DMan
buh bye
- Joined
- May 25, 2001
- Messages
- 499
Hello,
warning - long post!
My transmission doesn't want to downshift to 1st gear when I slow to a stop, once the car has warmed up. When the car is cold, it downshifts fine. This tranny was rebuilt around July-August 2003 timeframe. Maybe driven 500 miles since the rebuild.
I have searched the board for similar issues and came up with the this very informative thread started by Squeeze87: http://www.turbobuick.com/forums/showthread.php?s=&threadid=25247&highlight=downshift
Squeeze solved his problems by replacing the modified separator plate with an unmodified factory plate, however there were a number of other possible root causes identified in the discussion. I summed them up below:
- getting full line press. all the time
- either the governor is being flooded or that the governor is not sealing
- check balls [not] sealing off on the governor shaft.
- if pressures were just increased ( like shift kit installed or PR valve and/or spering changed) and the govenor still has the primary weight spring
- band too tight
- a spool in the 1-2 shift valve bore ( not the one with the spring on it ) put in backwards
- 1-2 shift valve sticking
- crossleak to servo port somewhere
- check ball problem?
- relief spring in the pump too stiff or binding
- different boost valve and TV setting is wrong
I know that my tranny has a modified plate of the rebuilder's own design, and I think it has larger 1/2" 'boost' valves, whatever those are. Also, some holes in the governor were created/enlarged to raise shift points a bit (they are now around 5300 which is fine). Of course, all the requisite clutches and bearings were replaced, along with a new billet drum, but I don't think those have a bearing on this issue. Unfortunately I don't recall everything that was done to my transmission, and bringing it back to the same builder isn't convenient.
What I would like help with is the following:
a) to prioritize the above possible causes (and any others not mentioned)
b) what procedures can I attempt myself (reasonably handy - just installed a new set of ported heads).
c) finally, suggestions for tranny builders in the local Boston area to attempt the more involved procedures.
Regards,
Denis Kefallinos
warning - long post!
My transmission doesn't want to downshift to 1st gear when I slow to a stop, once the car has warmed up. When the car is cold, it downshifts fine. This tranny was rebuilt around July-August 2003 timeframe. Maybe driven 500 miles since the rebuild.
I have searched the board for similar issues and came up with the this very informative thread started by Squeeze87: http://www.turbobuick.com/forums/showthread.php?s=&threadid=25247&highlight=downshift
Squeeze solved his problems by replacing the modified separator plate with an unmodified factory plate, however there were a number of other possible root causes identified in the discussion. I summed them up below:
- getting full line press. all the time
- either the governor is being flooded or that the governor is not sealing
- check balls [not] sealing off on the governor shaft.
- if pressures were just increased ( like shift kit installed or PR valve and/or spering changed) and the govenor still has the primary weight spring
- band too tight
- a spool in the 1-2 shift valve bore ( not the one with the spring on it ) put in backwards
- 1-2 shift valve sticking
- crossleak to servo port somewhere
- check ball problem?
- relief spring in the pump too stiff or binding
- different boost valve and TV setting is wrong
I know that my tranny has a modified plate of the rebuilder's own design, and I think it has larger 1/2" 'boost' valves, whatever those are. Also, some holes in the governor were created/enlarged to raise shift points a bit (they are now around 5300 which is fine). Of course, all the requisite clutches and bearings were replaced, along with a new billet drum, but I don't think those have a bearing on this issue. Unfortunately I don't recall everything that was done to my transmission, and bringing it back to the same builder isn't convenient.
What I would like help with is the following:
a) to prioritize the above possible causes (and any others not mentioned)
b) what procedures can I attempt myself (reasonably handy - just installed a new set of ported heads).
c) finally, suggestions for tranny builders in the local Boston area to attempt the more involved procedures.
Regards,
Denis Kefallinos
