Matt Gruber

this is a follow up on my speedshifting post. :D :D
Made the downshift switch trigger at 1/2 throttle. This is an incredible improvement.
Compared to my 61 wth a 4 speed, my 72 TH400 WAS lethargic when moving fast to WOT.(floored)
NO MORE! Now it LEAPS into action taking full advantage of the Holley double pumper!
The stock way as you floored it the carb shoots in lots of gas in high gear :rolleyes: then as it is fully open, it downshifts. terrible timing and it creats a flat spot when passing.
It feels like i just traded for a new vette! (but i don't know if a c5 will jump into 1st at 40 mph at 1/2 throttle, i kind of doubt it)
You can set yours whereever you like it. My back barrels are about 1/6 open when the trans gets the message to LEAP. :D

isosceles

Thanks Matt! I'm trying to restrain my purchases of parts for a while because I've been spending a little too much. Free mods!! :hurray:
Going to crack my books now: that's adjusted on the throttle linkage on the carb?

Rockn-Roll

Good thinking! Nice job Matt

NHvette

The kickdown for a TH400 is a switch on the accel cable - above the gas
pedal (inside under dash). A TH350 has the cable from the carb (I think).
Hey Matt - I think someone once futzed around with mine. There was a nut
use as a spacer in there. How did you adjust yours ?

:seeya

isosceles

DRAT! My Haynes manual claims the 78-81 TH350 is ALREADY set to downshift at 1/2 throttle! So much for that mod... :smash:

Matt Gruber

was missing.
i cut some sheet aluminum and bolted a lever microswitch (from an old VCR)(also available at radioshack for $1)
bolted to the manifold.
this only works on the TH400
it shifts so fast the 4 speed in my 61 is jealous ;)

Matt Gruber

someday if you change the cam, i'll tell you how to recalibrate the governor to match the cam. cost ZERO to $30

Matt Gruber

i suppose you could advance the TV cable so a th350 thinks it's floored at 1/2 or 3/4 throttle. if i had a th350 i would try that. :cool: i would expect very agressive shifting. :cheers:

nicecurves79

hey i must have missed the original thread. can you guys tell me exactly what it is and how to do this?-thanks :cool: p.s. i have a th350


[Modified by nicecurves79, 2:40 AM 6/15/2003]

Matt Gruber

mmine also downshifted at 1/2 throttle. But you miss the point, er a shift!
at 40 mph 1/2 would knock it down into 2nd gear.
Now it kicks into FIRST gear. You get no LEAP in 2nd at 30-40.

You and nicecurves79 hopefully will report on your results adjusting the TV cable so i can add this info to my web site. as far as i know this is the 1st discussion on the th350. I vaguely recall the procedure is to release the TV cable lock, have someone floor it, and re-lock. To LEAP, release lock, give 1/2 to 3/4 throttle, re-lock. Experiment to get the best results.


[Modified by Matt Gruber, 8:28 AM 6/15/2003]

nicecurves79

ill definately tell you how it went after i do it, but first: is the tv cable that you say to adjust the one that attaches to the carb? or is it under the dash? is it the same thing as the transmission kickdown?

Matt Gruber

this is so much fun! :steering:

isosceles

:

yes I DID :yesnod. You are right, I would get a big kick if it went down to first. hmm, I'll try it and let ya know how it worked. I'm a little leary though because I think my L48 has more torque at the lower RPM. Sounds like it's worth a try though!
:smash:

Matt Gruber

some like the low rpm torque, i even tried it years ago with the xe250 cam. it could pull good in traffic at 20 mph in 3rd. the novelty wore off soon as i wanted a vette, not a farm tractor.
i like the instant shifting using just the gas pedal. much faster than my 4 speed
now i don't have to floor it to get strong passing :D

DJ Serotonin

I am having trouble locating my kickdown. Did all cars come with this or was it an option? I have a 72 with an automatic in it


thanks

Matt Gruber

follow the wire from the right side of the bottom of the trans.
switch should be on carb. i've never seen one as owners in the 70's tore off anything that might be emmission related. Of course they were wrong on this wire, but it looked nicer and thery were happy

Matt Gruber

have u seen that bumper sticker:
I MAY BE SLOW BUT I AM AHEAD OF YOU :jester