66 t-5 gears and rear end??

[mcd]

I have a 66 conv that came factory with a 289 2v the rear end code is 2.80:1. What rear end is that? 8?? Also 5th gear on the t-5 is .68 so I was going to go with 4.11:1 in the rear anyone have any advice on this?

 

[67efivert]

when i had the t5 in my convert i ran a 3.80 a 3.40 and a 2.73 gear for awile the 3.40 im using now like it best all arount highway and town the 3.80 was great in town and a little to much for the highway in my opinion and the 2.73 was used in a bind for a long trip was great on the highway but sucked ass otherwise .
oh and yes ur rear should be an 8"

 

[gjz30075]

A friend of mine has a 4.11 with his T5 (.68 5th gear) and finds it tolerable. I think I'd stay in the upper 3's.

 

[LMan]

3.55s

 

[12sec67]

3.80's

 

[rbohm]

i say pick a gear in the 3.50-3.89 range, as this range will let you use first gear. the first gear ratio on most T5's is 3.35 and more than a 3.89 rear gear means that you are shifting almost after you launch the car.

 

[BobV]

Depends on which T5 you're using.

With the 3.35 1st gear, run a 3.00 3.25 or 3.50 rear gear.

With the 2.95 1st gear, run a 3.50 3.70 or 3.89 rear gear.

You usually want your overall 1st gear ratio between 10:1 and 12:1, depending on intended use.

 

[red65]

Agree with BobV - a 3.35 first gear with 3.55 rear gears are a sweet combination. That's what I'm running and find it a good combination of low end grunt and manners on the highway (2,700 or so RPM at 75mph)...

 

[steel1212]

I agree with bobv also. I have the 2.89 first geared t-5. I think its the t-5z or ford racing t-5. I had it rebuilt to those specs anyway and my overdrive is lik .63 instead of the .68 also. I have 4.11s out back and I think I run at about 2500 at 70 in overdrive. I also see track use as well though and the 4.11s keep my rpms high and the seat of my pants glued to my seat. I would say though if I dropped down to 3.89s I would notice it personally but my gas mileage would go up and my rpms down. I just have the 4.11s in there and haven't seen the reason for changing them yet.

 

[67coupestang]

i have the tremec with a 3.35 first gear and I love my 3.50s good first gear and still great manners @ 80mph. I'm running 225/50/16's