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Old 03-06-2013, 12:34 AM   #12
Stepside Jim
Registered User
 
Join Date: Aug 2012
Location: Salem Mo
Posts: 648
Re: Turbo 350 passing gear or more accurately wont pass...

Yes, the picture is upside down. When you pull on your cable, you should feel like a two stage spring. I'm referring to as you pull the slotted end of the cable, you will feel a slight resistance, then as you pull the last 3/4", the spring tension may have a stiffer spring resistance.

If you feel both stages, you're pretty well working the full motion of the detent valve.

One item that could also give a problem is the modulator valve. If the transmission is shifting fine this may not be a problem.

On the other hand, the modulator valve reads the manifold using the vacuum line off the intake. As you push down the throttle which inturn pulls the detent cable, the manifold vacuum drops. The manifold vacuum loss is read by the vacuum modulator, this loss of vacuum tells the transmission that the engine is working under a load, meaning, it maybe time to down shift.

As you go under the vehicle, pull the vacuum line off the modulator valve, sometimes as it goes bad, the diaphram leaks and you'll have transmission fluid drip out of the vacuum line. This could be a quick check to see if the modulator valve might be giving you problems also.

Hope this helps... Jim
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