Transmission Gurus, sponsors, anyone?! TH400 problem
07-19-2010, 09:23 AM
#1
Transmission Gurus, sponsors, anyone?! TH400 problem I keep having shifting problems ever since I went to this TH400 and electric shifter setup, so after doing more testing and logging IT HAS TO BE SOMETHING IN THE TRANSMISSION.
I can drive the car on the street and it will shift fine and on time. It's a fully built TH400 with a BTE RMVB (Transbrake). I just had it completely rebuilt about a week ago even though there was nothing wrong, I had the guy go ahead and replace the clutches.
Now onto the problem. I'm running the shiftnoid SN5070 electric shifter setup with an MDS 8950 activation. The shifter and everything is shifting correctly. I've adjusted it countless times and it's working great.
Now, like I said earlier. When I drive the car down the road under normal throttle it shifts fine and dead on.
When I'm at the track and go wide open, 1st to 2nd doesn't shift until 6700-7200 but going from 2nd to 3rd it shifts correctly at 6300.
I have a 6200 chip in the MSD activation box.
Could something be wrong with the valve body? Why would it shift so late in low and correctly into high?
I just didn't want to buy a valve body and be out the money if that wasn't the case.
I can drive the car on the street and it will shift fine and on time. It's a fully built TH400 with a BTE RMVB (Transbrake). I just had it completely rebuilt about a week ago even though there was nothing wrong, I had the guy go ahead and replace the clutches.
Now onto the problem. I'm running the shiftnoid SN5070 electric shifter setup with an MDS 8950 activation. The shifter and everything is shifting correctly. I've adjusted it countless times and it's working great.
Now, like I said earlier. When I drive the car down the road under normal throttle it shifts fine and dead on.
When I'm at the track and go wide open, 1st to 2nd doesn't shift until 6700-7200 but going from 2nd to 3rd it shifts correctly at 6300.
I have a 6200 chip in the MSD activation box.
Could something be wrong with the valve body? Why would it shift so late in low and correctly into high?
I just didn't want to buy a valve body and be out the money if that wasn't the case.
07-19-2010, 10:57 PM
#2
The gearing in low gear allows the engine to rev much faster than in 2nd, so the engine is going past the shift point before the actual shift occurs.
This is why at part throttle it is perfect but at WOT you see the additional rpm's.
You may have excessive clutch pack clearance in the intermediates, some clutches that don't grab quick, or other build issues.
IIRC the BTE RMVB is the same design as the TCI and they both have a pretty long circuit for 2nd, which doesn't help.
Also,
2nd gear oil has to fill the backside of the servo, which takes considerable oil volume before it makes a shift. A dribbler hole feeding drive oil to the 2nd circuit would help.
This is why at part throttle it is perfect but at WOT you see the additional rpm's.
You may have excessive clutch pack clearance in the intermediates, some clutches that don't grab quick, or other build issues.
IIRC the BTE RMVB is the same design as the TCI and they both have a pretty long circuit for 2nd, which doesn't help.
Also,
2nd gear oil has to fill the backside of the servo, which takes considerable oil volume before it makes a shift. A dribbler hole feeding drive oil to the 2nd circuit would help.
