Hello to everyone!

I already made a thread for this topic and i thought that i fixed the problem, but i havent

I just got my car back from changing my 8.5 2.56 open rear to 3.23 with an eaton truetrac carrier and i LOVE it! It really woke up my cutlass and the days of motorcycle-burnouts are gone

BUT! I still have the problem that my TH350 with transgo shift kit (orange spring, should i usr the red one?) wont shift up back to 3rd gear after kickdown on WOT until i let the pedal loose for a sec. The engine goes up to 5000 and it really sounds like overrevving. I red somewhere that this can be a ignition problem, 5000 should be no problem for a stock olds 350 i have an MSD ready to run distributor with vacuum advance installed and never played around with the springs in it.

I have the downshift cable adjusted as the CSM for 71 tells it. The self-adjust way (the pedal pushes the metal clip to correct adjustment position when push it to WOT position).

Governor is the stock one and the springs from the transgo shift kit are not correct for it. It looks different than the chevy ones.

for me, it seems like that this clip self adjustment procedure makes the downshift cable too tight, so its pulled out too far?

Can someone give me some ideas to fix this problem? Maybe its really an engine (ignition?) And not a transmission problem.

Thank you a lot for any help!

 

I don't see how it would be an ignition issue. My first thought is it has to do with the vacuum modulator, the valve behind the modulator, or the spring on that valve. Maybe not but those are the things I think of when you say letting off the throttle results in upshifting as that's a classic symptom of loss of vacuum at the modulator.

Which spring position are you referring to when you say orange or red?

 

Thanks a lot for your answer! I always thought (and red) that the modulator has no effect at WOT

i have an adjustable aftermarket modulator.

I have This issue only at WOT. At normal driving, the trans shifts good througt all 3 gears. Its only when i hit the pedal to the floor, the engine revs up, the car accelerates till the engine does about 5000 and sometimes more rpm, then it starts bogging and i loose the pedal because its doesnt sound healthy. In my opinion, it should shift back up to 3rd at about 4800, even when i stay on full throttle.

The Transgo shift kit comes with 2 different springs for the 2-3 shift valve. Red for street, orange for competition only. I used the orange one

 

That sounds similar to an issue I had on my first TransGo shift kit installation. I inadvertently put the spring between the modulator valve and the vacuum modulator. This caused the engine to rev higher than it should at WOT (over 5000 RPM vs 4800 RPM). I put the spring in the correct position and everything then worked perfectly.

 

Ok, i had to check that with looking in the transgo-box to see if the gold spring is there or not. And its not. I have it installed, and i remember that i had to put out the valve to install the gold spring

How do you guys adjust your kickdown cables?

I still suspect my problem there..

 

Modulator should not be ruling at WOT. Sounds like kickdown is working great. Kickdowns only kickdown, they don't say do anything else. They will also not say kickdown, but that isn't saying something.

What I mean is, I think your governor needs help. I think the kickdown is working, you're letting off, which should let modulator get control, but the governor should be overriding your kickdown. You should be dropping into high gear at about 4500 in second, with the hammer still pushed to the wood, at about, say, ~80 mph for a 3.23 and ready to power to 100 or more in top gear. What happens is the governor should be overriding the kickdown at too high of RPM.

 

Yeah, i had the governor out, it had no damage and rhe piston moved freely- i had another thread which is called odd governor.. so i wasnt able to try different governor springs from the transgo kit because my governor looks different than a 'normal' th350 governor.. should i get a different governor?

 

The red and orange spring your speaking of is the pressure regulator spring. The red one provides 200psi (I think) the orange around 180, depending on how good the pump is. The factory green spring is about 160 if I remember correctly. The more line pressure, the firmer the shifts, and the greater the clamping force on the clutch packs, within reason. For a mild 350, you could get away with using the factory spring, but there is no downside to using either spring other than firmer shifts.

Try disconnecting the kickdown cable. If it then upshifts normally, your going to have to do some modifications to the governor. You will need to get a governor calibration kit, and a couple extragovernor covers and seals I would suggest getting a couple spare govenors to work with, and take detailed notes.

If you want the trans to shift sooner, you need either heavier springs, or weights. It’s pretty time consuming to get it right.

The vacuum modulator has zero effect of full throttle shift points.