TH700R4 working fine after rebuild, except no kickdown
05-16-2017, 04:49 PM
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TH700R4 working fine after rebuild, except no kickdown
Hello guys !
I recently had my original 1988 TH700R4 rebuilt and slightly upgraded :
* Alto red clutch packs (original 3-4 clutch pack was burnt out)
* Reinforced Sun Shell (the splines had separated on the original one)
* 10 vanes HP pump
* Stronger HP pump spring
* Kevlar band
* Sonnax Super Hold Servo system
* Brand new torque converter (1700 stall, didn't want to go higher as I was satisfied with the original 1400 rpm stall)
After rebuild and reinstalling the transmission on my 1988 Iroc-z 350 TPI, at first I could not get 3rd and 4th gear. I removed the valve body, the guy that rebuilt the tranny reworked it a little bit, then I reinstalled the valve body in the transmission. He took profit of this to install a new TV valve. I have the pic somewhere, just tell me if you need it
Now the gearbox is working fine at part throttle, all the gears are coming on and off as expected.
The only problem is that I have no kickdown. Each time I bottom the throttle pedal, the engine revs up to around 3000 rpm, but wont downshift any gear. The car will accelerate, but the gearbox keeps the currently engaged gear.
I've tried several times to set the TV cable, but it's been of no help. The line pressures have been checked and are good (higher than original because of the new HP pump spring)
Does anybody here have an idea of what's going on and how I could sort this out ?
I don't understand anything about what's going on. The tranny works real fine at part throttle, but it's a totally different story at WOT. I took the decision not to use it anymore so far, as I don't want to burn anything else.
Thanks a whole lot for your help guys !
I recently had my original 1988 TH700R4 rebuilt and slightly upgraded :
* Alto red clutch packs (original 3-4 clutch pack was burnt out)
* Reinforced Sun Shell (the splines had separated on the original one)
* 10 vanes HP pump
* Stronger HP pump spring
* Kevlar band
* Sonnax Super Hold Servo system
* Brand new torque converter (1700 stall, didn't want to go higher as I was satisfied with the original 1400 rpm stall)
After rebuild and reinstalling the transmission on my 1988 Iroc-z 350 TPI, at first I could not get 3rd and 4th gear. I removed the valve body, the guy that rebuilt the tranny reworked it a little bit, then I reinstalled the valve body in the transmission. He took profit of this to install a new TV valve. I have the pic somewhere, just tell me if you need it
Now the gearbox is working fine at part throttle, all the gears are coming on and off as expected.
The only problem is that I have no kickdown. Each time I bottom the throttle pedal, the engine revs up to around 3000 rpm, but wont downshift any gear. The car will accelerate, but the gearbox keeps the currently engaged gear.
I've tried several times to set the TV cable, but it's been of no help. The line pressures have been checked and are good (higher than original because of the new HP pump spring)
Does anybody here have an idea of what's going on and how I could sort this out ?
I don't understand anything about what's going on. The tranny works real fine at part throttle, but it's a totally different story at WOT. I took the decision not to use it anymore so far, as I don't want to burn anything else.
Thanks a whole lot for your help guys !
Last edited by GhostRider_fr; 05-16-2017 at 04:52 PM.
05-17-2017, 02:39 PM
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Car: check
Engine: check
Transmission: check
Re: TH700R4 working fine after rebuild, except no kickdown
The TV valve is depressed via the TV plunger, that being depressed via the TV cable to the TB/carb. Since the TV valve was out so was the TV plunger.
The TV plunger and bushing has the detent port for part throttle downshifts. IIRC, the plunger and bushing can be removed without dropping the VB.
RBob.
The TV plunger and bushing has the detent port for part throttle downshifts. IIRC, the plunger and bushing can be removed without dropping the VB.
RBob.
05-17-2017, 03:26 PM
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Re: TH700R4 working fine after rebuild, except no kickdown
Thanks !
Will replace the sleeve + plunger + spring next week.
Here included is a picture of the TV Valve that's been installed in my valve body. I know it's an upgrade of the original one, but I don't know from which manufacturer it comes from.
My original TV valve is the silver one, the currently installed valve is the black one.
Anybody has another idea ?
Thanks a lot in advance for your help !
