Th350 Wot Shift Points, Governor Vs Modulator

Thunderbolt

Well-Known Member
Is it true that when the kickdown is activated its the governor only that controls the wot shift points?

I have earlier adjusted the modulator (years before the blower install) so it shifted at higher rpms when NOT using the kickdown at wot, after that test i bought the b&m governor kit to get it right.

Now, with the blower, the kickdown cable became to short, so its not hooked up, and as i wrote in my blower thread, it wont upshift at wot when boost reaches the modulator.

Could this "no wot upshift" be solved by making the kickdown cable working again? Like bypassing the modulator at wot?
 
Got a 78 Chevy K20 407 SB mildly built with a TH350 that I installed the B&M governor re-calibration kit into. I've got the 1-2 shift point at 1300 rpm, that is controlled by the modulator valve correct? I put the #4 and 5 weights in it with the yellow and orange spring. The 2-3 shift is now at 2600 rpm, the 3-2 shift is at 1500 rpm. With the stock weights and springs all the up-shift/down shift was done by the modulator, it seamed the governor had no control of the shift points. I have to grunt the motor around corners or pulling away from stop lights (it would already be in 3rd gear by 25 mph). The thing I'm noticing now is the there is "floating point" between the 3-2 down shift. Depending on the rpm it'll either stay in 3rd or downshift to 2nd. Is that normal, the "floating point"? Remember this is 4X4 pickup not some street racer.
 

Indycars

Administrator
Staff member
I installed the B&M governor re-calibration kit into. I've got the 1-2 shift point at 1300 rpm
How about a link to more info about your shift kit ?
Is the 1-2 shift at normal acceleration or WOT ?

The 2-3 shift is now at 2600 rpm, the 3-2 shift is at 1500 rpm.
At what throttle position? Are you concerned about 3-2 downshift, 1500 rpm sounds about right.

The thing I'm noticing now is the there is "floating point" between the 3-2 down shift.
What do you mean by the "floating point" ?
.
 
How about a link to more info about your shift kit ? Here's the link to the governor re-calibration kit I used https://www.summitracing.com/parts/BMM-20248
Is the 1-2 shift at normal acceleration or WOT ? Under normal acceleration. Like I said, its a 4X4 pickup, not a slot car.

At what throttle position? Are you concerned about 3-2 downshift, 1500 rpm sounds about right. The throttle position is about 1/4 throttle. Slowing down for corners, pulling out of a slow lane to pass.

What do you mean by the "floating point" ? It seams or feels like it is not in gear, no trans braking or acceleration until you apply the throttle. Then, depending on rpm it well either go to 3rd or 2nd.
 

Indycars

Administrator
Staff member
With the stock weights and springs all the up-shift/down shift was done by the modulator, it seamed the governor had no control of the shift points.
What makes you think that the governor has NO control over the shift points? It should be a combined effort.

I've read you comments many times, but I'm not sure what you are wanting the trans to do differently. It seems you are trying to raise the shift points since you have gone to the lighter side for both weights and springs. If you could give a clear goals, that would help.

What was the closest weight and spring from B&M to the stock OEM part ?
How many miles are on this transmission ?
Did it have any problems before you made a change to the governor ?

From the B&M Manual:
Heavier weights produce earlier shifts, lighter weights produce later shifts. Stiffer springs tend to
produce earlier closely stacked shifts, weaker springs tend to raise and spread apart shift points.

1672677970760.png
 
What makes you think that the governor has NO control over the shift points? It should be a combined effort.

I've read you comments many times, but I'm not sure what you are wanting the trans to do differently. It seems you are trying to raise the shift points since you have gone to the lighter side for both weights and springs. If you could give a clear goals, that would help.

What was the closest weight and spring from B&M to the stock OEM part ?
How many miles are on this transmission ?
Did it have any problems before you made a change to the governor ?

From the B&M Manual:
Heavier weights produce earlier shifts, lighter weights produce later shifts. Stiffer springs tend to
produce earlier closely stacked shifts, weaker springs tend to raise and spread apart shift points.

View attachment 17398
My goal is to get the shift points up a littler higher in the rpm band at part throttle shifts. Right now the modulator is doing the up shifting, the governor has no effect for some reason. I have replaced the kick down cable and it is adjusted correctly. With the current motor I don't need full throttle, remember, this is a 4X4 Pickup. When you go around a corner at a traffic light for example, there is no down shift to 2nd gear so you wind up torquing the motor in 3rd gear from say 25 mph up to 45. The motor does not care, it has the torque to do it (mildly built SB 407). One would think the tranny would down shift to 2nd, it's never done that all its life. The tranny was built back in 1998 and was installed behind a 350 with a blower. I know it has a B&M overhaul kit in it. 2500 rpm seams to be the ticket for the 2-3 shift point. The "floating" between 3-2 down shift is what has me concerned. Is it damaging the tranny (clutch slippage?)?
 

Thunderbolt

Well-Known Member
Part throttle shifts can be adjusted with the modulator, governor is more for WOT shift points.
They interact but generally the modulator are in charge of the part throttle shifts.
Most modulators can be adjusted with a flat screwdriver in the vacuum port.
 
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