Rear end advice for racing with a 4 speed
Hey guys,
I just got into drag racing my 69 dart last year broke my first parts, the rear end crapped out on me. My car has a 340 that makes 440HP at the crank, 4 speed, 741 case 8-3/4 rear end with 3.91’s, Mickey Thompson ET Street SS tires. After taking the rear end apart I found that the drivers side axle splines twisted and the inner side gears of my sure grip were wiped along with that portion of both axle splines, the outer side gears were fine. To get the car back in action and to make the last race of the season I rebuilt the sure grip with new, one piece side gears, new clutch plates, and found an old pair of factory axles. The ‘66 dated ring and pinion looked to be in good shape and I left them as is.
The last race of the the season was just this past weekend and I raced without issue and now I want to properly come up with a game plan. A lot of the local mopar guy’s think that the 8-3/4 will do just fine for my power level and that I should just get a new pair of axles and keep running it. I will say that they all run automatic’s and aren’t racing a 4-speed. I talked with Dr Diff and Cass figures if I’ve twisted axle splines than it will happen again, even with new axles so he’s leaning me towards a dana60.
I made around 50 passes last year and about the same this year and I’m hoping to keep that pace up. Down the road I’ll probably get slicks for the car and maybe coax some more power out of the car but nothing too drastic. It’s a true street/strip car.
I appreciate any advice from guys who race 4 speeds, thanks. Mike N
Hey guys,
I just got into drag racing my 69 dart last year broke my first parts, the rear end crapped out on me. My car has a 340 that makes 440HP at the crank, 4 speed, 741 case 8-3/4 rear end with 3.91’s, Mickey Thompson ET Street SS tires. After taking the rear end apart I found that the drivers side axle splines twisted and the inner side gears of my sure grip were wiped along with that portion of both axle splines, the outer side gears were fine. To get the car back in action and to make the last race of the season I rebuilt the sure grip with new, one piece side gears, new clutch plates, and found an old pair of factory axles. The ‘66 dated ring and pinion looked to be in good shape and I left them as is.
The last race of the the season was just this past weekend and I raced without issue and now I want to properly come up with a game plan. A lot of the local mopar guy’s think that the 8-3/4 will do just fine for my power level and that I should just get a new pair of axles and keep running it. I will say that they all run automatic’s and aren’t racing a 4-speed. I talked with Dr Diff and Cass figures if I’ve twisted axle splines than it will happen again, even with new axles so he’s leaning me towards a dana60.
I made around 50 passes last year and about the same this year and I’m hoping to keep that pace up. Down the road I’ll probably get slicks for the car and maybe coax some more power out of the car but nothing too drastic. It’s a true street/strip car.
I appreciate any advice from guys who race 4 speeds, thanks. Mike N