TH-400 help

[Shannen Durphey]

Possibly someone can :)

Jennifer and Brock Fraser wrote:
> 
> Possibly someone can help me with a TH-400 application.  I haven't ever had
> any dealings with these units, so I have a few questions...
> 
> 1.  The trans has a wire labeled "kickdown switch".  What does this do, and
> do you ground it or supply +12 to activate it? (I assume +12v, since there
> are no other wires and grounding could be through the case)

When you step on the throttle, it closes a switch supplying 12V to the
downshift solenoid.  You get downshift.  Like the kickdown cable on
other trans'.

> 
> 2.  Does anyone see any problems with deleting the speedo sensor, since the
> speedometer on my car takes its reading from the differential, and I'll be
> using a manual transmission calibration with the PCM... (96 LT1)  I think
> the only thing that a manual cal uses the speedo for is idle speed, and I
> can do without that.  Error codes aren't a concern...
> 
Deleting?  Leaving disconnected, no.  Removing it and leaving a gaping
hole, yes.

> 3.  There's a modulator on the side of the case.  What does a modulator do
> when it sees boost pressure?  Should I use a check valve to block boost from
> going to it?
> 
Modulator adjusts line pressure to make shifts harder/softer with
more/less load.  Also plays a part in determining which gear trans
downshifts to when throttle is stomped, and upshift points.  If you
use a check valve, the line to the modulator needs to be vented so
vacuum isn't trapped in the line.  Also, they make plugs to replace
the modulator.  You might investigate this route.

> 4.  How do you adjust the wide open throttle shift points?  I realize that
> the trans must be disassembled.

Modulator + governor springs.  Look for a "Shift Kit" by TransGo,
there's goodies + good info there, and price is right.  No
substitutions, either.  Also try to get A1 Trans or B+M catalogues.  I
can dig out some phone #'s for these guys tomorrow.

> 
> Thanks a lot,
> Brock
No problem.
Shannen