The original poster says that the problem is still there with the linkage disconnected. With the linkage disconnected the spring behind the throttle valve will return it to minimum pressure position.
Bill
Fordomatic late shifting ('57 thunderbird)
- Thread starter yblock57
- Start date
Bill
KULTULZ
Well-known member
But what is minimum pressure without TV activation?
Minimum TV pressure is when the valve and lever are against the stop/L shaped bracket.
When the throttle is opened the lever moves the valve away from the stop increasing the pressure. When the throttle is closed the valve and lever are returned to the stop by spring pressure lowering the pressure to minimum.
Minimum TV pressure is controlled by the stop. If the stop was to get bent in toward the valve it would raise the minimum pressure.
That L shaped stop bracket sticks out like a sore thumb and is easily bent.
Bill
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KULTULZ
Well-known member
You are correct, but all of this will not happen with the TV rod disconnected unless the lever itself is actuated in some manner to arrive at correct TV pressure.
The trans assy has to see proper TV pressure to operate properly according to its' calibration(s). You would/could fine tune and modify from that point. The same with a vacuum modulator valve, it is adjustable.
Or am I off on an incorrect tangent?
The trans assy has to see proper TV pressure to operate properly according to its' calibration(s). You would/could fine tune and modify from that point. The same with a vacuum modulator valve, it is adjustable.
Or am I off on an incorrect tangent?
yblock57
Senior Member
Ok, got the pan off and took at look at things. Made another video showing the TV linkage against the ‘L’ bracket. It’s obviously putting pressure on the valve at the ‘Rest’ position and limiting travel of the linkage. I think this is the key to the entire problem.
https://youtu.be/Qfe5KclSPkQ
I went ahead and pulled the valve body and disassembled. Everything looks good and all springs are present and accounted for. All pistons move freely.
Would y’all go ahead and bend the ‘L’ bracket back and check for free movement and reassemble? For grins I hooked up the TV rod to the trans with valve body removed and I get full articulation with no binding.
Here’s a closer look at the TV & L stop
https://youtu.be/6NRYD5EvOOA
I'm concerned that even bending this L won't give me the amount of travel I need without seriously distorting things. Thoughts?
Thanks,
https://youtu.be/Qfe5KclSPkQ
I went ahead and pulled the valve body and disassembled. Everything looks good and all springs are present and accounted for. All pistons move freely.
Would y’all go ahead and bend the ‘L’ bracket back and check for free movement and reassemble? For grins I hooked up the TV rod to the trans with valve body removed and I get full articulation with no binding.
Here’s a closer look at the TV & L stop
https://youtu.be/6NRYD5EvOOA
I'm concerned that even bending this L won't give me the amount of travel I need without seriously distorting things. Thoughts?
Thanks,
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Habusailor
Senior Member
I'm by no means a transmission expert but to me that bracket does not look bent. It is straight and parallel to the piston. Can it be rotated so as to contact the linkage at another spot or is it fixed in that position? Bending things that are straight just doesn't seem right to me.
Sent from my SM-T550 using Tapatalk
Sent from my SM-T550 using Tapatalk
Dominic Hide
Member
Don't try to bend the bracket, it looks fine as is. The piston does seem to be pushed out to far, the narrow part of the piston should not be visible outside of the main body. (compare to left valve body in earlier posted picture) I think that it has been assembled wrong. What was happening at the other end of that passage while you were pushing the piston in and out. I will take one apart tomorrow and take pictures for comparison.
You are correct on everything but minimum pressure. Minimum pressure is when the TV valve is extended fully against it stop. With the linkage at rest or removed the valve will be against its stop due to spring pressure. The stop is not adjustable so minimum pressure is not adjustable. Then when the throttle is applied the rod and lever moves the valve in increasing the TV pressure, This pressure is adjustable by lengthening or shortening the rod.
The original posters problem was the shift points are too high and too firm which is caused by TV pressure being too high at minimum throttle. With the rod disconnected something is keeping the valve from extending far enough to lower the pressure enough for a proper shift speed and feel. Either a binding lever or a bent TV valve stop. The binding lever can be detected by feel, spring pressure one way and a solid stop the other.
I 'm thinking the L shaped stop bracket is bent in increasing minimum pressure.
Bill
Please disregard this post I tried to delete.
Bill That picture is for reference only, not the original posers valve body.
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The bracket doesn't look bent. What about the spring and valve ahead of that valve, does it protrude out other end when fully depressed ?
Bill
KULTULZ
Well-known member
Well, not actually. I did not understand the OP as actually being in a diagnostic sequence.
yblock57
Senior Member
I did not bend the L bracket. Didn't feel right as others have noted. Didn't look like that was the actual issue.
After several of y'all pointed out and I initially missed, the back side of the throttle valve was NOT moving freely. It was being stopped by the back cover plate that had a small protrusion just barely covering the edge of the TV bore, thus creating a hard stop on the valve. Pics Dominic posted earlier in this thread clearly show the TV protruding out the backside of the bore. Mine was not. Apologies on the videos. I accidentally stopped in between showing the issue.
https://youtu.be/VVfgFdubxhs
https://youtu.be/yZUT4PGkFKU
I don't have an explanation on why that back cover plate was interfering with the valve, but I went ahead and filed it down to get the clearance I needed. It only goes on one-way so no way it could've been flipped or put on backwards. Now it operates with MUCH more movement than before. I suspect this will translate into the additional articulation I need to get the linkage set correctly and have full throttle without binding.
https://youtu.be/8Rr5ZH-up_w
I'll be sure and check movement of everything when I reinstall the valve body and before the pan goes back on. If anyone has any additional thoughts or ideas on what I should look at while the pan's off, I'm all ears!
I'll be setting the TV rod using my pressure gauge when it gets to that point. I want to verify this gets me back into the ranges shown in the FOM shop manual.
This has been a great learning experience. I can't thank everyone enough who's chimed in with all the help and suggestions. Very much appreciated! I'll be sure and post my findings.
After several of y'all pointed out and I initially missed, the back side of the throttle valve was NOT moving freely. It was being stopped by the back cover plate that had a small protrusion just barely covering the edge of the TV bore, thus creating a hard stop on the valve. Pics Dominic posted earlier in this thread clearly show the TV protruding out the backside of the bore. Mine was not. Apologies on the videos. I accidentally stopped in between showing the issue.
https://youtu.be/VVfgFdubxhs
https://youtu.be/yZUT4PGkFKU
I don't have an explanation on why that back cover plate was interfering with the valve, but I went ahead and filed it down to get the clearance I needed. It only goes on one-way so no way it could've been flipped or put on backwards. Now it operates with MUCH more movement than before. I suspect this will translate into the additional articulation I need to get the linkage set correctly and have full throttle without binding.
https://youtu.be/8Rr5ZH-up_w
I'll be sure and check movement of everything when I reinstall the valve body and before the pan goes back on. If anyone has any additional thoughts or ideas on what I should look at while the pan's off, I'm all ears!
I'll be setting the TV rod using my pressure gauge when it gets to that point. I want to verify this gets me back into the ranges shown in the FOM shop manual.
This has been a great learning experience. I can't thank everyone enough who's chimed in with all the help and suggestions. Very much appreciated! I'll be sure and post my findings.
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If you look close at Dominic's picture on the right the plate is supposed to go between the first and second lands on the valve. The first land is on the outside as pictured and the plate will stop the second land from coming out as shown by the wear marks on the plate. Hopefully you didn't file too much off.
l
I should add that the plate fits between the first and second lands and limits the travel both ways. It keeps the second land from coming out and keeps the first land from going back in to far. By removing the edge of the plate it can't limit the travel as designed. Your third video shows this as the first land can go in past the plate. I would get another plate so it can limit the travel.
Bill
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yblock57
Senior Member
Oops. I did file it off. Now it slides completely through. I wish I'd known that's how it was supposed to work.
Dad has an extra valve body at the house that Should have that piece intact that I can grab.
If I did install it the way it is now, I'm guessing it would get stuck? Possibly too low line pressure?
That's how we learn, I've made a lot of them.
rotorwrench
Well-known member
I'm more used to the old ones but something doesn't look right there. The book I have for the old Merc-O-Matic shows that their are the two valves there in that same bore. The one on the throttle control shaft side is the kick-down valve and it pushes the throttle valve through a straight coil spring on that side. There is a tool to bend that stop but I don't think that is the problem. On the other side where the throttle valve protrudes out, I'm used to seeing a leaf spring on the plate there. The plate that I'm used to actually has a leaf spring that controls how far the throttle valve can protrude there but also limits it on how far it can go back in the bore. Yours not only doesn't have the leaf spring but it is stopping the valve from moving farther out. Something has to be there the keep it from moving out too far and it appears to be missing that spring. Take a good look at the photos of the other valve body and you will see the leaf spring there. The valve should protrude beyond that plate and make contact with the spring.
yblock57
Senior Member
While I'm waiting on my valve body part, I wanted to try to get the linkage set the best possible by the book. I can't get the accelerator pedal height up past 3" and the book calls for 4 7/8" on a '57 thunderbird.
As a consequence of this, when you floor the pedal, you do not get full throttle engagement. When you work the 'grasshopper' under the hood by hand to full throttle, the rod pops out of the back of the accelerator pedal. Obviously there's something wrong here.
I've locked the 'grasshopper' in place with the 1/4" drill bit and the threaded rod that sets the pedal height is extended as long as it will go. 3" is all I can get out of the adjustment.
I went ahead and removed the piece of linkage from the accelerator pedal that goes through the firewall and measured and took a few pics. If anyone has one I can compare mine to, that would be great. Not sure if the curve in it is correct or not — it doesn't appear bent to the naked eye. I don't want to flatten that curve in a vise if it is indeed correct and the problem is elsewhere. Tip to tip is 5 7/8"
Nothing else in the setup looks bent or twisted.
Thanks!
As a consequence of this, when you floor the pedal, you do not get full throttle engagement. When you work the 'grasshopper' under the hood by hand to full throttle, the rod pops out of the back of the accelerator pedal. Obviously there's something wrong here.
I've locked the 'grasshopper' in place with the 1/4" drill bit and the threaded rod that sets the pedal height is extended as long as it will go. 3" is all I can get out of the adjustment.
I went ahead and removed the piece of linkage from the accelerator pedal that goes through the firewall and measured and took a few pics. If anyone has one I can compare mine to, that would be great. Not sure if the curve in it is correct or not — it doesn't appear bent to the naked eye. I don't want to flatten that curve in a vise if it is indeed correct and the problem is elsewhere. Tip to tip is 5 7/8"
Nothing else in the setup looks bent or twisted.
Thanks!
Attachments
scicala
Well-known member
Whether it has the correct rod length from the pedal or not, is it possibble to twist/bend the rod rod that goes through the bell crank on the fire wall, so you can get the correct height off the floor for the pedal ? In other words, make the bottom of the rod/lever closer to the firewall where the pedal rod goes through. Just a thought.
Sal
Sal