ST300 Rebuild Kits and Performance Upgrades

Good Morning All,

It's getting about down to that time where I am going to need to pull the ST300 out of the GS and rebuild it. This is a numbers matching car and I want it to stay that way, so no ST400 for now. I have done a considerable amount of searching with very little results. I thought it might be helpful to those of us who are still running the ST300's to try and get as much info as we can in one place.

I believe I want to take this car in a very similar direction as many others on the board do, which is to have a cruiser but also one that performs well on the street and maybe the occasional trip to the track just for fun. No slicks, just what I can get it to do on street tires, without going crazy enough that I feel like I am jepordizing the integrity of the car.

So, that being said. The first and foremost question is, what are the best resources for putting together a rebuild kit for the ST300?

In addition, what are some of the performance upgrades you have done to improve performance of your ST300? I know there isn't much with this trans that can be done, but looking for the tips and tricks to quicker and firmer shifts and maybe changing the shift point slightly for better performance. I know Rhett has been doing some work on his, but I wasn't able to locate specifics and the info was spread across multiple threads. If need be I can start an additional thread for the performance part of it.

Hope yall like the idea and I hope that we will be able to benefit several members here on the board with the information. Looking forward to seeing some good responses and feedback.

Thanks in advance,

 

Here's a nice pictorial of a rebuild by Kirk:
http://www.v8buick.com/showthread.p...a-Super-Turbine-300-(ST-300)-A-Pictoral-Essay

 

66 Bulldog - good luck on your rebuild, I still like the ST300 alot (even after blowing one up!) But what I found out was blowing it up was my fault, I was going after shift speed and firmness with increased line pressure, and that was the wrong way to go about it. I'm lucky I didnt wipe out my engine with a balooned converter. I was also lucky to find a nailhead specific ST300 core out of a 66 Gran Sport on 65GS.com, and the seller wasnt greedy (thanks Dr. Frankenbuick!)

So we built the new trans with a mix of 65 and 66 parts - I knew my 65 internals worked well, and we used as much as we could. I've got the new tranny in my car now, and it absolutley kicks @ss - quick, firm shifts that barks the tires, but soft transition into forward and reverse gears from park, and an easy drop into first on deceleration..an over-all great build. I worked close with my tranny guy on every aspect of it. My first trip to the track is next week, I'll let you know how it all tuns out.

So here's everything I know, in one shot:

Converter -Rebuilt by Precision out of Iowa (the're big on diesel converters, my tranny guy loves them) They used a hardened spline (Allison hub?) anti balloon plate, brazed fins and needle bearings - I guess a pretty standard performance rebuld. I stuck with the 12 1/2 inch converter, but they tweaked the stall speeds. Only problem is they tweaked the low stall, and now the hi/low speeds are only 200 rpm apart. l'm having them do my old unit over, and leave the stall speeeds right where they were (1800 and 2300, more or less). In the meantime, this one launches great, just diminishes the advantge of the switch pitch.

Pump pressure - I had stretched the 65 light blue relief valve spring a 1/4 inch to increase line pressure on my original tranny, but I never checked the pressure after and thats where I went wrong. On performance package TH400's I think they use a seocnd shim, and thats what I should have tried, certainly more scientific. I wound up sending the low servo through the cover, and took a bunch of the case casting with it! This may have been a problem in the 65 trannys because the 66 servo and cover are completely different and much beefier. The new unit uses the 65 pump and leaves the stock spring and shim in place, but mixes and matches 65 and 66 parts on the valve - I might have this wrong, but I beleive he used the 65 valve, shim and sleeve, a stock 66 purple spring but the 66 boost valve because it was aluminum and had a better diameter (?) I dunno, but it kicks...

Valve Body - Not much done here, but the 66 is a totally different configuration (!) - The 65 had a totally seperate valve body to control the converter pitch, the 66 moves the pitch solonoid up to the front pump and abandons the 2nd VB and all the associated case casting. GM actually cast in a blockage in the fluid path to do it! We decided to use the 65 SP valve body and pump, so we removed the blockage and bolted it all together.I was sceptical but it works great! In the 65 tranny I had opened up the high clutch feed in the VB spacer plate from .090 to .125 as detailed in the infamous "Blueprinting Buicks for Action " article. Thats worked well to speed the shift from the original bog slow transition. I kept that in this build.

Converter Control - Still messing with this, but I did two things - First, I wired in a modified Bruce Roe Timer box. He modified it to mimic OEM low stall drivability, unless a performance condition exists at launch (full throttle, etc..) Then the timer kicks in and only keeps it in high stall for a specified time (I"ve got mine set for 3 seconds). Once thetimer stops it goes to low stall until the system resets. Seems to work well for my 1/4 mile adventures, and the theoretical technique is also described in the "Blueprinting" article. One of the things I like about Bruce's box is it brings in a vacuum signal that seems to cover the stall when throttle position isnt enough in regular driving, like in the hills. I like it.
I also wired in a momentary switch to manually control the converter (I used a shifter mounted line-loc switch). I have been messing with disconnecting Bruce's box for racing, and going full manual on the converter and doing things like launching in low stall for traction,then immediately to high stall for full torque multiplication, back to low at the 60 ft mark, and doing it all again after the shift. Honestly it hasnt made me faster, but was fun to try.. maybe again next week and see if I can figure it all out.

Clutches, Steels and Bands - This is what I should have been doing all along. It turns out that some Powerglide performance parts fit the ST300, so we used Red Eagle brand clutches and band, and Kolene brand steels. With that, we increased the clutch pack from 5 clutches to 9 and got rid of the wave plate. This was the mod that gave me the kick in the back on the shift and barks the tires that I thougt I could accomplish through line pressure. So it kicks in anything over 1/2 throttle, but around town is easy on the drive train like nothing was ever changed. I'm sure line pressure comes into play, but I learned you dont have to kill it and build yourself a "hair shirt".

Governor - Stock weights on the GS governor seemed to be in the high 11 gram range (my scale doesnt have decimals) and shifted anywhere from 4600-4800 rpm. I found the B&M kit weights were worthless, so on my original tranny, I brought the weights down to high 10 grams by removing tip material, and left both springs in, which gave me a shift point of 5000 rpm on the nose with a normal part throttle shift. Removing one spring gave me a higher part throttle shift speed, kinda like what you would get with modulator pressure, but I didnt need that. My engine is stock (and tired) and doesnt make any power over 5k, and even 5k wasnt making much power at the shift, just bringing in 2nd at a more advantageous RPM. On this tranny, the same governor would hold that RPM for even longer, maybe 5100 rpm, so I put one approx 11.5 gram weight in, and that seems to have brought the shift down to 4900, which I think will work better and keep me in this engine's power band. In the "Blueprinting" article they talk about drilling 2 1/4 inch holes in EACH weight and removing a spring for a 5500 rpm shift speed, but that would probably grenade my motor..

So thats all I know. I'll know more next week if this tranny actually makes the car faster, but in the meantime it's alot more fun to drive. On the downside, I blew up my original "born with" transmission. At least the model specific numbers are on the servo cover which I still have, and there was no VIN on the broken case...

I think the most surprising thing to me was how different the 65 LK and 66 MK transmissions were....They knew they were going to retire the transmission for 67 , so why so much re-engineering? Was the LK just plain outmatched by the nailhead?

Good luck! PM me with any questions.

 

A great story to tell on the ST300. I'd like to see one of these built for a 455 in a light car. Too bad we couldn't get a smaller VP converter to get more stall when used in a 3000 lb or less car that would benefit most from a 2-speed. Would make a nice substitute for a Powerglide in a lightweight street-strip application.

 

Thanks Walt. I had seen that before a while back, its a great write up.

Thanks Rhett! That's some great info. I'm sure I may be touching base with any questions that come up. Please keep me posted on how she does at the track.

 

You bet - Weather is looking good for Friday, 0% chance of rain, no wind and early morning temps in the 40s and 50s....thats good air.

 

Sure sounds like it! Keep an eye on the Barometer too. We found with Don's car that the Barometric Pressure made a greater impact on how the car would run down the track more so than some of the other elements.

 

Good advice!

Big old high pressure system gonna be righ on top of us Friday. it was 30 in today, probably be about the same Friday. My best times have been in 29.6 plus pressure, and a .5 inch drop can cost me up to .4 seconds - I've seen it on back to back days.

 

Yeah, should make for a good day. We typically look/hope for 30", that seems to be what the Nailhead likes. On days where the pressure is right the car will talk to ya. Not sure how to describe it other than it "motor boats" while sitting at an idle. Don told me about the noise it made on those certain days, but I wasn't quite sure what he was talking about until I heard it for the first time. Then it was, "Yep. It's gonna be a good day".

---------- Post added at 10:33 PM ---------- Previous post was at 08:39 PM ----------

Rhett,

Any chance you could tell me exactly what Red Eagle Clutches, Steels, and Band you used? I know that probably sounds like a dumb question but from looking around on the net there are different thicknesses and such. Also, if you could tell me where you got them, or I guess maybe your Trans shop probably provided them. I am trying to find a good source for the clutches, steels, and band without having to buy a Powerglide Master Kit which comes with all the gaskets and seals that I probably can't use. Also, do you have a source for a rebuild kit for the ST-300? I am not trusting most of these sites I see that have it listed since they don't seem to tell you what brand anything is. Kinda sketchy and last thing I want is cheap China crap in my tranny if I can avoid it.

 

Let me check with my guys, and see who they used for a source - I think they used FATSCO for the kit....

 

Rhett - Any news on the actual parts used and the sources?

Also, I saw your post about taking the car to the track. Care to elaborate on how the tranny did here, so we have it all in one place?


Thanks!

 

I'm headed back to the tranny shop next week, so I'll have the clutch specs pretty soon, also have a question on thrust washer replacement with needle bearings I have to ask for Tom T.

The tranny performed great, although the converter seemed to create much more heat than usual. I'm having my old converter done over to get back to my original stall speeds. Looks like a cooler is the next order of business.

The launches were great even with less than optimal stall speeds (or maybe because of!), my 60fts were consistant and equal to my pre-build bests (2.1X 10 out of 13 runs, and the others were low 2.2s)

The shifts were hard and quick, and caught 2nd every time - on the videos it sounds exactly like my buddies RAIII TA catching 2nd - more than a chirp, but less than loosing traction.

One thing that was kinda wierd is that my shift points have been creeping up - I made a governor weight change before I went up to the track, and had to make another one while I was there - brought it down from 5k to about 4800-4900 - didn't gain me any ET but did gain me about 1 mph - I have no idea why, maybe because my car is so tired.

I hope that line pressure isnt creeping up as well. I tested it before I went up - it was at 145 for the forward gears, and 230 for reverse. Thats slightly higher than the shop manual specifies for the forwards. I wont be testing it again any time soon because the line plug took all the threads out of the case with it.....the day before I was supposed to drive. Thats a whole other story.

I'm putting my original converter in next week, and going to play with the distributor some and try to go back up sometime in October, I'll let everyone know.

 

I know this has been "dead" for over a year, but I'm hoping to rebuild the original ST300 for my 66 Lark over the coming winter. (Finances allowingray and I'd REALLY like to have the info mentioned in the above posts. Please? :TU:

 

Sorry - talked to my tranny guy a few months ago with the clutch/steel specific questions and he couldn't remember anything.....I would think Fatsco should be able to spec out a red alto/Kolene kit for you...

As a postscript though: the tranny probably has a couple hundred passes on it now and still works great, kicks like a mule under full throttle but totally docile around town.

 

Sorry if it's a silly question, I'm still on a learning curve.

I've got a 64 Skylark 300ci with ST300 switch pitch trans both running perfectly. I'm about to replace the 300 eng with a 430/455 with a build intended to get into the low 12 high 11 sec 1/4 mile times.

I was expecting to have to go the TH400 route but is there a chance the ST300 would be up to the task? Will it even bolt up to the big block?

 

Do you mean stock it won't last or even with a good re-build it's not up to the job?

 

It could last behind the BBB, they installed them behind Nailheads back when so it should hold up behind a BBB? If not a performance build(if performance parts are available for them)should make it live.

If the BBB you're installing is stock the trans should hold up no problem, if its built up maybe not but worth a try they seemed to be able to handle abuse back in the day. GL



Derek

 

http://www.bulkpart.com/2/category/ST300.html

I've not bought st300 parts from there but have bought 2004r parts from them. Looks like they have the parts you might need.