Should I Change From 3.55's To 3.31's - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

 
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post #1 of 6 (permalink) Old Jun 10th, 03, 1:33 PM Thread Starter
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Steve Johnson
 
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It is being suggested that I switch the gearing on my 70 with 454 LS6 to 3.31's. Will this be worth the cost and effort to make this change.

http://www.chevelles.com/showroom/da...rofile_pic.jpg

1970 SS with a .030 over 454 LS6 crate engine, 14096188 open chamber rect. cast iron heads, 3933163 intake, Quick Fuel Q850PV, Summit 110gph FP, Holley 12-803 fuel pressure regulator set to 7.0 psi, Bullet cam (238/245 @ .050, lift 540/540, LSA 109), Gm HEI 93440806, TH400, FTI 3500 convertor, Hedman headers, 2.5" exhaust with H-pipe, Pypes Race Pro mufflers, 3.55 gears, KYB gas shocks, UMI adjustable upper control arms and UMI boxed lowers, pinion angle negative 1-2 degrees), 245/60/14 BFG's and M/T Pro Bracket Radials, timing total 37 degrees.
1.725 60', 11.937 @ 111.91mph
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post #2 of 6 (permalink) Old Jun 10th, 03, 2:17 PM
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Mike
 
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Well, let's see, 3.31/3.55 = 93.24%

I'm not sure what you are trying to achieve, but the reduction in RPM for highway driving would only be 7%, probably only about 200RPM, and the performance differntial would be negligible.
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post #3 of 6 (permalink) Old Jun 10th, 03, 2:33 PM
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Where are you going to get the 3.31's? Just curious as I have not seen them available anywhere other than used on Ebay.

In it for the short haul
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post #4 of 6 (permalink) Old Jun 10th, 03, 3:49 PM Thread Starter
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Steve Johnson
 
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Thanks Mike, that's kind of what I felt. Your ratio shows that the reduction in rpm is neglible.

http://www.chevelles.com/showroom/da...rofile_pic.jpg

1970 SS with a .030 over 454 LS6 crate engine, 14096188 open chamber rect. cast iron heads, 3933163 intake, Quick Fuel Q850PV, Summit 110gph FP, Holley 12-803 fuel pressure regulator set to 7.0 psi, Bullet cam (238/245 @ .050, lift 540/540, LSA 109), Gm HEI 93440806, TH400, FTI 3500 convertor, Hedman headers, 2.5" exhaust with H-pipe, Pypes Race Pro mufflers, 3.55 gears, KYB gas shocks, UMI adjustable upper control arms and UMI boxed lowers, pinion angle negative 1-2 degrees), 245/60/14 BFG's and M/T Pro Bracket Radials, timing total 37 degrees.
1.725 60', 11.937 @ 111.91mph
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post #5 of 6 (permalink) Old Jun 12th, 03, 9:07 AM
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post #6 of 6 (permalink) Old Jun 12th, 03, 10:04 AM
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You can get that much change with a larger tire.
3.31 is hard to find, It's 3.08 or 3.42 new.
JMOP Bob J.
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