# TH400 Shift Points



## GTO JUDGE (May 14, 2005)

What are the correct sift points in MPH for a TH400?
Having my shift points adjusted and want to zero them in to where they ought to be.

1-2nd about 15 mph?
2-3rd about 35 mph? 

3:55 geared rear end

This seem right? 

Thanks!


----------



## jetstang (Nov 5, 2008)

I think it's more RPM related then MPH. If they can set your shifts for slow and hard acceleration, I would figure out where the engine is happy, if it is cammed up you may want the shift points at a higher rpm than a mild motor. I would say about 2500-3000 RPMs in slow mode would be good. Too low and it will just bog and not be happy.


----------



## GTO JUDGE (May 14, 2005)

jetstang said:


> I think it's more RPM related then MPH. If they can set your shifts for slow and hard acceleration, I would figure out where the engine is happy, if it is cammed up you may want the shift points at a higher rpm than a mild motor. I would say about 2500-3000 RPMs in slow mode would be good. Too low and it will just bog and not be happy.


Manually the car seems to like 2800-3,000 RPM which is about 20mph when going 1-2nd

and 2-3rd 35-40 MPH at 2800-3,000RPM

Was checking to see if this seems right.

2800-3,000 rpm shifting seems right to me but wanted opinions.

Thanks


----------



## geeteeohguy (Feb 2, 2008)

You've got a governer and a modulator that determine when it shifts. The more throttle, the more line pressure, and the later the shift. You can adjust some modulators for a later or earlier shift. At light throttle, it will shift into second at 15mph or so. At full throttle, with your gear, more like 40= mph. My 2.56 geared '67 GTO with TH400 shifts into drive at about 30mph under light load, and under full throttle, it shifts into drive at 105mph. Big difference.


----------



## 66tempestGT (Nov 28, 2009)

my st300 would shift out of low at 70 mph at full throttle. but the old 326 quit pulling at about 60 mph. it took a long time to get that last 10.


----------



## GTO JUDGE (May 14, 2005)

Finally got to the bottom of the TH400 shift range/hard shift issue.
Met a fellow at the Performance Years Open House who knows these transmissions inside and out. Spent a Sunday at his place while he preformed surgery, will share this fix for those who may be experiencing hard shifts or quick or delayed shifts. In my case:

The resolution was in the valve body. For the sake of racing, someone altered the valve body and installed a sift kit. While doing so they installed more check balls than necessary and one necessary check ball was missing. A spring hosing valve was undersized, an incorrect 2-1 downshift valve installed causing the downshift at any mph, separator plate had a few too large of holes, the 2-3 Accumulator puck was upside down, Vacuum modulator valve was sticking. A different governor was installed, A filter cone was installed in the wrong location. Someone not knowing what the hell they were doing got their lunch hooks on it, I wonder if the car ran well enough to win any races.

After this was corrected I noticed increased torque from the tranny, the harsh shift was drastically reduced, when I ratchet shift while getting on it, I am chirping in 1-2 2-3 instead of just 1-2. Shifting at 5000 RPM the car is beastly. Kickdown now engages abut 45mph at 4,000 rpm, before it was kicking in at 35. When it kicks in now the car launches to a different stratosphere. 

Just some food for thought for someone looking for solution to a similar problem that has them stumped.


----------



## likethat (Oct 5, 2007)

I hope the clutch packs didn't get the PO's skinners on them.


----------



## GTO JUDGE (May 14, 2005)

The original clutch packs were toasted. Black as can be. Everything looks good. Transmission when I got it kicked a$$. I couldn't believe it ran when I seen the insides of it. These things really are bullet proof.


----------

