Powerglide kickdown problem

[ARW]

Can anyone tell me how long the straight piece of kickdown linkage from the transmission lever up to the "bell crank" should be? I'm beginning to think this one is the wrong part. If hooked up, the car won't upshift and I can't adjust it enough to change it. Thanks.

Car is 66 327.

 

[ChuckG]

I can't tell you how long it should be, but I can tell you that to adjust it, you...


1. Have a friend hold the gas pedal all the way to the floor. Make sure the carb is opened up fully with the gas pedal depressed all the way.

2. Under the car, pull the lever forward, till you hit the spring loaded "detent". Then pull further ahead till you have the lever ALL the way forward, overcoming the spring tension.

With those 2 things done, the rod should slip between the two holes, one in the carb linkage, the other in the trans. lever.

In other words, with the throttle fully open, the lever should be fully forward.

That probaby doesn't help you much, but things get changed over the years. You might have to modify the rod. Might have to bend it. Maybe you do have the incorrect rod.

Maybe the throttle linkage on the carb is incorrect.

Hope this helps you out. Chuck

 

[ARW]

Thanks Chuck. Did all that but the rod was too long. I'm thinking wrong parts, but not sure which one. Carb is the original number, but could have been rebuilt with a wrong shaft at some point. I could eliminate the rod as the suspect if I can get the correct length.

 

[midyear]

Are you sure its the kickdown linkage?? First thing I would do is disconnect the kick down linkage and see if the trans will shift. often its the modulator valce or its vacuum source that is the problem. I have some of the rods in my misc vette parts and will dig one out if that shows to be the issue.

Dennis

 

[ARW]

I just had the transmission rebuilt in hopes of correcting this. (but also had a lot of leaks). With the linkage disconnected it upshifts at about 50mph or 15 mph, depending on where you leave the lever positioned. New modulator was installed. The bell crank "looks" perfect. The straight linkage rod is my prime suspect right now. If it came on another setup (maybe a 427 or Chevelle) it might be too long? Actually, I guess the bell crank could be from another setup too. The exact length of a known, guaranteed, Corvette 327/powerglide rod would eliminate one more possibility. Thanks, Dennis.

 

[midyear]

OK dug one out, lower rod is 11 1/4 at center mount points, upper rod is adjustable, total length is 12 3/4 w/1 1/2 of threaded ajustment (was set exactly in the middle on this one), can post a pic if needed. I dont need any of it, so all or part is available

Dennis

 

[ARW]

That carb linkage is the problem then. Mine is 11 3/8" instead of 12 3/4". The lower rod checked out with your aa 1/4. We thought we knew for sure that the carb link was the original part that came on the car. Thanks Dennis!

 

[midyear]

no problem, PM sent.

Dennis

 

[aquaholic_]

do NOT drive the car until you get this straightened out. you WILL most certainly damage your new tranny if driving for an extended period of time. your trans works based on pressure and that cable that connects to your carb controls the internal pressures in it along with your shift points. make sure you do a good job troubleshooting this or find yourself a 60 year old chevy mechanic that has done this type of adjustment before and knows how to use a pressure guage and where to hook it up (and knows what the pressures should be at certain rpm's while driving it). you will be better off in the long run to have this properly set up rather than having the tranny rebuilt again in a 1000 miles. btdt.