3.42 VS 3.90 rearend gears - Team Camaro Tech
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post #1 of 7 (permalink) Old Feb 14th, 01, 08:16 AM Thread Starter
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I have a '78 Camaro(3600LB pig) with a medium
built 406 and 2000 stall. The car has a 3.42 posi now which is great for highway cruising but seems to be holding the car back around town. I have been thinking of switching to a set of 3.90'gears(27'' tire) Anyone have an opinion on 3.90's?
Are they too low for a daily driver?

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post #2 of 7 (permalink) Old Feb 14th, 01, 09:33 AM
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The 3.90's might not be too bad with those 27 inch tall tires as long as you don't do much highway cruising. At 60 mph you'll be turning close to 3000 rpm's and at 70 it'll be turning almost 3500. This is without an overdrive, that is. It all depends on what kind of driving you will be doing, and what kind of rpm's you're willing to put up with.

I always felt that 3.42's were just about right for all around use. Maybe some shorter tires would solve the problem...

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post #3 of 7 (permalink) Old Feb 16th, 01, 10:03 AM
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In my opinion anything more thatn 3.42-3.55 is too much for highway driving, although I have done it with a 4.10 and I could not stand it, so I installed a Gear Vendors overdrive unit. Now the 4.10 gear is overdriven .78 or like as if I had a 3.20.
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post #4 of 7 (permalink) Old Feb 16th, 01, 10:43 AM
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i switched from 3.42's to 3.73's and am very happy with them. noticable improvement but still decent on the highway.
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post #5 of 7 (permalink) Old Feb 17th, 01, 04:52 PM
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4.10's in my '69Z finally drove me nuts (3800 at 70 - bummer), replaced it with 3.55's - nice compromise (3200 at 70), still decent around town.

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post #6 of 7 (permalink) Old Feb 19th, 01, 06:39 AM
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4.11's. Powerglide and 26" tire = OPEC Gold Card Member!

To be safe. I installed 3.73's with my six speed. Still went through the 1/4 in third gear! I am pulling them out now to put 4.10's in.


1992 Firebird 355/Six Speed (Soon to be LT1)
1991 RS 350 / 700-R4
1987 Toyota Pickup 383 / 500 + HP 10.963 @ 119.95 Slicks / 11.997 @ 114.23 Radials
"Speed KILLS, so drive a FORD and live forever!"

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post #7 of 7 (permalink) Old Feb 19th, 01, 07:06 AM Thread Starter
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Well I have 3.42 now with 26'' tire so I figure 3.90 with my new 27'' tire would drive about like 3.73 with my current tire. So that might not be too bad. After hearing everyone complain about 4.11's I guess that's too low for sure.
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