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Discussion Starter #21
Great! Now tell me the difference in the acceleration from a stop! I’m debating 3.55 gears also.

Allen
I can tell from normal driving the acceleration feels stronger, although I haven't really gotten on it because i've only put about 200 miles on the gears. It's recommended to take it easy the first 500 miles or so.
 

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Discussion Starter #22
I'm with you in this one. I just made that same gearing change, and it is fantastic - great acceleration, nice shift points plus ability to use 4th gear around town. But I'm confused - if you're able to cruise the expressway at 70 MPH @ 22-2300 RPM (mine is the same), then why are you concerned about 2700-2800 RPM for your 302? That would have you going 100 MPH - most municipalities frown on that!
Nah 2700 rpms put me around 85 mph on freeway with my tire size (25 inches)
 

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Discussion Starter #23
Thanks everyone for your replies to my post and your good advice over the past 9 years while restoring and making mods to my wife' mustang from High School. I told my son who's in college and muscled the new 3rd member in place, the next upgrades will be on him when I pass it down in about 15 years :cool:.

Now I need to take photos of all the extra parts including the 3.00 fairly new (less than 2000 babied miles) ring and pinion gear set to sell,

Thanks again
jcs
 

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For those that went with the 3.55 - did you keep the rear end or jump up to 9"?
I upgraded to 3.80 gears in my 8” and put an Eaton Truetrac in. Kept the same axles as before. Much faster and the cruising rpms are good due to the .63 overdrive in the T5. I’m in 4th around town and shift to 5th for anything 55mph and above. There are some big hills on the local highway and my car does fine pulling them in 5th with only part throttle. I don’t think you can go wrong with anything in the 3.55-3.80 range... if you are lower hp (like me) I think the 3.80 are the way to go. I still can’t break my tires loose unless I’m very generous with the rpms on launch. I’d recommend using this calculator to determine your cruise rpms given your proposed setup:

Thanks,
Rob
 

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1968 Mustang Fastback, 289, T5-5 speed
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Yep I purchased the Summit brand and it's great
Were you able to install the shifter with the tranny in the car? I already have the T5 installed. I'm hoping I can undo the crossmember and lower/tilt it enough to pull the shifter out and swap it. I hate to pull the entire tranny out. Took me hours to wrestle it in.
 

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For those that went with the 3.55 - did you keep the rear end or jump up to 9"?
I kept my 8" when I upgraded from the stock 2.80 open to a 3.55 Eaton Truetrac. Stock C code engine was warmed up a "tad" during the rebuild and all the other upgrade work we did. And the acceleration is fantastic behind my C/R toploader.

John
 
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Discussion Starter #28
Were you able to install the shifter with the tranny in the car? I already have the T5 installed. I'm hoping I can undo the crossmember and lower/tilt it enough to pull the shifter out and swap it. I hate to pull the entire tranny out. Took me hours to wrestle it in.
I had my T-5 for about 6 months before I located the original 67/68 clutch pedal bracket, so I purchased everything before the installation. I did have to trim about a 1/4 inch of both sides of the floor shifter hole so the shifter would fit, I followed the recommendation and installed the shifter to the tranny before putting it in the car.
 

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Makes quite a difference doesn't it?

I swapped my 3.50 gears for 3.89s behind my T5z and the car really responded. My engine loves to rev so it made a nice difference. My RPMs are similar to yours at 70.

My son has a 2013 Mustang V6 with 305 HP. He wanted to add an exhaust system and cold air intake and told him don't bother, change your rear gears from 2.79 to 3.73 and it will make a big diff. He has a 6 speed automatic
 

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Nice! I also have recent upgraded from a 2.79 open to a 4.00 Traction Lock 9" and I am loving it. Car really feels strong in its power band.


Only thing I had to do since doing this, was add some resonators to my Magnaflow system. The resonance at 2200 was getting pretty bad. These are the resonators I put in and the ground clearance is amazing!

I like those resonators.
But you should really have those sub frame connectors welded in
 

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you'll enjoy the new gears. i put a yukon trac loc in my 8" along with 3.80's. with my 235-60-14's and a t5z (.63 od) i turn 2100 at 70
 

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Cut the bottom off a T5 shift handle and a stock Mustang 4 speed shifter. Weld the T5 bottom to the 4 speed shift handle. Looks and works great. Just don’t forget where reverse is! Almost like theft preventive.
 
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