Technical 2 speed powerglide wont go into second gear

Hi,

The powerglide in my 1963 impala wont change into second without back off the revs, fluids are fine no leaks etc. what could be the cause?
Any information would be great

edit*
The modulator is new and the vacuum line is still connected, up until a week ago it was changing gears fine and nothing has been touched for months so its just randomly started doing this. As of today it dropped back to 1st at 80kmh and wont go into second at all. Also if you look under the car when its in drive gear you can see the linkages sitting lower then the chassis (again this has been like this for months)

 

Probably vacuum modulator hose is plugged or cracket.
Visual check, and if everythimg looks ok, then measure what vacuum reading you get at transmission end of vacuum pipe.

 

Agree on vacuum modulator. If you need a new one, TCI and others sell an adjustable version.
What's the condition of the trans ? Fluid / filter been changed recently? I've had a few GM trans "revive" themselves with fresh fluid.

If you've not driven PG's before, they rarely have crisp / hard shifts

 

it is definitely in need of a fluid change as i have only just got it on the road, its always shifted really well actually but now its shifting hard but not in a good way haha

 

the vacuum modulator is new but i have been having issues with the hose slipping off

 

Put a small zip tie around the hose at the nipple to tighten it up. Better yet, replace the hose! They stretch and harden with age. If you don't remember when it was replaced you might want to.

 

Sounds like the throttle valve linkage is out of adjustment, a powerglide will shift even when the modulator is unhooked.

 

That's what HE said...

 

One operation, no matter what the Doc says, I’m gonna leave it as is

To make this post relevant, I wasn’t aware the PGs had a TV rod. I had a ‘65 el Camino with one, never even knew it was there.

 

I might be wrong, I thought the early aluminum case glides still had one.

 

I’ve no idea. I had the car for about a year when I was 16 or so. I was mainly concerned about making sure the glass packs didn’t fall off

 

It has been decades since I worked on a glide, but I do know they will shift witht he modulator unhooked, part throttle shift will slip, down shift coming up to a stop will be harsh.

 

Yes they have a rod connected to the lower hole in the carb it controlled the shift point. The vacuum modulator worked with it for the harshness of the shift as I remember my 65.
When the discs got warn in the trans you extend the life of the trans my adding length to the split pin behind the modulator. I think an 8 or 10-32 screw would fit snuggly in the hole of the spacer pin.

 

Check your motor mounts!

.bjb

 

On an aluminum Powerglide, the vacuum modulator controls transmission operating pressure and only the operating pressure. Shift points are determined by throttle linkage position. I have a 64 C-20 and the previous owner deleted the throttle linkage. It shifted from low to high at about 15 mph regardless of throttle opening. I made up a throttle linkage and now shift points are determined by throttle opening like they are supposed to be. If you are having to let off to get it to shift, I would suspect that your throttle linkage is adjusted too long.

 

Back in the day we used to call that the "kick down linkage". Once again from the fuzzy part of my memory, the adjustment was made by pulling the carb wide open, then pulling the kick down linkage all the way forward and adjusting the pin on the linkage to a free pin fit in the carb linkage.

 

Same with my A pickup. I just used some bailing wire to secure the lever on the transmission in one spot where it shifts at ~ 27 mph. If I want a higher shift point I manually shift it to low and upshift it when I want to. It's not ideal, but it works fine for a jalopy.

 

hi, that could be the issue and today it actually dropped back to 1st at 80kmh and it wont go into 2nd at all

 

The modulator is new and the vacuum line is still connected, up until a week ago it waa changing gears fine and nothing has been touched for months so its just randomly started doing this. As of today it dropped back to 1st at 80kmh and wont go into second at all. Also if you look under the car when its in drive gear you can see the linkages sitting lower then the chassis (again this has been like this for months)

 

hi , thanks for the information mate.
I would agree but I haven't touched the adjustment at all this has just randomly started to happen and as of today i have lost second gear altogether

 

Could the band need adjusted?

 

Looks like maybe your linkage is falling off ?

Tommy

 

That's not good. In low gear you have a band applied, in high gear the band is released and the high clutch is applied. It sounds like the reason you had late shifts wasn't because of the throttle linkage, it was because the high clutch was slipping and you had to let off the throttle to get it to lock up. Looks like the trans will be coming out. The bright spot is that the aluminum Powerglide is about the easiest transmission there is to rebuild.

 

Drop the pan and have a look for debris and stinky's. Lippy

 

Could be the roll pin sheared in the rear pump.

 

Make sure that the transmission kick down linkage is attached. I have seen them come loose. It would be a long rod on the left side of the engine that hooks to the carb linkage.

Vacuum to the vacuum modulator. I once bought a chebby cheap because it would not shift. The line to the modulator had fallen off. That said, I see a lot of guys hook the vac modulator up with a rubber line. I use a hard line with a rubber stub on both ends. I have seen rubber line suck shut and that is never good.

After all those easy things, it may need the bands adjusted. That would be next for me to check.

 

Shouldnt there be black in the oil if the clutch is gone?

 

There is gunk in the pan more often than black in the oil.

 

Smell the oil. If burnt, you can tell. Just smell it off the dipstick.
If it’s black when you go to check it, then make a game plan to pull the transmission out.

 

oil is super clean, when the gearstick is in drive it is really loose and can see the linkage lower then the chassis in the above photo