Hi, I was wondering what is the ideal angle for the tranny? The article talks about getting the "net" pinion angle to approximately -2 degrees, but - 6 and + 4 doesn't sound too good to me on the ujoints. Is there a "best" angle for the tranny as it can be shimmed with washers off of the crossmember. Thanks. Phil Sedlon
Phil - If you're talking about the current issue that's supposed to be sent out before the GS Nats...it will probably be 'a while' before the rest of us see it! I'm pretty sure you wouldn't want anything less than -2, not sure about -4 or -6. Scott
I know that you're supposed to have a -2 total for a mostly street driven car, but what is optimal for the tranny to be at? Should it zero out or be -1 or +1 or what?
Hi Phil, Without question it would be best to have as little driveline angle as possible. It would also be best if the output shaft of the trans and the pinion shaft were in the same plane. In other words, the output shaft of the trans and the pinion shaft would be pointed directly at each other AND the u-joint angles would be zero with the car under power. However, neither of these ideals is very easy to achieve on a factory framed/bodied car. About the best you can expect to do with the driveline angle is -2 degrees, and that will most likely involve some "persuasion" to the trans tunnel. Items like transmission and bellhousing shields further complicate things. Also, if you're thinking of shimming the trans up to reduce the driveline angle be careful with the fan/shroud clearance. As for getting the output shaft and pinion shaft in the same plane....well, that's a pipe dream that can only be realized with a chassis car. Shoot for getting the front and rear u-joint angles to cancel each other out with the car under power, and do your best to minimize the driveline angle. Hope this helps. -Ron Rygelski
OK, I measured my angles and my tranny is at -4 and my rear is at -2. If I try and get the tranny as close to zero as I can, then I should be able to leave my rear alone. My understanding is that the rear begins to lift up under launch, so it would be best if it rose to a 0 angle rather than going past it if I left the tranny alone and put the rear at +2. Am I right here or should I adjust the rear to +2 to achieve my -2 total? Did that make any sense? Phil Sedlon
Hi Phil, Jeez.....you're making me dizzy. Trans is at -4, and rear is at -2, so you're at -6 total. If you were able to shim the trans enough to get to zero on the driveline side you'd be all set, no need to touch the rear at all (you'd have a pinion angle of -2). But I seriously doubt you're going to be able to shim up the trans enough to get to zero driveline angle. The front pivot point for the driveline assembly is the motor mounts, and they're located pretty far forward of the trans mount, which is where you intend to shim. What this means is you've got to add a lot of shims to have a relatively small effect on the driveline angle. You might have enough room to add, for example, 1/2" of shim to the trans mount. That will correct the driveline angle by perhaps one degree if you're lucky. Then you've got issues with fan clearance in the shroud, header clearance at the crossmember, and exhaust clearance at the floor. Reduce the driveline angle as much as is practicle (often a simple swap to a urethane trans mount helps). Then adjust the rear to give you the desired pinion angle. For example, the best I could do on the driveline angle of my '69 racecar was -3 degrees. The trans tunnel has been massaged a little to allow clearance for the trans shield, and the crossmember just clears the headers. The rearend is at +1 degree, for an overall pinion angle of -2 degrees. -Ron
OK, I did what you recommended (six washers and new bolts!). I did get the tranny to -3, and there is still clearance. I also got a poly tranny mount. I decided to put the rear end at 0, for a total of -3. Will see how things go. If I need to, I can easily change it to take it to -2. Shroud clearance, headers, etc., is still good. My only problem is that I have a driveshaft loop also and it's making things kind of tight, that's why I left it at -3 and didn't go any farther. Thanks for all the help. By the way, RedLine Racing ATF in the tranny, water wetter in the radiator, and oil in the engine as soon as I get 1,000 miles or so on it.
With a -3 for the motor/tranny, wouldn't the rear have to be at -3 to reach '0'. For that matter, shouldn't the rear be at -2 (-5 in your case)?? Scott
