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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.
 
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#2 ·
hmmmm.
 
#14 ·
That's what I'm wondering...
 
#6 ·
But since you are not WOT 99% of the time.....they are very beneficial to the person looking for long life out of transmission. If I understand you correctly you are simply saying at wot, the line pressure is no different, is that correct?
 
#8 ·
:popcorn: Subscribed... Interested what others have to say about this. Was a potential mod for the near future.
 
#9 · (Edited)
All I know is since bluetops were installed in my stock trans, I have never gotten limp mode from the trans missing that 1-2 shift. Use to get that alot. It does make the trans more harsh just driving around. You can really tell when coming to a stop amd it downshifts to 1st.
 
#11 ·
Simon is correct about the Tranzformer. A Blue top shortens the duty cycle so things happen sooner. The Tranzformer varies the duty cycle to the solenoids and can make things happen quicker than a bluetop. Same result at WOT though.
Valve body work allows you to increase the pressure relief valve setting which cannot be done with the Tranzformer nor a simple Bluetop install.
 
#22 · (Edited)
The blue tops are reacting to a duty cycle designed for the brown tops, making part throttle shifts shorter in duration, which translates into firm (or even harsh) part-throttle shift events.

i installed mine two weeks ago after having them laying around for almost a year along with a black mopar drain pan and No ESP.. The car to me seems better when applying quick small amounts of say part throttle on the gas pedal when starting out rolling around town, above the already given mods of a 3K stall, mtcm. predator mode two setting. and the tranzformers. Simon Thanks for the Technical Explanation and good Info on these. You should have been a Research Scientist. Danny
No doubt part throttle shifting feels more zesty :^)

Thanks Danny for the compliment, I appreciate it.
 
#12 ·
i installed mine two weeks ago after having them laying around for almost a year along with a black mopar drain pan and No ESP.. The car to me seems better when applying quick small amounts of say part throttle on the gas pedal when starting out rolling around town, above the already given mods of a 3K stall, mtcm. predator mode two setting. and the tranzformers. Simon Thanks for the Technical Explanation and good Info on these. You should have been a Research Scientist. Danny
 
#17 ·
The blue tops control pressure not flow. The PWM signal that our car sends out is scaled 0-100% (on/off duration, proportionality) of both the shift pressure & modulating pressure valves. The difference between the blue/brown tops is the maximum pressure that they are both capable of, blue being the higher pressure of the two.

So 0-100% signal may only be 80 psi on the brown but the same signal to the blue tops nets you 110psi, now I'm not sure what the actual pressures are but that is the easiest way to explain it. There are a whole bunch of things that are being taken into consideration when the car shifts, load, gear, rpm and throttle position and the PWM signal is adjusting to each of these. Then the valve body is doing its thing also, opening and closing the shift valves (on/off non-proportional), torque converter lock-up and feeding all the information back to the TCM.

So the simple statement that at WOT both of the valves are the same is kind of misleading because they are at max values but the pressures they both put out are different.
 
#19 · (Edited)
The blue tops control pressure not flow. The PWM signal that our car sends out is scaled 0-100% (on/off duration, proportionality) of both the shift pressure & modulating pressure valves. The difference between the blue/brown tops is the maximum pressure that they are both capable of, blue being the higher pressure of the two.

So 0-100% signal may only be 80 psi on the brown but the same signal to the blue tops nets you 110psi, now I'm not sure what the actual pressures are but that is the easiest way to explain it. There are a whole bunch of things that are being taken into consideration when the car shifts, load, gear, rpm and throttle position and the PWM signal is adjusting to each of these. Then the valve body is doing its thing also, opening and closing the shift valves (on/off non-proportional), torque converter lock-up and feeding all the information back to the TCM.

So the simple statement that at WOT both of the valves are the same is kind of misleading because they are at max values but the pressures they both put out are different.

Yes...

If at 100% duty cycle both the blue tops and the brown tops are full open and passing the same available maximum line pressure...which is on the order of 280psi across all NAG1's. Now if the valve body has been phyisically altered to supply greater line pressure by modifying the relief valve / spring then up to say 380psi would be available. No matter what, as I mentioned previously the pintle valves and orifices are the same and both near or at 100% duty cycle at WOT.
 
#26 · (Edited)
Duty cycle, aka pulse width modulation (PWM), the percentage of ON time versus OFF, the ongoing and dynamic square-wave command being sent to both units is what controls proportionality (how much the pintle valve moves off it's seat and for how long).

Spring functionality is to continually force the pintle valve closed, against whatever duty cycle is being requested.


So again, it sounds like these solenoids are proving to be a pointless waste of money...
My goal is not to drive folks away from employing them, just to ensure they are installing them for the correct reasons. This means first understanding what is actually going on down there. I get asked about them, from what folks are being told is that the blue tops are responsible for raising line pressure at WOT. It appears they don't, or not appreciably.
 
#21 ·
So again, it sounds like these solenoids are proving to be a pointless waste of money...
 
#27 ·
Oh I'm not implying that you're trying to drive anybody away from their online shopping cart, but it sounds like their ability to notably increase transmission life/durability is vastly exaggerated.
 
#29 · (Edited)
I know you're not :^)...but how does one measure this?
 
#30 ·
My thoughts on these are.......Ive had them in my car since 35000 miles and I have 182000 now and still shifts the same as the day they went in! I put them in because I wanted the trans to live a long time and it has in SPADES! Ive race the hell out of my car and driven a lot on the highway and its still strong as ever.
 
#31 · (Edited)
If your list of mods is accurate blue tops have done little to enhance longevity...
 
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#32 ·
So when would be the time to use blue tops? Only with a modified valve body? Upgraded trans?
 
#41 · (Edited)
I'll suggest with stock NAG1s the firmer shifts outside of WOT are appealing cause they feel firmer than OEM. I'd like to understand whether the larger orifice at WOT does offer a change in line pressure.

Great info Simon. I had assumed the blue tops helped WOT but now I know it is actually the valve body. I am taking from this that combining the blue tops with the valve body makes for a good all around street and track car providing you like firm shifting on the street?
I'm glad it's helping folks :^) I'm not so sure blue tops are a requirement with the valve body or even a complete high performance transmission, it's one of the questions I've got. For my scenario, I don't see how blue tops would be of value (I might try them anyways). Both the additional line pressure and the remapped MPTCM duty cycle make shift events shorter and shorter the deeper you get into the throttle.

For me the MPTCM does exactly what I want, it's a well-thought out unit. Since installing the more powerful engine, to get around the rest of the transmission being stock I shift it manually when driving it aggressively. Essentially off and back on the throttle while shifting to avoid as much clutch pack slippage as possible. The MPTCM makes manual shifting super-easy and very consistent. The last thing I want is a harsh shift event that induces oversteer on a long fast sweeper.

With so much torque at my disposal, this is one of the reasons I left in the OEM (RT) torque converter. And now that Mike (OST) has locked down my lumpy idle it's really fun to drive. It's a given my transmission is not gonna to survive. So before I damage it further I'm exploring my options. If you recall I've always aimed at road course duty, but now without a track (sniff) all I can do is take nice leisurely drives to twisty mountain roads (OK, maybe not so leisurely...I just mounted my 3rd set of 295/35 P-Zeros since April and I've not done a single burnout). Just recently, I compromised another halfshaft CV joint (starting to click in left turns under acceleration), even though I'm being relatively nice to the drivetrain by circumventing shift events by momentarily lifting.

It seems to me that blue tops assist the desire to mimic (for example) TH350 / 400's back in the day with manual shift body's that chirped the tires just shifting normally. Their effectivity at WOT throttle is what I want to understand better.
 
#33 ·
Great discussion here guys.
what blue tops do and perhaps what they don't do can be said another way:

They make part throttle shifts happen quicker, they have no effect on WOT shifts.

So when would one want them? When and if one desires quicker part throttle shifts, and no other difference.

yeah, me either.

A paramount transmission, for example, has firmed up shifts, to varying degrees depending on the build, at all shift points/up and down. The transmission responds to how you drive it. Seems if one used blue tops then they take away the built in adaptives, part throttle shifts are always going to be quicker and harsher.

IN general, for me, any potential mod must first enhance WOT performance I.E. quarter mile times, any potential gains are measured against any degradation of my daily driving experience.
 
#36 ·
Thanks for the great info Simon.
 
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#39 ·
What I gathered here is for a comfortable but sportier street car with some track time u want valve body and tranzformer.

Sent from my SM-G900V using Tapatalk
 
#40 ·
^^^ Makes a good combination that can be dialled in for best street and strip performance. I've always like the fact that the push of a button gets you back to stock and you can tune both autostick and normal "drive" behaviour differently. Basically 3 global setting in seconds.
 
#42 ·
This subject has always been of interest. My take is simple:
Install Blue tops, have AJ work his majik on your TCM.. No disappointments.. quicker 60', it's just going to happen, stock or modified, the original OEM design satisfied MB/ AMG, and our platform is the "working man's" version, all the theoretical in the world doesn't change the simple fact, Blue Tops work, vs the expense of a "Modified" Stage II VB, they are a blast to drive with, and again, in Manual mode, cannot get over the shear coolness of barking tires in 3 gears with an auto..
 
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