Toyota Modified Valve Body

[Transdude]

Hi all,

For my first post here I wanted to put up some valve body info in the form of an article that I had written some time back, as it is a popular subject in the world of Toyota trucks.

-John
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Toyota Modified Valve Body

-By John Lombardo

(c) John Lombardo- All Rights Reserved
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As many Toyota and Jeep owners know, the AW4 / Toyota 340, A340, and A341E series of transmissions are generally very well made and demonstrate excellent durability in unmodified applications. The framework is present for an extremely strong transmission that is to be used in a high performance or extreme duty application.

The problem is that the original calibration is engineered for driver comfort rather than ultimate component strength. The soft, sliding shifts that are part of the original design are not appropriate for increased horsepower applications, towing, off road use, racing, etc.

These calibration inadequacies quickly manifest themselves as extremely poor shift quality, and more often than not, severe damage to the gearbox is soon to follow. One of the most common symptoms of this is the engine stuttering or hitting the rev limiter during a full throttle upshift.

Without going into too much technical detail, the factory shortcomings can be addressed through modification and recalibration of the control valve assembly, a.k.a. the valve body.

The valve body is a component that is comprised of valves, solenoids, an orifice separator plate and an intricate series of passages- it is the most complex component in the most complex part of your vehicle- the automatic transmission.

The function of the valve body is to act as the "brain" of the automatic transmission- it directs hydraulic pressure to the appropriate clutches and bands at the right time to initiate upshifts, down shifts, selection of reverse, converter clutch application, etc. As well as controlling shift timing and shift quality, it is also responsible for directing hydraulic pressure to the cooler and the lubrication circuit.

As you can imagine, the transmission's operational characteristics can be drastically altered and also customized to the given application through modifications to this component.

Because there are no commercially available shift kits for these transmissions, we began working on valve body modifications that were appropriate for Supras, Jeeps with the AW4 transmission, Toyota Tundra, Tacoma and 4Runner, and also Lexus SUV’s and rear drive passenger cars- especially those that needed to handle the additional power that accompanies the installation of a supercharger, turbo or nitrous oxide injection.

At the risk of oversimplification, there are a few things that are done in concert to create much more favorable operation of the gearbox.

The first thing that needs to be done is to increase the hydraulic operating pressure of the transmission- this pressure is known as "line pressure". All hydraulic functions of the transmission are based on this pressure- what is especially of concern for these purposes is the clamping force which is applied to the clutches and bands to get them to hold against engine torque.

In simple terms, increased engine output is complemented by increased line pressure and increased "clamp" on the clutches- this can be likened to a performance clutch with a heavier pressure plate spring in a manual transmission equipped vehicle.

The idea is to raise this pressure only slightly at light throttle but increase it by 30-40% at full throttle- where it is really needed. The effects of this are shifts that are not overly uncomfortable at lower throttle openings, while at heavier throttle, firm shifts with much shorter clutch application time and increased clamping force can be achieved.

An additional benefit of this is increased flow through the transmission’s cooler and lube system.

Secondly, hydraulic pressure is normally routed through an orifice in a metal "separator plate" that resides between the two halves of the valve body before it gets to its intended destination. By altering these orifices, we can increase the volume of hydraulic oil that is used to apply the various clutches and bands.

The final part of modification is the alteration of the accumulator circuits. These are hydraulic circuits that are parallel to the components that are used for shifting. Their function is to absorb or "accumulate" some of the hydraulic pressure that is intended to apply a clutch pack or band. By limiting the action of what is essentially a "shock absorber" for each shift, we are able to further reduce clutch lock up time and shift lag at wide open throttle.

The end result is that shift time is reduced by 30 to 80%, depending on the amount of acceptable shift feel and the intended application. The clamping force that is required to apply the clutches and bands is increased by 30 to 40% at full throttle. Flow through the cooler and lube circuit is increased and the converter clutch application time is also reduced.

Transmission and valve body upgrades are not only for American made vehicles anymore. Increased performance and more efficient shifting is now available for vehicles of almost every manufacturer thanks to the few companies that are willing to do the research and development work required for this rapidly growing segment of the automotive aftermarket.

Author Bio: John Lombardo, a.k.a. Transdude, is owner of IPT Performance Transmissions and has been in the transmission and high performance industry for over 20 years.
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**Please feel free to reprint article for use in ezines, other forums, websites and blogs on the condition that the article is not altered and the resource box (about the author box) remains intact with all hyperlinks activated. If this article is reproduced an email to the author with a link to its location is greatly appreciated- john@ipttrans.com

[J-Man]

im sending you mine hopefully in the next 2 weeks for the VB upgrade

[SAR_Squid79]

Thanks again John, I'm loving the upgrade, and I can't thank you enough for the awesome service you gave me after my major screw up! Installation went as smooth as could be (other than my initially overfilling the tranny pan). The Upgrade is awesome stuff! I highly recommend this mod for everyone with an automatic, but ESPECIALLY for those with the Supercharged automatic.

More about my IPT Experience:
http://www.tacomaterritory.com/forum...ad.php?t=19804

http://www.tacomaterritory.com/forum...ad.php?t=19797

[Transdude]

Originally Posted by SAR_Squid79

Thanks again John, I'm loving the upgrade, and I can't thank you enough for the awesome service you gave me after my major screw up! Installation went as smooth as could be (other than my initially overfilling the tranny pan). The Upgrade is awesome stuff! I highly recommend this mod for everyone with an automatic, but ESPECIALLY for those with the Supercharged automatic.

More about my IPT Experience:
http://www.tacomaterritory.com/forum...ad.php?t=19804

http://www.tacomaterritory.com/forum...ad.php?t=19797

Thanks again for the thumbs up.

How about a picture of your truck to put in our website's photo gallery?

Email one (or some) out if you get time- john@ipttrans.com

-John

[montypower]

Just had my 99 4runner VB done (2 weeks ago)... and it's great. I'm getting adjusted to the firmer 1st-2nd shift. The rest are perfect (quick, solid). I'm very happy with it. The turn around time was incredible!!!!

If you are SC'd... it is a very good idea!!! I'd also recommend having a tranny shop do the removal/install as it is messy.

[LocoTaco]

Hello John,

Nice to see you around here. My truck is still shifting like a champ.

*** For all of auto tranny supercharged Taco owners sitting on the fence, it's time to take the leap and send in your Valve Bodies to John at IPT. Their work is high quality and the customer service is outstanding!

- Keep up the good work IPT.

Robert

[Transdude]

Originally Posted by LocoTaco

Hello John,

Nice to see you around here. My truck is still shifting like a champ.

*** For all of auto tranny supercharged Taco owners sitting on the fence, it's time to take the leap and send in your Valve Bodies to John at IPT. Their work is high quality and the customer service is outstanding!

- Keep up the good work IPT.

Robert

Hi Robert,

Thanks. Good to hear from you.

When did you have the mod done? It' seems like it was quite a while ago at this point.

-John

[LocoTaco]

Originally Posted by Transdude

Hi Robert,

Thanks. Good to hear from you.

When did you have the mod done? It' seems like it was quite a while ago at this point.

-John

It's been about 2 years since I did the mod. The positive shifting still feels nice a crisp. It has to be one of my best mods to date after the blower of course.

Robert

[DCabTaco]

I can't wait. I shipped it out earlier this week with a delivery confirmation and noticed it was delivered yesterday. I e-mailed to confirm it all arrived safely, and to my surprise it is done and shipping back today. Now that is great service!

[mt_goat]

What is the cost to upgrade a 2001 Tacoma valve body? What is the turn around time usually?

[DCabTaco]

All are the same from what I can tell. 495.00 and as stated above, they do it within 24 hours, so turn around time is shipping time to and from plus 1 day. It all depends on what you want to pay for shipping,... i.e. regular ground or overnight

[SAR_Squid79]

Yep - same price no matter what the year. $495 + Shipping.

As far as turn around time - I overnighted mine to IPT on a Saturday afternoon so John @ IPT would have it in his hand 1st thing Monday morning. He did the upgrade that day, overnighted it back to me, and it was back in my truck Tuesday night. Like "DCab" said - it just depends on how much you want to pay for shipping.