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700R4 problem - please help diagnose!


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I just rebuilt my '86 700R4 using many new, upgraded parts such as red clutches, 10 vane pump, a Transgo kit, wide 2-4 band, Corvette servo, etc, etc.

 

When cold, it shifts normally. When warmed up, it behaves normally everywhere except at the 1-2 shift, where it wants to rev way out before it shifts. It will, however shift immediately if you lift off the throttle. It also goes into 1st gear around a normal 10-15 MPH turn at an intersection.

 

I've disassembled the entire valve body, checking each plunger for correct assembly and movement. I also double checked all the check balls, gaskets, etc. Everything checked out perfect and a road test showed no change after the checkup/re-assembly.

 

I then tried adding heavier governor springs. The shift points for all gears were earlier (as expected) EXCEPT for the 1-2, which was barely, if at all affected.

 

Transgo tech said I might have a leaking 2-4 servo. I've not yet pulled it apart to check.

 

Fluid is clean.

 

Any ideas?

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Check your TV cable. Also if you can put a pressure gauge and check the main line pressure. There is a tap on the drivers side of the trans for this. It's been a long time since I adjusted mine so I don't remember the steps that well any more. I'll see if I can dig them up in the Monte File tonight. Big J.

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Sorry, forgot to mention, the TV cable is adjusted perfectly. It hit 100% pull at 100% throttle and has the slightest tension at closed throttle.

 

TV adjustment and pressure would affect all gears. Makes me think this couldn't possibly be the issue, especially since other functions that require lots of pressure are working normally.

 

Also, shifts are all very solid and there's plenty of holding power in each, so I don't believe this could be the issue.

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It sounds like the govenor could be the problem .they have different springs for differnt axle ratios.I know you said it shifts of when cold.It could actually be the valve in the govenor not moving freely when it comes up to operating temperature.

Yes I have also seen a cut Oring on the 2-4 servo keep from shifting, in my case it had no second gear frown If something else comes to mind I'll update .

 

mike

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