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What final (rear end) gear ratio should I go with?

  • Thread starter Thread starter jusinbailey
  • Start date Start date Dec 19, 2003
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RGS0907

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Aug 21, 2003
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Dec 22, 2003
#21
  • Dec 22, 2003
  • #21
67GTA-FB429 said:
I wish I could run 2600rpm at 70 mph...with my 429 and 3.50s I run 3500 at 70. But then again I have a quater mile C6 with only 3speeds.
Click to expand...

That's way to high for 3.50s. You shouldn't be more than about 2600-2800. Even my old 4.11's didn't rev that high. I used to have the formulas to calculate this out, I'll have to look it up at home tonight.
 

Edbert

Founding Member
Jul 13, 2002
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Austin TX
Dec 22, 2003
#22
  • Dec 22, 2003
  • #22
RGS0907 said:
That's way to high for 3.50s. You shouldn't be more than about 2600-2800. Even my old 4.11's didn't rev that high. I used to have the formulas to calculate this out, I'll have to look it up at home tonight.
Click to expand...
RPM chart for AOD

Edit: This chart is for AOD only, it shows 3rd (1:1) and 4th gear RPMs. If you have a C4 C6 you should just use the 3rd gear portion. If you have a T5 or Tremec the 3rd gear portion is for your 4th gear.
 
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68DARKHORSE

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Oct 9, 2003
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Dec 22, 2003
#23
  • Dec 22, 2003
  • #23
You should be using a T5 with 2.95 1st gear.
The 3.35 is weak.
 
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68DARKHORSE

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Oct 9, 2003
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Dec 22, 2003
#24
  • Dec 22, 2003
  • #24
The 2.95 trannys are also more of a close ratio setup.

You can get a trashed T5 for $50, then build it with Z spec parts. You can also increase the OD to .59.
 
K

Kman

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Dec 23, 2003
#25
  • Dec 23, 2003
  • #25
Agree with 68DARKHORSE. The old 3.35 T-5's were marginal in a relativley stock 5.0 mustang making 225 hp at the flywheel, when driven hard. Ford repaired and replaced a lot of these trannys (infamous for third gear problems) over the years. They will last a long time when driven "normally" but with 400hp on tap, some traction and a few powershifts, a long lifespan should not be expected.
 
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