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ss3011 · 10-17-2019, 06:56 PM

4L60 has a 3.06 first gear and a huge ratio change from 1gear to 2nd gear . Might want to checkout the Sonnax gearset that reduces 1st gear into the 2.8 range . Are you planning on using 4th gear ?
Back in the mid 80's I ran a Olds Cutlass with a 307 and a 200-4R with a 2.74 first gear , 5.57 rearend gear , and a 28" bias tire . The problem with all that ratio is the engine can't rev up that fast . Much of the engine power was trying to accelerate the drivetrain , and not the car . Ran better with a 5.38 ratio , and swapped in a different overdrive ratio (.72) and that helped a bunch . Converter clutch was worth 2 mph !

10-17-2019, 06:56 PM	#1
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Converter Slippage at top end 4L60 has a 3.06 first gear and a huge ratio change from 1gear to 2nd gear . Might want to checkout the Sonnax gearset that reduces 1st gear into the 2.8 range . Are you planning on using 4th gear ? Back in the mid 80's I ran a Olds Cutlass with a 307 and a 200-4R with a 2.74 first gear , 5.57 rearend gear , and a 28" bias tire . The problem with all that ratio is the engine can't rev up that fast . Much of the engine power was trying to accelerate the drivetrain , and not the car . Ran better with a 5.38 ratio , and swapped in a different overdrive ratio (.72) and that helped a bunch . Converter clutch was worth 2 mph !