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I am about to order gears for my 66. i am running a t5 with a .68 OD and 25" tall tires.
which will suit better?
I do about 50% highway driving but i do want to have a good launch off the line.
I have heard great things about both. I welcome all opinions.
My buddy has the 3.55s set up in his 85 qith the same t5 and loves it but he also says first gear is about useless. as soon as he lets out the clutch its time to shift.
what to do
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I'm running 3.55's with a TKO 600, and with the 2.89 1st, 1st is usable on the street, but you have to roll into the throttle. The T5's are like a 3.27 or 3.35 1st.
__________________
Who cares how much horsepower it has, all that matters is how fast it goes!
13.20's with 2.25-2.30 60's, 40+ year old suspension sucks!
Best trap 107.11mph, we'll see what the new intake/carb setup does.
12.80 at 110.5mph NHRA DA corrected
This winter I am going to put in a trac lok with 3.80 gears into the 8 inch.
It is a 289 with a T5.
Willing to give up a little bit of gas for better acceleration.
Good Luck and BE Safe
Ron
__________________ Ron http://chris66dad.tripod.com/
A code 66 coupe
289 4v, Roller Rockers, Electric fan
Performer & 650 Edelbrock
MSD ignition
Tri Y into 2.25 Shelby side exhaust
T5 conversion
Hydraulic clutch
CSRP Disks
I have the same exact issue for mine! I'm in between the same gear ratios as you and I have the same exact setup. The only thing I need to do is see if I want to fork over the $$ for posi or open rear. it's about $400 difference between the two
I'm running 3.55's with a TKO 600, and with the 2.89 1st, 1st is usable on the street, but you have to roll into the throttle. The T5's are like a 3.27 or 3.35 1st.
T-5 have a 1st gear of 2.95. They have all the ratios at: ddperformance.com
(FYI: The TKO-500 is 3.27. That's what I have with a 3.00 rear, works great in 1st)
just as Gun says thee, check out one of the ratio calculators
25" is on the smaller side of things and 3.8:1 is away from best for highway side of things. You will only know what you crunch all those numbers into a calculator
some people don't mind if engine turns 2000 or 2500 at 60mph but need every bit of accelleration, i'm the other way around.
I like my 3.5:1 with the T5. again, punch the numbers.
Needs to be a calculator that accepts rear end ratio, gearbox ratios and tire size.
__________________
1964 1/2
302ci, Edelbrock RPM heads and cam, 650 speed demon, Long Tube headers and Flowmaster 40s
Quick Performance Racing 9" rear, Moser axles, 3.5:1 trac-loc from FRPP and T5 transmission.
CSRP disc brakes front and FRPP discs back. http://www.gascc.ie
For only 7% difference between the two, you could go either way unless there's some very specific need to be able to use a particular gear at a specific speed.
Since the '66 is one of the lighter-weight years, it's easier to justify 3.55's for that car than it would be for a similarly powered but heavier car.
One of my cars is about at 10 lbs/cubic inch with 25.5" tires, 3.73's and a TR3550 (think light-duty TKO). But before they started shedding teeth, I had 3.27's back there which was entirely acceptable for daily driving and highway (full disclosure - it's an EFI car that does make a bit more midrange torque).
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3.55 or 3.8 gears
