I have had too many problems. After 3 tries last year, my friend got my tranny shifting fine. Now it zips up between gears. I need to get another tranny and start over. I want a strong rebuilt for maybe 650 HP 600 torque strength? So I can have one that lasts. Just leave it in drive like stock. No frills, just non breakable. My 67 GS weighs about 3750 and runs 11.80 with 1.60 60ft and 3.73 gears. That's about all it will ever do. In drive and no playing with gears, ever.
Should be no issues to get a 400 to do that, my car ran low 10s and the only internal parts I upgraded was the intermediate sprag and good clutches....this was a me built tranny
Mark Deconti did mine about 5 years ago. It's been rock solid. You should have no problem finding someone who can build a 400.
I would make sure the direct clutch has 6 frictions, not the usual 5. A special piston to convert it is available. Pretty much standard with big engines/cars in a TH425. Bruce Roe
This is a nice mod for sure, but at the OP power level not truly needed, a good 34 element sprag, dual fed direct clutch, high energy fractions, shift kit set to desired firmness, should be all thats really needed assuming the builder does the rest right
Ben, At 650HP/600TQ, I would think the 6 clutch option would definitely be preferable. The factory deemed it necessary for the Stage1 BB 400. Yes for the better sprag, premium frictions, and dual feed direct clutch.
There are tons of 400s out there swallowing that power level without 6 disk. Id rather spend money on the adding extra roller bearings like under the forward hub and output shaft, an extra disk to the intermediate and a larger piston in the center support 2nd gear, is by a very far margin, the weekest in the trans.....it only has 3 disk and a small apply piston. I know the factory added the 6th disk, but you almost never see a 400 loose 3rd gear, unless its a towing trans.....then I always add extra disk in high and second
This is also why a 34 element sprag is normally one of the 1st upgrades I do. The older smooth drum sprags were only 16 elements. These were the weakest but allowed direct drop in if the 34 element. The newer roller sprags are an upgrade to only the 16 element smooth sprag, but requires a a different direct drum to upgrade to 34 element. This 1 part increases the holding capacity of 2nd gear by more that 100% upgrading the center support to a larger bore piston adds another 400-900 pounds of clamping force depending on piston size and main line pressure.
Just had one built for my 71 Skylark. Turbo 400, and converter combo Built to handle between 750-850hp. Select Performance in NY.
I've always left my transmission work to a shop. I am pretty lucky to live near a very reliable shop who knows their stuff backwards and forwards (and also is pretty inexpensive). Maybe if you post where you live, someone might know a shop that can build you a solid TH400 and can give you a recommendation. A TH400 should be able to handle the job you describe... -Bob C.
Yes, but having spent over 2 thousand on this Coan converter and 400 tranny, I hate to dump the 400 and spend 2 or 3000 more. I'm on limited income now. However, I do love overdrives though.
