Escaping Transmission Purgatory

[markz]

Y'all might remember that twice in a row my fresh transmission went forward in all gears.  Very frustrating to say the least!

I am now confident the transmission is now fixed.  Just needs to be reinstalled.

I did find the root cause.  I should of pushed harder to find the problem the first time.  Make a long story short, the wrong reaction support was installed in it.  The internals are 71-77, and a 78 reaction support got installed.  The 78 reaction support used 3 sealing rings instead of 2, and the porting is different.  The rear clutch (that makes the car go forward) port output location was changed to the face instead of inside the support between the two sealing rings.  The rear clutch never saw fluid from the valve body as that port was effectively blocked off.

So would have expected no forward gears.  But what caused the car go forward in all gears is that the converter feed port now has 2 additional ports between the 2 sealing rings.  So the rear clutch saw converter pressure at all times hence the car moving forward in all gears.

The contamination had to be the clutches fighting each other when the rear clutch was engaged and it wasn't supposed to.

Live and learn.........

[65rbdodge]

Wow! Glad to hear you got it sorted out. It sounds like that was a difficult problem to find. I’m going to tackle a rebuild on a 46re this winter. Beyond installing a shift kit and swapping valve bodies I’ve never been inside an automatic.

[67440Dodge]

Lets hope 3rd time is a charm...

I hate automatics with a passion, esp the new ones that are "sealed" with no dipstick... found out mine came from factory quart low on fluid (no leaks) despite fact 2 other dealers and 3 trips said it was full. But since I had it checked at Canadian dealer, Canada Ram wouldn't honor the warranty, don't ask what a quart of 8/9 speed ATF costs, or what the dealer charged to install it.

[markz]

Wow! Glad to hear you got it sorted out. It sounds like that was a difficult problem to find. I’m going to tackle a rebuild on a 46re this winter. Beyond installing a shift kit and swapping valve bodies I’ve never been inside an automatic.

I was always very intimidated by the automatic transmissions. But the 727 is actually quite simple. I read the Carl Munroe book and watched disassembly of a couple. I am ready to tackle it myself next time.

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Lets hope 3rd time is a charm...

I hate automatics with a passion, esp the new ones that are "sealed" with no dipstick... found out mine came from factory quart low on fluid (no leaks) despite fact 2 other dealers and 3 trips said it was full. But since I had it checked at Canadian dealer, Canada Ram wouldn't honor the warranty, don't ask what a quart of 8/9 speed ATF costs, or what the dealer charged to install it.

I'm about to change the trans fluid in my 2012 Caravan. Same crap - no dipstick. What were they thinking?

[67440Dodge]

I'm about to change the trans fluid in my 2012 Caravan.  Same crap - no dipstick.  What were they thinking?

From what I heard, the moisture and dust coming in thru the dipstick tube was contaminating the newer fluids they were using, so they went to a sealed transmission.  Only way to check/fill it is like a manual trans, thru a plug in the side.  Even Volvo big rigs didn't have a dipstick tube for their transmissions.

Be thankful you still have a conventional pan/filter setup.. for a 8 speed ZF trans, the pan and filter are all one setup, and costs anywhere from $3-400 just for the pan/filter.  And depending on the size pan you have, it's 8 quarts at $35 a pop.. 

Funny thing.. my 2014 8 speed supposed to get changed at 100K miles...  my 2022 is "lifetime", never needs changing.. riiiiiighht...

[markz]

So the Caravan has a dipstick tube just no dipstick. You can buy a dipstick. Thankfully.