I have a 63 riviera with a posi unit i bought about a year ago on ebay. I did't take any pictures of the units numbersou: From what I remember I't said on the description that would fit on my year car and model, the gears I don't remember if they are 3.07 or 3.08. Im a little confuse now, what is the difference .08 -.07 ? What I know about the unit is that it did fit my 63-rivi differential, the axles got in with no problem, 30-spline, the drive-line hooked up fine, on the posi unit you cud not see any springs or gears from the outside, It was all sealed. I have another unit non-posi 3.42 from a 63 wildcat. My plan was to put the 3.42 gear and pinion on my posi-unit and the shop where I took the car to get it done told my that the 3.42 gears cud not fit without a ring spacer. I like to know what to look for wen looking for gears for my posi unit. stock 401 and trans. 3.07 or 3.08 gears, is this a good setup or 3.23-3.42 gears would be better. My rivi is still a project but love cruising in it, don't race but like to burn out once in a wile. One thing that I recently found out obout my lady-rivi crushed my heart and it keeps bugging me over and over and i cant let it go. I found out that 325 HP. was all a lie and that is more like 270 HP. ----------- : ( i fill cheated - broke hear-ted. I thought all this time I had bought a muscle car. Any info I can get is appreciated. thanks guys... i fill relived...
The SAE horsepower convention changed for the 72 model year from gross to the net methodology. In order to get to todays equivalent for a pre 72 car, you would deduct maybe 20% from the pre 72 model hp rating. Some others may disagree but I would say getting rid of the Dynaflow trans used in 63 may be more important than a change in the rear gear set up. I do not have a 63 Riv road test, but I do have one for a 65 Riv GS which has a 3.42 rear gear. I think a 65 would be quicker than a 63. The 65 ran the quarter in 15.5 seconds at 95 mph. I suspect a 63 would be 16-17 seconds in a quarter mile.
I can't answer all your ?? but the difference between 3.07 + 3.08 is the ring gear and pinion number. The actual performance diff is about zero. 3.07 is typically a Chevy gear I think and 3.08 BOP. But that's late 60's + 70's info, I'm not sure about early 60's or Rivs. You really need to ID what you bought and what's in the car right now. Then you need to figure how you will use the car, like some drag racing or just every day. Do you plan to build the engine? Others here like Monza can help you more.
To answer your questions, yes the 3.42 gears can be used with the 3.07 posi unit, but as you discovered it needs a spacer. You would need your drivetrain shop to double check, but the difference in heights between the gears should be about 1/2", which is the thickness of the required spacer. You'd have to have one machined, as they aren't something that is produced. The change in gear ratio is not super significant, however its not insubstantial. Whether on not its worth it depends on how much the shop would want to set up the new gears, and have the spacer made. And yes, the Nailhead was over rated from the factory. Part of it might be the SAE rating method, but I'm sure the marketing department had a hand in it as well.
thanks for the info. The only way to know what gear ratio I have is to take it out and snap some pictures of the numbers on the gear-ring. ou: maybe in the future. Im O.K with it now. So another question .? lets say I have a posi unit 9.3 on my 1963 buick riviera, the only gears that will fit with no spacer required will be a ring and pinion that belong to a 63-65 Buick equipped with a posi-traction. are there 2 different gear types, 1 type for posi and another for non posi?
The posi and non posi units use the same gears. 3.23 and higher gears (lower numerically) use one carrier, while 3.42 and lower gears (higher numerically) use another.
your right Andy. it makes sense to me now, different carrier is the only way to align the gears. great info, I'm have no mechanical skills and trying to learn. Will 3.23 or 3.42 gears give a big difference in performance over a 3.08, 63 Riviera 401-stock engine and transmission. ?
With a stock setup, I don't think you'd notice much difference between 3.07's and 3.23's. You might notice a slight difference with 3.42's though. Unless your going to work towards making more horsepower and making the car faster, I don't think it would be worth it to swap in the 3.42's. Besides, I'm sure someone would be willing to take them off your hands... :grin: Like Jim stated, if your worried about performance, you'd likely see much greater gains out of swapping a ST400 in place of the Dynaflow. I know I did!
Will it require a lot of modifications to swap my Dynaflow for the Super Turbine 400, do I need a 64 Riviera drive-line ? and do I need a buick expert mechanic to do it, there's a few shops in town that work on classics.
It isn't easy, do certainly do-able. You'd need a '65-'66 ST400, converter, flexplate, starter, and a crank bushing adapter to reduce the ID of the crank hub to accept the smaller snout of the ST400 converter. You'd also need a different trans crossmember, and to have your driveshaft shortened. You should be able to use the trans crossmember and driveshaft from a '64 Riv. The shift linkage is also different. You'd need to be fairly competent with cars and mechanics to be able to pull it off.
can I buy an aftermarket shift linkage or does it need to be from a 64-66 Riv. and can I use an aftermarket shift'er or one from 64-64 Riv. can I power-shift gears on the st400, I know I can't on the Dynaflow
Your factory shifter won't work, as the ST400 shifts PRND21, verses PNDLR with a Dyanflow. You should be able to make an aftermarket shifter work in the factory console though. And yes, you can manually shift the ST400. I converted mine to a full manual valve body, although there are kits available where you can retain the automatic function.
No problem! Any further questions feel free to PM me. Keep me in mind if you ever decide to get rid of those 3.42's. :beers2:
