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Discussion Starter #1
OK guys, what do you think that the best rear gear ratio will be for the up coming '03 Cobra? Some of you guys that know a math formula to figure this out please give us some input. I am thinking that either 3.90's or 4.10's will be just about right to be able to finish the 1/4 mile still in 4th gear, what do you guys think?
 

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Discussion Starter #3
Pull_T said:
Using 275/40/17 tires, 6500 redline and 1.00:1 4th gear, the 4.10s are good for 121 mph according to the corral tech calculator: http://www.corral.net/tech/

3.90s - 127 mph
4.30s - 115 mph
I've got 275/40/17's on some Cobra R's on my car and with the 4.10 gears that I have my car runs 122mph @ 6800rpm in 4th gear (dyno certified). Doesn't the T-45 have a 1.00:1 4th gear also? :confused: If that is the case how can an '03 run 121 mph at 6500rpm? :confused: Or does the 300rpm difference = just 1mph?
 

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Get 4.56 gears and run 28 inch tall slicks. If you are gonna do it, do it right!! :evil:
 

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TriBlkCobra said:

[except...] remember you have a T-56 know instead of a T-45 or 3650...
All the more reason for a 4.56 rear gear. T-56s have a TALL first gear ratio, so you need more gear in the back to get you moving.
 

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Pat, I agree completely with your observation...

[edit] and I would also encourage you to look at the 3rd and 4th gear ratios. Does the T-56 even have a 1:1 ratio?
 

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Pull_T said:



http://www.corral.net/articles/2003Cobra/Page_03

At least you can't flame me if this site is wrong since you're surfing it. :lol:
Pull_T I wasnt flaming anybody... I've been burnt enough today on gear posts. And I really didnt no that the T-56 had a 1:1 4th, I thought it was 0.91:1 or something like that in the Fbod's. Which would allow even more gear.

But now that I've been sucked in, I do agree with Pat's observation about the 2.66:1 first gear. I think this had a lot to do with why most guys still go with a TKO or 3550 over the T-56 on cars that see a lot of strip use.
 

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ALLNTRL said:
I've got 275/40/17's on some Cobra R's on my car and with the 4.10 gears that I have my car runs 122mph @ 6800rpm in 4th gear (dyno certified). Doesn't the T-45 have a 1.00:1 4th gear also? :confused: If that is the case how can an '03 run 121 mph at 6500rpm? :confused: Or does the 300rpm difference = just 1mph?
I just input the numbers...you could just take your numbers of 122 mph @6800 and scale that back to 6500 (122*6500/6800) and get 116.6 mph. I have no idea which is more reliable, the calculator or your dyno data??? :confused:
 

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i was going to go w/ 4.10s for mine but i think i'll hold off for a month or two. w/ the TQ curve of this thing i think it might not do bad w/ the stock 3.55s giving the mods that i will do in the first month... its not the torqueless wonder of the 96-01 cobras, keep that in mind..
 

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Discussion Starter #12
S/C yelo kobra vert said:
i was going to go w/ 4.10s for mine but i think i'll hold off for a month or two. w/ the TQ curve of this thing i think it might not do bad w/ the stock 3.55s giving the mods that i will do in the first month... its not the torqueless wonder of the 96-01 cobras, keep that in mind..
That is what I was thinking as far as the TQ that this thing is going to make. From what I have seen the Lightnings seem to perform best with the 3.73's, so I am still thinking that some 3.90's will be just about right after a few mods are added. Plus, the Cobra is still going to be 1000lbs. lighter than a Lightning.
 

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For what its worth, I've got the June 2002 Automobile magazine in front of me, and it has the '03 Cobra in it. It says how many MPH each gear is capable of. I'll first tell you that they got it to 13.4 @ 109 MPH, but thats besides the point.......

Per Automobile magazine....

SPEED IN GEARS

1st.........51 MPH
2nd........76 MPH
3rd.........104 MPH
4th.........135 MPH
5th.........155 MPH
6th.........155 MPH

6th gear, at least, is electronically limited to 155 MPH, and I believe 5th gear probably is, as well.

Man, 51 MPH in 1st gear in a 5-speed car!! The '03 Cobra, to me, screams "DON'T FEAR THE GEAR!!!"..... just like all the other mod Cobras do. :D

Hope this helps. I'm sure it does. :D
 

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I would put 4.88's in mine with a T-56
 

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Let's not forget the '03 is a high torque at low RPM car versus the '96 - '01 low torque even at high RPMs cars. We're also losing 500 RPM at the top (6500 fuel shut-off versus 7000). Putting in steep gears may have the car above the torque peak too quickly and too often. Consequently, gears may not do for the '03 what they do for the earlier cars. And let's not forget the traction issues either. I believe these are probably the same reasons why you very rarely here of an LS1/6 car with anything steeper than a 3.73. The LS1/6s also make abundant low RPM torque. It seems that the key is to gear the car to take advantage of the engine's strength. In the '96-'01s, this means steep gears to get the engine into the higher RPMs (where it makes more power) as quickly as possible. In the '03 it may make better sense to operate in lower RPMs more often and longer.

Remember, all this is just theory until the cars are out, people swap gears, and we see what happens. However, I still remember about three or four years ago, when one of Saleen's supercharged cars (can't remember which one though) ran quicker with the standard 3.08 gear than with the optional 3.55! So who knows, maybe the '03 will be the same :confused:
 

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This thing makes as much hp at 3k rpm as a GT does at 6k rpm. You'd be nuts to put a much steeper gear than it has. Ford actually might have overdone it with the 3.55 gears. For a street car, anyway.
 

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Bull****. It needs gear. Its DOHC and still a 4.6..

It has a T-56 in it.

3.55 through a T56 is not different then having 3.27's.

Please dont sit there and say this car doesnt need gear.

How many lightening owners have GEARS? How many 2V GT's with Roots blowers have gear? This car NEEDS gear period.

4.88's would be fine in this car.
 

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I wouldn't over do the gear thing... unless you are going to a taller tire on the track, or you WILL run out of gear...

This thing has a bit more horsepower than the older Cobras, and if it's redline is 6500, then that kills it a bit more.

I haven't seen any dyno charts or the like, the reason we need such big gears is our lack of lowend grunt, that blower will fix that...
 

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I knew I was holding on to those 3.27's for a reason, now if I can remember where in the garage they are.
 
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