727 Shifts Down to 2nd at highway speeds

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Austin Schlegel

Austin Schlegel

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Westfield Indiana
Hey guys,

I am having issues with my 727. The problem is that when I am cruising down the highway at around 50-60mph I am in 3rd gear then out of no where the trans will downshift and stay in 2nd for a few seconds then shift back up to 3rd. This happens often. I have been adjusting the kickdown back and forth but that does not seem to fix the issue.

I am wondering if the linkage is right for my set up. I have '74 360 with a Holley 4160 on top. Did that carb come with the 360 from factory? If not should I invest in a lokar cable setup?

If there is anything else you think I should adjust/check please let me know.

Thanks for any help
 
A '74 360 would have had a Thermoquad on it (or a 2bbl.) from the factory.
Post a pic of your linkage.
If you're not using the Holley linkage adapter for Mopars (#20-7), that could be part of your problem.
20-7.jpg

You wouldn't be getting the proper "throw" on your linkage for the part-throttle kickdown.
Also, make sure your trans. fluid level is correct- checked hot, on level ground, with trans in NEUTRAL (not Park, that will give a false reading).
 
Professor Fate said:
A '74 360 would have had a Thermoquad on it (or a 2bbl.) from the factory.
Post a pic of your linkage.
If you're not using the Holley linkage adapter for Mopars (#20-7), that could be part of your problem.
View attachment 1715837028
You wouldn't be getting the proper "throw" on your linkage for the part-throttle kickdown.
Also, make sure your trans. fluid level is correct- checked hot, on level ground, with trans in NEUTRAL (not Park, that will give a false reading).
Click to expand...

It does not look to me like I have that holley adapter

1216211550.jpg


1215211152.jpg


1215211152a.jpg
 
I did just do a fluid and filter swap on the trans. The haynes repair manual said to fill it with 4qts if just draining and changing filter. So I filled it with just around 4 qts.

My dipstick doesnt read correctly also. I need to get the proper dipstick one for this trans as well.
 
Yeah, something's not copacetic there.
It looks like you have the lever adapter on there, but the throttle stud is pinched on the edge of the lever instead of going through the mounting hole.
Besides being unsafe, that's goofing up your geometry. It needs to get assembled properly and the kickdown readjusted, then see where you stand as far as it slipping in and out of kickdown.
In the pic below, the kickdown linkage is slightly different because of the year and application, but should give you an idea of how the throttle stud mounts to the linkage. (Pardon the grody kickdown linkage, it was a trial fit and alignment before cleaning, painting and final install.)
upload_2021-9-25_10-54-37-jpeg.1715796015
 
The linkage above should have a spring and the flat bar with the slot should be fwd against the pin.
 
The linkage from the carb to the trans should move as the throttle is opened and end up with the lever on the tranny all the way back when the carb is wide open. The long slot in the bar at the carb is so that if the linkage sticks it can't hold the throttle open.
 
Austin you appear to have an adapter but your stud is in the wrong hole. Trans fluid on a mopar like yours is checked idling in neutral.
 
Tech857 said:
The linkage above should have a spring and the flat bar with the slot should be fwd against the pin.
Click to expand...
As I said, it was installed for trial mockup and preliminary alignment purposes.
Fluid level was addressed in post #3.
 
Austin did it seem to shift and hold before the fluid change?
 
How far are you into the throttle when it kicks down? After 60mph or so mine stays in 3rd even at wot. My car has 3.55 gears.
 
Looks to me like 2bbl linkage on your 4 bbl setup.

You can see your slider at the throttle Is angling up from the corner turn buckle.

Needs the 4 bbl manifold throttle cable and kickdown bracket. Not the 2bbl bracket.

So your geometry is off and looks like it is binding up tight at the turn buckle causing it to stick in the higher pressure setting, instead of backing off slightly when you are cruising with less pressure applied at the kickdown.

Too much pressure will make it want to drop down a gear.
 
Low fluid level will burn up your trans. If your pump sucks air it will drop out of third. I wouldn't even start my engine without enough fluid. Fluid should be at least to the top of the pan idling in neutral. Take out the dipstick tube and stick the stick down into it and see where the full mark shows up. Should be at about the o-ring.
Take your slotted rod loose from the stem and turn it clockwise (shorter) about four turns.
 
Tech857 said:
Austin you appear to have an adapter but your stud is in the wrong hole. Trans fluid on a mopar like yours is checked idling in neutral.
Click to expand...

I will check the trans fluid today after work

Tech857 said:
Austin did it seem to shift and hold before the fluid change?
Click to expand...
It was doing the same thing before the fluid change.

Tech857 said:
How far are you into the throttle when it kicks down? After 60mph or so mine stays in 3rd even at wot. My car has 3.55 gears.
Click to expand...
I am barely pressing the peddle and it will shift down. Not sure what the gearing is but I know it has 7 1/4 rear end
 
George Jets said:
Looks to me like 2bbl linkage on your 4 bbl setup.

You can see your slider at the throttle Is angling up from the corner turn buckle.

Needs the 4 bbl manifold throttle cable and kickdown bracket. Not the 2bbl bracket.

So your geometry is off and looks like it is binding up tight at the turn buckle causing it to stick in the higher pressure setting, instead of backing off slightly when you are cruising with less pressure applied at the kickdown.

Too much pressure will make it want to drop down a gear.
Click to expand...
The car came with a lokar kickdown cable. Would I be better of installing that you think?
 
Austin Schlegel said:
The car came with a lokar kickdown cable. Would I be better of installing that you think?
Click to expand...

No

You can get the linkages right by doing the firewall turnbuckle forward.

Remember that your 4 bbl sits farther forward than the 2 bbl, the 4 bbl linkage sits more to the left than the 2 bbl. Your Mid Rise intake manifold sits 1" taller than the stock intake manifold.

So all of this plays into getting the geometry correct and lined up with the proper length throws. find some pictures online of the same engine, trans, and body style, and carburetor and copy that layout.

At wide open throttle you want the pressure valve arm on the trans at full stop. Good place to start. Can adjust it from there as where you want your kickdown to come in at.
 
You could try it with the KD completely disconnected just as a test. When you changed the fluid and filter, was the fluid dark? Was there anything in the bottom of the pan; like flakes or black greasy sludge? You said it "usually" shifts right into reverse...usually? Is it delayed sometimes? especially when hot? And is the third gear problem never when it's cold; only warmed up?
 
CudaFactHackJob said:
You could try it with the KD completely disconnected just as a test. When you changed the fluid and filter, was the fluid dark? Was there anything in the bottom of the pan; like flakes or black greasy sludge? You said it "usually" shifts right into reverse...usually? Is it delayed sometimes? especially when hot? And is the third gear problem never when it's cold; only warmed up?
Click to expand...

Do not want to run your transmission with the kickdown disconnected at all. You need some pressure there at the kickdown arm otherwise you will quickly burn out your transmission.
 
Austin Schlegel said:
Hey guys,

I am having issues with my 727. The problem is that when I am cruising down the highway at around 50-60mph I am in 3rd gear then out of no where the trans will downshift and stay in 2nd for a few seconds then shift back up to 3rd. This happens often. I have been adjusting the kickdown back and forth but that does not seem to fix the issue.

I am wondering if the linkage is right for my set up. I have '74 360 with a Holley 4160 on top. Did that carb come with the 360 from factory? If not should I invest in a lokar cable setup?

If there is anything else you think I should adjust/check please let me know.

Thanks for any help
Click to expand...
Start with the chrysler throttle braket that bolts to the holley to attain the correct ratio of travel. Set it correctly....
Just seen the pics... okay... to simply test this.. get a nut and bolt.. stick it through the slot on the kickdown at the throttle bracket...tighten nut/bolt up near the kickdown pin on the throttle so that it hits and pushes the sloted kickdown rod back as the throttle is opened. Its should be all the way back at wot. Check your fluid level. Next time you have the pan off... stick the dip stick in and mark it right at the edge where it goes up into the case/tube. Then put the recommended fluid amount and compare the mark to the fluid line.
After that...then check the trans for maladjustment
 
Last edited:
It's common to have a dip stick from the factory that's off. Them add a deep pan and filter extension...
My 96 truck is like this. Full is really right at or barely above the 1st safe/ok line.
If I fill it to full... it will A. Hunt between 3rd & 2nd and or B. at wot blow it out the vent on the pump.
 
You can run a TF without the KD hooked up and not harm it at all. If you notice, the rod has a slot that allows the carb to open without affecting the KD arm. If you never go past that point; there will be no damage. IF you think you have a low fluid problem, add another quart. If it's too much, drain it out the neutral safety switch.
 
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