So I bought a custom torque converter from Jim and brought it along with my Skylark to my tranny guy. He works on a lot of older cars and was part of a race team when he was younger.here is how the conversation with him went when I called to check on the progress after the first road test. Him "You're gonna need better tires" Me "the only thing better than the drag radials on it are full on slicks" Him "yea" Cool huh? He wasn't happy with the governor so he was replacing that today. I should have it back tomorrow. Cliff
Cliff... when you talk to him can you get some input on a new governor and modulator (single red stripe?) thats on my to-do list? I have a stock 455 with a slight cam and headers with a 400 turbo and a 265 rear end. I just need streetability. I wanna change mine out strictly for dependability. Thanks! ws
Newbee question? Why does the governor need to be changed/upgraded? What the job of the governor and the modulator? And how about the torque converter, what is done to it to make it custom. Is it the same size as the stock one? Smaller? Different angles? Thanks, still learning.
Obviously I am not a tranny expert or I would have done the work myself but here goes. During the test run twice it only downshifted to second on a full stop so he said that was the governor acting up. The governor also controls at what rpms it will shift while in drive. The torque converter is a custom piece supplied by Jim Wiese (the owner of this board and Tri-Shield Performance),He set it up for my combo. Weight,cam gears,purpose, etc. google how a torque converter works. It’s cool stuff. Cliff
Thanks Cliff, the way a car works with all its systems working together just is amazing to me. Appreciate your answer, have a good Friday
The governor ( with a 40+ year old plastic drive gear that can fail as quick as a plastic timing gear) runs on the output shaft of the automatic trans. The fly weights on it determine (when in DRIVE) on when to shift. If you hold the shifter in low and get dangerously overspeeded on the engine, the governor will automatically shift up to prevent a catastrophic failure of the engine/trans. If the gear fails, you will only have L1 to get you home. I've had two fail (usually at -20F) when leaving work and a 20 mile ride home in low gear on a major expressway at rush hour aint no picnic. Once home you probably won't have reverse either! I Believe when the T400 first came out the drive gear was bronze; now its a 100K mile plastic part to fail. If you want to play with the shift points, the governor has different weights available. I just need bone stock. These are file photos; but if its apart its cheap insurance! The vacuum modulator also tells the trans when to downshift depending on engine load (more load, less vacuum). Pulling a trailer for instance in DRIVE and going up a hill, the trans will downshift to L2 depending on how hard you have to press the gas pedal. Lugging an engine is not good for it. Thats a good way to break a crankshaft. The modulator (a stock unit with a red stripe) is color coded for stock with several variables available including an adjustable unit. The vacuum diaphragm inside can leak causing ATF to get sucked up to the carb (intake). Ever see a car blowing out voluminous clouds of white smoke on the road? Thats a MOD failure. The downshift switch (400s are on the gas pedal and electric) tell the trans to shift down when accelerating hard, aka, passing gear. All three kind of work in conjunction with one another. I just want to change mine while doing the cooling lines for piece of mind. Pushing 4000 lbs isn't my idea of a good time; niether is walking 10 miles along an expressway. LOL. Cliff, if you can get some input from a real trans guy, I'd appreciate it (see above). AFAIK, the torque converter is stock as well. Maybe print this page when you go talk to the guys. Some of them talk fast like you're supposed to understand the mysteries of the auto trans as well as they do. And they work on them all the time. If the guy has a crystal ball on the bench look out hahaha... Thanks! ws
Late model transmissions use computer controls to decide when the transmission should shift under various conditions. The computer monitors road speed, engine load ( vacuum), and throttle position among other things. Back in the day, our 350 and 400 transmissions used the vacuum modulator to monitor engine load via the vacuum signal, the governor to monitor road speed, and the kick down switch or cable to monitor throttle position. The valve body using those inputs then decided when to shift. The governor also determines WOT shift RPM. Lightening the inner weights can make for higher RPM WOT shifts. Governors can get gummed up resulting in shift point problems and failure to downshift as the car slows from speed to a stop. Torque converters make a huge difference in the way a modified car behaves on the street. Stall speed is very important when running a performance cam. Smaller diameter converters stall higher. They get the engine into it’s power range quicker and allow the engine to idle in gear better. Some high stall converters can be too loose, which makes the car lazy at slower speeds. That’s why it is advisable to buy a custom converter. You want it to feel normal in everyday traffic, yet let the engine go right to it’s sweet spot when you romp on it. Jim’s converters are 9.5” converters, a lot smaller than a stock 13” unit and a lot lighter as well. Rotational weight makes a huge difference in performance. And Jim knows Buick engines. Everyone I know that is running one of his converters has nothing but good things to say about them. I’m going to try one eventually. It’s on the list. Right now, I am running a 10” from Ultimate Converters. It made a huge difference in the way my car drives compared to the switch pitch I had previously.
We've put a lot of Jim's converters in customers cars and they are excellent, and tuned to the combo. Very pleased.
OK, First drive with the new JW 9 1/2" 3000 rpm stall converter. I am not lying when I say it feels like I gained 50HP. It drives tame as can be till you punch it and then hold on! 15-20mph rolling with warm drag radials on hot pavement = lots of tire smoke, hit second gear, recover from being sideways again and I am hauling a**. On a side note my mechanic said he has worked on a LOT of Quadrajets over the years and he said whoever built mine did a really good job. He said he couldn't find a single flaw. Thanks Mark (Quadrajet Power)! Cliff
Great info here, not to highjack the thread but would it then be beneficial to swap to an adjustable modulator in my TH350 ? I'm running the Stock 70 350 with a Th350 I swapped over to a 2bbl intake and attempted to adjust the kickdown. I just feel like it takes a while to shift from a dead stop. Before adjusting the kickdown it would actually bog before it evening out. After reading your guys input I am thinking an adjustable modulator might have it shift a bit earlier giving a more of the seat of the pants feel & smoother and quicker transition into WOT speed
