[steve]

I recently learned I may not be treating my trans well by not using the kickdown switch (on the gas pedal). Months ago my kickdown seemed to quit working and I just started using the shifter to downshift when I needed to. So I decided to take a closer look and try and get it functional. It used to downshift once or twice and then stop working after I reset it. Just went for a test drive and it seems to be working now. I wanted to clear up the whole “tube” or spacer thing people put on the switch to try and get it to come in sooner. Many, many posts online state that is the way to get it to come in sooner. From what I understand this is totally incorrect. Am I right on this ?
This brings me to my bigger concern. The car seems to shift way too early. It won’t hold first through an intersection and second seems to shift into third way to early as well. It’s a little hard to know exactly when the shifts happen because they are so incredibly soft. This is also true when the kickdown works. It only downshifts from 3 to 2 for a second or two before returning to third. And when doing so the shift is also very soft. The shifts are barely perceptible when driving normally. So, first I want to clear up the whole adjustable modulator thing. So many posts claim this adjustment will make a difference with the shifts points. From what I understand this is also not true. It only adjusts the shift points by like 2-4 mph and won’t make a very noticeable difference. Is this true as I understand it ?
So if my kickdown is working and my modulator isn’t the answer what should I be looking at for possible solutions to increase the time the car holds the gears before shifting ? The transmission is custom built and made to sit behind a high HP engine. I did recently switch from a 3.08 rear to a 3.55 rear without making any other changes to the car. (other than working on the efi tune). Maybe it was built for soft smooth shifts ? Is that possible ? It’s been in the car for over 5 years and has always behaved like this. A friend suggested the cable linkage could be off, but it seems to check out to my limited knowledge of the subject. Hopefully I haven’t been abusing the trans for some time now by not having it set up correctly. The receipt I have for the trans rebuild is cryptic but it does say that it has a “shift kit” without specifying any details. Any insight would be greatly appreciated. I suppose it’s even possible it’s working correctly and I just don’t understand what’s going on.

[Tim Corcoran]

If you have a higher than stock convertor this will make the shifts come in sooner than expected. I believe the modulator does affect the shift point some if it has an adjustable modulator. The shift points and the kick down are operated independently of each other. On the side of the trans is a round removable cover and inside is the governor that controls the shift points. it's controlled by weights and springs. Kits are available with replacement springs and weights so it will allow you to change shift points. The process is complicated and takes time patience and a lot of trial and error.

[beemergary]

Your GOVERNOR has the final say on shifts. Those adjustable modulators are like above said only good for a few mph. If you changed to a higher rear end the rpm's are going up higher and quicker. A governor works off rpm's.

[steve]

Thanks guys. The converter is a TCI Breakaway 2,400-2,600 Stall Torque Converter 240901. I’ll look into what my governor is doing. I guess I can dial the modulator in a little just to see what I get as well. The transmission is due for a fluid change so I guess it’s time to pull some things apart before this spring.

[HWYSTR455]

Hm. I guess the governor MIGHT be hanging if there's crap in there, a fluid change might correct that.

Did it ever shift right?

Not sure, but shift cable adjustment may also have a say in the shifts, like if it's not fully engaged in the detent?

Maybe someone can chime in on that theory?

Is it the 1-2 or 2-3 shift doing it, or both shift points?



.

[steve]

Both shift points. Feels like it’s in 3rd all the time. If I floor it from a stop it will smoke the tires for a nice long romp but I never feel the gears shift or hear the revs change. I’m usually so focused on steering that I never look at the tach. It has so much power in 3rd that the only time I notice it is when I go up a steep hill. It will shift out of first before I even get going up the hill and I never feel second to third shift. The shifts are barely perceptible. I am assuming that if I hit the gas hard enough to launch fast without spinning the tires I would feel the car shift from 1 to 2 and then from 2 to 3. This is not the case. What I can feel is the car shifting from 1 to 2 sometimes after traveling about 10 feet on low acceleration.

[Half-Inch Stud]

Early Upshifts are typical for high vacuum, and you'll appreciate that.

Vacuum mod valve in case is prone to stick: pull modulator to access the valve; pull valve and 320 grit the valve in a drill press. until it slides in the case without binding. Turn vac mod screw ccw about 2-turns if you never adjusted it.

Govenor outer weights are to be left alone.
Govenor inner weights should be the short metal tabs (in chevys) compared to stock pontiac TH400s, and the springs should BOTH be flimsy. Pontiacs will have 1 medium tension and 1 flimsy tension.

A govenor with high inkstamp number: 21, 23, 25, 27, 29, will be all set as stock compared to PMD govenors like 11, 13.

[steve]

Originally Posted by Half-Inch Stud

Early Upshifts are typical for high vacuum, and you'll appreciate that.

Vacuum mod valve in case is prone to stick: pull modulator to access the valve; pull valve and 320 grit the valve in a drill press. until it slides in the case without binding. Turn vac mod screw ccw about 2-turns if you never adjusted it.

That’s great info ! Just to be clear. You do mean turn the modulator adjustment screw CCW not CW ?

[Half-Inch Stud]

Originally Posted by steve

That’s great info ! Just to be clear. You do mean turn the modulator adjustment screw CCW not CW ?

Yea, i might be mistaken on ccw. I'm 1000 miles away from my notes right now.

[chiphead]

Adj modulator clockwise raises shift points and shift firmness a little bit. That increases tension on the spring which requires more engine vacuum to move the valve. This raises line pressure which affects shift timing and feel.

Governor weights and springs adjust shift points and shift spacing. If you've gone from 3.08 to 3.55, the governor now thinks you're going a LOT faster than you really are, when it shifts. The gov is geared to the output shaft inside the trans.

Shift "harshness" is a function of torque converter coupling, line pressure, valve body calibration, spacer plate orifice sizing, number of checkballs, type of frictions and any waved apply spacers in clutch packs. Stock TH400 shift early and soft for cadillac shifts in big sedans. There are a lot of ways to increase shift feel and authority. I've found that a loose converter makes even an aggressively calibrated tranny feel soft. My TH400 makes 210 PSI line presssure (stock is 160) but it shifts softly at part throttle because my converter is so loose. At WOT, it's wham-bam, too hard and late for my liking. I suspect my tranny has a shade-tree shift kit, with pump line pressure jacked to the moon, checkballs removed, accumulators blocked and spacer plate drilled out. I need to open it up and see what's in there, but I'm afraid of what I might find.

You really need to know what shift kit was installed and line pressure in all ranges to know how much you can impact the shift firmness without changing the converter.

I want to install a TransGo II shift kit I've got, but I'm afraid I'll break something if the tranny has been modified for dual feeding of the direct clutch or the converter feed has been restricted.

From what I understand, you can pull a seal ring from the stator and and a seal from the direct clutch and block a passage in the valve body. This will dual feed the direct. The TG kit also dual feeds but it uses a special spacer plate and does not require pulling the tranny down to remove the seals. 160 PSI line pressure is good to 700+ HP. Above 180 you risk pushing the converter and taking out the engine's thrust bearing. To prevent that with high line pressure, you restrict the pump feed to the torque converter to reduce charge pressure. No idea if either of those modds were done to my unit. Can somebody comment on that? I'd really like to install this shift kit and drop the line pressure into the 180s.

[steve]

That’s great info chiphead. It’s been quite awhile since I bought it so I’m doubting I’ll find out what’s in it at this point. I guess I’ll do what I can with the governor and the modulator for now. It has less than 5K miles on it so will be some time before it really comes apart. I may have to live with what I have.

[Tim Corcoran]

Your high stall convertor will certainly soften your shifts and make the trans shift earlier. Before you do anything I would install the proper speedo gears for your rear end ratio and tire size. That plus an adjustment to your vacuum modulator might just be enough to make you happy. The ole Pontiac V-8 has enough torque to handle the early shifts for everyday driving it may be fine. You always have the shifter to control your shifts when you want to get with it. But if you want everything to shift like you want without grabbing the shifter handle then you know what to do.

[steve]

Tim the one thing I have done since changing the rear is swap out the speedo gear. It appears the gauge is very close to being correct (as measured by driving past those radar signs that post speed). This post has made me wonder how close my combo is to ideal. It was not put together all at once so there may be some elements that need attention. I’ll start a new post that lists all the components.

[Tim Corcoran]

Make sure your vacuum line to the modulator is hooked up to full vacuum and try adjusting it some as recommended above. After that run it as is, unless you want to get into the governor.

[tjs72lemans]

My 72 Lemans 400 (310HP, 400 ft. lbs.) with rebuilt tranny, shifts like yours. I wanted it like my Camaro (350 with about 330 hp). I put a shift kit in when I had it rebuilt with stock torque convertor. It shifted solid and quick in all three gears (turbo 350). My Pontiac I believe has a new stock style convertor (I told the rebuilder what I wanted to cruise with solid shifts), so I really don't know what I got. He said there was already someone in the tranny before with a shift kit, so left it. It's not like my Camaro as I wanted, but it works well manually shifting for my liking. I feel your desire for higher shift points and knowing when it shifts.

[steve]

I adjusted the modulator clockwise 3 turns and felt no difference…I’m using a hard line to the terminator efi. I may try to replace it with something else and see what I get. Maybe it’s the soft bit connecting it to the port collapsing. I have the stock molded line at the modulator end.

[PontiacHO]

Governor check out ok? No hanging up or weak, broken, missing spring(s)?

[steve]

I changed the fluid and filter also with no difference. I have not inspected the governor….would not know what I’m looking at. Never seen the inside of one so not sure I’d be able to diagnose.

[chiphead]

The governor is under a 4 bolt cover on the passenger side. Unbolt the cover and it slides right out. Put a clean drain pan or a large paint cup underneath to catch the pint or more of fluid that'll come out. The gov has two sets of flyweights and a set of small springs. It's very simple to work on and there are weight/spring kits to change the shift points and timing between shifts.

[Formulajones]

As far as the kick down switch goes, they are adjustable. You can move the ratchet mechanism and reset it by depressing the gas pedal all the way, without floor mat in the way.

They typically get out if adjustment for a number of reasons but sticking a vacuum hose on it to make it contact sooner is the wrong approach