4L80E high line pressures - now stalling in gear again
04-30-2016, 11:39 AM
#1
4L80E high line pressures - now stalling in gear again **Update in post 6 and 7**
The 4L80E in my Camaro has been fitted with the Transgo HD2 shift kit (with the exception of the pressure relief valve and the pump modifications), and also the Sonnax 34200-14K line to lube valve.
Every shift is very harsh - it shifts fine just way too hard for a predominantly street car
The line pressures at idle are as below, and I know that the PC solenoid is working as I could vary these by changing the duty cycle via my transmission controller.
Park 120psi
Neutral 125psi
Reverse 280psi
Drive 180psi
3rd 175psi
2nd 175psi
1st 175psi
These seem a lot higher than the stock transmission.
It also has Alto power packs in 1st, 2nd and 3rd, and red eagle clutches in all others. Wider carbon band, new sprags, billet input shaft and clutch hub.
I can't remember what size I drilled the plate - but sure it was only the mid setting, about .086" from memory.
A little help would be great
I just want to tone it down a bit from where it is now. What has the biggest effect on the shift firmness
The 4L80E in my Camaro has been fitted with the Transgo HD2 shift kit (with the exception of the pressure relief valve and the pump modifications), and also the Sonnax 34200-14K line to lube valve.
Every shift is very harsh - it shifts fine just way too hard for a predominantly street car
The line pressures at idle are as below, and I know that the PC solenoid is working as I could vary these by changing the duty cycle via my transmission controller.
Park 120psi
Neutral 125psi
Reverse 280psi
Drive 180psi
3rd 175psi
2nd 175psi
1st 175psi
These seem a lot higher than the stock transmission.
It also has Alto power packs in 1st, 2nd and 3rd, and red eagle clutches in all others. Wider carbon band, new sprags, billet input shaft and clutch hub.
I can't remember what size I drilled the plate - but sure it was only the mid setting, about .086" from memory.
A little help would be great
I just want to tone it down a bit from where it is now. What has the biggest effect on the shift firmness Last edited by gothic_sera; 05-01-2016 at 02:55 PM.
05-01-2016, 02:44 AM
#2
I'm guessing that as 170psi is max line pressure I have a problem with my pressure regulator or PCS.
I'm not using a standard controller, so there are no DTCs or way of getting them
In park I can vary the line pressure from the controller, so I expect this tells me the PCS is working ok.
Is the only other thing which controls line pressure in drive the pressure control valve in the pump?
I'm not using a standard controller, so there are no DTCs or way of getting them
In park I can vary the line pressure from the controller, so I expect this tells me the PCS is working ok.
Is the only other thing which controls line pressure in drive the pressure control valve in the pump?
05-01-2016, 05:47 AM
#3
Pressures do seem high for idle, I remember reading mine a few years back they were lower-my thought was were you using a stock converter, it would def bang, but I saw your thread, you had one made.
I thought Sonnax made a valve to help reduce pressure, but I would have to
look it up-I have used a couple HD-2 kits, with a high stall conv. the shifts felt light, even with high pressure commanded.
By the way, super build on the car
I thought Sonnax made a valve to help reduce pressure, but I would have to
look it up-I have used a couple HD-2 kits, with a high stall conv. the shifts felt light, even with high pressure commanded.
By the way, super build on the car
05-01-2016, 07:40 AM
#5
I have the same prob with a built 4l60e. Sounds crazy but lowering the tire pressure 10 lbs made it much more streetable and with 4:10's and 11 in wide wheel it still has a crisp throttle response. I'm leaning towards different types of trans fluids now. I have read there are some really thick tranny fluids out there made for heavy duty trucking that will change a stall converters feel and even stall rpm.
The new synthetic fluid is very slippery compared to dextron 3(builder advised}. I have read of someone mixing the two together till he got the feel he wanted.
Mine is making its shifts too high at low speeds not shifting till after the throttle is backed off almost totally then bang!
I'm getting HP tuners this week. Ill see what I can do with that changing pressure and shift points. I would think part throttle shifts would get much smoother if I can get them to come in at much lower speeds.
The new synthetic fluid is very slippery compared to dextron 3(builder advised}. I have read of someone mixing the two together till he got the feel he wanted.
Mine is making its shifts too high at low speeds not shifting till after the throttle is backed off almost totally then bang!
I'm getting HP tuners this week. Ill see what I can do with that changing pressure and shift points. I would think part throttle shifts would get much smoother if I can get them to come in at much lower speeds.
Last edited by handyandy496; 05-01-2016 at 07:53 AM.
05-01-2016, 10:23 AM
#6
Thanks guys. I'm starting to regret the decision of a 4L80 right now....
Fixed this issue only for more to raise their head. Not sure what fixed it, but I now have proper control of the line pressure from my controller.
Long story, but the short version is...
When I first installed the transmission the engine would stall as soon as you put it in gear. I fixed that with a Sonnax line to lube pressure valve. That seemed to fix the problem.
Today the problem is back, but not quite as bad. If I come to a stop very gently the motor will keep running. Stop any quicker and it dies, feels exactly like if you don't depress the clutch with a manual transmission.
My converter was rebuilt by a reputable shop in the UK. And I have replaced the TCC solenoid.
I should also say I can't really feel the converter lock up, my controller is telling it to, but I see no change in RPMs. I'm wondering if I have something else wrong in the TCC hydraulic circuit causing the converter to lock up. When it shouldn't be as I don't really seem to have much converter slip either...
Fixed this issue only for more to raise their head. Not sure what fixed it, but I now have proper control of the line pressure from my controller.
Long story, but the short version is...
When I first installed the transmission the engine would stall as soon as you put it in gear. I fixed that with a Sonnax line to lube pressure valve. That seemed to fix the problem.
Today the problem is back, but not quite as bad. If I come to a stop very gently the motor will keep running. Stop any quicker and it dies, feels exactly like if you don't depress the clutch with a manual transmission.
My converter was rebuilt by a reputable shop in the UK. And I have replaced the TCC solenoid.
I should also say I can't really feel the converter lock up, my controller is telling it to, but I see no change in RPMs. I'm wondering if I have something else wrong in the TCC hydraulic circuit causing the converter to lock up. When it shouldn't be as I don't really seem to have much converter slip either...
05-01-2016, 02:55 PM
#7
I'm convinced I have a TCC lock up issue - looking at the datalog from a drive, when the TCC is commanded to be locked by the controller, it doesn't (or it already is). There's no change whatsoever in RPM.
I'm also seeing virtually no slip in the converter (comparing RPM to input shaft speed),
I'm also seeing virtually no slip in the converter (comparing RPM to input shaft speed),