GM TH400 Auto Transmission Governor Shift Points Setup using TCI Governor Kit

GM TH400 Auto Transmission Governor Setup using TCI Governor Kit

Pontiac Firebird 455 V8 with TH-400, using TCI governor kit to change the shift points.
Kit contains weights and springs for the governor, to change WOT shift RPM in "D".
Governor easily removed from the side of the transmission in a few minutes with 4 bolts, for changes to weights or springs.
On this particular car I'm aiming for 1-2 shift @ 5,000 to 5,200 RPM, 2-3 Shift @ 4,700 to 5,000 RPM.

TCI Governor Kit Contents and Tuning

TCI Weights
Earlier Shifts <-----------------------------------------------------------------------------------> Later Shifts
Heavy Weights <-------------- #1 - #2 - #3 - #4 - #5 - #6 ---------------> Light Weights

TCI Springs
Low RPM Quick Shifts <---------------------------------------------------------------------> Shifts Spread Apart
Heavy Springs <----- Purple - Blue - Green - Yellow - Orange - Red -----> Light Springs

Results so far, tuning still in progress, changes at each step highlighted:

	Governor Setup				Results
	Weight #1	Spring #1	Weight #2	Spring #2	1-2 Shift @ WOT	2-3 Shift @ WOT	Comments
Stock #34 Governor	Stock	Green	Stock	White	3,500	3,500	Solid 1-2 shift, 2-3 very mushy. Changes 1-2-3 very quickly at part throttle, doesn't hold the gears at all.
Step 1	Stock	TCI Yellow	Stock	White	5,000	3,500	1-2 shift perfect. 2-3 shift very mushy as before.
Step 2	Stock	TCI Yellow	TCI #2	TCI Orange	5,000	3,700	1-2 unchanged. 2-3 now very firm.
Step 3	Stock	TCI Yellow	TCI #4	TCI Orange	5,000	4,200	1-2 unchanged. 2-3 excellent shift @ WOT. Very responsive part throttle driving, best so far.
Step 4	Stock	TCI Yellow	TCI #6	TCI Orange	5,500	4,900	1-2 shift now too high. 2-3 shift is perfect.
Step 5	TCI #3	TCI Yellow	TCI #4	TCI Orange	3,300	4,700	1-2 way too low. 2-3 is perfect.
Step 6	TCI #5	TCI Yellow	TCI #4	TCI Orange	5,500⁺	4,700	1-2 did not shift. 2-3 perfect.
Step 7	TCI #4	TCI Orange	TCI #5	TCI Yellow	5,000+ 3,500	4,800	1-2 did not shift. 2-3 perfect. Drove it again, results inconsistent. Shifted at about 3,500 WOT 1-2 on the second drive.
Step 8	TCI #4	TCI Yellow	TCI #3	TCI Orange			Springs to be swapped

Last updated 23 Jan 2007

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