4R100 Importance of Vacuum Testing.

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Hi Fellas.
I wanted to share some wisdom. Something that many transmission shops, builders and owners attempting to rebuild their transmission, is Critical Wear Area vac um testing. Failure to perform this crucial step is guessing that the transmission won’t fail in short order, or not get properly diagnosed.
Wear in valving, joints and hydraulic passages causes a whole host of terrible problems. Wear and leaks can be difficult to see and identify but they cannot hide from properly performed vacuum testing.
If you plan on diagnosing and repairing the transmission the correct way, vacuum testing is a must.
Sonnax offers a vacuum test stand through a number of different distributors. Sonnax’s website offers free downloadable and printable critical wear area diagrams.
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co04cobra

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Thank you for sharing the info. Also this reiterates how difficult it can be for “normal” rebuilds to have this level of thoroughness. Also would lead me to believe it’s why you hear those horror stories of constant repeat failures.
 
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It’s exactly why. Those guys just tear it down and put it back together like a puzzle and treat it as if it was a two year old transmission that some guy tried pulling a load that was way way too heavy across the country and back. No failure analysis and no testing. These things are over 20 years old now. Valves and other components have hidden wear that led/lead to to failure. These guys put these things back together like a puzzle and they really think they some thing special. Half of them do things that you should never do and or miss crucial steps and some of these guys have large business. That guy down in Texas with all of the videos and the Transmission Bench video guy are downright terrible. They are not the only ones out there by any means on the same par.

Always ask yourself why this failed. Do the analysis to find the cause of it. ALWAYS do vacuum testing on critical wear areas of hydraulic components. Wear can not hide from vacuum testing and that gauge does not lie.
 

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