727 will not downshift

[patrino]

Hello folks.

I've got a 1966 D200. Poly 318 engine (and possibly transmission) from a '64 Belvedere. Transmission is a three-speed automatic with a dash-mount shifter. (I assume it's a 727).

The transmission seems to upshift just fine. But when I approach a stop sign, stoplight, etc., the transmission often stays in 2nd or 3rd (depending on what gear I was in as I approached the stop.)

If I downshift manually to 1st or 2nd at the stop, then back into Drive, the transmission upshifts normally once I leave the stop.

I checked the transmission fluid level, it was good. It's also fairly new, too, I changed it around a year ago. No funny noises etc. from the transmission when I'm running.

Any suggestions? I searched the forum but did not see anything applicable.

[my5thmopar]

How did you check fluid? Must be hot, not warm, level ground, cycle between P,N,D a few times, check in N. most likely suspect is linkage adjustment since it's working manually. Could be the governor in the tail shaft. If its dirty or worn it won't downshift. Its pretty easy to swap. Craig

[712edf]

Would a band adjustment help?

Bucky

[my5thmopar]

Would a band adjustment help?

Bucky

Probably not if reverse is working ok. The OP can put it in 1st and accelerate to 15-20mph, let off throttle and if the car slows quickly, it’s not the R/L band. It’s probably dirty governor. Craig.

[martincom]

Did the truck sit for a prolonged period of time? If so, I'd just drive it. It'll likely work itself out.

[jeffc57]

First thing is finding out what you got. Is the dash shifter one cable or two cable type? If one cable it is a 66 and later trans, two cable is a 65 shifter.
64 cars used 2 cable type shifter with a push button shifter, with a parking sprague cable leaver. 65 cars and trucks use a shifter that had both cables
and both enter case of the trans.

Most shifting issue have to do with adjustment of the kickdown arm, remove kickdown arm from carb, hold arm as fare to the rear as it will go
adjust arm to fit carb at wide open throttle (done without truck running )

[patrino]

Thanks for all the suggestion, folks.

@jeffc57 I will check to see what style shifter I have.

@martincom, no, it usually gets driven at least once a week.

@my5thmopar, do I have the test right?
1. Stop truck, get it into 1st gear (I'll do that my manually downshifting to 1st, which works just fine)
2. While the truck is stopped, place shift lever in Drive
3. Accelerate to about 15 mph, then let off pedal
4. Note how quickly it slows
Does that sound right? Am I right in thinking you expect truck will stay in 1st the whole time? (I'm not sure when the 1->2 shift point is, but I'm guessing it's around 15 mph.

@my5thmopar, yes, confirming that's how I checked the tranny fluid.

More info soon!

[patrino]

OK, some additional information:

1. There's only one cable on the "business end" of the dash shift knob.
2. I did some "roll on / roll off" tests, hopefully getting at what @my5thmopar was asking about.
* Test 1: Stopped truck. Placed truck in 1st manually, left in 1st. Accelerated to ~15 mph, then let off the accelerator. Truck stopped very quickly.
* Test 2: Stopped truck. Placed truck in 1st manually, then put in Drive. Accelerated to ~15 mph, then let off the accelerator. Truck only gradually slowed ... took a lot more time to slow back to ~5 mph than in Test 1. (Truck remained in 1st throughout Test 2, I always let off before the 1 --> 2 upshift.)

Any of that information help?

[my5thmopar]

Test 1 is what I was getting at. Sounds like band is ok. Did you recheck the fluid as suggested? It’s sounds like the governor to me. Craig

[jeffc57]

one cable shifter that goes to the shift arm on the outside of the trans is a 66 or later trans.

Have you checked the kick down as I talked about in my last post? if not adjusted right it will cause all kind of issues and is hard on the trans

[patrino]

@jeffc57 that adjustment is next ... will probably tackle it this weekend. More info as I get it!

[patrino]

Update on the kickdown linkage adjustment ... the bellcrank on the back of the head's there, but it's hooked up neither to the carburator linkage nor the transmission.

So ... I'm guessing that the kickdown linkage adjustment is not the cause the problem. :|

All signs pointing to the governor, at this point? A reminder that though the tranny generally does not downshift itself when I stop, sometimes it DOES, and I can't find a pattern as to when it does and when it doesn't.

In the meanwhile, I'll try to rustle up a kickdown linkage assembly, and / or an alternative (I've seen hints of a Lokar setup replacing the stock linkages?)

[712edf]

Kickdown linkage not hooked up IS at least part of the problem. It controls more than just dropping from drive to 2nd when you romp on it.

Bucky

[patrino]

@712edf gotcha

[my5thmopar]

Kickdown linkage not hooked up IS at least part of the problem. It controls more than just dropping from drive to 2nd when you romp on it.

Bucky

Good point Bucky. You’re going to burn up the transmission without the KD connected.

[jeffc57]

Kickdown linkage not hooked up IS at least part of the problem. It controls more than just dropping from drive to 2nd when you romp on it.

Bucky

Good point Bucky. You’re going to burn up the transmission without the KD connected.

yes,yes, you will cook that trans without kickdown, if the rod linkage is not a available a cable linkage aftermarket is, that linkage controls the pressure inside the trans

[patrino]

Got it, thanks everyone!

I found the Lokar cable specc'd for my transmission, calling them tomorrow to see if any other bracketry is needed. Will install and follow the adjustment instructions carefully, and ask if I have any questions.

[jeffc57]

let me know if you have issues, I'm in Vancouver across just the river, i will PM you with my phone

[patrino]

Thanks, @jeffc57, will do. Parts shipped today. It sounds like I'll probably need to make some brackets, but that's not a problem.