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-   -   C4 Low gear? (https://classracer.com/classforum/showthread.php?t=62356)

Bobby Fazio 05-30-2016 09:11 AM

C4 Low gear?
 
Is it possible that going to 2.92 can actually slow the car down from a 2.75 or even a 2.46? It seems both my stocker and maverick super stocker have had best sixty foot times with 2.75. And maverick was better with 2.46 and 2.75 than 2.92. Here's the part I'm not quite getting:

In my stocker I have tried 4.88 with 2.92 but that was 200lbs heavier in N. Sixty foots were 1.62 back then. 4.88 x 2.92 = 14.25 most aggressive torque multiplier?

Next I tried 4.88 with 2.75 in L and 200lbs lighter and sixty foot was usually 1.53-1.56. 4.88 x 2.75 = 13.42

Next I tried 4.56 with 2.75 and sixty foots were 1.58, ok I expected that to slow up. 4.56 x 2.75 = 12.54 weak torque multiplier?

Next tried 4.56 with 2.92 and nothing really changed. Still 1.58 short times and now we are at 4.56 x 2.92 = 13.31 should have been damn near close to the 4.88 with 2.75 right?

Lastly tried 4.71 with 2.92 and sixty foots are 1.60. 4.71 x 2.92 = 13.75 should have been a perfect scenario?

All this was done with same converter which always seems to flash at same spot and 28 in radials. Is there more to it than just the ratios? Is there more drag in the trans? Is converter agitated? Has anyone else experienced?

Alan Roehrich 05-30-2016 09:21 AM

Re: C4 Low gear?
 
Bobby,
The big problem with a lower first gear is that it creates a larger drop between first and second. The lower your HP and torque, the less the engine likes the RPM drop between first and second, and the larger the drop, the harder the engine struggles trying to recover from the shift.

Lou Jeffery 05-30-2016 09:41 AM

Re: C4 Low gear?
 
Bobby, I can back you up at least on the outcome of the 2.92 ratio C4. We ran a 2.92 with a 4.88 in a crate motor Mustang 302. It was hard to drive, inconsistent and noisy 60 ft. 1.53. We went back to 2.46 - 4.88 60ft 1.51 and picked up over the whole run, much easier to drive 1-2 shift. I am not a fan of low ratio first gear. Louis Jeffery

BRETV 05-30-2016 12:06 PM

Re: C4 Low gear?
 
I ran a 2.92 first gear w/5.13 and a 30 inch tall radial with a 87 mustang in M/SA and went 1.49-1.51 every pass, even went a 1.47 at Indy one year, was stoked after that one. The 2.92 was always quicker than the 2.75. The KEY is the shift point coming out of first. Gotta be low rpm and quick. Just my $.02




Bret Velde
2003 SS/LA (hopefully soon)


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