I've read alot about different problems and repair suggestions for an alum. powerglide. My problem doesn't quite fit any. I can take off in 1st at any rate and its fine. At regular city driving my ear is expecting a shift to second around 20, but it doesn't. I need to get the car over 25 close to 30 and then let off the accelerator slightly, if I don't its content to travel along in first. It shifts and I'm off in second, everything right on up an into highway speeds. As the rate of acceleration increases, the higher the speed before the shift, of course. it seems that once I reach the speed of 40 it will finally shift on its own but the RPM plataeu for about 3-4 seconds before the actual shift, or I can simply ease off the accelerator and cause the shift. Now for the scary part, if I put it the wood everythings fine until I approach maybe 55 ( not sure I only did this once) and I'm expecting a shift, it seems the trans goes to neutral. my immediate reaction, let off the gas and it immediately shifted. Entire range of both gears seem fine, no slippage or unexpected shifting. Its never not shifted ( other than under 25). It does seem to down shift a little soon(20, sounds like I'm grabbing gears) . Any ideas or suggestions? By the way this is 62 impala 327 <!-- / message --><!-- edit note --><HR style="BACKGROUND-COLOR: #e5e5e5; COLOR: #e5e5e5" SIZE=1>
Have you adjusted the throttle valve linkage? have you made sure there is no vacuum leak in the hose to the modulator, and the modulator is not leaking? And you've carefully checked the fluid level and shift linkage adjustment? btw the factory repair manual is helpful for this stuff, but a Motors or Chilton manual will cover it too.
I agree sounds like the modulator is either bad or the line going to it is leaking.the modulator isn"t very expensive and the hose isn"t either,where is your va***n supply hooked up to on engine?
Thr modulator sounds like a good place to start. Is this behind a fairly stock engine with plenty of manifold vacuum, or something with a big stupid camshaft and a tunnel ram? Could it maybe be the governor sticking and not letting the governor pressure drop down where it should be at idle and low speeds?
^^ my first thought was the governor too, pull the valve body and make sure nothing is sticking too. these are really simple trans to work with you should be able to get it where you want it easy enough
I've checked the TV linkage adjustment. I believe it to be good (linkage fully extended at full throttle). Modulator looks brand new, but i don't think it's adjustable. I need to take another look with better lighting. If its not, it's my intention to replace it, for the money I might as well. I'm going to check the vacuum myself. When I first got the car I took it to a mechanic to give it a once over. His comment about the trans was " I disconnected the vacuum line and it shifted the same way so something's wrong inside, let's pull it out and put a 200R in it". Fluid is app. 1/2 pint under full, there is a pint hash at half way between full and add on the dipstick. I didn't think this was actually below operating level, but would certainly bring it up to full if that could solve the problem.
The back of the intake, behind carb. It's hard line all the way to the modulator with about 2.5 in rubber hose between modulator and hard line. instead of leaking what would happen if the steel tubing start to build up with I don't know what, but it has restricted air flow? After 48 years couldsomething being pulled out of the manifold cause problems? Steel tubing and rubber hose is even cheaper than a modulator.
Totally stock, I guess I could have answered all the questions in one post. i have even l*** experience in message boards than mechanics. squirrel mentions shift linkage adjustment, what do I need to do there? I'm less famaliar with the governor, is this behind a round inspection plate on the p***. side?
Your TV linkage is wrong. You have too much throttle presure. The modulator will only cushion the shifts. Be it up or down shifts.
Whoa, dude! You just gave me a flashback! On some GM cars, the steel part of the vacuum modulator tube would sometimes be crimped down to form a restriction for the vacuum signal to the modulator. I think they did this with certain engine and ****** combos that were a bit vacuum sensitive to make them shift more predictably. Anyhow, this restriction would occasionally get plugged with carbon or some other debris, so it wouldn't hurt to take a look. For that matter you could just cut the restiction out of the pipe and splice in a section of rubber hose. I'd be surprised if this fixed your problem, but stranger things have happened.
Yeah I was starting to think about that. I got the TV adjustment from other posts for when the trans is shifting too soon, mine's the opposite. So I'm going to backit off a bit and see what happens. Its my understanding the modulator is limited to 3-5 mph in its adjustment. But I still need to check the vacuum. I got the tester, I just need to get my lazy **** under the car.
Once you get it to upshift where you want it, check for harsh downshifts. If it downshifts are smooth, your modulator and vacuum line are prolly be ok. Hope you do good with it.
Disconnected the TV linkage, trans did exactly the same thing as described in my first post. I thought the TV was to keep the trans from shifting into second too soon during heavy accel. It seemed to just that with the linkage disconnect or at least no worse than when it is connected. I did find a split in the hose connecting the modulator and hard pipe. I had my fingers crossed, didn't work, trans still shifting the same after replacing the hose. I still need to check if the modulator is adjusted and check vacuum levels. Does anybody know the proper vacuum reading at the modulator? How about a good repair manual and where to find it?
From what you said, the problem seems to narrow down to valve body (throttle valve is stuck in WOT position) or the governor is not working properly. I would have the valve body examined and cleaned. Another possibility is that the TV lever shaft and or the lever that operates the TV inside is broken.
These sound like good possibilities.Throttle pressure is definitly not right,some Powerglides only had that rod for kickdown. I think they also had rear pumps though? As far as the vacuum reading it should be the same as manifold vacuum about 15-20 in.Hg. @idle and drop evenly on accel. Old Motors repair manuals were very good for these types of repairs Pre 1970 versions.
I've got a adjustable modulator coming tomorrow. I'll check the va***m when i swap the modulator. When I push the TV linkage toeards the fire wall, it rotates clockwise to 9PM freely. There doesn't seem to be any firmness until it's about 1 1/2 away from 6PM which seems to be the end of the throw. it looks like I'm going into the trans, first time for everything, wish me luck.
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