I am installing a T5 transmission in my '32 3 window and would like comments on the best ratio to run in my 9" rearend.
There is currently a thread here on the HAMB ......."optimum gearing....".something... I don't know how to post a link, but a search should find it easily. As of this posting, it is near the beginning, first few pages..........Lots of good info and formulas for calculating the ratio best suited for your application and preferences.
depends on your use of the car, engine, tire height, etc need more info. But usually less gear is better than too much, especially in such a light car. Unless racing, I would err on the side of less to much less than needed. I have a 2.42 gear in my 54 Buick with a 2004R overdrive (.67). I purr in overdrive at 85mph, and can smoke the tires still, thanks to the 455. But your light car will make up for not having a 455 torque monster. What is the engine? Shifting into overdrive is like going into Star Trek warp drive. Also, having a lot of gear makes the car use all the gears all the time, which can be pretty annoying if you drive it a lot. cruiser or race car? wil www.sakowskimotors.com
What do you want it to do, great mileage and high top-end, or awesome hole-shot and a lot of shifting?
Everybody should have a Dream Wheel, or ratio calculator. They're available from speed shops. You put in the tire size, the engine rpm, and the desired speed, and it will tell you what rear end ratio you would need.
here is one i use...just put your ****** ratio in the 'custom' section. i posted this link in the other thread too... http://vexer.com/68rt/speed.html
I have 3.55 gears in my '32 with a flathead and T-10 four speed. It's just right until I get on the freeway and wish I had that "other" gear. So 3.55s are going into the roadster I'm building with a flathead and a T-5 as well. Anyone want to trade a 3.55 pumpkin for a new 4.11 for an 8"?
It's a 274 inch flathead with a T5 transmission with 29" tall tires in a '32 3 window and I want it to be fun around town but be able to drive on the interstate.
I have a roadster with a 286 flatty, not much lighter than your car. I have a 3.89 and a T5. its perfect. once in a while, starting out on level or slightly down hill, I will start out in second. My T5 came from four banger, so first is very low.
That's a great tool and I've used it, thanks to you, but mine is a 5 spped and the link you gave is for a 4 speed. Thanks anyway for the help.
I would go with some higher gears with a flathead . Something in the 3.55 , 3.89 or 4.10 . I tend to run a faster hole shot gear than most do because I want that quick pick up from the stop . If I am just going to use as a cruiser or long trips then 3.55 will do you well . Also depends on your cam too . What cam are you running ? RetroJim
How about a T-5 for the T-10 ? Really the best way would be to have a " Quick Change" rear . Now that's the best of both worlds ! RetroJim
Here's another RPM calculator: http://www.csgnetwork.com/multirpmcalc.html Use the bottom calculator about 3/4s down the page. 4 numbers is all you need. Another thing you need to know is what kind of T-5 you have. There were two ge****ts in the S-10 T-5s, with a .72 5th gear and a .86 5th gear. Flat Ernie's T-5 tech: http://www.jalopyjournal.com/forum/showthread.php?t=171291 This will tell you everything about them and how you can i.d. yours. Example of what I plan on running: 28.58" tire height (Firestone 670 15" bias-plys) 3.78 banjo rear .72 5th gear ('86 S-10 T-5, code# 145) 65 M.P.H. = 2080 R.P.M. My '46 59a Flathead should be happy with that on the freeway.
There are a few different overdrive ratios for the T5, but most are between .62 and .75. In any case, a ratio between 3.70 and 4.11 should do it with your combination. It might also depend on which first gear your trans has. If it is a Mustang setup with 3.35 low, about a 3.90 should do it. If you have an S-10 trans with a 3.60 or lower first gear, 3.50-3.70 might be enough. Shoot for an overall first gear ratio of about 12:1, and a top gear ratio (od * rear gear) of about 2.60-3.00.
I've got an aluminum 3 speed Ford overdrive in my 39 with a 276 in flathead. At 2500 rpm I'm doing 73 mph. 3.70 9" with 225 75R-15 rear tires. Excellent combo. OD is .70.
Yep, 3.55 thru to 4.11 with 3.7/3.89 being optimum, the rest is all about your wheel/tire height and your expectations with respect to gas usage and speed range.
Yep, 3.55 thru to 4.11 with 3.7/3.89 being optimum, the rest is all about your wheel/tire height and your expectations with respect to gas usage and speed range.
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