T5 swap do i need to switch rear end gears

Hunterb302

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Mar 6, 2022
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Hi I have a 91 mustang 5.0 with the AOD transmission in it thats having issues. I am really interested in t5 swapping it and I have found most the information on how to do it and what I need. But I was wondering if I would have to change the rear end gears and what I should change them to. I have a 8.8 rear end in my car with 2.73:1 gears and I'm just not sure if or what to change them to. Does anyone have any recommendations?
 
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Mustang5L5

Put lubricant all over the balls
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Both AODs and 5-AODs came with 2.73s standard. So the gears will work with either and no need to change.

However, you might want to change for some added acceleration. For a 5-spd I would recommend 3.27/3.31, 3.55 or 3.73. I would do the 3.27/3.31 if this is a DD and you do a lot of highway driving. A 3.73 if it’s a fun car with not a lot of highway. And 3.55 for best all-around gear.

With the AOD you might want 3.55, 3.73 or 4.10.

Since you are swapping to stick, I’d probably try and decide between one of those ratios and think about what works best for you. You’ll get tons of opinions on this.
 
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Hunterb302

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Mar 6, 2022
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Both AODs and 5-AODs came with 2.73s standard. So the gears will work with either and no need to change.

However, you might want to change for some added acceleration. For a 5-spd I would recommend 3.27/3.31, 3.55 or 3.73. I would do the 3.27/3.31 if this is a DD and you do a lot of highway driving. A 3.73 if it’s a fun car with not a lot of highway. And 3.55 for best all-around gear.

With the AOD you might want 3.55, 3.73 or 4.10.

Since you are swapping to stick, I’d probably try and decide between one of those ratios and think about what works best for you. You’ll get tons of opinions on this.
Ok thank you im kind of new to this stuff and I didn't know
 

Gs1987GT

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Sep 25, 2019
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Both AODs and 5-AODs came with 2.73s standard. So the gears will work with either and no need to change.

However, you might want to change for some added acceleration. For a 5-spd I would recommend 3.27/3.31, 3.55 or 3.73. I would do the 3.27/3.31 if this is a DD and you do a lot of highway driving. A 3.73 if it’s a fun car with not a lot of highway. And 3.55 for best all-around gear.

With the AOD you might want 3.55, 3.73 or 4.10.

Since you are swapping to stick, I’d probably try and decide between one of those ratios and think about what works best for you. You’ll get tons of opinions on this.
This 100%. On the foxbodies I had in my 20s, i always installed 3.73s and they are a good gear. However 1st gear is very short with the 73s so this time I went with a 3.55 gear and I'm very happy.

It's a great all around gear for the t5, 1st gear still pretty short, but not as bad as the 73s. But as said there are many different opinions on that, none wrong, it's all personal preference.

Dont forget to change the speedo gear to correct the speedo depending on what gear you select.

I would change the 2.73s. I always hated them, total highway gear. 3.55s really wakes the car up on the bottom end, makes it much more fun to drive....to me anyway. Good luck.
 
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Willybill32

But at least it's tight!
Jul 16, 2019
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There's plenty of good advice here. I swapped my '86 from 2.73s to 3.55s and it does wake it up. However, if I were to do it again, I think I'd try 3.27 gears, just my personal experience.

Bill
 
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Rdub6

So while I wait to figure out my rear end issues
Dec 29, 2017
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I went from 2:73 to 3:73 with a 5 speed. I got the brand new gears with the car when I bought it, or I would have gone 3:55.
It is very fun to drive with the 73’s, but I think the 55’s would have been the better “all around” choice. But, like others have said, it’s all personal preference.
 

Noobz347

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I went the other way.

I added tons of torque to the equation and am pretty happy with my 2:73s. I still have a hard time getting traction in 1st and 2nd and am mindful of the weaknesses of 3rd in a T5.

In reality, I probably should have stickier tires and a more robust manual transmission.

I'll reevaluate when I get out of mothballs for good. I'm not going to a steeper gear unless/until I can find a way to make better use of the first two gears.
 
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Willybill32

But at least it's tight!
Jul 16, 2019
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I went the other way.

I added tons of torque to the equation and am pretty happy with my 2:73s. I still have a hard time getting traction in 1st and 2nd and am mindful of the weaknesses of 3rd in a T5.

In reality, I probably should have stickier tires and a more robust manual transmission.

I'll reevaluate when I get out of mothballs for good. I'm not going to a steeper gear unless/until I can find a way to make better use of the first two gears.
@Noobz347, I have a nice, moderately used set of 2.73s if you need a spare set!

Bill
 
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chrlsful

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dont forget the online gear cacuators. Once you do your research ("I;m kinda new to this") you may B come more familiar w/it all. Dont send, thry the caculators (tire sz, rear gear, tranny) to get more info w/o buying. HTH
 
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