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Grant Eldridge · 05-30-2009, 12:56 AM

Congratulations, Aubrey, great meeting you at Mission and seeing your car run! I raced 409 Chevys in the '60's when we were lucky to get into the 12's with the track prep and tires of the day. We broke dozens of those old rear ends, as well as the axles, driveshaft centre bearing supports, u-joints, clutch linkages and of course the old Muncie transmissions. With todays tires and traction I can't imagine attempting to use that rear end. We even broke the pinion right out of the carrier on one pass, hanging off the end of the driveshaft with half the casting, the rest still bolted into the car! The chevs were bad for not upgrading the rest of the driveline to handle the bigger motors, this was essentially the same rear end found in six cylinder cars, They bolt right into the early 4 cylinder Novas even! We did improve the situation by heat treating gear sets to soften them, as I recall from 40 years ago they were about Rockwell 62-64 and we drew them down to about 52-54 from ancient memory. That made them wear out faster, but less likely to break. We'd also set the gear pattern on the drive side well towards the inside of the tooth and use as close to zero lash as we dared. The case and carrier deflect substantially and the pattern shifts out on the tooth, so if you start centered you'll move out and break the teeth off on the outside of the ring gear. I recall guys using steel straps machined to fit on the main caps to strengthen them and longer bolts. I even seem to recall some guys brazing up the end of a bolt and threading it in through the side of the case so it would contact the back of the ring gear somehow to help stop the case from spreading, not sure of exactly how this was positioned or if it was effective. The point is exactly as Tony Janes said, it's junk and a waste of your time and money to attempt to keep it in one piece. Even if it were an automatic, it would be highly doubtful that it could be reliable. As others have posted, the 12 bolt should be no problem to rework with suitable mounts, etc and you'll be saving yourself endless problems with the old 10 bolt. Anyway, best of luck! It's a cool ride!
Grant Eldridge
E/SA 6650

05-30-2009, 12:56 AM	#32
Grant Eldridge Member Join Date: Jul 2007 Posts: 124 Likes: 0 Liked 0 Times in 0 Posts	Re: Aubrey's 62 409 goes 11.067 in C/S Congratulations, Aubrey, great meeting you at Mission and seeing your car run! I raced 409 Chevys in the '60's when we were lucky to get into the 12's with the track prep and tires of the day. We broke dozens of those old rear ends, as well as the axles, driveshaft centre bearing supports, u-joints, clutch linkages and of course the old Muncie transmissions. With todays tires and traction I can't imagine attempting to use that rear end. We even broke the pinion right out of the carrier on one pass, hanging off the end of the driveshaft with half the casting, the rest still bolted into the car! The chevs were bad for not upgrading the rest of the driveline to handle the bigger motors, this was essentially the same rear end found in six cylinder cars, They bolt right into the early 4 cylinder Novas even! We did improve the situation by heat treating gear sets to soften them, as I recall from 40 years ago they were about Rockwell 62-64 and we drew them down to about 52-54 from ancient memory. That made them wear out faster, but less likely to break. We'd also set the gear pattern on the drive side well towards the inside of the tooth and use as close to zero lash as we dared. The case and carrier deflect substantially and the pattern shifts out on the tooth, so if you start centered you'll move out and break the teeth off on the outside of the ring gear. I recall guys using steel straps machined to fit on the main caps to strengthen them and longer bolts. I even seem to recall some guys brazing up the end of a bolt and threading it in through the side of the case so it would contact the back of the ring gear somehow to help stop the case from spreading, not sure of exactly how this was positioned or if it was effective. The point is exactly as Tony Janes said, it's junk and a waste of your time and money to attempt to keep it in one piece. Even if it were an automatic, it would be highly doubtful that it could be reliable. As others have posted, the 12 bolt should be no problem to rework with suitable mounts, etc and you'll be saving yourself endless problems with the old 10 bolt. Anyway, best of luck! It's a cool ride! Grant Eldridge E/SA 6650