I have a BG Super t10 with ratio's 3:42,2:28,1:46,1:00. Any suggestions for a rear end gear ratio that will be decent on the highway and good light to light. I was thinking about putting in 3:73's, But am concered about my 3:42 first gear being to agressive from light to light. 383 Stroker 400-425hp.

I have a BG Super t10 with ratio's 3:42,2:28,1:46,1:00. Any suggestions for a rear end gear ratio that will be decent on the highway and good light to light. I was thinking about putting in 3:73's, But am concered about my 3:42 first gear being to agressive from light to light. 383 Stroker 400-425hp.
3.31's would probably work well. Depends on how tall your rear tire is.

3:73 .. your RPM's are going to be quite high on the highway with those I think you would be very happy with a 3:55 rear.

The 3.42:1 ST10 has a 17 tooth main drive gear and this is its weak link. You will surely break her with your engine combination!

I have a BG Super t10 with ratio's 3:42,2:28,1:46,1:00. Any suggestions for a rear end gear ratio that will be decent on the highway and good light to light. I was thinking about putting in 3:73's, But am concered about my 3:42 first gear being to agressive from light to light. 383 Stroker 400-425hp.
10:1 is considered optimal for most street engines.
10 divided by 3.42 = 2.92, I would go with the next gear up available, 3.07:1.
3.07 x 3.42 = 10.5:1

10:1 is considered optimal for most street engines.
10 divided by 3.42 = 2.92, I would go with the next gear up available, 3.07:1.
3.07 x 3.42 = 10.5:1

Explain this if you don't mind...I have a 420 HP 350 w/Turbo 350//factory 12 Bolt w/ 3.07 Posi...thanks

10 to 1 OVERALL or effective rearend gear ratio is about optimal for the track so 10/3.42 1st gear ratio = 2.92!

Therefore the next rearend gear set up is the 3.07.

3.07 rearend gear x 3.42 1st gear trans ratio = 10.5 OVERALL or effective rear gear ratio.

And you really need to factor tire height in here too b/c it plays in here too.

Use...

MPH = RPM x Tire Dia. (in inches) / rearend gear ratio x 336.

Set the rearend gear ratio to your tranny's 1st gear and try to hit 10 to 1!

This will help.

pdq67

Explain this if you don't mind...I have a 420 HP 350 w/Turbo 350//factory 12 Bolt w/ 3.07 Posi...thanks


When you start comparing auto to manual its not the same. You have a torque converter that a manual doesnt.

I love my 3:25s with a turbo 350.:D

I love my 5 speed.... and my 3.08 rear. Cruised almost a full tank of gas today, longest time out this year.

Yes, 10:1 overall in first is ideal. With that wide ratio 4 speed, I'd gear her pretty tall.
But.... as Jody pointed out, you might not want to count on this trans as a permanent solution.

Thank you for your help. I have decided to go with the 3:07. I am eventually going to go to a 5 speed. The 3:07 gears will give me enough performance and HWY fuel economy.

Love my 3.73 with 2.66-first T56. 3.73 *2.66 = 9.92. Hmmmm

math works... TKO500 first 3.27 * 3.08 = 10.07 here.
And Todd, don't let nobody tell you a 383 won't pull that gear in overdrive. Mine will pull it down to 1300 rpm / 40 mph...

3.42 or 3.55.. I always here nothing but happy endings with those with that drivetrain your going to run.

I love my 3:25s with a turbo 350.:D

amen, brother!:yes:

I have 4.11 in mine but I want to switch to a 3.73

Thank you for your help. I have decided to go with the 3:07. I am eventually going to go to a 5 speed. The 3:07 gears will give me enough performance and HWY fuel economy.
Thats a good all around choice.
I converted my 396/TH400/3.07 12 bolt coupe to a 5 speed and went with the TKO 500 to get near 10:1 overall with out having to change rear gears.
So far, I am very happy with the gearing.

(any one interested in an old TH400, PM me. Theres no going back!)

I've recently purchased a 67 RS/SS 350 which has a rear end that is not from a Camaro, and frankly I haven't counted teeth yet. The transmission appears to be a Muncie M20 4-speed with a 2.52 first gear ratio. The RPMs are over 3,000 at 65 MPH in 4th gear. Needless to say, it's not a good highway driver, but that is my goal. I need to re-gear the rear end, but am confused as to what to get. after reading this thread and referring to the 10 to 1 ratio, it looks like I need a 3.96. I read somewhere that the stock rear was a 3.55, but I don't know what transmission that was for. Any help would be sincerely appreciated.

Thanks!

If you are not racing, the 10 to 1 "off the line" ratio may be less important to your axle gear selection. You might be happy with something in the 8 or 9 to 1 range.

TX67Camaro,

"The RPMs are over 3,000 at 65 MPH in 4th gear. Needless to say, it's not a good highway driver, but that is my goal."

You forget that our old cars STOCK were meant to run ON THE HWY at 3,050 rpm w/ an M-20, 3.31 and 25.5" tall tires ALL day long!!

Only problem now is GAS MILEAGE!! Sure the heck WON'T hurt our ENGINES!!

Heck, my average speed back then was 80 mph!!

pdq67

I have an M20 with the original 3.08 posi. 60 mph is about 2500 give or take. Tire height about 25". I'm mostly running around town with an annual 4 hr trip to the Dream Cruise and a number of 90 minute jaunts during the summer.

I love the combo, even thought I'm well under the "10" rule. I think the only way I'd change the rear gear is if I went the TKO route.

Right ckaram,

Except my 3.31 reg's will allow my car to run ALL over your's b/c I have similar cars through the years. Bump it up to 3.73's up to 4.11's and I had to play torque motor catch up!

And I did!! He, He!!

My gas mileage was right at 16 to 16.5 mpg w/ the good old -151, 350hp/327 cam when I behaved.

It sucked when I "was in a hurry"! He, He!!

pdq67