I'm restoring my '63 Riv and am debating what tranny to put in it. Im going to do some mild mod's to the motor which is a 401. Im going with a dual carb set-up and going to try and stick to factory specs. My questions are- what about the 200r4 tranny out of a grand national? What modifications would it take? (I'm really leaning towards this) Second- what about rebuilding the dynaflow and just keeping it in there? Third- what would be the best tranny for it? I really appreciate your help....I am at the point in my restoration I need to decide. Kevin
Im no tranny expert, but here goes,,,, First question - I dont think you can go wrong with a 200r4 out of a grand national. They have nicer 1st gear ratio than say a 700 and a taller overdrive(If I remember correctly). Im not sure what you would all need to make it happen but with the right gears it sounds like it would be a match made in heaven with a healthy Nailhead. Second question - If your going with a mild build, Id suggest you set the dynaflow aside. My understanding is that they are great for cruisin, but not what you want behind a build. Third question - A nice switch pitch th400 would be a great choice in my opinion. Bulletproof, what else can I say. Now lets see what the experts say.:TU:
Thanks William....it will be interesting to see what everyone thinks. I'm looking forward to some responses and opinions.
Frankly, I'd leave it stock with the Dynaflow. You did say that you are "restoring" the Riv. My favorite Riviera is the '63, because of the Dynaflow. You can put the THM 400 in with a bit of work. The Dynaflow crank is different then the THM 400 crank, but I believe that there is an adapter bushing available. The Dynaflow and THM 400 use different starters. Doc or Tom Telsco know this stuff cold. Any other transmission will require an adapter. This will move the transmission rearward, creating linkage, crossmember, and driveshaft issues. These problems can be solved, but they will take a bit of time (and perhaps money). Good luck, whatever you do!
I'd ditch the Dynaflow. By far one of the best things I did in my '62. The easiest trans to swap in is a '65 or '66 ST400. However, it will require a bit of work. You'd need a different flexplate, different starter, different trans crossmember, shorter driveshaft, as well as a crank bushing adapter. It's not hard though, and is fairly straight foreward. You could swap in a 200R4, or 700R4, however you'd need a trans adapter, and that gets pretty spendy, IMHO. I love my manual valve bodied ST400 - I can still cruise at 70-75mph with 3.07 gears and a 26.5in tall tire (still under 3000rpms).
Not to answer for John. But I'm going to chime in here. I like Dynaflow, too. It goes everywhere i want it to go. I can go up and down the hills here, no problem. It's smooth. On the highway I can get 22 mpg at 70mph. Rebuild kits are available. I don't see the dynaflow as a liability. I see it as an asset. Much like, the; carburetor starter switch, the holes in the fender, the torque tube and, the Nailhead engine. They're what makes the Buick; a Buick. But , then; there is a reason, they make Chocolate and Vanilla :grin:
i agree that the dyna is good,,, a good strong trans that is hard to beat.... personally I would not swap it.... but if you have the ''swapitis'', the switch pitch th 400 is the only way to go.... the only advantage that it has is that the converter will change pitch , putting a lot of power to the ground... which the dyna will already do....but you cant leave a dynaflow in low gear all the time... a switch pitch will give you 6 forward speeds and 2 reverses.... you will have to change out the above mentioned parts to get it to work... and unless you do all the work your self,,, it is not cost effective...My folks had a 56 super that was hot,,, had the dinaflow,, I raced a 57 ford that had a 312 Thunderbird special with factory hot cam, 2x4s ect... while the Ford was setting there spinning , the buick hooked up and left him sitting in the dust.....never sell a dynaflow short...
And just to comment on what everybody else said - the Dynaflow is a good, strong transmission. If the car is just a cruiser, it's a great trans. Super smooth, and should be reliable. But, if you want more performance, then another trans (whether it be a ST400, 200R4, or 700R4) is definitely the way to go. I love being able to hold it in 1st and winding it all the way up the chip. :Brow:
There's really no advantage to the 200-4R or the 700-R4 over the St400 unless you go with a higher rear end gear. The performance comes from the taller gears. A 200-4R (2.78 low) with a 3.91 gear set gives you a lot more torque on the ground than an ST400 with the typical 3.42 rear end. If you put the 3.91 behind the ST400, you can really launch, but on the highway you'll be making a sacrifice in your engine RPM's and mileage over the o/d fourth gear (.67) with the 200-4R. The 3.91 gear set behind a 200-4R transmission gives you a 10.87 torque multiplication number. The 3.42 gear set behind an ST400 gives you a torque multiplication number is 8.49. If with the switch pitch in high stall, you have the same numbers, you're just pulling them at higher rpm's. On the highway, the 3.91 behind the 200-4R gives you a highway gear of 2.62 whereas the 3.42 behind the ST400 gives you a highway gear of 3.42. Thats probably in the neighborhood of a 1,000 rpm drop at 70 mph. Do the math, go with the 200-4R. It also fits better in the Buick's X-frame. You can get the 200-4R modified to handle as much horsepower / torque as you can get from a nailhead - find a reputable rebuilder or buy one all ready built from someone like Phoenix or Art Carr's transmissions. Here are some pictures of a 200-4R in a 65 Riviera frame. Ed
Advantage to which? You're unclear. From some research I did, it appears that all automatic transmissions have some parasitic loss when compared to a manual transmission, BUT the amount of that loss is directly proportional to the rotating mass. Because the 400 has a larger converter, and the internal rotating masses are larger in diameter, it would stand to reason the the 400 would have more parasitic loss than the 200.
On the later 400's the loss amounts to 48HP between the flywheel & tailshaft. On the older units it's slightly more. 10HP can be freed up by going to a Torrington needle bearing to replace the thrust washer in the rear of the case.
