May 03, 2019

Your Rebuild Is More Than The Sum Of Its Parts

Sonnax Parts, Tools & Tech Resources: Helping You Deliver Top-Quality Repairs

Complex systems are made up of parts that all must work together. In this regard, a valve body is much like a human body. Now, imagine preparing yourself to run a 5K race: everything from head to toe needs to be in tip-top shape to make it to the finish line. Getting a valve body into peak condition works the same way. Rebuilders know the interrelationship between valves is extremely critical, and proper function of one or two does not make the entire hydraulic system fully functional.

A great example of why it pays to take a holistic approach to valve body repair is a common issue with the GM 6T70: wear at the AFL valve bore can result in various solenoid codes and shift issues. This can be corrected using Sonnax oversized valve 124740-01. However, the AFL valve is fed line pressure, so if the main PR valve bore is worn and not addressed, reduced feed pressure is supplied to the AFL valve, which prevents it from optimum performance. And even if both the AFL and main PR valve bores are in great shape, wear at the various clutch regulator valve end plugs allows solenoid apply oil leakage and results in shift complaints. Fixing one area of the valve body without checking to see whether others are working right is asking for a comeback. Taking a holistic approach spares you the worry about what may have been missed.

If you’re getting off the couch and prepping for a 5K, it’s probably a good idea to get a physical, as the doctor will use special tools and testing to check for problems you might not see or feel. Vacuum testing is the same idea — while the transmission may have come in with a specific complaint, you can’t “see” what’s going on inside the valve body until you vacuum test.

Free Sonnax vacuum test guides are available for most common applications. They show locations to check for wear using Sonnax vacuum test stand kit VACTEST-01K, plus recommended parts for repairing leaks. Sealing up all the circuits ensures individual components can work properly. The ideal way to verify this is to vacuum test again after new parts are installed. Sonnax part instructions and website part pages show you where to test and what vacuum reading you should get after repair (Figure 1).

Figure 1 – It's a good idea to vacuum test again after repairs to verify there are no leaks.

Want to vacuum test significantly faster? Consider getting your shop a Sonnax valve body vacuum test plate, especially if you’re working on a high volume of a particular unit. Plates seal over the entire valve body, with test and exhaust ports open at all the proper locations for fast, easy testing.

Choosing the Right Repair

Once you’ve diagnosed the problem areas, it’s time to decide how to address them. Sonnax offers various solution options that are tailored to the level of wear, your warranty, your customer’s wallet and your time and familiarity with the particular application. Many applications have Sonnax Zip Kits® available — which are an easy, no-tooling way to restore the hydraulic system in units not showing high wear. Restoring valve function in bores with extreme wear usually requires reaming the casting and installing an oversized valve kit. Sonnax oversized parts are sold individually and often included in Sure Cure kits. When you’ve got a high-mileage unit that needs a complete overhaul, a Sure Cure is a great choice because you get all the parts you need in one box. No two valve bodies will wear the same, so Sonnax has made sure you have options when it comes to picking an approach to repairs.

Evaluating Rebuild Options When Time is Money

Sonnax encourages you to look at the dollars and cents of your repair options along with your warranty and customer needs to determine the best choice for your shop and the job at hand. Take reamer kits, for example, used to install oversized valves.

Reamer Tool Kit Amortization
Tool Kit Cost / # of Repairs = Tool Kit Cost per Valve Body
$270/100 = $2.70
If the application is a common one for your shop, purchasing tool kits knowing they’re going to pay for themselves over 100-plus valve bodies likely makes sense.

If the specific valve body only requires one reamed solution and a few no-reaming required parts, for instance, for a customer wanting about 12 more months before they trade-in their vehicle — repairing the valve body yourself likely makes financial sense.

DIY Valve Body Repair
Tool Amortization + Oversized Valve Kit + No-Reaming Req’d Part + Labor = DIY Fix Total
$2.70 + $28 + $55 + $50 = $135
For one reamed solution and a few no-reaming parts required, repairing the valve body yourself likely makes financial sense.

However, if a different customer repair requires a longer warranty and needs four bores reamed in addition to some other components, or it’s for an application that you don’t see very often so tool investment will take longer to recoup, a remanufactured valve body might make a lot more sense.

DIY vs. Remanufactured Valve Body
(4X) Tool Amortization + (4X) Oversized Valve Kit + No-Reaming Req’d Part + Labor = DIY Fix Total
$10.80 + $112 + $55 + $100 = $277.80
Longer warranty? Four bores reamed in addition to some other components? An application that you don’t see very often? Need to turn around the job quickly? These scenarios might point to purchasing a remanufactured valve body as the better choice for you and your customer.

Sonnax Remanufactured Valve Bodies:Your Choice for Guaranteed OE Performance

While Sonnax has figured out what parts you need to get just about any valve body in tip-top shape, we’ve touched on circumstances where purchasing a remanufactured valve body may be a better choice for you and your customer. Sonnax has you covered with quality solutions here as well. Not only will Sonnax take your extremely worn valve bodies, but we’ll provide you with a limited life-time warranty valve body that comes with significant additional benefits.

Sonnax takes the same systematic approach to remanufacturing valve bodies as we do to developing individual components. Bringing a unit back to OE performance is a multi-faceted process that goes far beyond the parts you put in it. First, the core is thoroughly cleaned and 100% vacuum tested. Then, we use the same Sonnax components you’ve come to trust to bring it back to proper functionality. In many instances, new electronics are installed. However, if we can clean, remanufacture, test and verify the integrity of the original electronics, we will reclaim them in order to pass savings on to you.

Testing Process

The only way to verify that a valve body works is to perform a system check in a vehicle. For that reason, Sonnax invests in test vehicles so we can validate our valve and remanufactured valve body solutions. This vehicle fleet also allows us to use sophisticated data acquisition software to pull real-time drive events from the transmission (Figure 2) to see the various pressures, shift timings, solenoid firing orders and frequencies, etc. This allows us to create a valve body test for our VBT-8000 that simulates comprehensive drive events as accurately as possible (Figure 3).

Figure 2 – The Sonnax test vehicle fleet allows for in-vehicle testing.
Figure 3 – Comprehensive Valve Body Testing

To ensure proper test simulation for Sonnax GM and Ford 6-speed units sold without a TEHCM or solenoid body, we create a slave unit on our test stand. The baseline standard that we set for these tests is a new OE valve body. Every remanufactured valve body is final tested against this OE baseline to ensure that it meets the criteria before being put into stock.

This comprehensive approach ensures that Sonnax remanufactured valve bodies are more than the sum of their parts. Verifying that all electronic and hydraulic components interact with each other correctly in a refurbished casting is crucial, especially in later-model applications with multiple solenoids, numerous valves and clutch-overlap shift timing. As the number of components in a valve body increases, the number of potential interactions between them increase exponentially, which requires a more rigorous system check to ensure all the connections are working correctly. To help shops with the installation and relearn processes, Sonnax includes Tech & Install Tips (Figure 4) with many valve bodies. And because the valve body is part of an even larger transmission system, these tips include other areas to check for drivability complaints that may be falsely attributed to the valve body.

Figure 4 – Tech & Install Tips

So whatever approach is required for your particular job, Sonnax is here to help. From tech resources, diagnostic tools and individual parts to remanufactured valve bodies, you can hit the ground running . When you succeed in winning your customers’ confidence (and repeat business) by getting the job done right and keeping their vehicle on the road, we join in your sense of accomplishment.

While Sonnax makes every effort to ensure the accuracy of technical articles at time of publication, we assume no liability for inaccuracies or for information which may become outdated or obsolete over time.