Which gear ratio?

[danbrunk]

Have a 302 and rebuilding front and rear diffs. Plan to go with 31” tires on 16” rims and running a C4 trans. Current ratio is 3.50. Should I stick with or move to 3.73? Will be used for a driver, not a rock climber.

 

[Broncobowsher]

For only 31" tires and never larger, keep the 3.50 gears. There just isn't enough of a change to justify the expense with such little change in ratio.

 

[danbrunk]

For only 31" tires and never larger, keep the 3.50 gears. There just isn't enough of a change to justify the expense with such little change in ratio.

The pinion gears have to be replaced in front anyways so now would be the time to swap. Thanks!!

 

[SteveL]

If you're in there anyways it might be worth throwing in some 3.73s or maybe 3.91.with that said the front carrier may need to be changed at 3.91s. The split is at 3.91 but I'm not sure if they require it or anything taller.

 

[Apogee]

4.11 gears would be about a 500 RPM increase (3300PRM) at 70 MPH versus 3.50 gears (2800 RPM), whereas, 3.73 gears would be about half that at 3000 RPM. I'd be inclined to stick with the 3.54/3.50 gears given the C4 transmission and smallish Ø31" tires so long as the 302 is healthy. If there's any plans to go slightly bigger on the tires to either 32's or 33's, then I would be looking at moving into some 4.11's over the 3.73's myself.

 

[rjrobin2002]

These things aren't made to go 70mph. Gear it for 60mph and do 4.11.

But that's just my opinion.

 

[Speedrdr]

These things aren't made to go 70mph. Gear it for 60mph and do 4.11.

But that's just my opinion.

They go FINE at 70 mph. That’s not a problem. The problem comes with the stopping and steering. . My ‘72 EB got to 85 very quickly…ONCE and only once. Terrifying to get stopped.

Randy

 

[bulletpruf]

4.11 gears would be about a 500 RPM increase (3300PRM) at 70 MPH versus 3.50 gears (2800 RPM), whereas, 3.73 gears would be about half that at 3000 RPM. I'd be inclined to stick with the 3.54/3.50 gears given the C4 transmission and smallish Ø31" tires so long as the 302 is healthy. If there's any plans to go slightly bigger on the tires to either 32's or 33's, then I would be looking at moving into some 4.11's over the 3.73's myself.

Concur with the comment on engine health -- if the engine is healthy, it will have better torque to handle the higher (numerically lower) gears. A crutch for a weaker engine is lower (numerically higher) gears.

Also depends on how you'll use it -- you say it'll be used as a driver, but didn't address highway driving. If you're going to be spending any time on an interstate (i.e., get run over if you're doing under 65) then I'd lean towards keeping the 3.50 gears.

Also agree with the comments about 3.50 versus 3.73. Not enough difference to me; I'd either keep 3.50 or go 4.11.

 

[spap]

Kinda depends where you live too, in southern ca everyone drives 75/80, if your at 60 it would. Be tough, I would stick with 3.50 s
plus you can prob get 3.50 gears used for cheap

 

[Rustytruck]

I would change the gearing the transmission will like you better.