TH400 Shift Early & Soft / No KickDown

[HotRodPC]

Yeah I could do that to my DD, its Th400. I might have to for giggles and making sure the trans rebuilding solvent fumes hasn't jacked up my head. I'm thinking maybe, just maybe, you been working on those -E trans a bit to long.

 

[HotRodPC]

You sumbish !!! Now I got all dirty, and have to wait for the exhaust to cool off before I go pull the bolt out of the vac line and hook it back up.

So with Vac Mod disconnected, and very light throttle take off, it took to 38mph to get to 2nd and I got to 55 and never got 3rd but gave up since I was in a 35mph zone. Normally on light throttle, it would shift to 2nd at about 23-25mph and in 3rd before I hit 40mph. That's also considering I have 3.21 gears, so that's about right. And when it did shift, it shifted much firmer than normal. It was an obvious governor take over shift. When I took off with about 3/4 throttle, it never did shift until I let off the gas. You almost had me convinced I was losing my mind.

 

[oneluckypops]

You sumbish !!! Now I got all dirty, and have to wait for the exhaust to cool off before I go pull the bolt out of the vac line and hook it back up.

So with Vac Mod disconnected, and very light throttle take off, it took to 38mph to get to 2nd and I got to 55 and never got 3rd but gave up since I was in a 35mph zone. Normally on light throttle, it would shift to 2nd at about 23-25mph and in 3rd before I hit 40mph. That's also considering I have 3.21 gears, so that's about right. And when it did shift, it shifted much firmer than normal. It was an obvious governor take over shift. When I took off with about 3/4 throttle, it never did shift until I let off the gas. You almost had me convinced I was losing my mind.

HA HA HA good to know.

 

[HotRodPC]

HA HA HA good to know.

Stick to your -E transmissions, I'll handle the old school !! I was actually shocked it shifted when it did. A Th350, damn near gotta have the motor reved up to about 7,000 rpm before it'll hit 2nd wo a Vac Mod. Obviously the Gov plays a bigger role in the Th400, which I knew it did, since the Th400 doesn't have a detent pressure valve like the Th350 does.

 

[oneluckypops]

Stick to your -E transmissions, I'll handle the old school !! I was actually shocked it shifted when it did. A Th350, damn near gotta have the motor reved up to about 7,000 rpm before it'll hit 2nd wo a Vac Mod. Obviously the Gov plays a bigger role in the Th400, which I knew it did, since the Th400 doesn't have a detent pressure vavle like the Th350 does.

 

[HotRodPC]

Don't jackin with the old schoolers !!! We'll sneak up and surprise your ass. We're not as dumb as some of new schoolers thinks we is.

 

[85k10383]

My vac mod is defineatly stuck in the sissy shift position and I suspect the bore is blocked and or dirty as well. There is vacuum at the mod as I unplugged it whilst running and held a fingertip over the end to check. BTW, try that with long tube headers some time for fun LOL I'm now missing all the hair from my right forearm. I went ahead and got the NAPA guys to get me a new redstrip modulator (10 bucks why not) since the old one is rather cruddy and already suspect. I'll install it tomorrow, weather permitting, along with all new rubber line to the carb, just to be safe and sure. I did go ahead and screw it all the way down until it wouldn't go any farther, then back a turn, just to see wha hoppen. I got a little taste for how this truck should have felt since day one with the new engine! Shifted from 1st to 2nd at 3500, HARD, never made it to third, ran out of road. Man, that was INTENSE! Really got to hear the 383 find its voice and I love it, can't wait o give it a go with a properly functioning modulator. A million thanks to all for the help, I'm so happy I'm gettiung all misty eyed LOL

 

[HotRodPC]

My vac mod is defineatly stuck in the sissy shift position and I suspect the bore is blocked and or dirty as well. There is vacuum at the mod as I unplugged it whilst running and held a fingertip over the end to check. BTW, try that with long tube headers some time for fun LOL I'm now missing all the hair from my right forearm. I went ahead and got the NAPA guys to get me a new redstrip modulator (10 bucks why not) since the old one is rather cruddy and already suspect. I'll install it tomorrow, weather permitting, along with all new rubber line to the carb, just to be safe and sure. I did go ahead and screw it all the way down until it wouldn't go any farther, then back a turn, just to see wha hoppen. I got a little taste for how this truck should have felt since day one with the new engine! Shifted from 1st to 2nd at 3500, HARD, never made it to third, ran out of road. Man, that was INTENSE! Really got to hear the 383 find its voice and I love it, can't wait o give it a go with a properly functioning modulator. A million thanks to all for the help, I'm so happy I'm gettiung all misty eyed LOL

Cool, so it was the vac mod adjustment. That Vac mod is likely just fine then, it just needed turned way inward. Which is why I suggested at least 2 full turns. That doesn't sound to bad right now if you were on it pretty good. If it was a light throttle take off, then its shifting late and you need to back it out a little more. But, as you said, $10 for the new redstripe and its a new. Not to mention only a 5 minute job to install it, so why not. However, I would suggest letting it cool down before you do it. I got a little warmed up today too when I went out to rehook up my vac mod to make sure I hadn't lost my mind.

 

[85k10383]

Installed and adjusted the new modulator and all is right with the world. She is shifting correctly for the first time since before I bought her. And to thank me for the effort my passenger side turn signal burnt up its socket on the test drive! Took it out and all the internal insulation has turned to crumbly cheese. So LMC will get a few more of my hard earned LOL

 

[HotRodPC]

Glad the trans if fixed. You'll likely even see a difference in fuel mileage if you did alot of around town driving.

Sucks about the light socket though. Hopefully they aren't to much. If they are, I am sure someone one here has a spare one that could be mailed.

 

[crazy4offroad]

Wife was wondering why I was doing my evil laugh and I had to explain to her about you finally getting to feel what that 383 can do! Glad you got it fingered out!! You'll have to lay a camcorder in the dash and wind that mother trucker up and give us something to drool over!

 

[85k10383]

^^^You have no idea! I can lay rubber on command now (not that breaking TSLs loose on pavement is anything to brag over) But let me tell you when she climbed over 3500 and came "on the cam" you could have lit New York with the grin I had on my face. Of course now I'm all power hungry, looking at Vortec heads and new cams My local Vato-Zone actually had the correct socket in stock, could've knocked me over with a feather on that deal, now I have to find my wire strippers.....

 

[89Suburban]

^^^You have no idea! I can lay rubber on command now (not that breaking TSLs loose on pavement is anything to brag over) But let me tell you when she climbed over 3500 and came "on the cam" you could have lit New York with the grin I had on my face. Of course now I'm all power hungry, looking at Vortec heads and new cams My local Vato-Zone actually had the correct socket in stock, could've knocked me over with a feather on that deal, now I have to find my wire strippers.....

That's awesome, congrats, lol.

 

[oneluckypops]

^^^You have no idea! I can lay rubber on command now (not that breaking TSLs loose on pavement is anything to brag over) But let me tell you when she climbed over 3500 and came "on the cam" you could have lit New York with the grin I had on my face. Of course now I'm all power hungry, looking at Vortec heads and new cams My local Vato-Zone actually had the correct socket in stock, could've knocked me over with a feather on that deal, now I have to find my wire strippers.....

better throw the junk ass butt connectors that they supplied away and use solder and heat shrink it.

 

[HotRodPC]

^^^You have no idea! I can lay rubber on command now (not that breaking TSLs loose on pavement is anything to brag over) But let me tell you when she climbed over 3500 and came "on the cam" you could have lit New York with the grin I had on my face. Of course now I'm all power hungry, looking at Vortec heads and new cams My local Vato-Zone actually had the correct socket in stock, could've knocked me over with a feather on that deal, now I have to find my wire strippers.....

I shouldn't have told him a damn thing. We created a monster. He's gonna kill hisself with the new found power.

Now the fun begins, you get to start breaking ****, like rear ends, driveshafts etc. Actually not likely. Automatics don't break near the crap, that manuals do.