700R4 shifting problems
 

ok took my beater 82 corvette out for a ride last night, :hurray: first night out since getting it started, some one replaced the TBI with a holley 600/and intake, the wrong bracket in back of the carb i think tv cab need an adjustment/ new bracket............ first gear take a long time to shift into second like 35mph...........thanks for the help......let the project begin :steering:

Re: 700R4 shifting problems (bnytro)
 

First of all most the factory throttle valve cables have a ratcheting housing. So if its adjusted too tight initially it will automatically adjust when you floor the throttle. Have you tried pressing the throttle to the floor to see if it ratchets out to the correct adjustment? You can do it with the engine not running. Second, if its adjusted too loose then that would cause a early and spongy shift. Are you getting a late shift that is really harsh? If so I would suspect that maybe the throttle valve itself is hanging up in its bore. This would be inside the valve body of the trans itself. Crud or whatever can get in there and cause it to hang up and not return to its resting position when you let off the gas. When this happens the transmission is thinking that you have the gas floored and thats why it shifts so late. There is a spring behind the TV valve thats supposed to push it back. Many aftermarket shift kits have you install a spacer or a hevier spring to help prevent this common problem of sticking TV valve. To clean the TV valve the pan would have to come off and the valve body removed. Then you will see a sear pin that holds the TV valve and its bore in the valve body. Remove the pin and remove the TV valve and its bore. Thuoughly clean the TV valve and bore and gentally sand the TV valve with some very fine sand paper like 600grit. This will help clean any burrs away that might be causing it to hang up.

Re: 700R4 shifting problems (bnytro)
 

This may or may not help you with your problem but it has at least a little something to do with it.
I rebuilt a 700r4 for a friend and after he reinstalled it he called me to say that it was shifting really late and sometimes wouldn't upshift. It would shift up throught the gears correctly at first (one or two times) then really late or no 1-2 shift. I was purplexed. The trans was perfect. No reason, I thought, for this to happen. So he and I dropped the pan and I rechecked the valvebody configuration. It was perfect. Then I remembered I had reinstalled the failsafe checkball on the rebuild. So I checked the TV cable at the carb and found that he left it loose. Thinking he would adjust it incrimentaly during test drives. I told him he shouldn't do it that way, and we adjusted the cable. It should have been the first thing I checked before pulling the pan. But I guess I had more faith in his abilities. After we put it all back togetter and filled it up, we both took it for a drive. It worked perfectly.
Some of the early 700R4's had a failsafe checkball under the TV bellcrank on the valvbody. Its purpose was to block the vented fluid from the backside of the TV valve should the TV cable break. What this did was increase the TV line presure to near maximum to prevent the owner from continueing to drive the vehicle in a low line presure condition, burning up the clutches. When you have high TV presure like that it makes the the shifts realy late and in some cases will not upshift.
If the failsafe checkball is not installed, then you will get soft/early upshifts with a loose/slack TV cable.
So I guess this means check the TV cable adustment, and get it right.


[Modified by arrio76, 8:55 PM 8/14/2003]

Re: 700R4 shifting problems (bnytro)
 

Should you be able to feel it shift down in to first (eg slowing down to a red light)? I had my cable adjusted a fair way up (extended toward the front of the car) and I had to nail it to get it to shift into 3rd. I'm figuring the more adjustment the more you feel the up and down shifts.

Re: 700R4 shifting problems (Chris O')
 

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