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Discussion Starter #1
Granted, I have zero experience messing with rear diffs/gearing.

I spoke to someone about swapping in higher gears, 3.73 or higher, and he said to watch out, I'll have more punch off the line, but I'll lose pull on highway speeds, let's say going from 60-90 would be slower. That didn't sound right to me, since I thought the only real difference is the powerband (rpm in reference to mph) is shifted and gas mileage b/c of this.

Any info would be helpful as to whether or not this is true.
 

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He's an idiot. Lower gears will improve pull in EVERY gear and at EVERY speed.
 

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That's BS. Your car will pull more strongly at all speeds.

He may have been referring to the loss of top speed. Your top speed will be reduced to about 85 MPH and you'll need to reprogram the computer to get your top speed back. A driveshaft upgrade is also a highly recommended with taller gears.
 

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Discussion Starter #4
He's an idiot. Lower gears will improve pull in EVERY gear and at EVERY speed.
sounds good. yeah, he was just some guy that I didn't even know and met at a car meet. didn't think it sounded right, but didn't have any personal experience to go with it.
 

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Discussion Starter #5
That's BS. Your car will pull more strongly at all speeds.

He may have been referring to the loss of top speed. Your top speed will be reduced to about 85 MPH and you'll need to reprogram the computer to get your top speed back. A driveshaft upgrade is also a highly recommened with taller gears.
will I be able to reprogram the top speed back with an xcal2? Will I be able to get the same top speed back?
 

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Yes, that's what the xcal2 is all about. You'll actually be able to go faster than the original top speed of about 106 MPH because the xcal can eliminate the top speed governor. But you must upgrade the driveshaft.
 

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....not sure the 3.8L can push the car much over 100 regardless of what the XCal2 does for ya though. :D
 

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....not sure the 3.8L can push the car much over 100 regardless of what the XCal2 does for ya though. :D
LOL... we'll see... we'll see :zdevil:
 

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well... i got my poor ol car up to 103mph. but that was in od, and it was about... 3500rpm - 4000rpm. i probably could of got it to 105-106, but that would of been redlining in od. I dont think i can give it more top speed than that.

How does reprogramming increase your top speed by the way, if my car red lines at 5000rpm, and the gear ratios are the same... i'm confused on how it does that.
 

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I just switched from 3.27s to 3.73s last month. I just broke it in by doing the whole Hot Rod Power Tour (2400 miles) and let me tell you that the highway speeds is where I feel the most improvement. Its like the car wants to keep pulling.

C.Hill
 

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well... i got my poor ol car up to 103mph. but that was in OD, and it was about... 3500rpm - 4000rpm. i probably could of got it to 105-106, but that would of been redlining in OD. I don't think i can give it more top speed than that.

How does reprogramming increase your top speed by the way, if my car red lines at 5000rpm, and the gear ratios are the same... I'm confused on how it does that.
There's a top end (speed) limiter built into the EEC program that keeps you from over reving the driveshaft by limiting how fast you can go. The Xcal2 either eliminates or resets the limiter to a higher point and allows your car to go faster. Like you said, the V6 can only go so high but on the V8's it makes a much bigger difference.

Here are some of my video's for comparison these videos are of my car with 3.73 gears installed. The first video is where I hit the rev limiter at 83 to 85 MPH.

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i138.photobucket.com/player.swf?file=http://vid138.photobucket.com/albums/q253/Rigmeister89/Speedlimiter.flv">

This video is with a program that gave me my top end back.

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i138.photobucket.com/player.swf?file=http://vid138.photobucket.com/albums/q253/Rigmeister89/508PM-MyRunagainstNina.flv">
 

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sweet, so it pretty much wont do anything for a v6.
 

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Without a program you'll be limited to 85 MPH. A program will get you back to 100 or so and 3.73 gears will get you there a lot faster.
 

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Discussion Starter #14
Without a program you'll be limited to 85 MPH. A program will get you back to 100 or so and 3.73 gears will get you there a lot faster.
hmmm, so what kind of top speed will I be able to get in the end, or is 100ish it?
 

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Yea, unless you do some other mod to the car. You'll have the same top end you had before. The reason the rev limiter is there is to keep you from spinning your driveshaft off of the car. So, in order to go faster you need to get a program and you need to upgrade your driveshaft. And you need tires rated for higher speed. Going fast is a complicated process. Neglect one part of the system and it will bite you.
 

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Discussion Starter #17
Have you read through the Gears section of the technical articles yet?

If not, Here's a link to them.

http://www.tccoa.com/articles/gears/index.html
thanks for the link, just read through everything. Still doesn't give me much hope on a higher top speed though... the only thing I can think is a larger overall tire/wheel diameter, but not sure how effective that would be plus I'm not a huge fan of super large wheels/tires.
 

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Just for the record, I had a 91 3.8 tbird with the speed sensor wire going to the computer cut, and was able to hit 127mph in it. That was with stock 3.08 gears, and I don't remember what the rpms were, but for people saying the 3.8 won't go over 100, you are very wrong. With 3.73s on a 3.8, and a tune, you would probably be able to go slightly faster than that since you would be at a higher rpm and making slightly more power than with the stock gears. You would definitely be able to hit 120+ though, even with a 3.8.
 

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Discussion Starter #19
Just for the record, I had a 91 3.8 tbird with the speed sensor wire going to the computer cut, and was able to hit 127mph in it. That was with stock 3.08 gears, and I don't remember what the rpms were, but for people saying the 3.8 won't go over 100, you are very wrong. With 3.73s on a 3.8, and a tune, you would probably be able to go slightly faster than that since you would be at a higher rpm and making slightly more power than with the stock gears. You would definitely be able to hit 120+ though, even with a 3.8.
yeah, i just confirmed over at SSM that the 3.8 will definitely go higher than the claimed 106, closer to 120 stock
 

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really, this is very interesting. I didnt think that the 3.8 could reach 120. i was out of rpms, although that could have something to do with my torque converter. Like i said, only had mine up to 165kmh. (digital tops out at 99)
 
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