What are your favorite gears behind a T-5?

scouttrooper · May 8, 2006

I have a 302 that should be good for about 320HP mated with a t-5 with a 2.95 1st and a 0.63 5th gear. I'm thinking 15-16 inch torq thrust II's with some nice meaty tires. I'm trying to decide what rear end gears to go with. My local guru (a mopar fan, but with excellent understanding of mechanics and physics) thinks that 4.10's are the gears to go with. Mustangers are suggesting everything from 3.55's to 4.10's with passion behind their answers. I will not be racing this other than to the grocery store and back, or maybe an occasional 4 hr road trip at 70-85 MPH. What do you, the experts think?

SoCalCruising · May 8, 2006

A "quarter-mile car" needs to be going through the traps at or near peak RPM for that motor's power band. That dictates gears that are 4.xx, depending on red line. If you are more interested in having a good road car, I would suggest 3.50-3.70 gears. I have 3.70s with the same T-5 gears and its fine. Any lower gear would be a waste, IMHO, for how I use the car (not a drag car).

302 coupe · May 8, 2006

I had 3.70's when I used to run a T5, I think it was a great combination.

68restoman · May 8, 2006

I'm running 3.70 gears in my '68 street/track car with a T5. It works well on the street and I can run my local road course using only 3rd and 4th gear...

68Restoman

coolblue65 · May 8, 2006

With you having the 2.98 1st gear, I think 3.70s are a good choice for you, with 3.70s and your trans you would have a 11:1 overall ratio in 1st. I have a Tremec which puts my total 1st gear ratio at 11.45:1 I am very happy with my gearing for my street and occasional trips to the track.

steemin · May 8, 2006

I agree with the previous posts.
Unless you are real serious about drag racing and wish to sacrafice
the street manners of your car don't consider anything more than 3.73's
I love my 3.73's and my G Force T-5.
I have the .59 overdrive in my car.
26" tire 75MPH @ 2000 RPM's.

First gear (2.95)would be worthless with 4.10's.
Remember these cars are also light so they will rev quicker
than your mechanics heavier Mopars
Scott

rbohm · May 9, 2006

a gear between 3.25 and 3.73 is the range i would select from. deeper than 3.73 and you start having to shift into second almost as soon as you launch the car. taller than 3.25 and you tend to lug the engine a bit. my personal recomendation for you is to run 3.50 gears out back. low enough to give you a good launch, and tall enough to give you a low crusing rpm on the freeway.

steel1212 · May 9, 2006

well I love my 4.11s but for a grocery getter I would suggest the 3.50s. I don't spend much time in 1st but then again I try not to spend much time in any and gear for long.

MustangMatt1966 · May 9, 2006

depends on what rear end you have..I have an 8 inch running 3.80 gears behind my t-5 and i love it!!!

SoCalCruising · May 9, 2006

Yeah, good point. What rearend do you have?

Cannoball888 · May 9, 2006

I think the general consensus for a street/occasional strip car is 3.73 for 8.8" and 3.90 for a 9" rear.

HistoricMustang · May 9, 2006

Help me out.

What has the size of rear end got to do with the ratio?

HistoricMustang
www.historicmustang.com/tech.html

SoCalCruising · May 9, 2006

Just the available ratios.

347Fastback · May 9, 2006

I am running 3.89 with 9inch.... works great with t-5z..

MustangMatt1966 · May 9, 2006

HistoricMustang said:
Help me out.

What has the size of rear end got to do with the ratio?

HistoricMustang
www.historicmustang.com/tech.html

yea as socal said, it helps narrow the number of possible ratios dependant on what rear end is used

scouttrooper · May 11, 2006

Thanks, I've tried not to rush to judgement...

...I am certain that I'm not conveying all the details to you. I suspect we are going to put out 320-350HP, but will have a usable torque range of 2000-5500 RPM's. Redline might be 9500 or even 10K. I have acquired an 8 inch rear end but believe I have a nine inch available to me if I need. I should never get close to hurting the 8". And honestly guys, I drive like a bit of a nut. I love to push from light to light. A friend across the street has a mercedes SL 500 with about 400HP and if I cant dust him, I'll be sick. These were included in the perameters given to my building-buddy. I think this is why he leans to 4.10's. I have a feeling that when it's all said and done, I'll end up with something like 3.89's and split the difference. I love the dialogue; you guys are so helpful!

MustangMatt1966 · May 11, 2006

scouttrooper said:
...I am certain that I'm not conveying all the details to you. I suspect we are going to put out 320-350HP, but will have a usable torque range of 2000-5500 RPM's. Redline might be 9500 or even 10K. I have acquired an 8 inch rear end but believe I have a nine inch available to me if I need. I should never get close to hurting the 8". And honestly guys, I drive like a bit of a nut. I love to push from light to light. A friend across the street has a mercedes SL 500 with about 400HP and if I cant dust him, I'll be sick. These were included in the perameters given to my building-buddy. I think this is why he leans to 4.10's. I have a feeling that when it's all said and done, I'll end up with something like 3.89's and split the difference. I love the dialogue; you guys are so helpful!

320-350 h.p at rpm's up to 10,000...for the sake of all of use...use the 9 inch lol keep the 8 for a backup if you break something.....but i dont think i have ever seen a v8 spin to 10,000 other than fully modified drag cars...interesting...

scouttrooper · May 13, 2006

I don't believe I'm exaggerating about the planned engine...

however, I don't think the rpm's will be of any use beyond about 6500. The more I do the math, the more excited I get about this engine. 1st gear, (2.95:1), rear end 4.10:1, tires 26.6" tall (225/50/16)... That means @1500, 9.8 mph and @ 5500, 35.99 mph. In 5th gear, 0.63:1, with the 4.10's, 45.96 mph @1500. won't have much push at all at 1500, but look at 2500 ---76.60mph. And at 5500rpm's a theoretical 168.53mph!! I'll never have that kind of power, but geez guys. Am I calculating incorrectly or what??

SoCalCruising · May 15, 2006

225/50-16 24.9" tall
3250 RPM: 50MPH 4th gear
6500 RPM: 100-110 in 4th - depends on how much the tire "grows" with RPM
5th gear top speed/RPM numbers: meaningless
2600 RPM: 70 MPH in 5th

This is what my spreadsheet tells me. I have to guess about how much the tire grows at speed. Some tires grow more than others.

What are your favorite gears behind a T-5?

scouttrooper

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