pwrtrip75

iTrader: (8)

This is the first time i've ever used a stock valve body in an automatic and wanted to try having a car actually shift automatically.

This is a complete rebuilt TH400, stock valve body with a Transgo valve body recalibration kit.


If I leave it in drive it hits the rev limiter and takes a few seconds to shift.
On 8psi of boost it shift late and wants to do this. On 14psi its wont shift till i let off and get back into it.


Ive ordered the Transgo boost check valve but hasnt showed up yet.
Will this likely fix it? Im kinda skeptical. Can anyone share what else might need to be done? Ive read people talking about doing other things to get these to shift under boost but they didnt actually say.

Gearstar Performance

The transgo boost check valve should fix your problem. Reason being, the vacuum modulator normally has vacuum affecting it but with boost pressure, it must be bled off under high boost conditions which is what this check valve does.

pwrtrip75

iTrader: (8)

Thanks. This boosts my confidence a little, i'll quit looking at manual valve bodies untill I get that chack valve in.

pwrtrip75

iTrader: (8)

Ok. The Transgo boost check valve does not work. 8psi of boost it works, 14psi not so much, 18psi hell no. I was told the boost check valve will not work at 800hp or more. Is there a cure to this to get the trans to shift automatically?

Jake's Performance

iTrader: (2)

The TransGo recalibration kit runs into issues on the TH400 at 500 or more HP, so that's your first problem.

You may need two of the check valves in line to bleed off pressure and make it work right.

pwrtrip75

iTrader: (8)

So manual valve body it is.