Different Rear-End?

motocross_masta

Registered User
I've heard several stories on how to up a t-birds power w/ a rear end from another car. I was sceptical at first, and still am a little. Here's how it goes. When we bought our SC that guy told us that if we removed a rear end from another car (not sure wut make, i think a t-bird LX) that it will give the car way more power and that u won't hit 5th till 200kms. So u can tell y i was sceptical!!!!! I've heard other things now as well that it just increases the efficientcy, so more hp makes it to the ground than b4. I just wanna find out the truth, and i wanna kno if its worth doing, and if it is.... wut car does it come outta?
 
He's talking about the rear end gear. If you get a higher number rear end gear the engine revs more and it *seems* like more power is making it to the ground.
 
All's I know is that if you have a higher rear end gear number you get into your power band quicker, not necessarily revving more, but getting you there quicker
 
Thomas A said:
How is changing the rear gear ratio going to effect how the engine runs?

Thomas

It doesn't change how the engine runs, but it does make it easier for the engine to move the vehicle.

Say you have a rear gearset that has a numerical ratio of 2.80:1. That means the driveshaft turns 2.8 times to the axles 1 revolution. But it is also the amount of times the torque applied to the gearset through the driveshaft is multiplied. So 100lb-ft applied through the driveshaft will get you 280lb-ft at the axle (frictional losses dispensed with for brevity). Now change the gearset to 3.73 and the change in torque multiplication makes that same 100lb-ft look like 370lb-ft. Basically the change in gearset give the engine more "leverage". Further, since the engine now has more rpm at the same vehile speed it feels peppier.
 
That is the answer I was looking for. I knew that, I just wanted everyone that read the thread to be clear on that. Using you calculations though, are you saying that by upgrading from a 3.27 to a 3.73 gear, you would add 46 ft.lbs of torque to the ground?

Thomas
 
Thomas A said:
Using you calculations though, are you saying that by upgrading from a 3.27 to a 3.73 gear, you would add 46 ft.lbs of torque to the ground?

When you put it like that it sounds pretty pathetic, doesn't it? But I suppose thats one reason why it's not generally recommended to make just a one or two ratio "jump" since you won't really get a big kick in the backside like you would with a five ratio jump like 2.73 to 3.73. I mean it helps but you kinda get this "is that all?" feeling.
 
Youre looking at it in the right direction but not getting the entire picture. Yes torque multiplication increases but engine speed also is a factor. The higher the ratio the faster the engine will turn which makes for a shorter gear. So basically youre trading your top end for low end if you do like a 3.27:1 --> 3.73:1.
 
i have a v8 s-10 that had a stock peg leg 2.73 rear end in it. i got a 3.73 rear end with disc brakes on it from a camaro for 400$. it went from a wet-weather devil to a twin striping bastard that would smoke em whenever i was on the gas. of course its not a SC and you probably wont experience the same feeling as me because your car is much heavier than my truck but, yes its worth it if youre lookin to munch some mustangs or for some lower e.t.s but itll kill your hwy mpg.
 
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