Catskinner51
Member
Where can A person buy the correct clutches for a Stage 1 turbo 400 trans. I believe they are the same as a Oldsmobile W30
Stage one turbo 400
- Thread starter Catskinner51
- Start date
I believe they are all the same. Some had more clutches then others. Just order a kit for your application. I think I got my last kit from my local NAPA. That was more then ten years ago.
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Here is a cut and paste from V8buick on the Stage1 Transmissions,
www.v8buick.com
Regarding Stage 1 identification (and the specific 'BB' code TH400):
Automatic transmissions have a tag on the passenger side (figure T2) that contains the code identifying the transmission application. Stage1 GSs came with heavy duty transmissions with a 2.48 first gear. ALL had (or were supposed to have) steel flat washers (instead of wave type) and 6 plate clutch packs (instead of 5 plates with wave washers). These types of transmissions were referred to as a 'Cadillac sprag' transmissions, and were used in high torque applications. The servo spring was different, in addition to the valve body pressure. The following was taken from a post on www.v8buick.com by TH400 expert Mark DeConti:
"The 70 BB Stage 1 was unique. The later valve bodies were not setup like it, though close. Not all 70 Stage 1 BB's had the 6 clutch drum, it depended on the build date as it was used after a certain point. A lot of 70 BA's had the 6 clutch drum too. The BB's used a different direct piston which improved the 3 gear shift. The 70 BA valve body is VERY close in design to the 70 BB and only a spring in the 1-2 accumulator valve needs to be removed to make it the same. No waved steel plates were used in the 2nd and 3rd gear clutch packs on the Stage 1 trans, and the 3rd gear valve body accumulator spring was softer to firm up the shift. The governor was setup to shift at approx. 5500 rpm and was specific to 1970 BB only (some model of Pontiac and maybe Olds used it too). Later governors were ok, but closer to 5200 rpm. The valve body separator plate has larger holes in places to increase pressure to the clutches. Am pretty sure that 70 was by itself and 71-72 was different."
...............................................................
"On the 70 models, higher rpm governor. no wave plates in 2nd and 3rd clutch packs and the 3rd clutch piston was different on 6 clutch pack units. Valve bodies were setup for firmer shifts (1-2 accumulator valve spring removed and softer 2-3 accumulator) and shift plates were different. Some of these mods were carried over to 71 and later, but not as extensive as 70. Also, not all 70 Stage 1 trans had 6 clutch 3rd packs. The 5 clutch packs were used until a certain build date in both. Then both used 6 clutch packs with the Stage 1 units getting the special piston. At least this is what I have found on the ones I have worked on."
.............................................................................
There are also several articles referencing prior interviews of Dennis Manner, former Buick powertrain Engineer (and regarded as the "father of the Buick 455") who claimed that he had to persuade Hydramatic and other Buick brass to build the 'BB' TH400. I think Denny's words were quoted as having to "fight" Hydramatic and other Buick brass to build it. Denny wanted the 3rd gear direct downshift to 1st gear for GS Stage 1's out on the street "doing battle" using rolling starts, etc. No 3rd to 2nd downshift below 40mph-ish, just direct to 1st gear and RPMs. Inquire with others who've experienced it ... it is pretty stunning.
You can build any THM400 like the Stage1 transmission. The only part that is difficult to impossible to reproduce is the specific BB valvebody. That 3-1 downshift at speeds below 35 MPH is one of the things that made the 1970 GS455 such a street terror. More on those valve body particulars in this article about the switch pitch valve body. The author discusses the 3-1 downshift.
http://www.buickperformanceclub.com/SPTrans.htm (Scroll down to the bottom of the article)
70 BB transmission on Ebay
So did the bb trans only come in stage 1 cars or other gs455s as well? Just curious as i sold a bb trans a few summers ago for considerably less money...
www.v8buick.com
Regarding Stage 1 identification (and the specific 'BB' code TH400):
Automatic transmissions have a tag on the passenger side (figure T2) that contains the code identifying the transmission application. Stage1 GSs came with heavy duty transmissions with a 2.48 first gear. ALL had (or were supposed to have) steel flat washers (instead of wave type) and 6 plate clutch packs (instead of 5 plates with wave washers). These types of transmissions were referred to as a 'Cadillac sprag' transmissions, and were used in high torque applications. The servo spring was different, in addition to the valve body pressure. The following was taken from a post on www.v8buick.com by TH400 expert Mark DeConti:
"The 70 BB Stage 1 was unique. The later valve bodies were not setup like it, though close. Not all 70 Stage 1 BB's had the 6 clutch drum, it depended on the build date as it was used after a certain point. A lot of 70 BA's had the 6 clutch drum too. The BB's used a different direct piston which improved the 3 gear shift. The 70 BA valve body is VERY close in design to the 70 BB and only a spring in the 1-2 accumulator valve needs to be removed to make it the same. No waved steel plates were used in the 2nd and 3rd gear clutch packs on the Stage 1 trans, and the 3rd gear valve body accumulator spring was softer to firm up the shift. The governor was setup to shift at approx. 5500 rpm and was specific to 1970 BB only (some model of Pontiac and maybe Olds used it too). Later governors were ok, but closer to 5200 rpm. The valve body separator plate has larger holes in places to increase pressure to the clutches. Am pretty sure that 70 was by itself and 71-72 was different."
...............................................................
"On the 70 models, higher rpm governor. no wave plates in 2nd and 3rd clutch packs and the 3rd clutch piston was different on 6 clutch pack units. Valve bodies were setup for firmer shifts (1-2 accumulator valve spring removed and softer 2-3 accumulator) and shift plates were different. Some of these mods were carried over to 71 and later, but not as extensive as 70. Also, not all 70 Stage 1 trans had 6 clutch 3rd packs. The 5 clutch packs were used until a certain build date in both. Then both used 6 clutch packs with the Stage 1 units getting the special piston. At least this is what I have found on the ones I have worked on."
.............................................................................
There are also several articles referencing prior interviews of Dennis Manner, former Buick powertrain Engineer (and regarded as the "father of the Buick 455") who claimed that he had to persuade Hydramatic and other Buick brass to build the 'BB' TH400. I think Denny's words were quoted as having to "fight" Hydramatic and other Buick brass to build it. Denny wanted the 3rd gear direct downshift to 1st gear for GS Stage 1's out on the street "doing battle" using rolling starts, etc. No 3rd to 2nd downshift below 40mph-ish, just direct to 1st gear and RPMs. Inquire with others who've experienced it ... it is pretty stunning.
You can build any THM400 like the Stage1 transmission. The only part that is difficult to impossible to reproduce is the specific BB valvebody. That 3-1 downshift at speeds below 35 MPH is one of the things that made the 1970 GS455 such a street terror. More on those valve body particulars in this article about the switch pitch valve body. The author discusses the 3-1 downshift.
http://www.buickperformanceclub.com/SPTrans.htm (Scroll down to the bottom of the article)
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Pick up a copy of Ron Sessions Turbo 400 book: How To Work With And Modify The Turbo Hydra- Matic 400 Transmission by Ron Sessions: Good Paperback (1987) Later Edition., No Signature | Tacoma Book Center if you are serious about rebuilding it yourself. I have used it several times. I had ATI go through one I had built using Ron’s book and the ATI rebuild did not ET or MPH any faster. They did add some Torrington bearings and upgrades that would help longevity, but did not improve performance.
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Catskinner51
Member
Thanks guys, appreciate your inpu.
The Th 400 was basically the same until replaced by the TH 375. This was similar, but plastic parts replaced metal and was less durable in general.
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