Reinstalled engine and transmission after several years out for overhaul. Please advise where to hook up vacuum line from engine to transmission. The tube left over in my parts (see photo) does not appear to reach the only fitting I can find on the transmission (which is on the passenger side of the transmission). Any help is appreciated.
I have never looked to see where the vacuum line hooks into the transmission on my '52 PG.
However it is connected to the manifold through a T fitting then goes down past the parking brake linkage then turns behind the oil pan heading to the passenger side of the engine.
I just remembered! I recently picked up a 73,000 mile, 1951 235 engine with PowerGlide trans and most lines still attached. Here is the manifold fitting on it.
A side question. If the early PG do not shift themselves what does the vacuum do?
PowerGlides do shift themselves when placed in DRIVE. If however, you wish to get a quicker start, you can shift the lever to LOW as you start, then shift to the DRIVE range as you gain speed.
What does the vacuum do? It operates the modulator which increases or decreases oil pressure as required. This is the way the 1950 Engineering Features Book states it.
"The purpose of the vacuum modulator is to impose additional resistive force on the pressure regulator valve to increase oil pressures when high torque is being transmitted. Also, it removes this force, reducing oil pressures when less torque is handled".
1951 Fleetline Preservation
'51 Fleetline DeLuxe, POWERglide 2-DR (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Faded Red)
'50 Styleline DeLuxe 4-DR (Mist Green)
Hmmm, my understanding was the PG didn't automatically shift until 1953 and the torque converter is different pre '53 to provide more torque for starting in Drive.
My father told me the '52 didn't shift automatically. I have never heard or felt any sign of a gear change when starting in drive and have ridden in this car since it was 6 years old.
From Wikipedia:
The 1950 through 1952 Powerglide transmissions did not automatically shift between low and high (direct drive) which made for very sluggish take-offs and many drivers started in "Low" and shifted to "Drive" at about 30–40 mph (48–64 km/h). The 1953 and later units when in "Drive" started in low and automatically up shifted to high at a speed determined by the throttle opening. By the mid-1950s, more than half of all new Chevrolets were sold with Powerglide.
Edited by 52_Belair on 10-07-24 10:36 AM. Reason for edit: No reason given.
Okay, let me restate this...there was no "shift" per se, or feeling of a definite "lurch" in the original PowerGlides but there were things going on inside the unit itself that reduced and increased power to the the drive train; the modulator and the vacuum modulator that was discussed and also stators that would lock and unlock. The engine had a tendency to rev higher without much appreciable increase in speed...but eventually things caught up to one another and the phrase "SLIP AND SLIDE WITH POWERGLIDE" was born. The transmission did not automatically shift to the LOW gear unless the driver did that manually. Later as you and wikipedia specify...the PowerGlide was redesigned to not only shift to low from a stand-still, but it was also redesigned to automatically down shift to low when accelerating aggressively...i.e. passing.
View the Jam Handy film below
1951 Fleetline Preservation
'51 Fleetline DeLuxe, POWERglide 2-DR (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Faded Red)
'50 Styleline DeLuxe 4-DR (Mist Green)
Cool video, I wish it would have talked about the vacuum operation in the transmission.
There is another video called the "Velvet Glove" where, toward the end of the video, they compare acceleration against a manual transmission equipped Ford from a standing start. They mention that to get the edge required, the driver of the Chevrolet needs to really give the accelerator a good nudge to start. Doing that delivers higher oil pressure in the torque converter via the vacuum portion of the modulator valve. That's the way I understand it anyway. It gets things going quicker and acts sort of like a low without bringing the low gear cluster into play...in other words, without actually manually shifting to low to get the advantage and just using the torque converter portion of the transmission. Here is that video:
1951 Fleetline Preservation
'51 Fleetline DeLuxe, POWERglide 2-DR (Fathom Green)
'51 Styleline Special BUSINESS COUPE (Shadow Gray)
'53 6500 Dump Bed (Faded Red)
'50 Styleline DeLuxe 4-DR (Mist Green)