3.73's limiting top end

nickleman60

Registered User
i'm just wondering after i installed 3.73 gears with trac loc in my 94 sc auto it pulls real good thru first and second but seems to not pull as hard when it shifts into drive around 75 mph.i guess my question is does the speed limiter or anything else computer related causing it to lose power in the upper speed ranges?
 
nope. your powerband has been moved way down on the scale of your cars actual road speed. 3.73 are good gears for drag racing but not so awesome on the open road. lot easier to do burnouts now though i bet:D . my 701 fury had 4.10's an d 3 speed auto and it would run 4500 rpms at 80. WAY too much gear so i swapped back for my old peg leg 2.73:(
 
The speed limiter in 4R70W cars is 107mph. With 3.73 gears that speed limiter will be around 85 mph. A chip should fix that.

Also.. what gears did the car start with? 3.27's or 3.08s?
 
the car had 3.27' s in it.i read somewhere that the computer with the speed limiter could cut power at a certain mph but since i installed a lower gear i'm sure i lowered that number as well.it pulls too strong in first and second just to fall on its face in third.i plan on getting a sct chip shortly but just looking for answers
 
I think what your feeling has more to do with when the converter is locking up than anything else. I'm sure it can be corrected with a custom chip.

David
 
SanDiegoLXBird said:
The speed limiter in 4R70W cars is 107mph. With 3.73 gears that speed limiter will be around 85 mph. A chip should fix that.

Also.. what gears did the car start with? 3.27's or 3.08s?

There is no speed limiter in an SC the only thing that would keep him from going fast is the stock 5100 RPM fuel cut in his auto car. Also for comparison I have 4.10 gears in my car and have the fuel cutoff at 5800 but it will still run somewhere around 140 like it would when it had the stock 3.31 gears. Like David N said get a chip and have shift points and convertor lockup optimized and everything should be fine.

Charles
 
I thought all auto cars had a speed limiter for two reasons: TC ballooning and the 54" (or so) drive shaft on the 4R cars, which likes to vibrate like a SOB during high RPM driving. I know my 5speed SC is not speed limited, but I'm pretty positive the auto cars are. All of them.

With the steeper gears you'll need a different TC lock-up schedule, to remove the speed limiter and alter the shift points. I'm surprised you're not bouncing off the rev limiter. Or is that piss poor 94/95 4R J-modded already?

All of the above is from my experience with 4.6 birds, so take it how you will.
 
SanDiegoLXBird said:
I thought all auto cars had a speed limiter for two reasons: TC ballooning and the 54" (or so) drive shaft on the 4R cars, which likes to vibrate like a SOB during high RPM driving. I know my 5speed SC is not speed limited, but I'm pretty positive the auto cars are. All of them.

With the steeper gears you'll need a different TC lock-up schedule, to remove the speed limiter and alter the shift points. I'm surprised you're not bouncing off the rev limiter. Or is that piss poor 94/95 4R J-modded already?

All of the above is from my experience with 4.6 birds, so take it how you will.

No the 4R70W SC's are not speed limted except by the RPM limiter of the engine, so a stock car with 3.31's will run whatever MPH 5100 RPM is in overdrive. My car actually worked just fine after installing the 4.10 gears, the reason for changing shift points and TC lockup is mostly to help make the setup more effecient, convertor locks basicly as soon as the car goes into second gear so no more power lost to slip and shifts at 5600 to be able to use all the power I have based on dyno pulls.

Charles
 
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