Is there any "safe" way to get the 700R4 to downshift easier? I always had to really cram the gas to get it to downshift.

The trans has been rebuilt with the TransGo stuff and all the goodies. It has always been like this. It's just now making me crazy...

 

www.tvmadeez.com's TV system 101 seemed to indicate a
short or weak TV spring could cause your problem. This post to
Transmission Talk at www.turbobuick.com by Chris Kokonis on
Jan 17, '03 may also be of some interest. The last line of his post helped me correct the problem I had with my 200-4r, which was a 2nd gear start. It is a little long, but worth reading.


chris718
Senior Member

Registered: Dec 2002
Location: new york
Posts: 712
lets clarify this a little so some dont get confused .the tv plunger comes with the white spring ,not the tv valve .the tv valve is in front of the second rol pin in the plungers bore .i always use the stock spring UNLESS I FIND THAT THE PLUNGER MOVES BEFORE IT CONTACTS THE SPRING .this is unacceptable and should be corrected during rebuilds or servicing .herw is why .the plunger is fed 90 psi of oil .this 90 psi at the plunger is now reregulated to between 0 and 90 psi leaving the plunger to reregulate line pressure at the tv boost valve in the pump .now ,as we know the throttle blades of the throttle body rotate between 0 degrees when closed and 90 degrees at wide open throttle we can understand that for every degree of throttle opening there should also be a corresponding 1 psi in oil pressure entering the modified tv oil circuit where it now controls the pressure regulator system between 90 and 245 psi (roughly )after passing through the line bias valve .also controls tv up and down oil. as you can see it does have a big influence on trans operation. A WEAK SPRING CAN DELAY LINE RISE BY NOT PUSHING ON THE TV VALVE CAUSING NO MODULATED BOOST OIL TO CONTROL PUMP MAINLINE PRESSURE RESULTING IN REDUCED CLUTCH CLAMPING FORCE AT UP TO 25 DEGREES OF THROTTLE OPENING .now if the spring is too long it can cause the vehicle to shift late at lite throttle and also cause rough engagements from park to drive or park to reverse . extreme cases can experience a myriad of kickdown over aggressiveness as well as other crap . the plunger should have .001 of an inch clearance between it and the spring .


__________________
Chris Kokkonis
www.ckperformance.com

 

very interesting, thanks Nordbert. So a slightly heavier spring on the TV plunger would cause a sharper pressure rise, and therefore a downshift to occur sooner?

any trans rebuilders out there have any comments?

 

First, make sure the TV cable is set correctly. If it is near impossible to get a kickdown without flooring it, then I understand. If the transmission downshifts to easily (3-2), it can wear out the band faster due to not having enough line pressure. By the way, throttle blade movement is not 90 degrees, it is approximately 78 degrees. If you want it to downshift easier, and the TV cable is adjusted properly, and it does downshift at near or at WOT, then you could install the "over the center correcter" from Sonnax ($3.00-$5.00). This will give later part throttle shifts and easier downshifts, while retaining the same WOT shift points. There are other ways to do this, but require getting into the transmission.

 

That is the way I see it. A spring that is a little stiffer than stock, but not longer. I wonder if that is what the bootstrap in the
SK series of Transgo shift kits is for. Anyway, if your
line pressure is no more than a couple of psi higher with the
TV cable hooked up than unhooked, you should be OK. The line
pressure on my 200-4r was 130/100 and it had problems
I hope this helps.