The Powerglide on my 1967 should have a kick-down feature or as it was known in its day, a passing gear. Simply a drop from Drive to Low under certain conditions. But it does not. The car has been this way for some time and this is a case of round-to-it.

The transmission works perfectly in other respects. It shifts at low speeds on moderate acceleration. WOT from a stop produces the L to D shift at about 50 mph. Downshift when coming to a stop is normal. But running along at say 30mph in D and flooring the car produces no kick-down to L.

I'm stumped! I have adjusted the kick-down rod every which way, even to the point where I lost the normal L to D shift. It was stuck in L. It is now OK and the car drives very nicely aside from the subject of this thread.

Any comments/suggestions would be appreciated. The Chassis Manual speaks of doing fluid pressure tests but I do not have the equipment. Is it time for a visit to a GM shop? I do know a transmission expert there who remembers these transmissions. I bought a TransGo kit three years ago. Maybe this is an opportunity to have it installed.

 

Paul,

If I remember correctly my 66 Chevelle with a PG in it shifted at about 65 to 70 mph with WOT. The reason I remember that is when I put a 435 in the car I took it for a run and the rear tires broke loose with a small chirp when it shifted on the first run. Not sure what your problem would be. If the rod is working and you can set the unit to hold into L then I have to believe that it is something internal. By the way, doesn't the PG have what I call a 3rd gear for passing. When I wanted to pass a car with the Chevelle when I was going say 55 to 60, I would step on it and the car would run up to 75/80 before it shifted out into D. Normal L would not get you to that kind of speed.

Steve

 

Paul, I had this problem with my '66 after installing the same carburetion setup that you have, in my case it turned out to be the kick-down rod. As I remember, I had to shorten the linkage (via the threaded adjuster) considerably, it wouldn't kick down and would upshift from low to high very early. I also found it took quite a lot of pulling on the rod going to the transmission to get to the full limit of travel when setting the adjustment to specs. The first few inches of travel when pulling out have minimal resistance, but a little more pressure in my case resulted in more travel.

I'd try readjusting the linkage, full throttle should get you pulling the kickdown rod all the way to it's limit of travel out, less the one or two threads of adjustment you have to back off to prevent it from bottoming out. I'll look at the manual and check, but it also seems to me that WOT upshift should be a bit higher than 50mph, but having said that, I'll also say I don't trust my memory!!! I'll check & get back.


Hope this helps. And no, there is no third gear for passing, only kicks down into low range. Powerglide only has two speeds (unless you count reverse as one! lol).



A little further checking of my manual only shows specs for my '65, but the '67 should be the same, or very near thereto. The thru detent upshift should be between 62 & 70 mph indicated on the speedometer. (Note also that the indicated speedometer mph stated is independent of tire/wheel size). Since you state your upshift is occurring around 50 mph, this would indicate to me that your kickdown rod linkage still need to be shortened somewhat, since I was upshifting too soon also.
Hope this is of some help.

Ron

 

Paul,

Read part of your comments regarding your Powerglide kickdown on your NGK vs ? sparkplug thread, and thought you might need the adjustment process for your kickdown linkage. Proceed as follows:

Remove the throttle return spring from the throttle, remove the kickdown adjuster threaded link from the carburetor arm. Use a rubber band or other means to hold the throttle linkage at WOT position.

Pull the kickdown linkage out to it's full limit of travel, and holding it there, adjust the threaded connector to freely enter the carburetor linkage at WOT.

Then, lengthen the kickdown linkage by two full turns on the adjustment threaded connector (this prevents WOT from actually bottoming out).

Reconnect the kickdown linkage carburetor return spring, etc. This should give you a properly operating upshift/downshift/passing kickdown, assuming no other problems are present.

Hope this helps.

Ron

 

The comments are appreciated!

Ron,
Would you check the WOT position of your throttle bracket for me? I am beginning to think that I have not adjusted for WOT correctly. This first pic was taken with the gas peddle to the floor and at an end point of minimal resistance of the bracket movement.



This second pic shows further movement (by hand) of the bracket that is not taken up by the gas peddle. That is associated with a greater degree of resistance that indicated to me that things were being forced so I did not adjust for it. But it's quite possible that the resistance is the opening of the secondaries....? If so I have been driving for three years with a two-barrel carb :o . If you have a few moments to have a peek at your WOT bracket position it would be appreciated.

 

Paul,

My WOT position is more nearly like the one shown in your second photo. I agree with you that your accelerator may not be fully opening the throttle bores.

The comments I'm about to make apply specifically to the '65 and '66 models, but should be applicable to the '67 as well:

What happens in many cases is that when carpet and padding is replaced in these cars, the padding is installed under the accelerator pedal and arm inside, preventing the accelerator pedal from it's full limit of travel and preventing the throttle plates from fully opening in the carburetor. As I recall, the assembly manual specifically states that the padding should be omitted from beneath the pedal arm inside the car.

Regardless, you should be able to disconnect the throttle return spring, and the throttle arm too, if necessary, and hold the throttle linkage fully open in order to adjust the kickdown linkage. Proper adjustment should give you kickdown even if the throttle is not fully opening, and should also get you into the proper mph range for proper upshift/downshifts.

Regardless, assuring that the throttle plates are fully open with the accelerator held to the floor will also help WOT performance!!

Hope this helps!

Ron

 

After fooling about for 2-3 hours here is the new WOT throttle bracket position. Compare that to the pic above. Hopefully that will engage the secondaries. To get to that position and retain idle (OK per specs in N and D) I had to move the throttle rod to the middle hole on the throttle bracket. The upper hole did not work out: too much pull away from idle stop. That results in a heavier gas pedal feel but is in fact where the rod was when I bought the car five seasons ago with a Holley.

The kick-down rod is fairly loose at moderate speeds but gets "loaded" at the position in the pic. My hope is that means engagement of the spring-loaded mechanism inside the Powerglide. This was a three-beer job and as I do not drink and drive, the test will be tomorrow.

Mods to GM original configurations are always difficult for amateurs like me.

 

Hope that does the trick for you, Paul. I didn't notice the position of the accelerator rod on my carb, but I did notice that your kickdown linkage is different than on the '66 I've got. Yours appears to have a slotted fitting while mine is only a fixed fitting threaded to the rod.

Let us know how everything works out, and thanks for sharing your carburetor setup with me earlier, I'm 100% satisfied with the setup since changing from the factory style Holley I did have.

Ron

 

Thanks Ron,
I have some family issues this evening. Hope to try the car tomorrow where I can do WOT. That is obviously not on city streets so I have to travel some 10 minutes away to get to a freeway. I will report on the outcome.

*Edit* - Not much interest in the post. I guess it's not surprising: only 1,725 327/300 Cars with M35 in 1967. A rare option that few want.

 

A rare option, I agree. But I find that the older I get, the more desirable it is, at least to me!!

 

Paul: It is not that I have no interest, but when I worked as a mechanic for Chevrolet in 1969 the PG transmissions in each vehicle shifted out from low to high under WOT around 60 MPH plus. Even the six cylinder cars.

If your kickdown linkage is correctly adjusted and you are doing less than 40 to 45 MPH there is nothing to kick down to. You are still in low gear.

Rich

 

Interesting thread. I plan on attaching the kickdown linkage on my '66 powerglide car hopefully this weekend. Paul, let us know how you make out. Thanks. John.

 

Wow!! This car is fast. The four barrels and kick-down now work. I punched the gas pedal down at 30mph and the darn thing scared me. Normally the car just humms and hahhs trying to get into a proper RPM zone. It now flies .

I did not get out on the highway but in a 50mph zone I got to 55mph and the transmission was still in Low: the upshift had not occurred. The kick-down engages very close to the floor so the rod may have to be adjusted one full turn or as mentioned earlier, I may have padding under the carpet. After fooling about for several hours balancing throttle and transmission rods on the weekend I may just leave things as is. (If it works don't fix it.)

Imagine I have been driving for four seasons without a four-barrel function :o . It's a different car now.

BADBIRDCAGE,
The attached chart is somewhat confusing (throttleup/throttledown??) but with Full Detent is looks as if the shift comes about 56 to 67mph, depending on what Up and Down means (lower left for 3.36 axle).

http://img.photobucket.com/albums/v1...werglide-1.jpg

 

I thought that might be at least a part of your problem, glad to see you're dialing it in a little closer. You can tinker with the adjustment to get the upshift/downshift closer to your liking.

The chart you reference shows the throttle position below where the title "Throttle" is shown. To the right is "up" and "down", and below that is the mph that "upshift" or "downshift" should occur. The "Up" and "Down" columns show the mph that upshift or downshift should occur. For example, as shown by this chart for the 327, with the throttle fully opened (at full detent position), under the "Up" column it shows that the upshift should occur between 60.3 and 67.4 mph. (Specs I previously gave you had this at 62 to 70 mph, I believe, from my manual). Both are close, either will work.

Glad to see you're back in the "Fast" club, the Powerglide's not so slow after all, is it!!!

Ron

 

Well, with that interpretation then things are very close. With modest acceleration (they call that "throttle closed" ?) I get upshift at ~20mph. At about 3/4 throttle ("detent touch"), my former full throttle, I get the 50mph shift mentioned in post #1, and now with the new full throttle ("full detent") it looks like 60mph+. Almost bang on if I have read the chart correctly.

Yes, the Powerglide really grabs when kicked down. This exercise make me want to get the TransGo kit in the basement installed to firm up the shifts a little further. I understand that it makes things easier on the shift clutch discs.

 

Paul, I believe you're close to spot on!! I believe the "Throttle Closed" position means exactly that, throttle closed. You may not get an upshift with the throttle closed (may not get enough speed) without being on somewhat of a downgrade, or by adjusting the idle speed upward ever so slightly on a temporary basis. But, you really don't need to concern yourself with that, it's fixed by the tranny internals and the throttle rod adjustment. So, once the detent upshift is adjusted, the others should fall into place assuming a properly operation transmission.

Going from my experience, I can feel the 4-barrel kick in too, but I think you're getting more "bang for the buck" with the downshift and torque converter than from the back two barrels, thought they're nice to have as well!!

Ron