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Discussion Starter · #1 ·
I have a stock 88GT with stock engine, stock 5 spd, and stock rear. I think it has 2.73s, I checked the badge on door. What would be a better rear gear? I will be putting a GT-40 intake( upper and lower), AFR or Edelbrock heads and LTs in the future. I would like to have the new gear installed before I upgrade to rear discs.
 

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i enjoy the 3.73's... some people might tell you higher depending on what you plan on doing (track/street)
but i daily drive my car atleast 100 miles a day and they work well
 

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3.73s are a nice all around gear and will really wake the car up. If you do alot of driving, you may want to consider 3.55s if mileage is an issue for you. Then again, if its just a weekend toy, you may consider 4.10s
 

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do some searching on this, as it has been beat to death already. I just put 3.73's on my gt vert, however, it is NOT a daily driver any longer.

If you do mostly street driving, you'll love the hell out of the gears, however, It kinda sucks on the freeway.

You know how the optimum cruising rpms seem to be 2000?? that is where the car feels most comfortable, well, now with 3.73's and a t5, 2000 rpms comes up around 65-70 tops. Can you go faster?? SUre, it just doesn't feel comfortable to cruise it faster than 65 or so, which leaves all kinds of people passing you up. Like I said, I don't really care, as it is not a daily driver, but if 9/10ths of your driving is freeway, you may want to consider 3.55's


there will be alot of people who say, **** it, get the 4/10's, I do, and drive it every day. It is just a comfort level thing, as I like to just "cruise" on the freeway, and not have the engine sounding like a nascar ride at 60 mph.
 

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Besides wanting to keep revs as low as possible during cruise, the other thing is with a lower ratio it is much easier to crawl along in crowded traffic. I don't know about you but I hate slipping the clutch when the engine is already turning at idle in 1st trying to stay with the flow of 4mph traffic.

How about this... Take gears 1-3 out of an old 2.3 turbo transmission and put them in your 5.0 transmission, keeping the rearend at 2.73 or 3.08. Here's the ratios:

1st, 2nd, 3rd, 4th, 5th - Rev
85-86 2.3 turbo: 4.03, 2.37, 1.49, direct, 0.81 - 3.76
85-89 5.0: 3.35, 1.93, 1.29, direct, 0.68 - 3.15

Purchase parts necessary to replace gears 1-3 with lower ratios and you get
4.03, 2.37, 1.49, direct, 0.68 - 3.15

The stock overall reduction with 3.73 gears
10.9545, 6.3111, 4.8117, 3.73, 2.5364 - 11.7495

After tranny modification, with 2.73 gears
11.0019, 6.4701, 4.0677, 2.73, 1.8564 - 8.5995

Is this possible at all?? If you could do this, it would be the best of both worlds because you have low creeping speeds and high acceleration through gears 1-3, then slip it into overdrive and the revs drop dramatically for cruise. Whereas with the 3.73 rearend, you not only drop the lower ratios, but your overdrive suffers as well. Comparison with stock tires:

modded tranny: 1st at 700 RPM = 4.25 MPH, overdrive at 2000 RPM = 82.3 MPH

3.73 gears: 1st at 700 RPM = 4.27 MPH, overdrive at 2000 RPM = 60.2 MPH
 

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Discussion Starter · #6 ·
is it diffucult to install the gears yourself?
 

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Taking a manual transmission apart is more difficult than swapping a rearend, but it's pretty straightforward. The hard part is making sure all the parts are as you found them and getting the shifter assembly on correctly (shift lever and shift rods exactly in neutral). It would take a few days to remove, disassemble, reassemble, and reinstall transmission.

The real question is whether it would work... I have not been inside a T5 and I'm not positive on the construction. From what I understand on the corral, gears 1-3 have a one-peice countershaft with all the gears milled out of one peice of steel, and therefore you cannot change the ratio of any one of these three. However, it should be possible to install the gearing for 1-3 out of a lower ratio transmission and retain the other ratios, because 4th is a direct coupling of input and output shafts in all T5 transmissions and overdrive has a separate gear assembly from the low gears, as well as reverse. Hopefully nitrostangracing can comment on the feasibility of this idea.

A computer program I have calculates mileage for the 85-89 T5 with 3.73 rear gears as 10.8 city, 17 highway, and mileage for the 85-89 T5 with 85-86 2.3 turbo low gearing and 2.73 rear gears as 12.3 city, 21.8 highway. (stock motor)
 

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Discussion Starter · #10 ·
anyone know a good reputable place in the Northeast that would be able to change the rear end gears?
 

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the88gt if you havent bought your gears yet i am running a special on 3.55 3.73 and 4.10s for 129.95 plus shipping if you are interested let me know
 

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I like ray's idea of changing the tranny ratio's instead of the rear end, but it's not for a newbie to try to do. Now if he were to haveit done at a shop that would be cool, but then in the futrure he would really have to be careful about changing rear end gears because of his new tranny gear ratio's. but it is fesable and good idea for someone who wants the best of both worlds.
 

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I just switched the gears in my car from 2.73s to 3.73s and cruising on the highway I saw zero loss in milage. The rpms went from cruising at 2000 (83mph)to 2400 (73mph), but the milage stayed the same. I'm not exactly sure how, but at the same time I'm definitely not complaining. I was expecting to loose at least 2-3 mpg.
 

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Dont fear the gear folks. My friend drives his stang everyday , street, highway, snow, rain all of it. He has 4.88's, gets 20mpg in the city, runs high 12's on slicks with stock motor. My last stang had 3.73's i drove it daily it was great. I now have another 5.0 with stock gears and upgrading to 4.10's and expect to run low 13's with stock motor.
 

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i have the z-spec which has a .59 final gear, i have been told that i can put 4.10s without too huge a loss on MPG and highway rpms'. right now i get 2000rpm 75 +/- . the only problem now is my 5th geat seems like its bogging down if i'm not on the highway and going 2500 plus. so a bigger gear like 3.73 is needed,i have 3.08's now.
 

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I just got 3:73s last year and I like them a lot. I really didn't notice a drop in highway gas mileage at all. The only lousy thing is if you drive above 65 mph for extended periods of time, the engine noise can get annoying. At 70 mph I am at about 2500 RPMs which is pretty loud with my Flowmasters and convertible top. However, my stang is not my daily driver and I usually just cruise around town in it. It just depends on your driving habits and what you are willing to deal with for the extra power. My uncle has a '88 LX vert and he got 3:55s before I got my gears. I drove his car and it made up my mind right then (definetely 3:73s).
 

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Its a mustang, meant to go fast and sound bad ass. I could never complain about noise from any 5.0 stang. Turn the radio on! :joy:
 
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