Switch rear gears?

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Daryl

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Yea that’s the tag
Thx, was blurry when I expanded the photo so wanted to be sure. I appreciate that and thx for taking the time to take the pic and post! Helps a lot and I’ll definitely double-check in case somehow I missed it the first time.
 

Musturd

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no problem otherwise you can always go for a drive and see how fast you’re going at 2000rpm and see what it matches on the gear charts I posted . I’m betting you have one of the close ratio trans .
 
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Daryl

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TCET18086 Ford 10 spline Tremec TKX 5 speed
3.27 1.98 1.34 1.00.72 ratios

.72 is my 5th gear ratio, according to what the shop that installed it has told me. The above is a cut-and-paste from their response to my text.
 
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Daryl

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Here’s what the Tremec calculator calculated for 3.55, 3.08 gears and 2.73’s (just to see)
 

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Daryl

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IMG_1923.png
Cut & paste from Tremec website
 

Musturd

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3.08’s should be a happy medium for ya the 2.73’s will be to lazy
 

96blak54

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I agree with you guys with 2.73. Unless you are turbo lag stricken or want 80mph fuel saver, dont do the 2.73
 

302hobronco

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I like this chart I found somewhere.
 

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Daryl

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Unfortunately that’s true, but it’s a pretty cool resource. Thanks for posting anyway! Cheers
 

Mr horsepower

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Daryl
The shop that installed it def should have discussed the different trans model / gearset options with you. The 17765 would have been a better option for you even thought it required the change to 26 spline clutch disk, but it is a stronger input.
 

Musturd

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Daryl
The shop that installed it def should have discussed the different trans model / gearset options with you. The 17765 would have been a better option for you even thought it required the change to 26 spline clutch disk, but it is a stronger input.

Yea the 17765 he would have been happy running 3.55’s
 
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Daryl

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Finally able to get out and Ron 2000rpm in all 5 gears:

1st: 12mph
2nd: 20mph
3rd: 30mph
4th: 42mph
5th: 57mph

Keep in mind that I’m collecting this data using the stock tach and a GPS app for speed. So I’m holding the rpm’s best I can for long enough so the GPS app gives me a constant speed. There’s probably a 1-2mph standard deviation and/or 100rpm+\- derivation.

Here’s the numbers compared to the Tremec gear calculator:
IMG_1926.png
 
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Daryl

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So, I must be geared EVEN LOWER than I would have expected (or hoped for!) because my speeds per gear are lower than the Tremec calculators calculate. Errrrrgh! :-(
 
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Daryl

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Here’s a screenshot of the TKX with a .81 5th gear. It’s A LOT closer to the numbers I just came up with on my drive.

IMG_1928.png
 

Mr horsepower

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Knowing what model your transmission is, your tire diameter maps out to 24.5" - see 1st graph below. Can you post what the actual tire size is from the sidewall info to confirm? Based on the adjusted tire size, I posted 3.08 and 2.73 rear speeds in gears in 2nd and 3rd graph.

You would have been better off with the TKX with the .68 overdrive or much better off with a T56 with 2 overdrives.

Changing only the rear gear, it pains me to say that your best setup for cruising would be with a 2.73 axle ratio.

Unfortunately Tremec changed the highest available overdrive ratio from .64 to the .68 when they changed from the TKO-600 to TKX, even though EVERYTHING ELSE about the TKX is MUCH better.

Current speeds in gears:
1703965256567.png

Speeds in gears with 3.08
1703965488984.png


Speeds in gears with 2.73
1703965777016.png
 
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Daryl

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Only my tire diameter is not 24.5”. The rears are 285/40x17 = 25.97….” Which I took the liberty of rounding up to 26” (25.976377952755904)!
And the fronts are 275/40x17 = 25.66…”

See attached:
 

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