Hi .. I have a 63 Wildcat with 401 Nailhead, With Dynaflow transmission.(2 Speed) My question is: it possible to Change the Dynaflow for Modern 4-speed automatic? Without much modification?? Excuse for my bad English,, I'am a french Canadian !!! Tank's .... L'Poux....:TU:
You can but there are a number of issues to overcome. Regardless of the route you take the minimum you will need is a crankshaft adapter. The 63 is the last year with the Dynaflow and has a different crankshaft flange to later models. After that your options include - TH400 w/Gearvendors type overdrive, a 200-4R or a 700R4. There are also the 4L80 and 4L85 but they are fully electronic boxes and I dont know of any kits for them. So ... For my 63 Wildcat I went with a ST400 (3 spd) off a 66 Riviera and changed the 3.42 pegleg to a 3.23 posi diff. Couldn't find a 3.07 at the time. I got the tilt column and all the linkages and crossmember out of a 64 Wildcat and got it all working like it was installed in the car from new. I also had to change to a 64 starter motor. The ST400 has a 2 speed converter and the BOP bolt pattern, so no trans adapter was required. Drive shaft had to be shortened and balanced but that'll happen regardless of the box you choose. A 63 Le Sabre owner told me the following - the 700R4 he fitted required panelbeating on the floor, he said the 200-4R would fit without the hammering. You MIGHT get a TH400 with the BOP bolt pattern but the 200-4R or 700R4 will require an adaptor kit to mount, plus youre faced with linkages or floor shift and adding and adjusting the TP cable so you dont blow your trans. And the crank adaptor of course, starter motor. Hope this helps. I'm sure others will add more detail for you.
I agree a 65-66 Buick (switch pitch) trans would be the simplest, strongest, and cheapest solution, if you find one with your bell housing pattern. The switch pitch can emulate a 4 speed, and there is no TP cable to worry about. I would like to hear about the crankshaft flange solution. Bruce Roe
Russ at Centerville Auto is a Nailhead wiz and has many parts including trans adapters http://nailheadbuick.com/transadaptors and crank adapters If you go the ST400 Switch Pitch route get one from a 65-66 Nailhead (NOT 64) and make sure to get the flex plate, electric kickdown switch and driveshaft yoke as well. Obviously, the main point of a modern 4 speed is the overdrive but consider this for a moment - I did the sums and found by the time I bought the new trans, adapters, etc and had it all fitted I'd need to do something like 45,000 miles to rack up the equivalent gas savings. A good overdrive DOES make sense if you want to race with a low ratio diff then get some decent mileage on the freeway. If youre doing highway driving the Dynaflow is a lovely smooth box; not sure if I'd change mine if I had it to do over - all the parts are available for rebuilds. I only had 1500 miles on mine but the decision was kinda taken out of my hands - the rebuilt radiator w/internal trans cooler leaked and flushed my new Dynaflow with water tainted fluid. As the clutches use water soluable glue it was game over. Further reading ... http://nailheadbuick.com/automatic-transmission-options-for-the-nailhead-to-get-rid-of-the-dynaflow
Thank you very much my friends ... I is back with more questions .. I do not have time for now ... I not long back in .. L'poux............ray:ray:
Happy to try and answer any questions you might have. Send me a PM if you dont hear back, I'm not here all the time and might miss the post.
