Here is a little info on my project its a 1950 Chevy truck with a 1961 401 Nailhead. My question is what transmission should I run I been deciding between a 700r4 and a 64-66 ST400. Which one would you guys use. If you use the 700r4 what adaoter kit would you use?
Heres the place that two people I know used. Both were very happy with the product.:TU: http://www.transmissionadapters.com/Nailhead_install.htm
I dont have the dynaflow I was offered it but at a rather expensive price $500. I guess I am hesitant buying it because I have heard its a sluggish transmisson.
All 3 are great transmissions and any of them are a great choice. It would have to be a personal choice and how much fussn you want to do. Dynaflow- Cheapest and easiest. Just bolt on and go. Smooooooooth too. ST400- My personal preference for the perfomance of the switch pitch feature, but will require the switching, and apropriate adapters. Bendtsens should have you covered here too. How classic can it be as a good 'ol Turbo 400? 700R4- Better gearing and more "modern" and more readily available. Bendtsens adapters would be my choice here. In fact I think its your only choice... Erik
Are ST400 good performance transmissions? Are they good freeway engines? Does anyone know the max cruising freeway speed?
I'd stay away from the Dynaflow. Go with the ST400. All you will need to run the '65-'66 (don't get a '64 unit) unit behind your '61 401 Nailhead is a crank bushing adapter from Russ Martin, as well the appropriate flexplate and starter.
Actually that's who (Russell) I got the engine from and he is also selling me the ST400. The only question that I have is that I want to know is if I will be able to drive comfortabily on the freeway and if need be maybe do a little drag racing at stop lights with the ST400?
The ST400 transmission is the same as all of the TH400's that Chevrolet, Pontiac, GMC trucks, and Oldsmobiles have used since '64. Buick callled it a ST - Super Turbine - because they had used the word turbine in their automatic transmission since way back when. 65 - 67's had a switch pitch converter which creates two distinct stall speeds (67 used the BOP bolt pattern.) All ST/TH 400 transmissions have a final drive ration of 1:1. Easy freeway cruising is a function of rear end gears and tire size, not the transmission. TH400's are the drag racer's choice when it comes to toughness in the GM line. They take more hp to run than a TH350, but the reliability is worth it. In one of your earler post you ask if ST400's are a good engine. Did you just make a typo or are you confused?o No: If you go with the 700R4 (or 200R4) o/d transmission, you'll no longer control upshifts with a vacuum modulator on the transmission. You'll be controlling ALL transmission functions with a Throttle Valve cable that connects to the carburetor - critical adjustments are necessary in order to keep from burning up the o/d units. The o/d transmission swap is definately not a "bolt on" as the ST400 would be. If you plan on doing any towing, stick with the ST400. You should be able to find a Dynaflow for next to nothing if you look around. It's a really good reliable transmission, not performance oriented though. But what other automatic transmission will allow you push start your car when the battery dies. :TU: Ed
Avoid the 1964 ST400 specifically. It was the black sheep of the ST400 family, and did not share as much with the '65 & later. The '64 ST400 does not have the variable pitch torque converter and is quite odd in that it will not normally allow you to select 2nd gear unless you're willing to shift back & forth between D and L (the only detents available) while accelerating. Devon
Sorry it was a typo I meant transmission. So the ST400 is a good transmission for my daily driving and occasional red light racing ( no towing its going on my traditional style hotrod truck). I am going to look into what year the trans is hopefully its not a 64.
Any overdrive you can get behind it. The ultimate would probably be a S/P 400 with a gear vendor or a 4L80E. Good Luck with your project.:beer Bob H.
A ST400 will definitely be good stop light to stop light, but highway driving will depend on rear gear and tire size. You could go with an OD trans like the 700R4/200R4 or 4L80E, but that would require the use of a trans adapter, and that will be significantly more expensive. Basically you need to decide if you need OD for highway crusing. You could always go the less expensive route by using the ST400, and if you decide later you need OD, you could simply swap in a Gear Vendors OD unit.
If you put a th400 behind a 61 nailhead, you will run into some mechanical problems to solve.... 1. the flange on the back of the crank is a different diameter.... 2. the flex plate for the th4 is different and has the ring gear on the flex plate.... not triangular like the 61.... 3. the starter for a th4 is a ''short nose'' ... the starter for the dyna flo is a ''long nose''..... in short the dyna flow starter aint gonna work.... it wont go in the hole... the bell housing will bolt up,,, the flex plate for a th4 will bolt up once you solve the problem of the center hole being too small.... what I did was to have a machine shop open the center hole enough to barely make it over the earlier flange... raced it that way for several years and never had a problem.... then it is just a matter of how you want to solve the starter problem... complete swap out is best, with a rebuilt one....
Ya not to sure what my rear gears will be I think I'm gonna use a camaro rear end as that is about the same width as my stock rearend as for tire size I'll be running 15's. Would anyone happen to know the approximent fwy speed ST400's usually go. If I can go 75mph with no problem that would be fine as this truck willl most likely be a town cruiser Thanks for all the help
It depends on you're rear tire height; rim diameter is irrelevant. For my 28" tall tires and 3.07:1 gears, at 70 mph I'm turning only 2600 rpm. Lots of different calculators here to help you decide on axle ratio and tire height: http://www.tciauto.com/Products/TechInfo/Calculators.asp#6 Devon
The final ratio with a th4 is 1.1 ,,,, the same as the dyna and a stick shift.... in my car with 4.11 gears in back the highway rpms was about 3100 at 55-60 mph.... with 14 in tires..... if memory serves me right.....
Hi Ed (nailheadnut) You can push start the early GM dual-range Hydramatics used from late 1939 through 1955. In fact any of the early automatics with a rear pump can be push started. They can also be towed with the drive wheels on the ground for 15-20 miles. I have a Brendtsen's adapter attaching my '65 425 to a 700R4. The only issue that I have is that the nailhead is a torquer and the 700R4 has a "stump pulling" first gear - much lower then the nailhead needs. Supposedly, Raptor (down in Lousiana) was coming out with a planetary gearset for the four-speed that had a higher first gear. With a nailhead, I like the gearing of the THM 400 better - but you will need a higher (lower numerically) rear axle ratio then with the 700R4.
200-4R has a "taller" first gear (2.74) than a 700R4 (3.06) plus the OD is better at .67 rather than .7 PLUS, Plus, it is shorter and easier to work with cruciform frame clearance.
