OK- here's the deal, are you stock 350 guys with 2.77 gears, using overdrive in the quarter? I'm not a regular drag guy, but I'm thinking no? Yes or no?
I'm thinking about swapping in a set of 3.42 gears to make it more "fun" on the street. I know i'd need the 3 to 4th upshift kit ,right?, because I'm sure it would now require overdrive in the quarter mile.
My question is,(assuming I'm right about only using 3 gears with the 2.77) Is the 3.42 better for the 1/4? I'd get off the line quicker, but now i'd be adding a shift, AND using overdrive, which is pretty tall right? I dunno, the deeper gear may still be worth it...yes?....no?

 

Hmm I wouldn't think so. I didn't need it with a 305 auto w/ 3.27's. And the 350 has a higher redline than the 305 so I don't think OD is necessary with 3.42's...

Jess

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1988 GTA - 5.0 Auto now with 5-speed power!
1989 Firebird - 2.8 5-speed: Sold

My Page - http://transam.freeservers.com
Firebird owners check out http://transamgta.com

 

With 3.42 in third gear at 5000rpm you are running about 112mph, depending on tire size. Should not be a problem in the quarter mile.


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350 with stealth intake, holley carb, 470 lift cam. 700r4 with .5 boost valve, vette servo, tci lock-up kit, B&M megashifter. Richmond 3.73 gears, powertrax locker, timkin bearings, synthetic lube. Custom 3 inch single into 2 2.5 pipes. 1 1/2 drop springs, 1 5/16 solid front sway bar, 1 inch rear bar, custom subframe connectors, custom LCA relocation brackets. Kobel ground FX, currant red metallic paint. Lots of other stuff...
82camaro

 

You never want to upshift into an overdriven gear in any acceleration situation as it eats up all of the torque/power your engine is making through the increased effort the engine has just to turn the gears in the transmission. A highway gear like the 2.77 definately won't like being upshifted into OD (4th gear - NOT tcc lock-up) nor will any other gear in a 1/4 mile run. You should run through the traps in third gear and not have any problems with a 3.42 gear. A 2.77 gear would just be getting going in third gear through the traps on a 1/4 mile run which is exactly why it is not a good gear to run in a qaurter mile oriented car. Go with 3.42s. The 3.42 gear is widely accepted as a near-perfect gear ratio for a street car that sees a few 1/4 mile blasts a year but is mainly street driven. A 2.7x gear is deemed a highway gear as it gives pretty sluggish off-the-line performance but will let your car go about 165 even without that much power! Thus, it gives the best mileage figures as well. A 3.42 gear will not destroy your mileage, but you might notice a small decrease in mileage - depending on your driving habits.

The other issue that is a big factor on what gear to run is what your powerband is like. If your car is all done making power at 4500rpm, you won't want to run much over a 3.42 gear - even if it is a track-only car as your engine won't be pulling the car down the track at the top end since the engine is just winding out without making any power. On the flipside of that, if your engine makes power to 7000rpm, a 4.10 gear is more to your engines likeing as that will put your engine at it's peak power output right at the end of the 1/4 mile, which is exactly what you want. You want to go through the traps, on a 1/4 mile run, with your engine making slightly past it's peak power, in a 1:1 gear ratio (third gear in virtually every trans) of the transmission. This relationship, with respect to your powerband, is what dictates which rear axle gear ratio is ideal for your application for 1/4 mile performance. The trick is to balance this with everyday manners for a mostly street driven car.

Good Luck

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

I have 3.73's in my car and am pretty much maxed out across the line but I don't need to shift into overdrive.