Small block tranny replacement

[Moms68]

I’m have a transmission question. I am at a crossroads as to the drivetrain in my car.

It is a ‘68 Charger with a moderately built 340, about 350hp. When the engine was installed several years ago, I had the original 904 rebuilt by a local shop. The tranny was slipping badly under a load immediately so I drove the car back to that shop. They supposedly installed a shift kit which stopped the slipping, but soon after the car starting shifting weird. 1 to 2 second gear shifts almost back to back. The engine makes a lot of power but it’s not getting to the rear wheels.

Fast forward to now. I want to replace the small block transmission and upgrade to a 727 or.... go to a big block. I understand the small and big transmissions are different so I don’t want to throw away money.

If I go with just a SB transmission what do you guys suggest. I see Mancini Racing has several.

 

[dvw]

Learn to do them yourself. You'll save money. 904 for your current application is fine. It was already wounded when the kit was installed. a well built near stock 904 can handle 650 hp easy, probably more.
Doug

 

[R/T Boy 67]

When the new trans. goes back in,make sure the transmission's throttle (kickdown) linkage is adjusted correctly. You can toast your new trans. if it is not.

 

[CMC4u]

I have brand new in box 727 for ya
I'd like to sell

Email [email protected]

 

[Sparky Anderson]

If you can get a used 727 cheap that needs a rebuild, that's the way to go, not too expensive to reseal it plus put all new clutches and steels, a couple of 100 bucks, it the easiest tranny to rebuild, if you go 904, it will cost about the same but not as strong as a 727. You can rebuild this yourself, watch You tube video's, some of them are very good. I'm not a transmission tech and have rebuild over a dozen of them, all worked great.

 

[dvw]

I just finished a 904 for a customer. Also built the engine. He wanted a 383. But after talking he had a 68 Satellite convertible with a 318. For ease of using existing parts we decided on a 360 Magnum 904 combo. The 904 used a low gear set, Raybestos frictions, TF 2 shift kit, 3.8 lever, 4 clutch front drum, E bay deep pan. TCI street converter. Nothing fancy. The engine used a .550 roller cam, Performer RPM, Eddy heads, Eddy 650 carb, headers. We used the 904 because we had one. It used the existing drive shaft. It's quicker. There is a low cost low gear set available so with the 3.23 gear 1st gear ratio mirrors a 3.70. This combo will live a long time.
Doug

 

[Moms68]

I just finished a 904 for a customer. Also built the engine. He wanted a 383. But after talking he had a 68 Satellite convertible with a 318. For ease of using existing parts we decided on a 360 Magnum 904 combo. The 904 used a low gear set, Raybestos frictions, TF 2 shift kit, 3.8 lever, 4 clutch front drum, E bay deep pan. TCI street converter. Nothing fancy. The engine used a .550 roller cam, Performer RPM, Eddy heads, Eddy 650 carb, headers. We used the 904 because we had one. It used the existing drive shaft. It's quicker. There is a low cost low gear set available so with the 3.23 gear 1st gear ratio mirrors a 3.70. This combo will live a long time.
Doug

Doug- thank you very much for the detail in your response. Even before I read your post, I decided to pull the 904 and have it professionally rebuilt by a local performance tranny shop. I have a feeling there’s issues with the shift kit that was put in mine as well as other problems from the first rebuild. I like the idea of the lower first gear for take-offs and have the cruising of the 3.23’s. Also will consider the 3.8 lever and other suggestions. What stall is the converter you used in this build?

 

[dvw]

2400. The owner bought it. To be honest not sure that it was the best available. I'd check with Kenny Ford at PTC.
Doug