I had the ST300 completely rebuilt about 3 years ago. This was done at a reputable shop about 45 minutes from me. I stopped in a town 20 minutes from me and I noticed it was shifting funny. Called the shop the next day and they had me bring it back since it had a 1 year 12K warranty. Also noticed it was leaking. After having it for a few days, they called saying the car was done. It drove fine while it was cold, just like before, until the car warmed up then it shifted funny when I started out from a stop. I never know how it is going to act.It even shifts funny when it shifts from L into Drive at times. The shop says the trans is perfectly fine. They would not go for a ride with me when the car was warm(too busy). And oh yes, they got it back to "fix" the leak that returned again after 2 days. The car has an Edelbrock carb on it with an electric kick down from Russ Martin that works perfectly. The electric switch stator and micro swith etc was removed since it was not configured properly when someone switched carbs. SHOULDN'T this trans act pretty much like a 2 speed powerglide?
The ST300 in your car is originally a variable pitch converter. (unless it was "de-featured" during any rebuild) Other than the "hi-lo stall" function of the converter, it does operate similar to the PowerGlide. If the solenoid is not working correctly, or the switch (at the carb), it can cause it to shift from high/low stall incorrectly. If the converter or pump is not functioning correctly (pressure) is can affect the stall of the converter as well. Please describe "shifts funny" in terms of leaving from dead stop and how it shifts with light throttle through RPM/MPH, and how it acts under moderate then full throttle. Also try from dead stop in low and do not shift, but drive it to about 60MPH in first light, moderate and WOT, and report back. It can be hard to tell if it is converter (Switch Pitch) or clutches, but the above may help. You can "defeat" the stall (and downshift) of the converter by pulling the wire from the side of the transmission case and then test again under light, moderate and WOT. There is ways to test the solenoid to see if it is at least cycling, but without a pressure gauge it is difficult to be sure the pump is working, and even more difficult to tell if the clutch drum seals are not leaking (internal leaks) or any spools sticking from dirt/debris. (all of those checks should have been done upon assembly) Let us know anything else you can think of. But I think the shop may either be unfamiliar with correct adjusting of the stall switch, or perhaps overall poor shop practices. (auto transmissions want clean, clean, clean, and no burrs, nicks or things that affect movement and sealing internally, as well as proper pressure, fluid volume and temps)
Thanks for responding. Where is the solenoid located? The only switch at the carb is the aftermarket kickdown switch that works with the Edelbrock carb. Shifting funny is not quite a slip, its more like a hesitation. You mention defeating the downshift, what would be the purpose of doing that? I will take some pictures of my current setup and try and post them tomorrow.
The stator vane control solenoid is mounted to the front of the valve body on the passenger side as the transmission is installed. Two bolts hold it in place, so it can be replaced with the transmission installed. I was stating that testing the transmission with the plug disconnected from the driver's side of the case, would eliminate the kickdown from drive to low, and also the converter hi/lo stall for troubleshooting, so temporarily defeating the two features. The vacuum modulator and the governor can also cause shifting issues. The point is to isolate as many parts of the system that affect shifting and start narrowing down the possible cause. (Because the tranny shop is not stepping up to address this correctly, from what you are stating they have done since the rebuild) If you can, drive it as it is and do the following: All from a dead stop. 1. Light acceleration from 0-70 and note how and when (RPM/MPH) when it shifts from low to high and describe it as it actually changes in any aspect. 2. Moderate acceleration from 0-70. Same as above. 3. WOT from 0-70. Same as #1. 4. In Low gear, light accel, 0-60. 5. In Low gear, moderate accel, 0-60. 6. In Low gear, WOT accel, 0-60. Light means no rush, just easy acceleration, like your grandma is in the passenger seat. Moderate means like you would normally drive in todays traffic. WOT. Your John Force... (only driving a Buick) If you mean the "hesitation" is like the transmission is "flaring", (it takes a second or two during the shift and feels like RPM is "ballooning" during the shift), or explain what that "feels like/sounds like".
Forgive me if I am wrong, but do you know what a switch pitch transmission is? If not, here is an explanation, http://www.buickperformanceclub.com/switchpitch.htm Basically a switch pitch transmission uses a dual stall speed torque converter. It is electrically controlled just like the kick down, but the two functions are separate. There are two questions we have. Was the transmission converted to a fixed pitch design, and if not, how is the switch pitch function being controlled? Your description of "funny shifting" could be an uncontrolled stall speed switch. There are two separate electrical connections on a switch pitch transmission, two spades perpendicular to one another. The vertical one controls the kick down, the horizontal one is the stator (stall speed) control. What Michael was suggesting is that you disconnect the stator connection and drive the car, see if it makes a difference.
Flaring does fit the description of what it's doing, but at other times it is crisp. When doing the tests, it would be with nothing disconnected (unplugged) correct?
The trans was not converted. Nothing is controling the switch pitch function. The wire is disconnected at the top. The other wire goes to a kickdown switch mounted on the passenger side of the carb. (switch was made for use with the Edelbrock carb and sold by Russ Martin) It has a power wire also. The stator (plunger type thing) and micro switch have been removed and bagged.
Disconnect the kick down and drive the car. It is possible to reverse the connections inside the pan, on the inside of the case connector. The stall change can feel like a kick down. What I am saying is it is possible that the switch pitch function is operating off the kick down, not likely, but possible.
Pics show the way the engine is set up. Results of the tests are: While in DRIVE 0 to 70 MPH Slow:flare shifts only slightly at 15 MPH. Moderate: Bangs in at start sometimes, other times is ok. Flare shifts at 35 to 40 MPH. WOT: Smokes tire shifts good at 60 MPH. 0 to 60 MPH in LOW. Slow: Slips. Moderate: Catches but slips a little. WOT: Bangs in, smokes tire. This test was done with the car at 180 degrees operating temp. It took 28 oz of fresh fluid to bring it to full because quite a bit had leaked out into my catch pan over about 2 months.
If you apply 12v to the top blade of the connector with the car off, you should hear the "click" of the solenoid from the right front of the transmission pan. You could run a wire to the top blade, and ground with a toggle switch and test the hi/lo stall of the converter while driving at a steady speed in low (about 20 MPH. (it may feel like a mild shift, or even a "flaring" as the RPM changes but not feel like a slipping clutch)
If the plug was disconnected during the above tests, the "bang", "flair" and "slip" indicate a clutch pack may be slipping not applying correctly, but it could also be a torque converter problem as both can give such symptoms. If it was driven with low fluid, low/loss of apply pressure to clutches will burn them in very little time, especially with the torque of a nailhead coming on at low RPM. Someone in your neck of the woods should know another shop that would give you a straight and reliable diagnosis.
So by running a wire from the + terminal of the battery (car off) and touching it to the top terminal on the side of the trans would produce a click from the solenoid which means it is working?
I always check my levels before driving. I've been thinking all along that maybe the wrong torque converter was used. How about if the trans fluid itself is getting too hot? I do have one guy that Ive never gone to that can look at the car in a few weeks. Most shops won't touch it and can't get me in for two months and the car will have to sit outside for 2 months. Not happening.
The click would mean it is energizing, and that it "should be" functioning. Driving with a switch and toggling it, you should notice the lo/hi stall of the converter changing the RPM/feel of the car. You cannot have the wrong converter as the hub and stator and input shafts are specific to the variable vane. You can have a bad converter, bad solenoid, incorrect switch operation/adjustment or plugged orifice (affecting the converter's stator vane supply pressure). All of them can negate the hi//lo stall. If it is stuck in high stall, or the cooler is not installed, or plugged, it could be overheating the fluid. You could put a hand on the pan and get an idea if it is too hot. (or use an IR temp gun, they are pretty cheap) Pan temp should be about 140F (fluid temp would be about 160F as dilution and cooling by heat sink of the pan/case and returning fluid would leave the bottom of the pan about 20F less than the hottest fluid leaving the transmission to the cooler) (call out to the board) Anyone in the area that might be able to take a look a this? It's a long drive from Arkansas... Else I would be happy to help.
How about if I don't care about the stall speeds switching back and forth? I just want it to shift properly from Low to Drive and back down and for my kickdown to work.
Verify that the switch pitch converter is working. Rig up a single wire with a toggle switch. One end to the + post of the battery or other 12 volt source, the other end to the stator spade. With the car stopped in gear, flip the switch. If the converter goes to high stall, you should feel and hear a slight increase in engine RPM, and less of a push by the engine. If you rig the same wire to the kick down spade, when you flip the switch, the transmission will not upshift to 2nd gear except at full throttle. If you flip the switch in second gear, it will downshift to 1st. In any case, no voltage to the stator spade, and the converter will stay in low stall. That will make the car push more at stop lights, and it will be slower overall.
I'd find a competent trans rebuilder to go thru the unit, again. If it "bangs" when shifting and leaks oil and slips than it wasn't assembled properly or parts that should have been replaced were reused/ overlooked . Not every new part(s) for that unit are readily available, but, are out there if you take some time to shop around. I would spend some time and money and get your own "kit" together for a complete comprehensive overhaul. I know this isn't what you want to hear, but, the "banging" and slipping is not going to repair itself and whether or not the VP feature works has no bearing on those issues.
Well it appears that I paid about $2000 for a complete rebuild that didn't even last long enough to get me home because it didn't even last that long before acting up. Almost 3 years and only about 4,000 miles on that job. And on a car that's not run hard. Do you know which other Buick trans that bolt up to the nailhead without an adapter?
