braeburn22

Hi

Just had my 700r4 fully rebuilt including hd clutches, .500 boost valve, uprated low/reverse boost valve, billetforward clutch piston and pinless accumulator pistons.

Shifts great through all gears, however shifts at 3800 rpm WOT , the TV cable is set to factory settings, at WOT the cable is tight and is pulled out 1/2 inch at idle.

​​​​​​Could the boost valve be affecting the shift point,. The car has a Corvette governor and it is new.

Manually it holds gear until shifted.

Any ideas for the early shifts

Thanks for any advice.

gerardvg

Hi
The shiftpoint should vary with throttle position, early low rpm shifts with minimal throttle.
High rpm shifts at around 5,500 to 5,700 rpm is the norm, check the TV cable with throttle fully open there should be no slack on the cable.
The TV cable regulates the fluid pressure for firm high rpm shifts at full throttle, smooth low rpm shifts during normal driving.
The governor regulates shiftpoints via weights, it is accessible on drivers side with trans in car just need to remove front exhaust.

Good Luck

Kevova

Governor controls WOT shift point. Governor could be incorrect or faulty. I would refer to builder if you paid to have it done or governor supplier if DIY. If normal shift timing is correct, cable adjustment should be ok.

braeburn22

Thanks for the replies, I'm going to get the rebuilder to check the governor

It was new, but that is no guarantee that it is will work properly, is there any possibility that the higher pressure in the transmission from the uprated boost valve could effect the WOT shift point.

Kevova

Shouldn't unless it's not operating correctly. Builder needs to do pressure test to see what's going on. Then go from there.

C409

….. B&M sells a governor calibration kit that has a variety of springs and weights in it … I had to re-cal mine when I built my 700R4 … its a time consuming process but necessary to get the shift points where you want them … the governor is on the drivers side under a "derby hat" shaped cover … when the cover comes off , you will get some ATF out … how much depends on how high the front of the car is vs the rear … pry it off with screw drivers and push it back on with a piece of wood wedged against the trans tunnel … as l recall there's an o-ring seal on the cover … when you get it where you want it , take the cover off and seal it up good … don't dent the top too much or it will contact the governor and strip the plastic drive gear …..

RichS

I agree that you need to play with the weights and springs in the governor. It takes awhile but mine shifts at 62-6400.

383vett

When I had a 700r4 I spent a lot of time fine tuning the springs and weights to get the correct shift points on the track and also the street. Lighter weights will raise your wot shift points. Lighter springs more for part throttle, but they are both affect part and full throttle shifts. Takes a lot of patience, If you lift just the driver's side and place jackstands, the oil will drain out of the cap and governor recess and you will not lose any oil. Ultimately, I found it easier to change to a 4l60e and control ;shift points with a laptop. Good luck.

Gibbles

I found it easier and more enjoyable to shift manually...
i have it setup so i can shift into 4th @60 mph, and hold the gear pretty solid unless wot.
all fun driving is via manual shift now.