Gear ratios on federal cars (Type 65)

[Music City Lotus]

My Type 65 revs 6500 at 90mph in 4th with it's original gearbox. Seems quite high even for a federal car. What was the official top speed claim back in the day?

[SwiftDB4]

Contemporary magazine tests ran between 109 mph and 116 mph. Even with smaller diameter tires I can't see your 90 mph. Is your speedometer accurate?

[jbcollier]

That seems off.  All the four speeds have the same final drive and gear ratios.  I have a spread sheet for gear ratio, tire size and speed in gears.  Ping me off list if you would like a copy:

j b c o l l i e r (at) s h a w (dot) c a

I would start by checking the speedo against GPS and the tach against another.  Had a Coventry Climax powered Turner come in complaining of no power.  Tach (mechanical) was reading way, way too high.  Read 6.5K when he was barely turning 3.5K.

[Music City Lotus]

Readings are accurate, against GPS. Tacho is accurate, too. It must be the final drive, because all gears are awfully short. And on the Interstate the thing screams just flowing with traffic.
I think there were shorter final drive gears available? I wonder if a previous owner used it to autocross

[chrisbeck]

I've just posted a spreadsheet for various gearbox options having just bought a second hand diesel Espace 'box for my Special restoration (thanks to you for finding the ratios). Checking the workshop manual, your S2 has the same ratios as my Type 74 4-Speed TC/Special, I don't believe the Federals were different to the domestic models.

[chrisbeck]

I've got a very comprehensive spreadsheet that will give you speed vs. revs for many combinations of transaxle, wheel and tyre. If you pm me with your email address I'll send it to you. A 336 'box with 13" 170/70 tyres should give you nearly 120 mph at 6,500 rpm in 4th.!

[SwiftDB4]

As JB said your speedo or tach have to be way off. To get 90mph at 6500rpm you would have to have a 4.3 or greater final drive. 336 boxes have a 3.56 final drive. As far as I know Renault never made a final drive higher than 3.77. Unless your tire diameter is under 19.5" you wouldn't get that top speed either.  Do you have clutch slip?

[Music City Lotus]

As JB said your speedo or tach have to be way off. To get 90mph at 6500rpm you would have to have a 4.3 or greater final drive. 336 boxes have a 3.56 final drive. As far as I know Renault never made a final drive higher than 3.77. Unless your tire diameter is under 19.5" you wouldn't get that top speed either.  Do you have clutch slip?

No clutch slip. I will check the tacho next with a digital shop tool. But it can't be that much off, because the thing really screams, just from experience with other high revving 4 cylinders. I installed 185/70-13 tires over the weekend, and the larger diameter of those made a difference. With the cops all over the interstates here, I was not able to test rpm vs. speed so far. But as soon as I find a quiet stretch of road...