68 Belvedere keeps kicking down into passing gear

[1337du0]

Recently picked up a 68 Belvedere with a 318 and it runs great except one thing, every time I hit 25 - 30 mph in D it kicks down into passing gear. I have tried adjusting the kickdown linkage using the open throttle method and there was no real change. After I made the adjustment, it did shift into third but only at 50 mph and with the throttle wide open. As soon as I let off of it, she kicked back down into passing gear. The shift linkage in the column is a little loose, but D2, D1, and R work just fine. It shifts smoothly from first to second, but as soon as I hit what should be third it slips into passing gear. At this point I am open to any advice. I thought that maybe investing in a Lokar cable may fix it, but I don't know at this point.

 

[Mr Belvedere 30144]

I run a Lokar cable on mine and love it! I suggest it for you as well.

 

[1337du0]

Do you think it will actually solve the problem though? I don't want to invest the money if I may have to blow a whole paycheck to get the transmission rebuilt.

 

[dsd1967]

It almost sounds like your linkage is hooked up backwards....if that is even possible. With the 3 piece linkage....maybe so.....if you got one of the legs on the wrong side of the pivot. As you apply throttle, the linkage should be pushing the kickdown lever on the tranny towards the rear of the car. Push your linkage down by hand and look at the last link...it should move to the back of the car. If it's coming forward then one of the pivots needs rotated 180 degrees. If it's going back like it should then I would think it's something internal to the tranny.

 

[sleepar]

Are you low on fluid?
Pull the pan and see what the filter and in side looks like.... it should be really clean with nothing but atf in there. The slightest dirt will cause all kinds of problems

 

[1337du0]

dsd - No the linkage was hooked up all weird when I got it, but I have set it back in right and adjusted it using the open throttle method. How does the kickdown linkage work on the inside of the trans? Is there a way to adjust it in there?

sleepar - not low on fluid, I will pull the pan as soon as I get a chance and let you know.

 

[sleepar]

If the arm was at one time messed up that could prematurely burn out the pump. The valve body could have a sticking plunger or weak spring or a million things if something failed and circulated through the system. Or as simple as a screw loosed up and fell out into the pan and created a leak

 

[dsd1967]

I agree with sleepar....if the plunger is stuck or not coming fully back, it may be giving the transmission a signal to downshift. I'm no tranny expert....but it sounds internal related. Hopefully someone on the site can give you some guidance on what to look for if you drop the pan.

 

[1337du0]

For the kickdown linkage at the tranny, should there be any resistance when it is pushed back? Mine has no resistance and I was told that it should.

 

[dpstark2]

When moving the kickdown lever toward the rear of the car, there should be significant and increasing resistance. You are working against a spring and valve internal to the valve body. If you feel no resistance, your kickdown valve or spring in the valve body are broken or stuck. There will be free play in the lever toward the front of the car, but there is resistance to the rear. You can even feel it in the gas pedal.

Valve bodies are relatively easy to disassemble, clean, and reassemble. It's just messy as can be... A FSM has all the diagrams you need, and there are several cheap TF books available.

 

[sleepar]

I got a book on transmissions by monroe.... and rebuild the trans. For piece of mind because one .99¢ O ring can mess up things in there and its about $400 to make a killer trans from you're core and then it's done.

 

[1337du0]

Ok awesome thanks! Do you know where I could find a good diagram online? I have done some searches but I didn't see anything.

 

[gtxno1]

Ok awesome thanks! Do you know where I could find a good diagram online? I have done some searches but I didn't see anything.

sounds silly but make sure the return spring is in place and pulling the linkage forward