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Discussion Starter · #1 ·
I put a 4 cylinder T5 in my 1986 Mustang GT and it has all the light to light power in the world but I tried to take it on the highway for the first time and I was in 5th gear at 3500 rpms and I was barley going 55. What can I do to get longer gears to go on the highway but still keep my low end power, I have 4.10's in the rear end, can I change the gearing in the transmission?
 

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I put a 4 cylinder T5 in my 1986 Mustang GT and it has all the light to light power in the world but I tried to take it on the highway for the first time and I was in 5th gear at 3500 rpms and I was barley going 55. What can I do to get longer gears to go on the highway but still keep my low end power, I have 4.10's in the rear end, can I change the gearing in the transmission?
you're probably better off just putting longer gears in the rear end. You'll have to remove and completely dissassemble your trans to change it's gearing.
 

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people in the foxbody section might be able to help a little more.
 

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I'd check the spedo and tach. Run them thru any gear calculator and it shows a 17" dia tire required per the data you supplied.
Dave
 

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what size are your tires?? 3500 in 5th on the fwy at 55 isn't right...even with 4.10's. 3500 with that trans at 65-70 is more realistic...I suspect your speedo is way off and you're going faster than you think
 

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Discussion Starter · #7 ·
@v8only, my speedo doesn't work, but I know I was going at the most 55 because I was getting passed like I was sitting still, would 3.73 gears in the rear end help?
 

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you need to have a more scientific way of guessing your mileage before you make such a costly decision..fix your speedo, have someone with one that works drive next to you, or use the gps in your phone...

my car with 373's ran at 2000-2100 at about 65 mph or so...4.10's would be at most 200-300 rpm's higher than that.
 
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