Thread: Adjusting shift points on 1985 turbo 350 automatic

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I have been told that the shift points on an older (1985) turbo 350 automatic transmision can be adjusted by turning a screw inside the modulator valve clockwise, 1/4 turn at a time untill it shifts at the proper time. I have used the 305 engine and turbo 350 transmission out of a heavy car (4-door Pontiac Bonneville) in my model A roadster pickup which is quite light, and now when I stand on the pedal (hard acceleration) ot even in normal driving, the car only moves about 15 to 20 feet before it shifts from low to second. The shift from second to third happens at a more "usual" time/RPM range.
I would like to know more about this.--Where inside the modulator valve is this screw? is it on the side that the vacuum line ataches to, or on the side that screws into the transmission? If I take the modulator valve off the tranny, will my transmission fluid run out the hole ,or is the modulator valve above the fluid level? Does this adjustment only adjust the shift point between low and second, or does it also have an effect on the shift point between second and third? I would like to adjust this shift point, but don't want to have to drain the fluid, drop the pan, and incurr the associated costs at a transmission shop.
If anyone has some good solid information on this, please let me know.
I do not want to put in a shift kit at this time, as I am looking for a low budget way to do it in my garage without having to take much apart, and without going to a transmission shop $$$$$$.
-----Brian

The modulator screw is right beind the vacuum hose, just remove the hose and take a small screwdriver to it. There is no need to remove the whole modulator. It would affect both shift points. If it is shifting that early, you might want to try turning it in 2-3 turns. It think it would be better to go too much and turn it back out then having to go 1/4 turn then drive and 1/4 turn and drive etc. There is another thing but is alittle more indept. The governor weights and springs could be at fault. Since it the transmission was out of a heavy car the governor is for a heavy car. A diferent set of springs and weights could make the difference but that is more of trail and error. One final thing, what gear ratio do you have in the rear end? The higher the ratio number, the quicker the shit may be. Hope this helps.

The rearend does have a rather tall ratio, as it is out of a stock S10 pickup truck. I think they are probably 3.08:1 gears, more for mileage than torque.

blue57ford....
hope the last line is a typo

Originally posted by robot
blue57ford....
hope the last line is a typo

I might be wrong but it looks right to me

The higher the ratio ''number'', the quicker the shift may be. Hope this helps.

The higher the ratio "number" 3:08 being a low number (For example) and 4:10 being a higher numerically would shift quicker. Higher ''number'' = lower gear ratio.

Pro,.....the last line is "the quicker the shit may be"
Kinda fits in with gear ratios

and found this from the TCi web page FAQ:

Is there a right way or a wrong way to hook up my vacuum modulator?

Answer: Since the transmission is so dependent upon the modulator to function properly, a good vacuum signal must be transferred from the intake manifold down to the modulator. The best way to insure this is to utilize hard steel line to carry the vacuum signal with approximately three inches (maximum) of rubber hose on each end for the connections. This setup will prevent the hose from cracking or burning in areas that are close to the exhaust system and will also reduce the chances of the hose collapsing onto itself. Most modulators require a minimum of 15 inches of Hg (Mercury) at idle to function properly.


Are there any adjustments that can be made to the modulator?

Answer: Stock factory modulators are pre-set and most are sealed. TCI® StreetFighter® modulator-type transmissions are all equipped with adjustable modulators. By turning the adjusting screw (found in the vacuum nipple) counterclockwise, you will lower the spring pre-load. This will cause earlier shifts. By turning the adjusting screw clockwise and raising the spring pre-load, the shift points will go up. The range of adjustability is only a few mph either way.

Originally posted by robot
Pro,.....the last line is "the quicker the shit may be"
Kinda fits in with gear ratios

Kinda' missed the forest for the trees HUH
I corrected that on my copy N' paste and it still didn't register. I need sleep.

EXLAX

Denny---I seem to be getting a lot of opinions on this, and I am inclined to believe yours. If the modulator adjusting screw only changes the "cushion" of the change, then what does change the shift points? Is it an internal issue as I had originally thought?

Pro.....
I had to read it a couple of times myself......now, if the
typo applies, B&M needs to change their trans fluid label
from "Trick Shift".....to _______

mike in tucson

from the transmissioncenter.net web page:

350 / 400 Vacuum Modulator. Adjustable, allowing you to tailor your light throttle shift points with-in a range of 2-4 mph. Supplied adjusted for normal shift points. If your engine doesn't make adequate vacuum you will not be able to make the stock modulator work properly, usually resulting in late, hard shifts. Cost $15.00.

I thought that not all modulators had the adjustment screw. IF you remove the vacuum line, the shift is delayed (or not at all)...

"Of course, I could be wrong, I thought that I was wrong once but I was wrong."

Sorry about the typo, my mind was tired from working i guess I missed it. On a 350, shift firmness could be adjusted more so by adjusting the throttle valve cable. Some modulators such as those in fords could be altered by using longer or shorter modulator pins, if they were screw in type, adding modulator gaskets could alter them. Additives that claim that they can soften hard shifts are actually just causing them to slip. That is why the shift feels softer. For the most part, additives are not good. There is an item called Lube Guard. That is a good product.

Originally posted by brianrupnow
I have been told that the shift points on an older (1985) turbo 350 automatic transmision can be adjusted by turning a screw inside the modulator valve clockwise, 1/4 turn at a time untill it shifts at the proper time. I have used the 305 engine and turbo 350 transmission out of a heavy car (4-door Pontiac Bonneville) in my model A roadster pickup which is quite light, and now when I stand on the pedal (hard acceleration) ot even in normal driving, the car only moves about 15 to 20 feet before it shifts from low to second. The shift from second to third happens at a more "usual" time/RPM range.
I would like to know more about this.--Where inside the modulator valve is this screw? is it on the side that the vacuum line ataches to, or on the side that screws into the transmission? If I take the modulator valve off the tranny, will my transmission fluid run out the hole ,or is the modulator valve above the fluid level? Does this adjustment only adjust the shift point between low and second, or does it also have an effect on the shift point between second and third? I would like to adjust this shift point, but don't want to have to drain the fluid, drop the pan, and incurr the associated costs at a transmission shop.
If anyone has some good solid information on this, please let me know.
I do not want to put in a shift kit at this time, as I am looking for a low budget way to do it in my garage without having to take much apart, and without going to a transmission shop $$$$$$.
-----Brian

sounds like to me you may not have the kickdown cable tight enough brianrupnow. if you can stand on it and not effect the shift then the kickdown cable cant be working. sound like its shifting about right at light throttle. wot or even 1/2 throttle the kickdown cable should override the mod. and gov. and make it stay in low gear longer. something to check. my S10 dif. from the factory is a 4:10 gear, it was 4 cyl. with a stright shift trans.

Alright Guys---too many opinions. I just came back from the transmission shop. I explained what I wanted to do to 2 young guys about 30, and they both came out to the car and started to mess with the kickdown cable. They frigged with it for a while, then an older guy (not quite geezer status) came out and told them to "leave that damn thing alone". You mess with the TV cable on a 700 or 700R to adjust the shift points. On an old turbo 350 like mine (1985), all that cable does is kick your transmission from high gear back into second gear when you floor the pedal at speed to pass someone. It has almost no effect on the shift between low and second gear.----If you have an adjustable modulator valve, then you can turn the adjustment screw in about 1 or 2 turns maximun to move your shift points up but it will make for a "harder" shift too, with less cushion. If ya really want to change the shift points on a 350, then you have to open up the case and change the governor weights.----

Denny---I did see that the other day, and thank you very much. However, being a cheap old poop at heart, I wanted to know if there was some way of tweaking what I already have. I know its only $55.93 in the USA. Thats $77 in Canada money---then the shipping is about $20 Canada money, then the incoming "inspection" at the border is $20, then the provincial sales tax is 7%, then the federal goods and services tax is 7%----ya see where this is going??? Then add in the fact that I don't really know squat about automatic transmissions, so would end up paying some local robber baron to install it. I do appreciate the help and advice, and if I lived in the States, I would rush out and buy one this afternoon. As it is, I have no engineering work right now, and I've just got stung for $4600 (bounced cheques from a "good" customer). I won't be buying much untill I get some finances straightened out and some more design contracts.