30, 31 & 32 Spline Mainshaft Conversions
12-14-2010, 11:14 AM
#1
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30, 31 & 32 Spline Mainshaft Conversions First there is the "ever-so-popular" "Viper Spec" build. This over-glorified term simply means the mainshaft has been changed from the stock 27-spline to a Viper 30-spline. All the rest of the tranny is the same. Of course you can also upgrade to a one-piece countershaft, but not really worth it if you have to pay full price for the part. I'm just talking about mainshaft conversions in the thread anyway. Just trying to clear up the above-mentioned marketing hype. The Viper shaft is almost a direct replacement for the stock shaft. All that needs to be done is 1.375" has to be cut off for it to match the length of the stock f-body shaft. When doing this, you lose about 1/3 of the splined portion at the end of the shaft. At this point, the splines will only go about 2/3 of the way into the yoke at best.
The 31-spline shaft has to be cut down the same amount (1.375"). Both the 31 and 32 spline shafts have longer splines to begin with. So when you remove the 1.375" from the 31, you still have enough spline length to bottom out in the yoke. So this is one reason that I prefer these over the Viper. The second reason is that more splines=more strength. You don't see a lot of shops using these shafts due to the fact that they aren't a direct fit and must be machined to work. Also, most machine shops won't even want to mess with this hardened steel. So it is really hard to find a place to do it, let alone do it correctly.
The 31-spline shaft fits the typical f-body style rings/gears/synchronizers. The 32-spline shaft fits the tripe cone rings/gears/synchronizers found in the GTO/Corvette T56s.
Below, I've attached pictures of the modifications done to the above shafts.
The 31-spline shaft has a journal added for the speedo gear to be a press-fit. Also, you can see the snap ring grooves that were added. The 32-spline shaft has been modified to accept a typical snap ring for the 1-2 synchro assembly. Sorry I forgot to take a "before" pic. Maybe someone else here has this pic (Mike?). Basically it starts out as a big groove and is filled and machined back down. This shaft is the proper length, so no cutting is necessary. With some minor honing, the CTS-V speedo gear will hold a good press fit at the bottom of the splines, so its not necessary to machine a journal into the shaft. It needs about 0.0015" of interference in order to stay in place.
The 31-spline shaft has to be cut down the same amount (1.375"). Both the 31 and 32 spline shafts have longer splines to begin with. So when you remove the 1.375" from the 31, you still have enough spline length to bottom out in the yoke. So this is one reason that I prefer these over the Viper. The second reason is that more splines=more strength. You don't see a lot of shops using these shafts due to the fact that they aren't a direct fit and must be machined to work. Also, most machine shops won't even want to mess with this hardened steel. So it is really hard to find a place to do it, let alone do it correctly.
The 31-spline shaft fits the typical f-body style rings/gears/synchronizers. The 32-spline shaft fits the tripe cone rings/gears/synchronizers found in the GTO/Corvette T56s.
Below, I've attached pictures of the modifications done to the above shafts.
The 31-spline shaft has a journal added for the speedo gear to be a press-fit. Also, you can see the snap ring grooves that were added. The 32-spline shaft has been modified to accept a typical snap ring for the 1-2 synchro assembly. Sorry I forgot to take a "before" pic. Maybe someone else here has this pic (Mike?). Basically it starts out as a big groove and is filled and machined back down. This shaft is the proper length, so no cutting is necessary. With some minor honing, the CTS-V speedo gear will hold a good press fit at the bottom of the splines, so its not necessary to machine a journal into the shaft. It needs about 0.0015" of interference in order to stay in place.
Last edited by TDP; 08-07-2011 at 03:26 PM.
12-14-2010, 11:23 AM
#2
Here's a pic (from bottom to top) of the 1-2 synchro area of a triple-cone stock '05 CTSv, the 32-spline SSR, a GTO, and finally at the top, a standard double-cone F-body.
By changing the 32-spline to match the GTO, you won't have to purchase the ~$200 of over-priced GM 3-pc synchro lock... nice work Jason..
By changing the 32-spline to match the GTO, you won't have to purchase the ~$200 of over-priced GM 3-pc synchro lock... nice work Jason..
08-06-2011, 10:27 PM
#4
I hate to bring this thread back but I have a GTO spec trans that I'm putting in my Camaro and I want to upgrade the output shaft before I do so.... How much does the 31/32 spline shaft run along with whatever other parts are needed to make it work?
