Thread: TH350 shifting question, HELP!

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Hello again friends,
Everyone helped with my last thread about rear ratio and thank you all. New rear is ordered and on its way! (ford narrowed 9",moser axles,3.70 gears,detriot tru track). Very excited!!!
Heres tonights question. Just installed a new B&M megashifter. Its great, as my column had no reverse lockout!
When i shift from 1 to 2 and 2 to 3 there is quite a hesitation, meaning, the shift is not instantaneous (tire chirping).
Now, there is an adjustment for the vacuum on the turbo 350 trans. Do I turn it more in? (clockwise) or more out? And will this help. Also, which vacuum line on the Edelbrock does that line go to, Or, does it go to the manifold port? Thanks...

Phil

>PS I almost forgot, just bolted on my brandy new Doug Thorley headers! Fit like a glove!

Hi Phil,
I have a '68 Camaro w/ a 402 BBC backed by a TH350. I have the same issue with the shifting hesitation and can't figure it out either. However, I can answer the question about where your vacuum line attaches and that's to the manifold port. Hope this helps a bit.

-Brian

Originally posted by fiftee6
Hello again friends,
Everyone helped with my last thread about rear ratio and thank you all. New rear is ordered and on its way! (ford narrowed 9",moser axles,3.70 gears,detriot tru track). Very excited!!!
Heres tonights question. Just installed a new B&M megashifter. Its great, as my column had no reverse lockout!
When i shift from 1 to 2 and 2 to 3 there is quite a hesitation, meaning, the shift is not instantaneous (tire chirping).
Now, there is an adjustment for the vacuum on the turbo 350 trans. Do I turn it more in? (clockwise) or more out? And will this help. Also, which vacuum line on the Edelbrock does that line go to, Or, does it go to the manifold port? Thanks...

Phil

>PS I almost forgot, just bolted on my brandy new Doug Thorley headers! Fit like a glove!

You need to put a shift kit in the trans. for a better shift. Leave the modulator alone. if you had low or no vac. at the trans. then you would have a late shift. be sure the kick down cable is adj. properly.

Phil,
Re: the last posting...I have a B&M shift kit in my TH350 and it still hesitates. Correct me if i'm wrong, but you're saying that when you shift.....there is a slight hesitation from when you actually shift until your trans switches gears. Correct? I've been told that this does have to do w/ the vacuum...and that Summit offers a adjustable modulator (i'm going to check it out). However, that's just info i've received from others and could be incorrect. Good luck to ya!

Originally posted by nastbscott
Phil,
Re: the last posting...I have a B&M shift kit in my TH350 and it still hesitates. Correct me if i'm wrong, but you're saying that when you shift.....there is a slight hesitation from when you actually shift until your trans switches gears. Correct? I've been told that this does have to do w/ the vacuum...and that Summit offers a adjustable modulator (i'm going to check it out). However, that's just info i've received from others and could be incorrect. Good luck to ya!

you seem to be ignoring my post, but I'll keep talking anyway. the adj. on the modulator tell the trans. to shift earlier or later, not hard or soft. you're saying you have a soft shift and the modulator want help that.

Gotcha! Mike, I see what your saying. Phil: while my car does hesitate slightly, when it does shift, it shifts hard. If your shifts are soft, Mike is correct, the shift kit is the way to go.

Originally posted by nastbscott
Gotcha! Mike, I see what your saying. Phil: while my car does hesitate slightly, when it does shift, it shifts hard. If your shifts are soft, Mike is correct, the shift kit is the way to go.

sounds like you need to go into the trans. and add a few clutch disc to the clutch packs, it sounds like your problem is the distance the clutch piston has to travel is the hesitation you have.

Thanks Brian, it is on the manifold port.

Mike, question, when cruising around and not getting on it, the shift is quick and seems like there is a shift kit already as it is hard. I bought the tranny that way and am not sure. But how can I know if the cable is in fact hooked up properly? Is it when the pedal is to the floor, the cable should be fully pulled out? Is there a certain method? And also, do you know if turning the modulator in or out makes a shorter or longer shift?
Phil...

Originally posted by fiftee6
Thanks Brian, it is on the manifold port.

Mike, question, when cruising around and not getting on it, the shift is quick and seems like there is a shift kit already as it is hard. I bought the tranny that way and am not sure. But how can I know if the cable is in fact hooked up properly? Is it when the pedal is to the floor, the cable should be fully pulled out? Is there a certain method? And also, do you know if turning the modulator in or out makes a shorter or longer shift?
Phil...

sounds like the cable is right, but you can shorten the cable a little and make it down shift quicker at WOT. at light throttle it want make any dif. in the up shift. turn the mod. in makes the shift later. if its a stock mod. dont turn it much, like a 1/2 turn. this is a pic. of a 700r4 TV cable adj. but the 350 cable adj. the same way.

http://www.transmissioncenter.net/subject.htm

my understanding , only from reading, is that the cable adjustment is different for the 700r4 (and very critical) than for the 350 as the 350 cable is only controlling wot downshift and not the shift points, whereas the 700 cable controls more.

Originally posted by 38racing
my understanding , only from reading, is that the cable adjustment is different for the 700r4 (and very critical) than for the 350 as the 350 cable is only controlling wot downshift and not the shift points, whereas the 700 cable controls more.

thats true, but we're working on a 350, not a 700r4, in which case I would have told him the dif. I don't have a pic. of a 350 cable so I was trying to give him some idea what he was looking at. this is what I told him and believe it to be true,

I said... " sounds like the cable is right, but you can shorten the cable a little and make it "down shift" quicker at "WOT". at "light throttle" it "want make any dif. " I believe thats the same thing you said.

you said..350 cable is only controlling wot downshift.

Thanks again Mike, and 38 racing. It shifts ok on WOT so I think the cable is ok. In drive when I stomp on it, it downshifts fine. My real concern was to try to stop the lag or delay when up-shifting using the ratchet mode on the B&M shifter. I think the tranny I have just needs some work, but It will be ripped out soon anyway. Just wanted to get through this summer with it.
Maybe you guys can help me with another issue also. I am poting a new question about a universal joint.

I think there was a lengthy discussion of this problem on the streetrodding.com forum started by brianangus. I think it gave a lot of detail on adjusting the vacuum modulator.

Originally posted by fiftee6
Thanks again Mike, and 38 racing. It shifts ok on WOT so I think the cable is ok. In drive when I stomp on it, it downshifts fine. My real concern was to try to stop the lag or delay when up-shifting using the ratchet mode on the B&M shifter. I think the tranny I have just needs some work, but It will be ripped out soon anyway. Just wanted to get through this summer with it.
Maybe you guys can help me with another issue also. I am poting a new question about a universal joint.

no problem fiftee6, to get a harder shift you gonna have to increase your pressures (shift kit) or take up a little slack in the clutch packs, but the modulator with the help of vac from the motor tells the trans when to shift, not how hard to shift. I guess if the rpm'm are high enough then it shifts it will feel harder, but that's not the way to increase the oil pressure. I've rebuilt a lot of 350 and never saw the need to adj. the mod.(GM says don't do it) if you can't get to shift hard enough with a kit then you got some int. problems anyhow.

Have you looked at the spring on the accumulator piston? It might be weak or broken. Hank