[ponyakr]

" Make sure your actually buying a bop 350..."

You can use a Chevy TH350. Just takes a simple adapter plate. You can buy one or make one. I made one and used it with a PG & a TH350. My 455 broke both trans, but the plate worked great.

http://www.jegs.com/i/JEGS-Performan...60172/10002/-1

Or, if you really wanna build a heavy duty TH350, you can replace the bell with a JW Ultra Bell.

https://www.summitracing.com/parts/j...xoCmE4QAvD_BwE

http://www.jegs.com/i/J-W-Performanc...BoC-pAQAvD_BwE


"...A bit cleaner look under the hood without the 350 TV cable."

Can build to run without the cable. Lots of rebuilt performance TH350's come without the cable. I've read lots of back & forth about whether the kickdown cable controls line pressure, or is only for shifting to a lower gear, when you floor the pedal. I'll leave that discussion/argument for others. Some have reported great operation, for many years, without the cable.

http://nastyz28.com/threads/had-th35...le-hole.20499/

Even this Jegs basic rebuilt TH350 is built to run without the cable.

http://www.jegs.com/i/JEGS-Performan...60300/10002/-1

[FrankieT/A]

I would stick with T350 myself. I have a T400 in my 78 TA, I put in 25 years ago. If I were to go through the effort again i would just go overdrive, otherwise a T350 can handle way more abuse than most people think.
I would go with a Continental converter for sure. They work the best in our cars and not expensive...

[77poncho]

I Beleive the guy said it was from a 67 Buick. Here is a few pics of the trans. How can I tell for sure it's a BOP??

['ol Pinion head]

Chevy case goes to a point at top of case, what pic show is a BOP case.

['ol Pinion head]

Not sure on '67 Buick T400's, but '66 Buick T400's take an odd driveshaft yoke that won't slide in typical T400's. Ran across this several times, the first time, many ago after pulling a switch pitch '66 Buick core & spending nearly an hour in a yard fighting to get the yoke off the Buick's driveshaft. Switch pitch t400 will have two spades coming out of the small connector, regular T400's only have one spade.

[LeighP]

I used a TH350 behind the 455 in my 71 build....used 36 element sprag, steel drums, HD vasco input shaft etc etc......had a tight built converter design to flash to 3000 under the 455's full throttle torque. can't say enough about how impressed I was with it....plus, I could put my hand on my heart and look my insurance company in the eye and say ..."its all stock".....lol

[77poncho]

Originally Posted by LeighP

I used a TH350 behind the 455 in my 71 build....used 36 element sprag, steel drums, HD vasco input shaft etc etc......had a tight built converter design to flash to 3000 under the 455's full throttle torque. can't say enough about how impressed I was with it....plus, I could put my hand on my heart and look my insurance company in the eye and say ..."its all stock".....lol

LOL.. nice.. yeah im seeing more and more comments that the th350 if built right will have no problem to handle that what my engine is pushing. thanks

[77poncho]

ok so after digesting the info discussed here i beleive the following is what i should be purchasing.

https://www.tsr-racing.com/chevy-th3...ent-sprag.html

or this are both the same?? or one better then other?? or come with different parts??

https://www.summitracing.com/parts/ati-355682/overview/

rebuild kit # 032905HPSK (super kit)

http://dragtrans.com/dragtrans_html/HPOHK.html

shift kit
https://www.summitracing.com/parts/t...BoCv0UQAvD_BwE


anything else i need to consider??

[poncho447]

Originally Posted by 77poncho

I Beleive the guy said it was from a 67 Buick. Here is a few pics of the trans. How can I tell for sure it's a BOP??

These are pictures of a ST-300 two speed transmission, not a th-350.

[ponyakr]

Originally Posted by poncho447

These are pictures of a ST-300 two speed transmission, not a th-350.

That is correct. This is the same type of 2-speed that came in the '64-'66 GTO & lots of other '64-'69 Pontiac & other GM models. Some GM models used a SP converter.

My tranny guy said he could easily beef one up enuff for my high 11-sec bracket car. But not many guys want a 2-speed, for street use.

Mr. Google will turn up lots of ST-300 info, as well as info on most any other trans you can mention.

https://www.google.com/search?q=2-sp...F9Ew0lPtm2SvM:

Lots of bracket racers prefer a 2-speed, for fewer traction problems at launch, & more consistent ET's. But not many street guys want a 2-speed, although it might help traction, when running the hard street tires, behind a big torque engine. I suppose there might be a very few big cube street cars running a PG.

[77poncho]

Thx for info. Bummer. I was gonna try to meet wih the guy to to pick it up. But rather find out now before I get into it and figure out it's not what I need. Thx as always.

[Grand73Am]

In addition to Cliff's th350 book, I've found this th350 rebuild book by Ron Sessions was invaluable. It has great detail on the interchangeability of parts if you are swapping parts from one th350 to another. There are some differences with internal parts from early years to later years. I was using the best parts from several parts transmissions from different years, and could not have done it without this book. I don't know of another source for this valuable interchange info.
https://www.amazon.com/Turbo-Hydra-M.../dp/0895860511

And I bought a th350 rebuild video off of eBay that was helpful too, since it helps to follow along as somebody else does it. It didn't have the interchange info, but a basic take apart, inspection of condition of parts, and put back the same parts replacing wear items like new clutches, seals, etc. It's much easier if you're able to re-use all the hard parts from the original trans that you're working on, and not mixing and matching.

I also referred to the factory service manual a few times, just to double-check some things. With all these references, you'd have all the info necessary to do it. Add a few special tools, and you can do it.

[#1965GTO]

#1 thing to consider is the cooling system. With a more modern cross flow to start with you can probably get a radiator that will handle the extra load of heat. The proper tune up will help lots with the heating issue too.
If you're going to spend the money anyway consider a lower rear gear and a 200-4R transmission. Our 65 GTO has a warmed up 68 400 with 6X heads too. With a 3.55 rear gear on an Eaton posi carrier and the 200-4R you can cruise It at 75 and turn 2400 RPM with a 26" tall tire. You can build it your self or buy one that's good for 600 plus HP.
Have Fun

[LeighP]

On cooling my Th350, I chose one of B&M stacked plate style coolers (11" x 11") and did not use the radiator tank cooler. Worked great. If you live someplace cold I might suggest that you have a trans temp gauge and if has issues being too cold in winter, either fit up a thermal bypass or make a cover you can fit over part of the cooler in winter.

[#1965GTO]

Originally Posted by LeighP

On cooling my Th350, I chose one of B&M stacked plate style coolers (11" x 11") and did not use the radiator tank cooler. Worked great. If you live someplace cold I might suggest that you have a trans temp gauge and if has issues being too cold in winter, either fit up a thermal bypass or make a cover you can fit over part of the cooler in winter.

Cooling your transmission is another important issue but I was referring to cooling the engine....
As for your idea to use a 400 transmission would not be my recommendation. These transmissions are indeed bullet proof. But due to their heavier internal parts they waste a lot torque just to turn them. The 400 trans would be a great choice for a big block tow rig but wasted over kill for a car like yours. A well built 350 would be my second choice after a 200-4r.

[jonmachota78]

I had my th350 rebuilt years ago with a hardened outer sprag race and heavy duty clutches, and a shift kit. Its still working fine but i worry about the sprag. Some say the outer sprag race is the weak link others say it doesn't help much upgrading it alone. Its been working for me so far. There been alot of debate about the 36 element sprag and how it lubricates for extended street use. Drag racing its supposed to be fine. For street/strip use the 4l6e sprag which is wider and the case saver is supposed to be better. Transgo shift kit gets the nod, however im running and old b&m kit and its fine. The key here is programming the shift so its not too harsh which shocks and breaks the sprag on the 1-2 shift. Once you upgrade the sprag i think the weak link becomes the input shaft. I disabled my kick down, i prefer to take control of my downshifts, i don't like supprises. Might want to upgrade you driveshaft and ujoints while you're at it.

[jonmachota78]

Here is a direct quote i got from Jakes Performance when i asked about the 36 element sprag on the street :

"We know of customers that have run the 36 element sprag on street."

Not real encouraging if u ask me!

[n2ogpsj462]

See what I mean! Know what your buying because a lot of people don't even know what they're selling. As far as the adapter plate, I have it for my 700

[ponyakr]

"...There been alot of debate about the 36 element sprag and how it lubricates for extended street use..."


Has anybody used the mechanical diode set-up ?

http://www.ckperformance.com/View/SU...CHANICAL-DIODE

http://www.yellowbullet.com/forum/sh....php?t=1686522

http://classracer.com/classforum/sho...9&postcount=19

http://www.epilogics.com/md/index.htm

[Sirrotica]

A lot of talk about parasitic drag on a T 400 as compared to a T 350, unless you're running a 10 second or quicker combo drag car, the parasitic drag is negligible between the two. That thought is a quote from Jake himself on his website talking about 4L80E parasitic drag as compared to lighter duty OD transmissions used for performance rebuilds. A 4L80E uses 75% of the same internals as a T 400 has so the comparison is a valid one.

A street car is never going to need the lighter internals to see any difference, lighter internals also have less strength for the same materials used.

Does anyone find it strange that Cliff Ruggles runs a T 400 in his own street car as opposed to a T 350, even though he has written a book about the T 350?

My money is on a T 400 or a 4L80E (basically T 400 internals with overdrive capability) for longevity. The extra beef will have no noticeable effect on performance, but will withstand abuse over the long haul more effectively.

One more point is, to get the lighter duty transmissions to live in a performance environment the hard parts in most cases, need to be replaced with better materials. The stock factory hard parts in a T 400, 4L80E, will live just fine to 750 HP, giving your project room to grow as far as future improvements in your engine program.

There is a reason that the T400 and 4L80E transmissions weigh more to begin with, they have more mass to take abuse from the initial design. They don't need the band aids that the aftermarket has designed to try to make them live in an abusive environment.

I like to do a job one time and not keep re-doing it because the original design was deficient, and the weak link in the chain was uncovered. Spending my adult life in vehicle, stock car racing, and shop maintenance areas, has taught me to remove as many weak links in a mechanical device as possible, and never have to revisit it for breakage. JMO............

Other than a slight weight penalty, a stronger transmission platform has no drawbacks that are evident to me.........

That said, the OP seems 99% committed to the T350, but he has asked for opinions, and I have stated mine, FWIW.