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03 cobra

  • Thread starter Thread starter mustangmas
  • Start date Start date Jul 12, 2007
M

mustangmas

New Member
Jul 12, 2007
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Jul 12, 2007
#1
  • Jul 12, 2007
  • #1
Just purchased a 03 cobra, used to have a 94 gt, i was just wondering if there is any diffrence in changing rear gears between the two? i had put 4.10 in the 94 and it was fairly easy, plan on putting 3.73 in the cobra.
 
U

Uncle Meat

Banned
Jun 13, 2002
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Prattville, Alabama
Jul 13, 2007
#2
  • Jul 13, 2007
  • #2
The '03 does not need gears. The stock 3.55's are fine. Even mildly modded Terminators can blow the back tires off in 2nd with ease with the 3.55's. You would barely notice a difference by moving to a set of 3.73's.

U.M.
 

RB88

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May 31, 2004
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Mobile, Al
Jul 13, 2007
#3
  • Jul 13, 2007
  • #3
I think he want's to know(from an installation point of view) the differences between the two year models.
 

ShortThrow50

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Oct 22, 2006
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Pa
Jul 13, 2007
#4
  • Jul 13, 2007
  • #4
Uncle Meat said:
The '03 does not need gears. The stock 3.55's are fine. Even mildly modded Terminators can blow the back tires off in 2nd with ease with the 3.55's. You would barely notice a difference by moving to a set of 3.73's.

U.M.
Click to expand...

I guess thats an opinion. I always thought the stock gears sucked major ass in my 03 cobra.
 
U

Uncle Meat

Banned
Jun 13, 2002
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Prattville, Alabama
Jul 14, 2007
#5
  • Jul 14, 2007
  • #5
ShortThrow50 said:
I guess thats an opinion. I always thought the stock gears sucked major ass in my 03 cobra.
Click to expand...
In what way?

U.M.
 
K

Kilgore Trout

Fried or Broiled ?
10 Year Member
Mar 30, 2005
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Jul 14, 2007
#6
  • Jul 14, 2007
  • #6
To answer your larger question no the Cobra is not going to be similar to the GT when it comes to modding. For example while a GT guy would be considering installing gears a Cobra guy is more likely to consider billetflow diff brace, aluminum diff bushings, and maybe even a diff cooler when considering mods for the diff. The 3.55 is fine for a Terminator. Do some reasearch and be sure and read Cobra Bob's FAQ.
 
M

mustangmas

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Jul 12, 2007
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Jul 15, 2007
#7
  • Jul 15, 2007
  • #7
RB88 is correct, is there any diffrence in the installation between the two? And thanks all for the helpful info.
 

BennyBlown2v

New Member
Dec 9, 2004
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Carmel, INdiana
Jul 15, 2007
#8
  • Jul 15, 2007
  • #8
Some people like more gear...let them be.


The install is the same as far as diff setup goes, you must pay careful attention to pinion preload and backlash though as there is a tendency for the gears to get extremely hot if improperly set due to the lesser amount of fluid, smaller surface area, and material construction (aluminum vs steel) of the differential housing (as Kilgore alluded to with the idea of buying a differential cooler).
 
U

Uncle Meat

Banned
Jun 13, 2002
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Prattville, Alabama
Jul 16, 2007
#9
  • Jul 16, 2007
  • #9
BennyBlown2v said:
Some people like more gear...let them be.
Click to expand...
...and some people don't understand why the 03/04 Cobra's do not require lower gears. Let us educate.

U.M.
 
M

mustangmas

New Member
Jul 12, 2007
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Jul 16, 2007
#10
  • Jul 16, 2007
  • #10
Thanks all for the great advise, I'll probably stick with the 3.55 for a little long, even though the 3.73 arrived today. always good to have a back up!
 

SVT98Snake

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Apr 15, 2005
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Jul 17, 2007
#11
  • Jul 17, 2007
  • #11
Uncle Meat said:
In what way?

U.M.
Click to expand...

lower gears get bad gas mileage??? I guess that sucks if you like filling up every day
 
M

mustangmas

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Jul 12, 2007
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Jul 17, 2007
#12
  • Jul 17, 2007
  • #12
I really don't mind filling up a little more, that the price you pay for performance, if that were the case i'd be driving a geo, but really, i just finish the in stall, was a little bit more difficult than expected, alot more suspention than i was used to but the instalation went fine, i can tell a real difference in the take off, i go through the gears alot quicker, but thats the name of the game, i now would recommend the change.
 
U

Uncle Meat

Banned
Jun 13, 2002
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1
0
Prattville, Alabama
Jul 18, 2007
#13
  • Jul 18, 2007
  • #13
mustangmas said:
I really don't mind filling up a little more, that the price you pay for performance, if that were the case i'd be driving a geo, but really, i just finish the in stall, was a little bit more difficult than expected, alot more suspention than i was used to but the instalation went fine, i can tell a real difference in the take off, i go through the gears alot quicker, but thats the name of the game, i now would recommend the change.
Click to expand...
No offense man, but I find it hard to believe you can "feel" the difference between 3.55's and 3.73's due to them being so close.

With the stock tires on the car (25.6" diameter) and running the stock T56 trans with a 3.55 rear end an '03 Cobra's speed based on engine RPM's looks like this:

1st gear
RPM - MPH

1000 - 8
2000 - 16
3000 - 24
4000 - 32
5000 - 40
6000 - 48

2nd gear
RPM - MPH

1000 - 12
2000 - 24
3000 - 36
4000 - 48
5000 - 60
6000 - 72

3rd gear
RPM - MPH

1000 - 17
2000 - 33
3000 - 50
4000 - 66
5000 - 83
6000 - 99

Now lets run those numbers, but we'll substitute 3.73's for the stock 3.55's:

1st gear
RPM - MPH

1000 - 8
2000 - 15
3000 - 23
4000 - 31
5000 - 38
6000 - 46

2nd gear
RPM - MPH

1000 - 11
2000 - 23
3000 - 34
4000 - 46
5000 - 57
6000 - 69

3rd gear
RPM - MPH

1000 - 16
2000 - 31
3000 - 47
4000 - 63
5000 - 79
6000 - 94

You can see there is very little difference in the speeds achieved for each gear when comparing the two. If you really just HAD to have gears you should have opted for a minimum of 3.90's because the miniscule difference between stock and 3.73's is a waste of time and money IMHO.

U.M.
 

BennyBlown2v

New Member
Dec 9, 2004
1,233
1
0
Carmel, INdiana
Jul 18, 2007
#14
  • Jul 18, 2007
  • #14
Uncle Meat said:
If you really just HAD to have gears you should have opted for a minimum of 3.90's because the miniscule difference between stock and 3.73's is a waste of time and money IMHO.

U.M.
Click to expand...

Gotta agree with you there, as far as 3.90's being a better choice...

Back to tech, as far as backlash goes you should run EXACTLY .010, any less and there is too much slack, any little and you'll be dealing with one wheel peal, overheated gear sets (warped gears), and quicker fouling of the rear end fluid.
 
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