I am looking for a picture of the gas pedal kick down switch assembly on a 70 GS455 Auto TH400 When I floor the gas pedal, the black rod of the pedal is no where near the switch. I don't know if I am missing part of the assembly or not. Not sure if the bracket that holds the switch is bent to far rearward towards the driver seat. Not sure if the gas pedal rod is incorrect for 70 GS Plus my trans is all of a sudden sticking in first gear. Wont shift to second unless I manually shift from Drive to second so I was thinking the switch was stuck. Read on forum someone had a bad switch. When I get on it and floor the car, it'll haul thru the gears, 1, 2 and 3rd. But not cruising 15 mph up the street. Full disclosure, installed new radiator so I'm playing the trans fluid game again, but not sure if too much fluid would cause that. My switch ohms out. Open circuit normal and continuity when actuated. It's just that the gas pedal rod when floored is inches away from hitting the bar on the switch. so something isn't lining up. Thanks, Nick And yes, I know the switch is missing for this picture
If the transmission is getting a constant 12 volts from the switch, it won't upshift. Unplug the switch to see. If the vacuum line to the modulator falls off, same thing, no upshift.
Vacuum lines all intact. Do you think or how would you check to see if the vacuum modulator crapped out? I'll have to check voltage later. but the switch was not actuated or engaged, so it was an open switch like if you remove it. Pedal is no where near actuating it so that's why I was looking for a picture as well to see if my pedal rod is missing something. I saw a pedal rod with this extra piece on it and was wondering what that is for
No worries...I found a couple better pictures before and after I restored it. Just to make sure it's the correct one. Obviously in the before picture with no throttle cable, the pedal rod touches the switch. However when assembled now, I guess when I mash the pedal to the floor, it doesn't come close to hitting the switch. So that's issue #2 I noticed. Issue #1 was the not shifting to second while driving slow unless manually shift from drive to second. Maybe I over filled the trans or maybe the modulator Larry mentioned above may have crapped out.
To check a modulator, put a hand operated vacuum pump onto it and see if it holds vacuum. When a modulator fails, the diaphragm leaks, and ATF can be sucked into the engine and burned. I doubt that your modulator has failed. If the transmission gets a constant 12 volts, it won't upshift except at WOT. This seems unlikely as well unless you have some sort of wiring problem. Pull the connection off the side of the transmission, and test it with a multimeter or test light. If you overfilled the transmission to that extent, fluid would come out of the vent. Again, unlikely. The picture you posted is the pedal for a THM350 car. It uses a kickdown cable. There is a procedure for adjusting the gas pedal switch. Push the switch end labeled "A" in the picture below. The switch end will bottom out and stay that way. Then floor the gas pedal and the switch will self adjust. You may end up having to bend your gas pedal arm so it makes better contact with the switch. Another trick is to put a piece of 3/8" fuel line hose onto the switch to narrow the distance.
Removed the switch and Just measured. Battery voltage on double yellow wire side and 0V on the black wire which I’m assuming triggers the kick down when switch is activated. Won’t shift up unless wide open and just checked and saw some bubbles on trans stick. too much fluid now is my guess. Guessing I need to stick a tube down there and try to siphon some out.
I don't think simply overfilling the transmission would result in no up shifts. There is something else going on. If you start the engine up cold and cycle through the gears, then back into Park, the proper level on the stick should be 1/4" BELOW the ADD mark. Carefully read this page from the 1970 Chassis Manual,
@LARRY70GS Yeah, I read the manual and saw that this week. I am definitely above the mark when cold. But, I've seen contradictory things. I've read where if you let it sit, all the fluid backfills so it looks higher when cold when sitting for a week. So that's what confuses me. But yeah, my car after sitting from last week, it was above the full mark. and then took it out tonight, seemed ok, banged thru the gears but when hot, lost third and say bubbles on the dip stick. and measured above the full mark. so that made me think too much fluid. I did pour about half pint in from when I thought I was having issues. So I'm waiting till it cools down (like tomorrow or Sunday) and was going to put a hose down and siphon what I believe half pint out. All this time tonight the kickdown switch was not installed
Yes, converter drain back raises fluid level, but that goes away as soon as you start the engine. Looking at the fluid level engine off is meaningless. Start the engine, move the shifter through each range, then to PARK. Then check the dip stick. If it is above FULL then it is overfilled.
Nick, hopefully it’s something minor with your transmission but here’s pictures of the kick down switch on my car which has never been disassembled. I just got my car back the other day from the shop.
@Stage 2 iron - Thanks for the pics. At least it looks like I have the right set up. Just probably need to bend my bracket back a bit so it engages the kickdown switch. But that's the least of my worries. Pulled over, started from a dead stop with it manually in 1st, hit the gas slowly, manually shift to 2nd, it shifts into second, get up to about 2000 RPM and I manually put it into 3rd, it shifts into third for a brief second or two and then the trans puts itself into 2nd gear and revs high all by itself. Is the modulator bad? Here is what I did this morning before all that: Siphoned about 16oz out of the tranny this morning. When cold, the fluid level was way up over the fill mark sitting overnight. When I drive the car, shifted fine from first to second to third until the fluid warmed up. Once warm, would rev high and only go to second when I manually put the shifter into second. I then found a crack in the vacuum hose down by the trans on the modulator. Fixed that and still the same thing. I even turned back the modulator 1 turn to the left thinking to lower shift point and no change. I even disconnected the kick down switch underneath In drive, it will shift from 1st to 2nd at 3500 RPM and then I got somewhere between 3500-4000RPM and no shift to 3rd. I let off the gas. Didn't want to go too fast in a 45mph zone. Too much traffic out there today. Measured close to 15 vacuum and pull the throttle it goes up over 20
Yes I am. Barely see it on stick. It’s like a faint red. Not as dark as when it sits overnight. But see that the stick and it’s is glistening. It goes into third briefly as you let if has it downshifts by itself into second. I swapped out the trans modulator with the original that I kept. No difference.
It sounds like you have something else going on there. It might be worth it to remove the governor and just inspect it for something obvious. Look at the gear, and weights/springs. Make sure the valve in the stem is moving with the weights. Make sure there is no damage to the plastic gear.
Thanks again Larry! I'll do some research to see what that looks like and how it comes out. I see that it's only 4 bolts to take the cover off, but I just don't want that falling out in my hands and having no clue how to put it back. Plus will trans fluid come out. Its just weird how I have about 400 miles on it and no issues, then all of a sudden issues. I changed my distributor from the lectra limited back to points to fix the no spark issue you helped out with. And then I put a new/used radiator in. Previous owner had a manual trans and only put 200 miles on it, and not sure how long it sat. So maybe some crude loosened up in the trans cooler side and got into my trans and maybe making something stick. Question on the valve body I've been reading about, if I take the pan off, does the valve body unbolt and bolt back in? Just thinking maybe I can clean it or something. Or maybe just draining the pan and new filter would maybe help. Thanks again, this is all new to me. Nick
Nick, The governor will not fall out. The cover comes off easy enough, but you will lose some fluid. You can minimize that by getting the back of the car as high as possible. The governor simply twists out. The gear is helical like a distributor gear. Installs the same way, very easy. https://www.youtube.com/shorts/AtV53UE1OmQ
well, there was about a 2 hour worm hole down you tube and looking for parts. I'm guessing I need at least to have a gasket on hand and a new gear when I check the governor gear assembly. This way if it's good, I can put it back. And if not, changing the gear should be fun after watching some videos Can't seem to find a full up assembly already made but I'm sure that'd be more expensive. Now just trying to figure where to buy the parts. Looks like Ames has everything I need (plus my TH400 is from a 72 Pontiac). Mine as well get a pan filter and gasket while I'm paying for shipping
I wouldn't buy anything just yet. The governor cover gasket usually comes off in one piece, and you can reuse it. Removing/checking the governor is very easy. It will be very obvious if something is amiss. There is no governor O ring. The THM350 uses a round cover with an O ring. That listing is wrong. I would not mess with the valve body. If you want to drop the pan and check the filter pipe where it plugs into the case, that's a good idea. If it came loose, the pump may be sucking air. It's possible. Some guys use 2 O rings for the filter pipe to case hole.
