUTCH PWM SOLENOID VALVE

The torque converter lockup clutch PWM solenoid valve (1) is located in the shell of the electric valve control unit and pressed against the shift plate by a spring.
The PWM solenoid valve (1) for the torque converter lockup controls the pressure for the torque converter lockup clutch.
The torque converter lockup PWM solenoid valve (1) is sealed off to the valve body of the shift plate (4) by an O-ring (5) and a seal (arrow). The contact springs (2) at the solenoid valve engage in a slot in the conductor tracks (3). The force of the contact springs (2) ensures secure contacts.




SHIFT PRESSURE CONTROL SOLENOID VALVE

The shift pressure control solenoid valve (1) is located in the shell of the electric valve control unit and pressed against the shift plate by a spring.
Its purpose is to control the shift pressure depending on the continuously changing operating conditions, such as load and gear change.
The shift pressure regulating solenoid valve (1) has an interference fit and is sealed off to the valve body of the shift plate (4) by a seal (arrow). The contact springs (2) at the solenoid valve engage in a slot in the conductor tracks (3). The force of the contact springs (2) ensures secure contacts.

 
#55 · (Edited)
I'm looking at this differently, maybe because I'm certified fluid power mechanic who worked on electric over hydraulic solenoids in bucket trucks. Follow my reasoning;

If I have a fixed period of time to fill a cylinder having a higher flowing valve during that fixed period of time will give my cylinder more pressure, unless I have enough flow to fully pressurize the cylinder. I know that the brown tops do not since when I'm tuning my transmission running my HP tuners with the factory brown tops I get a much more firm shift with less slip by extending the advance fill time and increasing the total time the solenoid runs. Telling me I could get more pressure for the cylinder that compresses the plates and a quicker shift with a higher flowing solenoid. I would wager that if you could measure the pressure inside the cylinder pressing the clutches down that you get a higher pressure shift with blue tops than you do with brown tops at fully open do to the increased flow though the orifice.

Just my 2 cents.
 
#56 ·
This is not how it works. They are control pressure only. None of the solenoid valves directly supply any of the clutches. They all act as controls for spool valves and regulate position for pressure control.
So total flow rate is irrelevant. It is actually a mystery as to why Mercedes changed these. Even the operating range is nearly identical. The only thing I can think is that they are actually a higher resolution solenoid and it was about control and not total pressure. The blue tops flow less at a given duty cycle and so each % change has less effect than the brown tops but ultimately you can completely open them or completely close them and the supply pressure is the same and the springs are the same on the valves so the ends are the same.
 
#58 ·
Time to throw some more questions in to an old thread. In addition to there being blue and brown top solenoids, there are actually 2 different part numbers for the blue tops. A2402770098 and A2402700089. The former being the old part number. Anyone know if there are any differences between the 2? Or are all blue tops the same in operation?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top