Quote:
Originally Posted by 1986nate
The earliest failures were from bad torque converter linings which were prone to "wearing" quickly and particles getting clogged in the screen, causing a lack of flow, lack of pressure, therefore causing slipping, causing heat and the process quickly got out of hand causing failures The very earliest 92's also had low/reverse clutches/drums that were much to small leading to reverse failures.
Most of the holes drilled in the later transmissions were actually in the clutch drums/hubs and not the valve body to allow more fluid to reach the friction discs in the clutch pack. Keeping them lubricated and working better. Also, by the time the 95+ were around, the word was out to watch the transmissions. Fluid/filter changes were kept more aware which also leads to longer transmission life.
All in all, there are a huge number of factors and variables.
They also had no reason to believe there would be transmission issues. It was the same basic transmission that had already been out for a few years in their other models without a high catastrophic failure rate. They used the existing design but upgraded the amount of clutch packs which in theory should have worked. The same 4eat are used in all other subarus of the 90s that go well into the 200k+ mile range and much higher with transmissions that are technically weaker than the SVX one. Keep that in mind.
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It was the faulty Converter clutch facings that sealed its fate. Their reluctance to do a recall at that time, allowed it to become widespread.
This cooler flow problem had nothing to do with line pressure. This oil is returned to the mainshaft for cooling and lubricating the gear trains that overheated with out it, causing the early failures.
Quote:
Originally Posted by Huskymaniac
If I hear you correctly, there is no benefit to opening up the valve bodies on the new trannies (post-1994). Is that correct? If not, and there is a benefit, my real question is, why wouldn't they have opened them up? Is there a tradeoff by opening up the valve bodies?
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First, Subaru did not design this box; it was Jatco's box that Subaru used for their application.
The holes that are drilled out larger, are the restrictor holes that have more to do with the timing of the operation of the clutches. These are used to slow the speed of engagement, to make it operate smoothly. Opening these will allow faster, but rougher operation.
An example is in the restrictor plate behind the C solenoid/transfer assemble. The restrictor holes there slow the engagement of the transfer clutch so that it does not engage with a bang, but because of it, it lets the front wheels start spinning before the clutch engages to drive the rear.
Harvey.