Hey Everyone, I wanted to find out if anyone had installed Bruce Roe's switch pitch controller to modify the switch pitch features in their ST-300 (Super Turbine 300) transmission. I know the original design concept is for the S/P TH 400, but the principal is the same for the ST-300. I want to keep the 2 Speed, as it is just a cruiser and not a racer and the additional driveablility sounds intriguing. Any rate, any input appreciated !!! Michael Roseville, CA
I have one on my ST400. The ST300 actuates the stator exactly the same way. There is no reason why you cant use the same box. Everything is adjustable.
Hey Larry, So, do you have 6 speeds, so to speak, or does the box just enhance the whole transmissions driveability, or both ??? Thx !!!
No, all the box does is control the stator change, and when it happens under various driving conditions. Hi to low stall never feels like a shift/gear change. If the original switch pitch control is not working or missing, Bruce's box will make a difference for you. I don't use the box during normal driving. I manually switch it to low stall. I have a modified 12" converter, and hi stall feels too loose for driving in traffic. I use the box at the track, and when I am driving the car aggressively.
How much is the Bruce Roe box? If it is more than $50 then that's too expensive. What does it exactly do, check RPM'S, vacuum, and speed of car?
It has 3 separate timers. One for vacuum, one for the kick down switch, and one for the brake pedal. I have mine wired with a 3 position switch, so I can have low stall, hi stall, or automatic (box control) One timer is activated by the brake switch. Step on the brake, you get high stall. Take your foot off the brake, timer counts down to 0 and shuts off the converter. There is a vacuum switch. Drop below 4" of vacuum, back to high stall. There are two options here, low stall return when vacuum is restored, or strict timer control. Then the kick down switch activates the full throttle timer. This activates high stall for a different amount of time, then switches back to low stall(Drag Racing Mode). All timers are adjustable from 3.2 seconds to 23 seconds. I have my brake timer set to 3.2 seconds, the full throttle timer to 6 seconds, and the vacuum switch set for low stall when vacuum returns (10 seconds if it doesn't). I like the box a lot. It is very easy to adjust and install. Works great. For normal driving in traffic, I switch it off so that I have low stall all the time. I found that my 12" converter's high stall stall is a bit too loose for stop and go traffic. For aggressive driving and sticky tires, the automatic mode is great. The box is 160.00. I think for what it does, that is a fair price. A much more sophisticated control than the factory system.
As I understand it, it gives the car "alot" more flexibility as the stock setup never really took advantage of the variable vanes designed into the switch pitch ST-300 & ST-400. Larry's set up appears to be mostly for semi to full throttle applications, mine needs are much different and was wondering if anyone had this setup more as a daily driver ??? As I read Bruce Roe's literature it gives some benefits, such as when you want to pass, it gives you more torque multiplication and you stay in your existing gear, instead of dropping down to 1st, if you have a 2 speed like I do, which is easier on the motor, not tp mention it is better for passing as I am more in the meat of my torque curve, given it is a stocker 300ci 2Bbbl. It is extremely popular for the TH 400 S/P, especially for the RV crowd. I have read some really good reviews on the RV websites, I guess they go out of there way to put in a 45 year old transmission design in their RV's, so there is certainly something to it. I just want to keep the car as stock as possible without changing to much, just a few modern improvements. If I were going to wedge a 455 in 'er, I would definitely go the TH 400 route, but maybe next project. Michael Roseville, CA
A little update on my experience with the Bruce Roe Switch Pitch control box. As I posted before, I found that the hi stall on my 12" converter was just a bit loose for stop and go driving. Taking off normally from a stop, the converter made the engine feel lazy unless you gave it a lot of throttle, and then the tires would go up in smoke. Problem was I already had the brake timer adjusted down to the minimum 3.2 seconds, but what I really needed was 0 seconds, or no delay. I e-mailed Bruce and we discussed several options on how to modify the box to better suit my needs. Bruce was very easy to work with. He offered to modify the box for free, I would pay the shipping. I felt this was very fair and sent the box to him. Got it back on Thursday, and installed it back yesterday. All I can say is, PERFECT. Bruce modified things so that with my foot on the brake, the converter is in hi stall. Take my foot off the brake, and I get low stall immediately. There is a vacuum switch that will put the converter back to hi stall when it sees less than 5" of vacuum. The drag racing mode is controlled by a wire going to the kick down switch. I removed that wire and ran it to 12 volts via a toggle switch. That wire controls the max throttle timer (Drag Race mode). It over rides all the other functions and provides 6 seconds of hi stall after brake release, then lo stall for the balance of the run. The car is much more enjoyable to drive now. I started to think about this, and realized that this is the way Buick originally had the SP transmission controlled. Hi stall at idle, lo stall off idle, and hi stall above 60% throttle. This is exactly how my converter is controlled now. Taking off from a light, the car is much more responsive now. You can give it moderate throttle and it will stay in lo stall. If you go beyond 1/2 throttle, the converter goes right to hi stall. If you stay in it, a vacuum timer leaves hi stall on for 10 seconds. If you lift, and the vacuum switch sees hi vacuum, it puts the converter back in lo stall. The box works seamlessly. I am very happy with it now. If anyone else has installed Bruce's box, I'd be interested in hearing what you think of these modifications and if you think you might benefit from them as I did.
I bought a controller from Bruce and installed it on my 65 ST300 Gran Sport last week... It's a quality piece and well worth the money spent! I installed the unit under the dash, and ran all the wires and hosed through the cowl - the installation is all but invisible. The controller does everything just as described, but I was surprised to find out on my test drive that the terminals inside my transmission have always been switched! The bottom terminal went to the converter, and the top controlled kick down. I never knew as both would fire at the same time during WOT, and never knew what high stall felt like at idle. Imagine my surprise when I now hit the brake and the transmission would downshift, and hold it for 9 seconds! I pulled the pan and switched wires, all fixed now... But now that I drive the car I fully understand what Larry was talking about.. I've never driven a car with a high stall converter, and it is very loose around town. Best I can tell this thing is at 2500 rpm or better in high stall, and power delivery is no longer linear. It is very tricky to launch now. Larry - I'll most likely call Bruce and having him re-work my controller to minimize the brake timer like yours. I'm a little confused, as Bruce told me the Max Throttle timer had to be set at less than the brake timer, but it seems you two worked through this. Then I thought: If I kill the brake timer, I'm almost back to totally stock function of how a 65 car was set up from the factory. The only gain was the automatic flip to low stall under max throttle (overriding all other inputs) at 3-9 seconds into a run. I'm going to start at 8 seconds - under normal circumstance, it shifts into second about 6 seconds/60+ mph into a run, then about 2 seconds into second gear it'll go to low stall. I'll also try 4 seconds - same strategy, just the car makes the 1-2 shift IN low stall. I'll make a few runs in the morning and report back, but it sounds like Larry likes to make the 1-2 shift in high stall, where GranSportSedan seems to like low stall just past 60' (2.2 seconds for me) Any other experiences, comparisons or advice? Thanks,
Rhett, What Bruce did with mine was modify it so that it went from Brake-on Hi Stall, directly to low stall as soon as I came off the brake. I also connected my yellow wire to 12 volts and a switch. That way, I can select the Maximum throttle timer (Drag Race Mode) with the switch. The vacuum switch puts the converter back into hi stall if you get on it hard enough to drop the vacuum below 4.5" The car is alot more responsive that way. In effect it acts just like Buick had them controlled stock. High stall, brake on, low stall off brake, back to high stall above 60% throttle.
Thanks Larry - I might do the same....if I keep the unit. I had the chance to make some runs this morning, and I figured out I dont like launching in high stall.. it wasnt as tricky as I thought, but it does seem to have alot of wasted energy. I can torque the car up to 2500, almost 3000 rpm, release the brake and floor it, the car just walks away with a chirp and seems to still slip some. I dc'd the brake timer wire, and got the same positive launches I was getting before in low stall (and associated wheelspin) Further on down the run, i tried both 3 seconds and 8 seconds to low stall (launching in both high and low stall), didnt seem to make an ET difference (compared to all runs I've made in full high stall all the way before the installation). I have to play with it more, but for my car the controller doensnt yet seem to offer an advantage over the factory linkage switch set up.. I know there's a learning curve, but I made 10 runs this morning, lost three to wheelspin. 7 runs were in the 14's but only 3 were in the 14.6's. Before the unit was installed, I could consistantly click off 14.6's, and even a 14.5. I dont like going slower. Overall, it seems my best runs were on the factory set up - launch in low stall, hit high stall probably a second or so into the run (from 60% throttle on) and staying in high stall all the way. Again, interested in anyone's elses experience.
Torque Multiplication, it's driving me up the wall trying figure out why I keep reading torque multiplication numbers, as if it is like having extra gears in the transmission. Any rate, from what I am reading if a torque multiplication is 2.8:1 then the engine is turning 2.8 times to the transmission turning 1, so in essence the torque converter is slipping or is the process of transitioning to a 1:1 to ratio. Somebody please correct me if I am wrong. Thx !!! Michael
The converter does multiply engine torque, but torque multiplication is at it's maximum at full stall, it drops off though. The converter is made up of the impeller(front half), and turbine (rear half), and the stator in between. Stall speed is the maximum RPM the engine can turn the impeller with the turbine stationary. As the turbine catches up to the impeller, torque multiplication drops off, until the converter is transferring torque at close to a 1:1 ratio. It never gets quite there as there is always some slip.
Thanks Larry, I still am trying wrap my head around this, still don't get it, I feel like that Guy who is being explained the technology of the VCR in "City Slickers". Still looking for that torque multiplication for dummies article. Any rate, found this article which shows some of the advantages of the switch pitch and it is a pretty good read. http://www.gminsidenews.com/forums/...ble-vane-torque-conveter-reconsidered-218545/ Michael
