TheSamba.com :: View topic - What RPM should I be turning at xx speed?

Thu Mar 18, 2010 7:04 pm

I tried looking up how a '74 Super trans is geared so I can slap it in a calculator found online to tell me how much RPM I'm spinning at xx mph. I want a loose grasp without having a tach. Can't find anything, though. My trans is the original transmission that came with the car, and I can't find the specs on it.

I basically want to know what RPM I'm spinning with 195/60/R15s in the rear at:

15mph in 1st
30mph in 2nd
50mph in 3rd
70mph in 4th.

Thu Mar 18, 2010 8:31 pm

Here's the specs

1st Gear 3.78
2nd Gear 2.06
3rd Gear 1.26
4th Gear 0.93
Final Drive
Ratio 3.875

Thu Mar 18, 2010 8:39 pm

Here's some calculations you can do:

http://www.offroaders.com/info/tech-corner/reading/mph-rpm.htm

Thu Mar 18, 2010 8:41 pm

You can user my calculator:
http://www.glenn-ring.com/tech/tranny_calc.xls

Fri Mar 19, 2010 3:48 pm

i use my tach more than my speedo
im running a stock geared SSP box with 3.88 R&P

in 4th its doing 1900 at 60kmh, 2500 at 80kmh and 2900 at 100kmh

but for those who only know MPH thats 37, 50 and 62

oh yeah and its doing 4800rpm at 170kmh in 4th whatever that is in miles :lol:
havent been game to go any faster than that yet

Fri Mar 19, 2010 6:50 pm

Those figures are a lot higher than I thought they would be! I thought I'd be turning near 5000RPM at 30mph in 2nd because it's screaming, but maybe that's just my exhaust. Unless I have a close ratio trans, which I highly doubt. PO's PO was the original owner and he said it was all original, and the PO was my uncle and I know he didn't change anything.

Thanks guys!

Those numbers in my first post were usually my absolute max shift points, guess I can bring them up a tad if I need to now.

Fri Mar 19, 2010 7:22 pm

Aw hell son it dont matter,just dont beat the hell out yer car if ya want it to last...most collectors with money have a few cars...a fast one,a driver,a show car and mebbe a bus...but one things for sure...it wont last being your fast car and your daily driver unless you got unlimited time and money...enjoy it for what it is and stay within its bounds,ya get style points just for rollin one...