727 not shifting right

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GTSDustin

GTSDustin

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Ok, need some help. I took out the manual valve body in my wife's 67 Cuda and put a stock valve body in it. The car starts out in second gear, shifts great to third. Dies not downshift at all on it's own even after a complete stop. It shifts great manually. Any suggestions?
 
TV linkage adjusted incorrectly, shfit linkage as well. Shift linkage would or could cause the second gear starts. TV adjustment would delay upshift as well as not allow kick-down, one or the other .
 
X2^^

Or the E-clip on the link-rod went MIA.
There is a gov. pressure take-off port on the extension housing just below the speed-o housing.Pressure varies between 0 and 90psi, depending on vehicle speed, and differential gear ratios.Very generally, the psi should be near zero at standstill, rising smoothly about 1psi per 1 mph. So about 50 psi at 50 mph. This number should also decrease smoothly back to zero at 0mph.
 
AJ/FormS said:
X2^^

Or the E-clip on the link-rod went MIA.
There is a gov. pressure take-off port on the extension housing just below the speed-o housing.Pressure varies between 0 and 90psi, depending on vehicle speed, and differential gear ratios.Very generally, the psi should be near zero at standstill, rising smoothly about 1psi per 1 mph. So about 50 psi at 50 mph. This number should also decrease smoothly back to zero at 0mph.
Click to expand...

I love this kind of info! never knew this! Thanks! MT:burnout:
 
Was the stock valve body known to be good? If unknown it's possible the 1-2 shift valve is stuck in the valve body. A governor pressure test such as suggested will reveal if it's a gov or VB problem. If the gov pressure drops to less than 2 psi it should start out in 1st gear. If it drops but still starts in 2nd I'd look at the 1-2 shift valve in the VB
 
fishy68 said:
Was the stock valve body known to be good? If unknown it's possible the 1-2 shift valve is stuck in the valve body. A governor pressure test such as suggested will reveal if it's a gov or VB problem. If the gov pressure drops to less than 2 psi it should start out in 1st gear. If it drops but still starts in 2nd I'd look at the 1-2 shift valve in the VB
Click to expand...

I wasn't too sure about the 1-2 valve so I didn't mention it, but to the OP the valve bodies have to be really clean.
Flushing, blowing out and moving the valves in their bores type clean.
The only thing I could think of was the valve in the VB could be stuck in the second gear position. (which I have personally never seen happen before.)
And I couldn't imagine it getting put on that bad of condition.

One other thing and can think of is that it's possible the VB was over tightened causing the valve to get jammed.
 
I thought of that too, and began to post on that, but thought better of it, as I realized that if gov pressure was working, theres more than enough pressure to blow that 1-2 valve out of "stuck". Maybe not out of "seized". But in 45 years, Ive never seen seized, so I let it go.
It just seemed far more likely to be the gov, especially since it happened to me once.

It does seem strange though, that the OP makes no mention of any issues prior to VB exchange. But then with a manual VB, the gov circuit is ignored or blocked anyway. Did I say blocked?
Crap there it is!
I forgot about that. In the old days we used to drive a cup-plug into the gov passage when installing a manual VB.
 
AJ/FormS said:
I thought of that too, and began to post on that, but thought better of it, as I realized that if gov pressure was working, theres more than enough pressure to blow that 1-2 valve out of "stuck". Maybe not out of "seized". But in 45 years, Ive never seen seized, so I let it go.
It just seemed far more likely to be the gov, especially since it happened to me once.

It does seem strange though, that the OP makes no mention of any issues prior to VB exchange. But then with a manual VB, the gov circuit is ignored or blocked anyway. Did I say blocked?
Crap there it is!
I forgot about that. In the old days we used to drive a cup-plug into the gov passage when installing a manual VB.
Click to expand...

bOb shingler said:
and also the governor valve may be removed completely
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Ah hell, Ill bet you guys are right.
The governor is probably blocked off or removed because it was part of the manual VB installation instructions.
Good call guys
 
The stock valve body worked great in the road runner when we got it. Only took it out to put back in 4 speed(factory 4 speed car)I was thinking governor as well. So is it possible someone removed the governor completely for manual shifting/race purpose only? The guy I bought the car from said it was a professionally built trans.
 
Well, the way I see it, you have 3 choices
1) put the manual VB back on.
2) drop the VB and look for the cup-plug in the gov. passage, or
3) drop the extension house and look for a missing gov. assy
3b) you may be able to shine a light in through the speed-O hole, to see the governor.
 
I haven't had much experience with manual valve bodies so I haven't seen everything but if it had a governor plug installed wouldn't that prevent fluid from reaching the governor? If so wouldn't the governor pressure always be at zero? If that's the case it'd always stay in low gear. Someone correct me if that's wrong
 
fishy68 said:
I haven't had much experience with manual valve bodies so I haven't seen everything but if it had a governor plug installed wouldn't that prevent fluid from reaching the governor? If so wouldn't the governor pressure always be at zero? If that's the case it'd always stay in low gear. Someone correct me if that's wrong
Click to expand...

They block off the governor on manual shift valve bodies because they use a manually directed oil flow to apply gears.
The valve body is designed to where all it does is redirect flow from one set of internal parts to another set to change gears without any effect from driveline speed at all, so the governor is pointless and therefore blocked off or removed completely.
Probably removed completely if it was professionally built for racing, and in that case the plug would HAVE to be there so line pressure wasn't lost through the open passages where the governor was.
 
fishy68 said:
I haven't had much experience with manual valve bodies so I haven't seen everything but if it had a governor plug installed wouldn't that prevent fluid from reaching the governor? If so wouldn't the governor pressure always be at zero? If that's the case it'd always stay in low gear. Someone correct me if that's wrong
Click to expand...

.............Well Tracy the trans will start off in 2nd unless u manually shift it to the 1st gear position, if their is a gov plug installed...u need to remove it or drill a hole in it, I believe u only need a 1/8th inch hole.....this info is in the TF-3 kit if u want to return from manual to auto shifting, ofcource there is alittle more to it that, u also have to reverse the plate that was installed to make it manual in the first place.......kim.......
 
Let me throw this one in there. Do you have any engine braking? Or does the transmission freewheel until you stop?
 
oldkimmer said:
.............Well Tracy the trans will start off in 2nd unless u manually shift it to the 1st gear position, if their is a gov plug installed...u need to remove it or drill a hole in it, I believe u only need a 1/8th inch hole.....this info is in the TF-3 kit if u want to return from manual to auto shifting, ofcource there is alittle more to it that, u also have to reverse the plate that was installed to make it manual in the first place.......kim.......
Click to expand...

Ok. thanks for clarifying that Kim. I would have thought with a plug in it there would be zero pressure reaching the governor so with zero pressure in there would be zero pressure out which would allow the 1-2 shift valve to stay in the idle position
 
TrailBeast said:
They block off the governor on manual shift valve bodies because they use a manually directed oil flow to apply gears.
The valve body is designed to where all it does is redirect flow from one set of internal parts to another set to change gears without any effect from driveline speed at all, so the governor is pointless and therefore blocked off or removed completely.
Probably removed completely if it was professionally built for racing, and in that case the plug would HAVE to be there so line pressure wasn't lost through the open passages where the governor was.
Click to expand...

I do have the jist of how a MVB works. Didn't mean I was totally ignorant of how they work. Just haven't had much exp in installing them. Thanks for the input
 
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