727 Will Not Kickdown

[Charger_Dart]

I am looking for some suggestions on my wife's 68 Dart with a 340 / 727 combo.
I can't get the tranny to kickdown a gear when its wide open.

I dropped the pan and adjusted the two band adjustments per the FSM. I changed the filter and put new fluid in it, and I set the kickdown linkage correctly (checked it lots of times)  - no change.
I also checked the downshift arm on the side of the transmission to make sure it was tight to the post and it is. Not sure what to call this piece, but its what the kickdown linkage attaches to on the transmission.

The tranny shifts up and down just like it should and performs really well, except it just won't downshift unless I manually force it.

What else should I look for ?   

[John_Kunkel]

Make sure the TP lever on the transmission is NEAR full back at WOT; have someone sit in the car and mash the throttle to the floor then, from under the hood, make sure the carb is wide open and the lever is near full back. If you can push the linkage rearward more than 1/4" with the carb full open the linkage needs adjustment.

Are the carb/manifold stock? An aftermarket carb needs a Mopar throttle lever extension in order for the TP linkage to work correctly.

[Charger_Dart]

Thanks John, I will take a look at the actual lever movement

I do have a Edelbrock RPM intake with a high rise throttle / linkage  bracket but I am using stock length rods. Let me know if I should look for anything else.

[John_Kunkel]

The Edelbrock carb needs the #1481 lever extension in order for the linkage to work correctly.

http://www.summitracing.com/parts/EDL-1481

[Charger_Dart]

I have that hooked up. Anything else?

[Paul G]

I fought your problem for some time. I finally decided that the throttle arm on the carb did not have enough travel to make the kick down linkage arm make it all the way back to kickdown the trans.

Can you adjust the kick down linkage so the arm on the trans will go all the way back at full throttle? And if so will it then kick down? Might shift improperly then. That was my problem. I had a choice, long shifts with kickdown, or normal shifts and no kickdown. I made my own bracket extension piece to mount on the carb throttle extension bracket, it moved the linkage arm point 1/2" higher up, that gave the arm more travel, was then able to adjust for correct shift points and still get it to kickdown. I was running a 440 with an RPM air gap manifold.

[Charger_Dart]

Thanks for all the replies. Sorry for the long delay.

I finally got around to checking the trans arm movement with the gas pedal to the floor. At the tranny, the arm moves almost all the way back as far as it can. There is just a very, very small amount of backward movement left. I am at the limit of the two adjustment rods so i can't go any further.

Does the tranny kickdown arm need to move all the way back in order to cause the tranny to kickdown?

[John_Kunkel]

"Near" full back should be all you need but you may have to lengthen one of the rods a little to get more travel.

[Charger_Dart]

I don't have any adjustment left. Is there a longer rod I could use to gain a little more travel?

Is there anything inside the tranny that would cause it not to want to kick down?

[lisiecki1]

Are you positive the valve body has never been modified?

[Charger_Dart]

Are you positive the valve body has never been modified?

No I am not, but it looked very stock when I dropped the pan. Everything looks stock under the car, but I guess somebody could of changed something somewhere in its life. If shifts like a stock tranny both up an down (very smooth) - just won't downshift under hard acceleration.

[Paul G]

Did you check full travel by having some one step on the gas pedal while you watched the linkage? I had the situation where the throttle cable was not moving the carb full stroke.

[Charger_Dart]

Did you check full travel by having some one step on the gas pedal while you watched the linkage? I had the situation where the throttle cable was not moving the carb full stroke.

Thanks for the reply. Yes, that is how I know the arm on the side of the transmission is moving almost all the way back. I don't have any adjustment left in the two kickdown adjustment rods so I can't get it to 100%, but its real close. I can't think of what else I might cause it to not want to kick down.   

[lisiecki1]

Are you positive the valve body has never been modified?

No I am not, but it looked very stock when I dropped the pan. Everything looks stock under the car, but I guess somebody could of changed something somewhere in its life. If shifts like a stock tranny both up an down (very smooth) - just won't downshift under hard acceleration.

There are internal modifications that may have been done that wouldn't be readily noticeable from the installed position of the valve body.  Is this a new problem, or has it existed the entire time you've had the car?

Also, I see you checked for full operation of the levers on the trans, but did you verify that the bell crank hasn't moved up to where it isn't correctly engaged on the transmission?  Maybe it's moving fully, but not actually performing the intended job....

[Charger_Dart]

Are you positive the valve body has never been modified?

No I am not, but it looked very stock when I dropped the pan. Everything looks stock under the car, but I guess somebody could of changed something somewhere in its life. If shifts like a stock tranny both up an down (very smooth) - just won't downshift under hard acceleration.

There are internal modifications that may have been done that wouldn't be readily noticeable from the installed position of the valve body.  Is this a new problem, or has it existed the entire time you've had the car?

Also, I see you checked for full operation of the levers on the trans, but did you verify that the bell crank hasn't moved up to where it isn't correctly engaged on the transmission?  Maybe it's moving fully, but not actually performing the intended job....

Thanks, when I dropped the pan and changed the fluid & filter I checked the bell crank and it is firmly attached to the post. ( Earlier I read in another post where this was a problem )It did seem to tighten the band as the arm is moved.

The tranny has never kicked down for me for as long as we have owned it. I kept putting it off for years until I had a chance to change the fluid & filter. 
 

[Cooter]

Make sure the lever on the trans at the valve body on top isn't the incorrect one...(Takes too much movement of rod linkage to move very little at trans.)

[John_Kunkel]

In some very rare cases the shaft that the throttle lever attaches to will come loose from the cam inside the transmission (weld breaks), this can be determined by disconnecting the linkage and manually operating the lever full back....if the lever doesn't hit a firm stop the weld has broken.

I doubt if this is the problem here, just lengthen the top rod with the Edelbrock #8003 or #8004 threaded extension.

[Charger_Dart]

Make sure the lever on the trans at the valve body on top isn't the incorrect one...(Takes too much movement of rod linkage to move very little at trans.)

Does this look like the correct arm ?

[Charger_Dart]

just lengthen the top rod with the Edelbrock #8003 or #8004 threaded extension.

I did not know they made these! Thanks, got one on order now and maybe it will fix things!

[oldkimmer]

..............there is a shorter arm 4 the kd on the tranny.........also there is at least 3 legnths of the rod down to the bell crank, with 440 being the longest...........u may have 1 of the 383 rods.........measure it then i'll check to see if i have a longer 1  4 u......kim......

[Charger_Dart]

..............there is a shorter arm 4 the ld on the tranny.........also there is at least 3 legnths of the rod down to the bell crank, with 440 being the longest...........u may have 1 of the 383 rods.........measure it then i'll check to see if i have a longer 1  4 u......kim......

Thanks for taking the time to look for BB rods, but this is on my 340 Dart so I don't think they will work.

[oldkimmer]

............OK Sorry, idk how i missed that.........there is different swivel [bell cranks] for the top at the intake also, but maybe a bb rod would make up the difference u need...there is also a different top rod, if u get me measurements i can check all........can u take some bend out of the bottom rod that attaches to the kd lever....kim......

[millicon]

To revive an dead thread - did the extension fix the issue?

My '68 Charger R/T (stock 440 with an Edelbrock 1406 that came with the car, the Edelbrock 1481 adapter with the stock linkage) is doing the same thing and I was hoping it'd be as easy to fix as installing the extension.

Long term, I'll be getting the original carb rebuilt and re-installed so I'll be going back to an all-stock set-up then.

Thanks!

[Charger_Dart]

I wish I could tell you it did, but unfortunately I was never able to get the kickdown to work. I ended up getting a decent 727 from a good friend and hooked everything backup and set the kickdown. Tranny has worked great ever since.